She was the goddess of water in Greek mythology. Both Zeus and Poseidon loved her and did their best to win her hand in marriage until Prometheus warned them of a prophecy that her son would become greater than his father. She married a mortal king instead, and dropped their son into the river Styx to make him immortal – holding him by the heel of his foot.
I had exercised patience regarding the time required to recover from a dislodged peroneal tendon, but when the swelling subsided and I could no longer move the tendon around with my finger there was still a hard bump on the back of my heel. Even relatively easy exercise made it sore. It was time to visit the doctor.
My husband and I sat quietly while the doctor examined my heel. As he left to order the x-ray he mumbled something about a pump-bump. My husband immediately took to his phone and by the time the good doctor returned he had discovered everything there was to know about Haglund’s Heel.
Dr. Haglund was a friend of Dr. Roentgen, the inventor of the x-ray. Haglund began researching the boney anatomy of humans for his dear friend, and came up with a fairly common deviation of the heel bone, which became known as Haglund’s Heel (also Hagulund’s Syndrome or Deformity).
This deviation is associated with decreased range of motion of the ankle and increasing age, typically hitting women in their 40s, 50s, and 60s after years of wearing high heel shoes. Jumping, running and navigating stairs can exacerbate the condition making inflammation and heel pain worse. It develops gradually, but we usually take notice when the tendon becomes inflamed. In many cases, especially with runners, Haglund’s Heel evolves into Achilles tendinitis.
Insertional Achilles Tendinitis is a common overuse injury among athletes causing stiffness in the heel especially in the morning, pain along the tendon that increases with activity and possibly swelling. A bone spur gradually develops around the tendon that can cause irritation (bone tends to generate new bone in an attempt to heal itself), and eventually the tendon may calcify and harden.
Note: Insertional Achilles tendinitis affects the back of the heel where the Achilles tendon inserts into the heel bone. Non-insertional Achilles Tendinitis causes pain in the lower calf, where the Achilles tendon and calf muscle meet.
Male and female athletes alike can develop insertional Achilles tendinitis with or without the underlying Haglund’s Heel, but in many cases Haglund’s Heel will trigger or evolve into insertional Achilles tendinitis.
Whyithurts: When a healthy tendon experiences an increased load, it responds by increasing its stiffness to handle the greater demand as it also increases the production of collagen cells. Researchers propose that this non-inflammatory cell response is an attempt by the tendon to increase the cross-sectional area to better handle the load. This short-term adaptation is reversible if the load is diminished or the tendon has a chance to rest before the next stress is applied. Over time a healthy tendon adapts to the stress by growing larger and stronger. An overused or diseased tendon does not recover from the stress and the injury progressively worsens.
Tendinitis is inflammation of the tendon (the suffix “itis” indicates inflammation), in this case of the Achilles. The condition lasts about six weeks although most practitioners view tendinitis as the first in a continuum of tendon injuries that subsequently increase in severity (you’ll also see it spelled tendonitis). If you feel pain in your heel, this is the time to take action.
Tendinosis is a non-inflammatory degeneration of a tendon that can include changes to its structure or composition. These changes often result from repetitive micro-traumas or failure of the tissue to heal and will likely require several months of treatment.
The suffix “pathy” is derived from Greek and indicates a disease or disorder. Tendinopathy is the term also applied to a chronic condition that fails to heal. For example, a runner who has suffered a hamstring tendon rupture that does not heal properly may be diagnosed with tendinopathy.
Insertional Achilles Tendinopathy is inflammation, and later, degeneration of the tendon fibers that insert on the back of the heel bone. Since the Achilles tendon connects the calf’s gastrocnemius and soleus muscles to the calcaneus, or heel bone, by the time you’ve reached the Achilles tendinopathy stage you will likely also notice reduced strength in the calf muscles.
Treatment: The Achilles’ tendon is exposed to greater amounts of strain in the dorsiflexed or upward position where the forward section of the tendon is exposed to low loads. Researchers suggest the lack of stress on this forward aspect of the tendon may cause that section to weaken and eventually fail. The treatment goal of insertional Achilles tendinitis is to strengthen the forward-most aspect of the tendon, which is accomplished through a series of eccentric exercises.
TheAlfredsonProtocol: The story goes that Hakan Alfredson, an orthopedic surgeon and professor of sports medicine in Sweden, developed Achilles tendon problems in the mid-1990s. When his boss refused his request for surgery because the injury was not yet advanced enough, Dr. Alfredson attempted to deliberately aggravate the injury with a series of exercises. Instead of getting worse, however, his injury disappeared.
These exercises, now known as the “Alfredson protocol” are considered the most effective first line of treatment for Achilles tendinopathy. The eccentric movements are designed to physically stimulate the cells in the tendon as they move relative to each other, causing the cells to initiate a tissue repair process.
Stand on your toes at the edge of a step (holding onto something for balance). Slowly lower the injured foot until the heel drops below the edge of the step. Return to the starting position (on your toes) by using the non-injured foot. The injured foot should never be used to raise onto your toes.
Perform 2 sets of 20 reps with the knee straight, which strengthens the gastrocnemius muscle, and another 2 sets of 20 with the knee bent to strengthen the soleus muscle. Repeat the exercises twice daily for 12 weeks. If the effort become too easy, add weight to increase the load.
(The original protocol called for 3 sets of 15 reps with the knee straight and another 3 sets with the knee bent for a total of 180 reps daily.)
Note: as with everything science, there is a corresponding study that found no difference when performing the heel drop using a straight knee only, and performing the exercise from both the straight and bent knee position.
Another study published last year involves a 3-prong approach combining the eccentric exercises mentioned above with compression band therapy, or CBT, and Lacrosse Ball Management (basically massaging the tendon using a lacrosse ball).
LBM: Once daily apply firm but comfortable pressure with the lacrosse ball while rotating the ball over the tendon.
I’ve followed the exercise and massage protocol for 4 weeks (although I will admit that I have performed the flossing motion without the band). After not running one step for several months (because it hurt), I ran three times last week with no pain during or after the run. My results have been similar to the results achieved by the test subject at this same interval in the study. At the study’s nine month follow-up, the test subject was exercising up to nine hours each week with no pain. It would be premature for me to claim victory over this injury, but I am cautiously optimistic.
It’s been almost a year since we began renovations on this little cottage. After it spent several decades in a 1970’s decor, it has been fairly receptive to our suggestions both inside and out. Two new porches and a metal roof were added earlier this year, but it was this summer that the side yard got a total make-over, including a koi pond, stone steps, a raised flower bed, and lots of plants.
September 25, 2017: the side yard day one.
May 1, 2018
We covered a hundred years of roots (and ivy) with mulch instead of grass. I have never planted so many plants straight up in mulch rather than dirt.
July 20, 2018
There was an awkward slope up from the front of the house, and I thought it would be helpful to have a couple of steps.
September 10, 2018
A koi pond fit perfectly in the corner, and we added five goldfish that I’ve worried over every day.
We visited the discount rack at the Lowe’s garden center after lunch most days. If there was a perennial there, we brought it home – most of them just $1 each.
And I convinced my husband to rip off the lower boards of the front porch so we could crawl underneath and dig out the ferns that had been trapped there since the remodel began. Anything for a fern.
The flower bed was my idea for covering a set of concrete steps from a kitchen door that was closed off during the renovations. It was either build over them or take them out, and none of us seemed to want to take on that chore. Lewis did most of the carpentry work during the renovation and all of the stone work. He filled the flower bed with mulch, and I filled it with herbs.
After a year of debating whether to paint the living room paneling, we compromised and painted one wall. Then I played musical chairs with several rooms of drapes back at home so I could move a brighter pair to the cottage, which complements a new rug. The result is a significantly brighter living room.
September 10, 2018
We’ve also swapped out the too-small-queen-size-bed for a beautiful king bed, there’s a new fig tree – barely visible to the far right of the picture below, and plans are in the works for the next phase of construction. . . which will entirely change this little cottage yet again.
This post reviews generic muscle characteristics and how they relate to runners, including muscle contractions, muscle/tendon/ligament injuries and treatment, muscle cramps and remedies, lactate, strength vs mass, slow vs fast, muscle fuel, endurance and loss, flexibility vs inflexibility, stretching and fatigue.
In a future post, we’ll look at how specific training methodologies affect each of these areas for short-, medium- and long-distance runners.
Key points from this post:
Muscle is a result of three factors that overlap: physiological strength (muscle size and responses to training), neurological strength (how strong or weak the brain’s signal telling the muscle to contract), and mechanical strength (the muscle’s force, leverage, joint capabilities).
The most common muscle injuries occur during eccentric loading and usually involve muscles that cross two joints, although the hip abductor muscles are also commonly affected even though they only cross the hip joint.
A stretched tendon can cause muscle spasms, but will typically resolve on its own. Ligament injuries can destabilize the associated joint and require many months, and sometimes surgery, to heal.
Eccentric training, such as downhill running, is the most effective in strengthening muscle and connective tissues, is effective for increasing flexibility, and can increase hip and joint range-of-motion, but is also known for causing muscle soreness (DOMS). Muscle rapidly adapts to the damage caused by eccentric training, however, and protects from the future damage of long distances.
Although the brain is responsible for creating strength (i.e., muscle recruitment), increased size or muscle mass (muscle hypertrophy) happens within the muscle. Following a period of inactivity, it is initially the brain’s ability to excite the muscle that declines in correlation with the muscle’s decrease in strength, rather than a physiological change in muscle size.
Our diets provide three sources of fuel: carbs, fat and protein. The body always uses a combination of carbohydrates and fat for fuel depending on the intensity of exercise. Low intensities use more fat, but by the time you’re gasping for air the proportions have flipped to mostly carbs.
Carb-free diets have become a popular way of encouraging fat burning, but there are trade-offs with this approach.
Lactate is an important source of energy, and is produced in muscles even at rest. The use of lactate as fuel varies with how well a person’s endurance muscle fibers are trained aerobically. Highly trained athletes use lactate more efficiently, which prevents it from accumulating to high levels in the muscle.
Protein is used as an energy source if calories are insufficient, although with sufficient calories, protein contributes only minimally to the total amount of energy used by working muscles.
In addition to strengthening teeth and bone, calcium also helps with muscle contraction. If a person’s diet provides too little calcium or too much phosphorus, their body siphons calcium out of teeth and bones and stops providing it to the muscles.
Exercise-induced muscle cramps have long been misunderstood to be caused by ”dehydration” and “electrolyte depletion” (water-salt imbalance). Muscle injury or muscle damage, resulting from fatiguing exercise causes a reflex ‘‘spasm’’, resulting in a sustained involuntary contraction, or cramp. Stretching is the most effective way to resolve cramps.
We break down and rebuild 1 to 2 percent of our muscle each day, meaning that you completely rebuild yourself every two to three months. The research shows you literally are what you just ate.
Studies show adults ages 50 and up with low muscle strength were more than twice as likely to die in follow-up periods of studies than those with normal muscle strength. Having low muscle mass (vs strength) didn’t seem to matter as much. The best outcomes of all were those adults who met the aerobic and strength-training guidelines: at least 150 minutes of moderate exercise or 75 minutes of vigorous exercise per week and performing a “strength-promoting exercise” at least twice a week.
When running frequency increases past 4 days a week or the intensity of endurance exercise increases above 80% VO2max, endurance exercise prevents the increase in muscle mass and strength typically associated with strength training.
Being inflexible creates greater elastic energy in the stretch shortening cycle. In fact, as much as 40-50% of the energy needed for distance running can be obtained from the elastic ability of skeletal muscle. Being less flexible is not as valuable for sprinters.
Static stretches before running caused a decrease in running distance, increased ground contact time during a 1-mile uphill run, increased muscle activation, and resulted in an approximately 8% decrease in performance.
In women, the variables related with muscle mass are generally 60-75% of the exercise physiology values recorded in men. When measured in terms of strength per square centimeter, however, the female muscle can achieve the same force of contraction as that of a male.
There are THREE TYPES OF MUSCLE in the body: 1) Smooth, involuntary muscles, 2) Cardiac heart muscle, and 3) Skeletal, or voluntary muscles that move the body, arms and legs. This post will focus on Skeletal muscle.
Muscle is a result of THREE FACTORS THAT OVERLAP: physiological strength (muscle size and responses to training), neurological strength (how strong or weak the brain’s signal telling the muscle to contract), and mechanical strength (the muscle’s force, leverage, joint capabilities).
Muscle tissue has THREE CHARACTERISTICS THAT GOVERN EXERCISE:
Contractility – Ability to shorten
Extensibility – Ability to stretch without damage
Elasticity – Ability to return to original shape after extension
The fundamental behavior of skeletal muscle is shortening, which produces joint motion and allows the body to move. Skeletal muscles attach to bones via tendons and often appear in antagonistic pairs, so that when one muscle contracts, the other lengthens.
THREE TYPES OF MUSCLE CONTRACTIONS:
Concentric contractions: muscle shortens, or contracts, pulling on the bone causing the joint to move. A reciprocal muscle on the other side of the joint contracts and shortens to return the joint to its original position. Muscles don’t push joints, they only shorten and pull.
Eccentric contractions: muscle shortens and lengthens at the same time, resulting in a resisting force to decelerate the lengthening movement. By opposing the downward force, a joint is safely repositioned and tissue is protected. Examples of eccentric contractions include walking down stairs, running downhill, lowering weights, and the downward motion of squats, push ups or pull ups.
Note: Eccentric training is effective for increasing flexibility, can increase hip and joint range-of-motion, and has been used as a form of training for several pathological conditions such as Parkinson disease (Dibble et al. 2006), and older cancer survivors (LaStayo et al. 2010),
The last form of muscle contraction is an isometric contraction where the muscle is activated but is held at a constant length rather than lengthened or shortened – there is no movement.
WHY IT HURTS
Muscle injuries commonly occur during eccentric loading of the muscle; that is, when the muscle is contracting while it is also elongating. Muscles that cross two joints, such as the hamstrings (the hip and knee joints), the calf (the knee and ankle joints), and the quadriceps (the hip and knee joints) are the most susceptible to injury. The hip abductor muscles are also commonly affected, though they only cross the hip joint. (Click here to discover more information about specific muscle injuries in other anatomy of a runner posts.)
Although exercises that involve eccentric contractions are the most effective in strengthening muscle, they are also the cause of muscle soreness. All forms of vigorous exercise can become painful, but only eccentric exercise causes delayed onset muscles soreness (DOMS). Muscles are very adaptable to eccentric exercises, however, and rapidly adapt to the damage, resulting in less muscle stiffness or soreness during a second bout of eccentric exercise.
When muscle is initially injured, significant inflammation and swelling occurs. Following the inflammatory phase, muscle begins to heal by regenerating muscle fibers from stem cells that live around the area of injury. However, a significant amount of scar tissue also forms where the muscle was injured. Over time, this scar tissue remodels, but the muscle never fully regenerates. This is thought to make injured muscle more prone to subsequent injury. Other factors that can predispose an athlete to injury include older age, less flexibility, lack of strength in the muscle, and fatigue.
Muscle (and tendon) injuries can be categorized into three grades ranging from mild damage to individual muscle fibers (less than 5%), causing minimal loss of strength and motion, to a complete rupture of the muscle or tendon.
Treatment and Recovery
The majority of acute muscle injuries are partial thickness tears. These can usually be treated successfully with rest, ice, compression, elevation (also known as RICE), and nonsteroidal anti-inflammatory drugs (NSAIDs), such as ibuprofen. This will be done for the first week, followed by progressive functional physical therapy, as needed. A return to full activity is usually possible when you are pain free, and when full range of motion and full strength is restored.
Recovery can be 2-3 weeks for Grade 1 injuries, or 2-3 months for Grade 2. The most severe injuries may require surgery to reattach damaged muscle and tendon. The resulting scar tissue of each injury makes athletes more susceptible to subsequent injuries at the same location.
In a study that examined professional football players with severe hamstring tears with palpable defects, an intramuscular cortisone injection led to a return to full activity time of 7.6 days, and 85% of the players did not miss a single game. However, the use of cortisone injections in the recreational athlete should be reserved for chronic or lingering injuries since there is a chance of weakening the remaining muscle and increasing the severity of the injury.
Several new therapies are in the investigational phase, including platelet-rich plasma (or PRP) which requires blood to be drawn and then spun in a centrifuge to concentrate the platelets and injected into the site of the injury. These platelets contain several growth factors that may stimulate healing and muscle regeneration, and limit the amount of scar tissue that forms. There are currently no reliable scientific studies that show if this therapy works. Antihypertensive medications have been shown to reduce scar tissue formation and improve healing in experimental models.
Tendon & Ligament Injuries
Tendons connect muscle to bone and ligaments connect bones to other bones. Tendons allow muscles to move bones, whereas ligaments stabilize joints. When tendons and ligaments are stretched beyond their basic capacity, they become damaged. For tendons, this can result in tendonitis, which occurs when the tendon becomes torn. This damage causes the tissue of the tendon to inflame while it heals; as a result, tendonitis causes swelling and soreness, as well as temporary loss of muscle function. Ligament injuries weaken the joint and threaten its integrity. A common ligament injury among athletes involves the ACL, or the anterior cruciate ligament in a person’s knee.
A stretched tendon can cause muscle spasms, but will typically resolve on its own. Ligament injuries can destabilize the associated joint and require many months, and sometimes surgery, to heal.
Tendonitis is inflammation of the tendon (the suffix “itis” indicates inflammation). Achilles tendonitis tends to be an acute (or quick-onset) condition lasting 6 weeks or less, although some view this diagnosis as the first in a continuum of tendon injuries that subsequently increase in severity.
Tendinosis is a non-inflammatory degeneration of the tendon which typically occurs from long-term overuse of the tendon leading to weakening of the tendon fibers. Unlike tendonitis, which can often be successfully treated within several weeks, tendinosis can take several months to treat.
Paratenonitis is inflammation of the tissue surrounding the tendon, which may thicken and adhere to the tendon. This diagnosis is controversial, as some practitioners do not believe paratenonitis is a separate condition from tendonitis.
Tendinopathy: The suffix “pathy” is derived from Greek and indicates a disease or disorder, in this case of a tendon. The term is also applied to a chronic condition that fails to heal. For example, a runner who has suffered a hamstring tendon rupture that does not heal properly may be diagnosed with tendinopathy.
SLOW VS FAST
Every muscle contains some combination of three basic types of fibers or motor units: slow twitch, intermediate, and fast twitch.
Slow-twitch fibers (Type I or Red Muscle) – are smaller, develop force slowly, maintain contractions longer, and have higher aerobic capacity that is well suited to long-distance/marathon oriented running. Red fibers are easier to target with exercise. For example, any repetitive, weight-bearing action above your accustomed-level intensity produces red muscle adaptations such as growth and increased endurance.
Fast-twitch fibers (Type IIx or White Muscle) – are larger, capable of developing greater forces, contract faster and have greater anaerobic capacity – better for sprinting or <400m races). White muscle specializes in high-intensity actions lasting fewer than 30 seconds and responds well to heavy resistance training and ballistic exercise such as fast, yet controlled, weightlifting, or plyometric training.
Intermediate fibers (Type IIa) – intermediate in size, speed, power, and susceptibility to fatigue such as those needed for prolonged fast running; the kind demanded for 800m and 1500m races.
Not all runners inherently have the same percentage of each type of muscle fiber. Elite distance runners have high percentages of slow-twitch and intermediate fibers, and as expected, sprinters have more fast-twitch. Since genetics determine our individual percentages, you may find you are more successful in sports that complement your specific muscle configuration. Finding your muscle type can be as simple as defining your preferences: Do you prefer long interval and tempo training (slow-twitch) or short, fast workouts (fast-twitch)? Despite genetic disposition, it has been suggested that training can cause type II fibers to take on the properties of slow-twitch type I fibers. (Specific training considerations will be covered in a future post.)
Muscles are recruited by the brain according to the Size Principle. Muscles with fewer slow-twitch muscle fibers are recruited first and, as more force is demanded by an activity, progressively larger, fast-twitch units are recruited. As the intensity of exercise increases in any muscle, the contribution of fast fibers also increases.
Top athletes in explosive sports like Olympic weightlifting or the high jump appear to have the ability to recruit nearly all of their motor units in a simultaneous or synchronous fashion. In contrast, the firing pattern of endurance athletes becomes more asynchronous. During continuous muscle contractions, some units are firing while others recover.
Initially we might maintain the desired pace/duration with no involvement from fast motor units. As these slow units become fatigued, however, the brain will recruit more motor units in an attempt to maintain pace. Recruiting these additional motor units brings in the fast, but easily fatiguable units. This explains why fatigue is accelerated at the end of a long or intense run.
Lactate is an important source of energy, and is produced in muscles even at rest – something that has been previously misunderstood. Lactate is sent to the brain and heart for fuel, or to active and inactive muscles for energy.
During exercise, we breathe faster to supply more oxygen to working muscles which also clears excess lactate. If exercise intensity increases beyond our ability to supply required oxygen, the muscles continue energy production, but in an anaerobic condition (without oxygen). The muscles produce energy in this anaerobic condition for only one to three minutes, during which time lactate can accumulate to high levels.
The potential for lactate accumulation varies by muscle type with fast-twitch muscles having the highest potential because of their maximum oxygen delivery requirements. “Producer” cells make lactate which is used by “consumer” cells. In muscle tissue, for example, the white, or “fast twitch,” muscle cells convert glycogen and glucose into lactate and excrete it as fuel for neighboring red, or “slow twitch,” muscle cells. Type II muscle fibers are highly glycolytic (they use lots of glucose) which results in the production of high amounts of lactate.
We’ve always associated these high levels of lactate with the burning sensation of muscle fatigue that ultimately causes us to stop exercise – a process that is thought to prevent muscle damage – although lactate may not actually be the cause of the burn. (Continuing research indicates muscle fatigue may be caused by other factors.) Lactate production is a strain response; it’s there to compensate for the metabolic stress of high intensity exercise. The deep breaths we take post-exercise helps clear excess lactate from muscles and restores balance.
The use of lactate as fuel within the muscle varies with how well a person’s endurance muscle fibers are trained aerobically. Highly trained athletes use lactate more efficiently as energy preventing it from accumulating to high levels. Conditioning in sports is all about getting the body to produce a larger mitochondrial reticulum in cells to use the lactate and thus perform better.
The muscles of untrained athletes, and also bodybuilders, produce energy without oxygen; a condition that produces high lactate levels in the muscles. At the same time, muscles begin to fatigue and the muscles feel “heavy”. This is considered an anaerobic training process (without oxygen) as compared to marathon training, for example, which is an aerobic (with oxygen) process.
Endurance training changes the metabolism of muscles by stimulating the production of a protein, PGC-1a. Trained mice that developed a high PGC-1a maintained their performance levels, and their lactate levels remained low despite a high training load. Endurance training programs, such as for the marathon, reduces the formation of lactate, while the remaining lactate in the muscle is converted and used immediately as energy substrate.
The energy drink, Cytomax, is based on research that indicates lactate is the body’s primary fuel. The combination of lactate, glucose, and fructose takes advantage of the different ways the body uses fuel: lactate can get into the blood twice as fast as glucose – peaking in just 15 compared to 30 minutes after drinking. Most sports drinks contain only glucose and fructose. (This reference is not an endorsement of the Cytomax product.)
1) High lactate levels are also seen in the blood during illness or after injury, such as severe head trauma, and are a key part of the body’s repair process. Lactate is now being used to help control blood sugar after injury, to treat inflammation and swelling, for resuscitation in pancreatitis, hepatitis and dengue infection, to fuel the heart after myocardial infarction and to manage sepsis.
2) Disturbances in lactate metabolism are common in obese and diabetic patients. The stimulation of PGC-1α achieved by endurance exercise means endurance training can be an effective approach to improve the metabolism of these groups, and could help prevent the resulting damage and progressive physical limitations caused by metabolic diseases.
POST EXERCISE OXYGEN DEBT
After exercise has stopped, extra oxygen is required to metabolize lactic acid and to replace (“pay back”) any oxygen that has been borrowed from other parts of the body. This debt is paid by labored breathing that continues after exercise has stopped. Highly trained athletes are capable of greater muscular activity without increasing their lactic acid production and have lower oxygen debts, which is why they do not become short of breath as readily as untrained individuals. Eventually, muscle glycogen must also be restored. Restoration of muscle glycogen is accomplished through diet and may take several days, depending on the intensity of exercise.
EXERCISE INDUCED MUSCLE CRAMPS (EAMC)
There are two theories about the origin of EAMC. The older one is the “dehydration” and “electrolyte depletion” theory (water-salt balance), while the more recent one is the “altered neuromuscular control” theory, or a sustained, involuntary muscle contraction brought on by muscle fatigue. In 1904, muscle spasms (cramps) were reported for the first time in two men at the Episcopal Hospital and were presented as a new disorder due to exposure to intense heat, which gave us the term “heat cramps”. Except, we’ve since learned that EAMC occurs in hot conditions, moderate to cool temperatures and in extreme cold. Also, multiple studies of endurance athletes, marathoners and triathletes have shown no evidence of low salt levels or electrolyte imbalances after cramping during a race (Schwellnus et al, 2004; Sulzer et al, 2005; Schwellnus et al, 2007).
One of the first studies showing that fatiguing muscle can develop cramping in normal healthy subjects during exercise was reported in 1957, but it wasn’t until 1997 that muscle fatigue was credited as the predecessor to EAMC. Click here to read the technical details behind this theory (Part III of a 5-part series on the history of EAMC studies) or here to read the full study.
A previous history of EAMC and a positive family history of cramping are also considered risk factors for EAMC. Muscle injury or muscle damage, resulting from fatiguing exercise, are thought to cause a reflex ‘‘spasm’’, and thereby result in a sustained involuntary contraction, or cramp.
Prevention & Recovery
Prevention of EAMC primarily is use of dietary supplements and kinesio taping, massage therapy, corrective exercises that will lead to the improvement of the function of a particular group of muscles or the biomechanics of the organism itself, although stretching exercises are said to be the most effective. Post-isometric relaxation techniques, plyometric or eccentric muscle strengthening programs have also proven effective. Mustard and pickle juice are listed as the nutritional form of EAMC prevention.
Note: non-exercise related cramps include rest cramps (also known as nocturnal cramps). These may be more prevalent in older adults, but can occur at any age. Rest cramps are started by making a development that abbreviates the muscle; for example, pointing the toe downward while lying in bed, which shortens/abbreviates the calf muscle, resulting in cramping of the muscle. Rest cramps can also occur in other areas, such as the arches of the feet or abdominal muscles.
STRENGTH VS MASS
Strength: People generate more strength if they can recruit and fire 50,000 muscle fibers than if they can only recruit 25,000 fibers. Muscle recruitment is controlled by the brain, and initial improvements are achieved because the brain gets more efficient at communicating with the muscles, using more of them, and using them more efficiently. In fact, muscle recruitment is the mechanism that allows us to gain strength before our muscles even increase in size. It is only through practice, or training, that the brain improves muscle recruitment.
Mass: Although the brain is responsible for creating strength (i.e., muscle recruitment), increased size or muscle mass (muscle hypertrophy) happens within the muscle. Microscopic damage (microtears) occurs in the muscle fiber during strengthening activities, which stimulates the body’s repair response to repair the damage. This repair response causes the muscle fibres to enlarge or swell, ultimately increasing their volume and size. Once running frequency increases past 4 days a week or the intensity of endurance exercise increases above 80% VO2max, however, endurance exercise prevents the increase in muscle mass and strength that typically occurs with strength training.
Note: Even with the greater muscle mass typically found in short distance runners, a sprinter cannot win a marathon. A sprinter’s specially-trained and strengthened muscles will fatigue faster than the endurance-trained muscles of a long distance runner. The research group of Prof. Christoph Handschin of the Biozentrum, University of Basel, shows that during endurance exercise the protein PGC-1α shifts the metabolic profile in the muscle.
The three basic fuel options are carbohydrate, fat and protein.
Fat is the preferred fuel for light-intensity to moderate-intensity exercise, such as slow running or hiking, cycling, and recreational swimming. However, the body always uses a combination of carbohydrates and fat depending on the intensity of exercise. Low intensities use more fat, but by the time you’re gasping for air, the proportions have flipped to mostly carbs.
Endurance (low-intensity) training teaches the body to preserve glucose and utilize more fat as fuel, but you’ll burn the same fat-carb mix at any given relative intensity. One study found that marathoners running a 2:45 pace relied on 97 percent carbohydrate fuel, while slowing to a 3:45 pace reduced the carb mix to 68 percent.
It is now believed that lactate is produced in healthy, well-oxygenated muscle and is preferentially used for energy throughout the body. In fact, about 30 percent of all glucose we use during exercise is derived from lactate “recycling” to glucose.
Carbohydrate-free diets have become popular in recent years to encourage the body to burn predominantly fat as fuel. Studies show it takes several weeks for the body to adjust to a mostly carb-free diet and that any benefits in terms of performance are mixed. In exchange for their enhanced ability to burn fat, a study of cyclists seemed to lose their ability to harness quick-burning carbohydrate for short sprints resulting in “a severe restriction on the ability of subjects to do anaerobic work.”
The conclusion among researchers is that high-fat (carb-free) diets don’t just ramp up fat burning; they actually throttle carbohydrate usage by decreasing the activity of a key enzyme called pyruvate dehydrogenase. This may or may not matter depending on your running goals. Fat burning is ideal for long distances that never require speed. Racing, on the other hand, may be enhanced by having carbohydrates in reserve for that end spurt, or for more intensive training sessions.
Protein is used as an energy source if calories are insufficient, although with sufficient calories, protein contributes only minimally to the total amount of energy used by working muscles. When a person begins a moderate endurance exercise program, they initially lose more protein than they ingest. This corrects itself within 2–3 weeks without dietary intervention. To increase muscle size and increase strength, however, athletes must ingest more protein than is lost. On the other hand, ingesting too much protein can result in dehydration, loss of urinary calcium, and will put stress on the kidneys and liver.
Luc van Loon, Professor at Maastricht University in the Netherlands, and his colleagues developed a technique to track protein as it progressed from a person’s mouth to their biceps in the hours following a meal. Just over 50 percent of the protein made it into the subjects’ circulation within five hours (the remaining protein was presumably taken up by tissues in the gut or not absorbed.) During the same period, 11 percent of the ingested protein was incorporated into new muscle. Literally, you are what you just ate. Overall, van Loon points out, we break down and rebuild 1 to 2 percent of our muscle each day, meaning that you completely rebuild yourself every two to three months.
Calcium is predominantly used by the body to strengthen teeth and bones, but also helps with muscle contraction. If a person’s diet provides too little calcium or too much phosphorus, their body siphons calcium out of teeth and bones and stops providing it to the muscles. Cola based soft drinks and some junk foods are high in phosphorous, unduly increasing the body’s need for calcium.
Fun Fact: studies in the 1960s found that people who retained more of their own teeth tended to have more muscle.
Our ability to engage in physical activity for long periods of time is thanks to efficient energy production in the mitochondria—the small “powerhouses” of our muscles. Endurance training increases the number of mitochondria and their structure, and the more we have, the longer we can exert ourselves. Endurance athletes have more than twice as many mitochondria that generate about 25% more energy as non-athletes.
During a two-week period following inactivity, it is the brain’s ability to excite the muscle that declines in correlation with the muscle’s decrease in strength, rather than a physiological change in muscle size. Getting older is another factor that causes changes within the muscle since muscles are less sensitive to protein signaling as we age. Studies show adults ages 50 and up with low muscle strength were more than twice as likely to die in follow-up periods of studies than those with normal muscle strength. Having low muscle mass (vs strength) didn’t seem to matter as much.
A similar study of 80,000 adults found those doing any strength training were 23% less likely to die and 31% less likely to die of cancer. The best outcomes of all – a 29% reduction in mortality risk – were those adults who met the aerobic and strength-training guidelines (at least 150 minutes of moderate exercise or 75 minutes of vigorous exercise per week and performing a “strength-promoting exercise” at least twice a week).
Note: A recent study led by researchers at Keele University has shown for the first time that periods of skeletal muscle growth are ‘remembered’ by the genes in the muscle, helping them to grow larger later in life.
Long-term observations of runners have shown improvements in running economy when the athletes are less flexible – being inflexible creates greater elastic energy in the stretch shortening cycle. In fact, as much as 40-50% of the energy needed for distance running can be obtained from the elastic ability of skeletal muscle. One of the reasons plyometric and resistance training improves running economy is due to an increase in muscle stiffness. Imagine a ball bouncing off a wall – if it gets softer, it bounces off more slowly, whereas a stiff ball returns quickly (golf ball vs squash ball, for example).
Being less flexible does not appear to be as advantageous in shorter distances, sprinting, or the long jump. A sprinter (i.e., events <800 m), for example, requires a greater range of motion at the hip that benefits from more flexibility as compared with a long-distance runner (i.e., events >800 m).
The sit and reach test is a common measure of flexibility, and specifically measures the flexibility of the lower back and hamstring muscles.
Researchers have sought to determine whether acute bouts of static stretching before exercise would affect running economy. (Static stretches hold a stretched or elongated position for 15 seconds or more.) Findings show runners who performed these stretches before running caused a decrease in running distance, increased ground contact time during a 1-mile uphill run, increased muscle activation, and resulted in an approximately 8% decrease in performance.
Stretching, considered an exercise, also fatigued the muscle resulting in more muscular recruitment to perform a given task. Considering that one of the adaptations to endurance training is asynchronous recruitment of the musculature, having to recruit more muscle fibers per given intensity would be counterproductive to performance for distance running.
Static stretching is helpful to increase range of motion or improve flexibility and is a useful component of an overall training program depending on your sport (i.e., for sprinters and short distance runners). If you feel a need to stretch before running, dynamic stretches use controlled movements that can make muscles more limber while also activating major muscle groups.
Fatigue was defined in a previous post as peripheral (within the muscles) or central (within the brain and spinal cord). Although fatigue produces the belief that our resources are limited, exercise generally ceases before all the muscle fibers have been activated. In fact, just 35-50% of active muscle mass is recruited during prolonged exercise. Read more here.
Limited studies show that women appear to be more resistant to fatigue than men during long efforts. A study that was published in the journal Medicine and Science in Sports and Exercise measured fatiguability of subjects completing an isometric arm contraction. Women were able to perform the task until failure almost three times longer than men, 23.5 minutes versus 8.5.
One difference between the sexes is that women have a greater number of fatigue-resistant fibers (Type I) while men have more faster-contracting fibers. Secondly, men have larger muscles that demand more blood, which makes their hearts work harder. Female endurance athletes also have a metabolic edge in moderate-intensity aerobic exercise by deriving more of their energy from fat as compared with males. In women, the variables related with muscle mass are generally 60-75% of the exercise physiology values recorded in men. When measured in terms of strength per square centimeter, however, the female muscle can achieve the same force of contraction as that of a male.
Note: Muscle fatigue is usually resolved within hours, while muscle damage can impair force generation for up to 7 days.
THE TRAINING EFFECT
Skeletal muscle has three basic performance parameters that describe its function: 1) Movement production (speed), 2) Force production (strength), and 3) Endurance. Increasing muscular strength will increase muscular power, which is the product of force (strength) and speed.
Athletic performance is ultimately limited by the amount of force and power that can be produced and sustained. The theories behind the various components of a running training program will be discussed in the next anatomy of a runner post.
American College of Sports Medicine position stand. Progression models in resistance training for healthy adults. Keele University. “Study proves ‘muscle memory’ exists at a DNA level.” ScienceDaily. ScienceDaily, 30 January 2018.
The topic of the next anatomy of a runner post is muscle. It’s not that we haven’t covered various muscles in previous posts, but their generic characteristics are fascinating as it relates to running and seem to warrant a separate conversation. After all, the brain and muscle are the most malleable of all the anatomical components. In other words, they can be trained.
The purpose of the paper is to illustrate the link between an athlete’s physiology and success in distance running. “The maximal oxygen (O2) uptake, O2 cost of running at sub-maximal speeds (running economy), and blood lactate response to exercise can all be determined using standard physiology laboratory exercise tests and the results used to track changes in ‘fitness’ and to make recommendations for future training,” Jones writes in the introduction.
Once or twice a year Radcliffe was given a physiological assessment that measured height, body mass, body composition (through skinfold thicknesses), haemoglobin concentration ([Hb]), pulmonary function, vertical jump height, a sit-and-reach test, and a multi-stage incremental treadmill test. The resulting data from these tests demonstrate how 15 years of directed training created the ‘complete’ female distance runner and a World champion.
Radcliffe committed herself to many years of hard training and used these yearly assessments to objectively analyze her progress and to inform her training. The data also accurately predicted actual finishing race times within 0.2-0.4% over a variety of distances.
Training consisted of “steady” continuous running, tempo runs, 1-2 higher intensity sessions at 95-100% V’02 max, interval or repetition sessions at the track or cross-country, and two weight training sessions weekly. Total mileage increased considerably over her career from less than 25-30 miles initially to 120-160 miles per week during full marathon training in the final years.
It’s difficult to pinpoint one thing that specifically creates an exceptional athlete although running economy, or enhanced exercise economy, is considered by many to be a critical component of success. Running economy is defined as the oxygen (O2) cost of running at a certain speed, or the O2 cost of running a certain distance. The more efficient we become the less oxygen we use, which means we can run further or faster with the same effort.
Radcliffe’s data demonstrate a 15% improvement in running economy between 1992 and 2003 suggesting that improvements in this parameter are very important in allowing a distance runner to continue to improve their performance over the longer-term.
There is evidence that explosive strength training can improve running economy. Studies of runners that participated in strength training decreased their running pace by 4% as compared to runners who did no strengthening exercises even though there were no significant changes in their maximum aerobic capacity, blood lactate accumulation, body mass, or body fat percentage. This is an important finding because it suggests that the improvements in running economy come from a mechanism other than cardiovascular or metabolic changes. A possible explanation is enhanced mechanical efficiency and muscle recruitment patterns – both of which are a result of the neuromuscular adaptations achieved from strength training.
As Radcliffe’s weight training program became more sophisticated her leg strength and power improved. Her vertical jump test performance improved from 29 cm in 1996 to 38 cm in 2003 while lower body “flexibility” declined slightly. This corresponds to a suggestion that “stiffer” muscle-tendon structures might improve running economy by allowing a greater storage and return of elastic energy (something we’ll pursue further in the upcoming post).
Exercise economy is influenced by a wide variety of factors so it’s not easy to say this or that is directly responsible for the improved running economy experienced by Radcliffe over her career.
One suggested explanation offered by Jones is that our type I (slow-twitch) muscle fibres are more efficient than type II (fast-twitch) muscle fibres; that is, compared to type II fibres, type I fibres consume less O2 for a given amount of muscle work, and if endurance training causes a reduction in type II fibres being recruited, this would reduce the cost of O2 and, therefore, improve running economy. Alternative studies also suggest that, with chronic endurance training, type II fibres take on some of the same properties of type I fibres, or that this same training results in a transformation of type II fibres into type I fibres.
You might ask, do we care? Depending on your running goals, the answer would be yes since the type and quantity of training causes a definitive change to the muscle structure and can affect performance across the spectrum of distances.
The distinction is made in this paper that while a high V ̇O2 max is a prerequisite for success at the highest levels of elite runners, and Paula Radcliffe certainly had this, factors such as running economy and a delayed accumulation of lactate in the blood are also important and can be positively affected by our training.
Mr. Jones concluded the paper by saying,
“Study of the great human athletes therefore continues to provide insights into the ultimate limits to exercise performance. Through determination, commitment, and consistently hard training, PR has achieved her athletic potential and become one of the greatest endurance athletes of all time. I have been greatly honoured to have been associated with her.”
The upcoming post about muscle will include a behind-the-scenes kind of look at the types of training that create the most improvements for runners, strength vs mass, slow vs fast, elastic energy or active stretch, fatigue and endurance.
There would be no fartlek through the woods. No peaceful run down the mountain, and definitely none of those mind-numbing sprints around the track. In fact, there may be no substantive running at all this year. It’s shocking to the core.
If you’ve ever talked at length to a runner, chances are the discussion evolved into the topic of injuries. There’s not a single memory of an injury from the nearly 20 years of competitive tennis in my earlier years, but I can’t even put a number to all the running injuries.
You’d think it would be discouraging, but it’s not. The goal is to avoid injury, somewhat like the goal is to avoid misjudging your arrival at the airport and never miss a flight. It still happens sometimes.
This latest injury happened within the first two steps of a run when I heard a loud pop. It’s curious that I heard the pop despite music blasting into my ears, which I’ve later realized is because the pop came from inside my body. The peroneal tendon of my right foot had moved out of its groove. If it moved all the way across the ankle bone and snapped back, it‘s called Peroneal Tendon Subluxation. Treatment seems to be the same nonetheless. REST.
One authority on the subject claims this injury is one of the few running injuries that’s not a consequence of overuse. They correctly observe that some athletes experience this ailment even when we’ve followed all the proper training rules. The alternative label appears to be “repetitive use with biomechanical dysfunction” because those of us with high arches that also run excessively are more prone than others to succumb to its ill fate.
Initially it hurt to do everything. The back of my heel was swollen, the tendon was tender to the touch, and would move around slightly. It was during these early weeks that it hurt to walk, run, or even ride my bike. Some weeks I did nothing at all. It was depressing, frustrating, and every other aggravating ‘-ing’ word imaginable.
My husband told me one day that I needed to get out there and do something to exhaustion. We found a new bike route and I went for a long ride. There were the steepest hills I’ve ever climbed, nail-biting descents, and the hairiest of all hair-pin turns. I used every gear in my arsenal that day. It was exhausting.
I’ve learned something. I love running so much.
I love the long runs, and the total exhaustion that comes from a grueling race. I simply adore the daily routine of charging up my watch and following a training plan. I miss all those things that runners learn to endure over years of practice.
The advice I’d want to give to every new runner is to stick with it. It gets better. It doesn’t always hurt. Focus on training your mind, and some day you’ll be pleasantly surprised that you’ve actually enjoyed yourself.
Exactly the conversation I’ve finally had with myself about doing every other exercise besides running.
For more information about a peroneal tendon injury or the dreaded subluxation, click on one of the articles below.
We’ve lived life in 975 square feet for about four months. I expected to give cottage life a definitive thumbs up or down within the first few weeks, but surprised myself when I couldn’t muster a decision. My husband was decisive early on, but only because he didn’t want to move again. So it’s up to me I guess to tell the truth.
There’s not a level floor-wall-door-surface in all 975 square feet. In past years that would have made me nuts. Maybe it’s age, or acceptance, but I actually coached the workers to hang some of the doors out of level so they appeared level to the eye. We’ve done the same thing to shelves, pictures, mirrors. . . you name it. I hardly notice anymore.
The size of the rooms were an adjustment, but there’s a full stop choke point in the center hallway. It’s bad enough if my husband and I happen to be there at the same time, but add Mr. Boggs to the mix and it’s a total impasse.
I guess we’d both agree it’s the bedroom, or more specifically the bed that was the biggest change. Having spent decades in king quarters, a queen’s bed is just shy of enough, especially when one of us is in the middle of menopause. Of course, we’d be fine if not for Bentley (the dog). There’s not enough muscle in the world to move a dog that doesn’t want to move over – no matter how small he may be.
Our long-term plan is to add a garage, a guest suite, and a proper driveway. We want to paint the dark wood in the living room, upgrade the refrigerator, and bring over our own furniture, including my piano. Every day I debated whether to trade the baby grand piano for an upright so we’d have room for a dining table, or forego a dining table altogether. It was a brutal decision.
This was the only room in the cottage that could hold my piano, or a dining table. That’s Bentley in the center hall above, and Mr. Boggs in the picture below.
There’s lots of things that make this little cottage wonderful. It’s cozy, and full of character. When you settle in for the night, or wake up in the morning, it’s almost cocooning. Cleaning is a breeze instead of a chore, and there’s some amount of time spent every day rocking on the front porch. Folks walk by and stop to say hello. They tell us what a transformation the little place has gone through, or how they grew up with the original owner’s kids. And we won’t forget, it sits beside a native garden. It’s like walking into another world.
Then summer arrived.
Lake Junaluska is a beautiful resort that comes to life in the summer. The lake is at the end of our street where there’s canoeing and kayaking, a 3-mile trail around the lake, a gym, fishing, tennis, swimming pool, shuffle board, mini-golf, ice cream stand, coffee shop, a playground for the kids, and a labyrinth for contemplation. Once a week there’s a community bonfire, an outdoor movie, and concerts.
The 4th of July parade shut down Lake Shore Drive followed by a picnic for just $5, and fireworks after dark. There’s half a dozen gardens throughout the resort with guided tours every Tuesday. Bands played in front of the gardens on the 3rd of July tours. Forty-nine people toured the native garden next door to our cottage that day.
I went back to our larger home one morning to water the plants. It was quiet and peaceful. The neighbors are separated bynearly an acre of land. There’s no pending construction, no further renovations, all the furniture is in its rightful place. There’s room for my piano, and a dining table.
I realized I couldn’t bear the thought of living through the construction, and the little cottage couldn’t be perfect without it. I wasn’t sure about the crowds, or whether the entire neighborhood would hear me play the piano, and every wrong note that might ensue.
We moved back home a couple of weeks ago.
I wrote in a previous post that this little cottage has tormented me every day since we met. The torment continues. My husband was ready to live out his days there, “snug as a bug” as he would say. In the end, I was the one that panicked.
When we were settled back comfortably in our larger home, he (once again) declared he would never move again.
THE BRAIN is what makes us human. It gives us the capacity to make decisions, produce rational thoughts, or spectacular works of art. It’s responsible for our personality, storing the memories we cherish, and how we view the world. It also governs our ability to speak, eat, breathe, and move.
Disciplined, smart training is the foundation of any athletic endeavor, and proper training is also what earns us a seat at the table of endurance. Some athletes have genetic endowments and natural advantages that predispose them to sports. Maybe they respond better to training, the shape of their bodies or the genes they carry make them specifically optimized for certain athletic endeavors. Another subset of great athletes also have cultural and environmental advantages, such as the Kenyans who spend a lifetime being active at altitude. Then there are great athletes who have none of these advantages – the only common denominator between all groups of athletes being the brain.
The question of this post is not what can the human body do, but rather, what more can the human mind add to that?
The 1922 Nobel Prize in Physiology or Medicine winner, Archibald Hill, proposed in 1924 that the heart was protected from anoxia (absence of oxygen resulting in permanent damage) in strenuous exercise by the existence of a governor. Dr. Timothy Noakes, a professor of exercise and sports science at the University of Cape Town, re-introduced Hill’s governor model in 1997 on the basis of modern research. The essence of Noakes’ original central governor theory is that the brain monitors activity, predicting outcomes, and involuntarily implements an appropriate pace that prevents total exhaustion and permanent bodily damage by creating the distressing sensations we interpret as fatigue.
Physiological catastrophes can and do occur in athletes, however, that present conflicts in the governor theory. A story from the 2015 Austin Marathon serves as one example from many.
Kenyan runner, Hyvon Ngetich, had been leading most of the race. With two-tenths of a mile left to run, she began to wobble and stagger, and eventually fell down. After failed attempts to get up, Ngetich crawled to the finish line leaving her knees and elbows bloodied and hands stained from the pavement. Ngetich crossed the finish line in third place with a time of 3:04:02, and was immediately treated for dangerously low blood sugar. In a post-race interview with CNN, she said she didn’t remember finishing the race. She had continued the race despite the distressing sensations of fatigue and debilitating physiological failure.
Over time the central governor theory has been revised to include the role of psychological and motivational factors, which is where we begin to uncover the story of endurance.
muscular endurance: the ability of a muscle or group of muscles to repeatedly develop or maintain force without fatiguing.
cardiorespiratory endurance: the ability of the cardiovascular and respiratory systems to deliver blood and oxygen to working muscles, which in turn enables the working muscles to perform continuous exercise. It is an indicator of a person’s aerobic or cardiovascular fitness.
athletic endurance is defined as the ability to continue an activity despite increasing physical or psychological stress, as in the effort to perform additional numbers of muscle contractions before the onset of fatigue.
The human brain weighs about 3 pounds (1.4 kilograms). The surface area is 233-465 square inches (1500-2000 cm2), or roughly the size of one to two pages of newspaper. If we flattened the brain’s 1/4 inch thick outer layer, it would cover the size of an office desk. But to keep the brain compact enough to fit into our skull, it folds in on itself.
The simplest commands of the brain are monosynaptic (single connection), like the knee-jerk reflex. The knee-jerk response is a muscular jerk that happens quickly and does not involve the brain. There are lots of these hardwired reflexes, but as tasks become more complex, the circuitry involved is more complicated, and the brain gets involved.
The cerebellum, “little brain”, consists of both grey and white matter, and is responsible for coordinating muscle movement and controlling balance by transmitting information to the spinal cord and other parts of the brain. The cerebellum is constantly receiving updates about the body’s position and movement. It also sends instructions to our muscles that adjust our posture and keeps our body moving smoothly.
The cerebrum is the largest part of the human brain, controlling memory, movement, speech, emotions, and voluntary motor activities. With the assistance of the cerebellum, the cerebrum controls all voluntary actions in the body. Voluntary actions include running, clapping your hands, or lifting weights – things you are consciously doing.
The cerebral cortex is the outer layer of the cerebrum and consists of gray matter. This is where our conscious thoughts and actions take place; many of the signals our brain receives from our senses are registered in the cerebral cortex.
Basic life functions, such as heart rate, breathing, and blood pressure, is carried out by the brain stem. It regulates whether we feel tired or awake, as well as coughing, sneezing, and swallowing. The brain stem is the body’s “autopilot”.
About the size of a pearl at the base of the brain, the hypothalamus regulates physiological processes, such as blood pressure, heart rate, body temperature, cardiovascular system function, fluid balance, and electrolyte balance. This portion of the brain plays a vital role in maintaining homeostasis: the process of maintaining the body’s equilibrium by monitoring and adjusting physiological processes. It also influences emotional responses, sleep, appetite, and tells the skin to produce sweat when it’s hot to keep you cool.
The hippocampus (HC) region of the brain deals with the formation of long-term memories and spatial navigation. In diseases such as Alzheimer’s, the hippocampus is one of the first regions of the brain to become damaged, which leads to memory loss and disorientation.
The atrophy rate of the hippocampus (HC) is shown to be 2-3% per decade (Raz et al., 2004, 2005), and further accelerated to an annual loss of 1% over the age of 70 (Jack et al., 1998). Recent research, however, has shown the HC is among a few regions of the brain that generate new neurons.
In particular, exercise causes hippocampal neurons to pump out a protein called brain-derived neurotrophic factor (BDNF), which promotes the growth of new neurons. Higher cardiorespiratory fitness levels (VO2 max) are associated with larger hippocampal volumes in late adulthood, and larger hippocampal volumes may, in turn, contribute to better memory function (Erickson et al., 2011; Szabo et al., 2011; Bugg et al., 2012; Maass et al., 2015). (22)
Running Fact:A study published in the Journal of Neurobiology of Learning and Memory finds that running mitigates the negative impacts chronic stress has on the hippocampus region of the brain. “Exercise is a simple and cost-effective way to eliminate the negative impacts on memory of chronic stress,” according to the study’s senior author, Jeff Edwards, associate professor of physiology and developmental biology at BYU.
THE PERSONALITY OF A RUNNER
Observational studies have identified common personality traits among runners, including a strong vision, focus and resilience. Runners consistently exhibit mental toughness, an extraordinary capacity to plan ahead, and the ability to handle unexpected problems with a calm yet competitive demeanor; we are more willing to accept feedback, and acknowledge our mistakes.
Imaging of a runner’s brain show connections in areas required for higher-level thought, including more connectivity between parts of the brain that aid in working memory, multi-tasking, attention, decision-making, and the processing of visual and sensory information. Less activity is noted in a part of the runner’s brain that tends to indicate lack of focus and mind wandering. (24)
A 2009 study found ultra-marathoners were less dependent on rewards (self-motivated), they were more individualistic, and, not surprisingly, exhibited a far greater tolerance for pain. Studies of older runners show them to be more intelligent than their non-running peers, more imaginative, self-sufficient, reserved, and forthright.
The most common trait among runners of all ages is the belief that they possess the resources needed to achieve their own success. (13) (14)
Running Fact: An abstract presented at the 2018 American College of Sports Medicine Conference indicate runners who exhibit ”perfectionist” tendencies were 17 times more likely to suffer an injury that forced them to miss training as compared to other runners.
When we exercise, the brain recognizes this as a moment of stress, and invokes a “fight or flight” response. The body’s protection mechanism to this new threat is to release the BDNF protein in the brain. The greater the exercise intensity, the more BDNF proteins are released. At the same time, endorphins, another stress-reducing chemical, is released in the brain. The main purpose of the endorphins is to minimize discomfort and block the feeling of pain, sometimes also associated with a feeling of euphoria.
As exercise continues, physiological changes are signaled to the brain, such as body and skin temperature, increased heart and breathing rates. These signals are interpreted by the brain and compared with previous experience to determine allocation of resources.
The brain begins to change as soon as the athlete begins a sport, and the changes continue for years. In just one week, athletes develop extra gray matter, and different regions of the brain begin to interact – some neurons strengthen their connections to other neurons as they weaken their connections to others.
After deciding on a specific goal, to run a fast lap around the track for example, several regions of the brain collaborate to determine the best course of action to complete that goal. Initially, neurons in the front of the brain (the prefrontal cortex) are active; a region vital for the top-down control that enables us to focus on a task and consider a range of responses. By predicting what sensations should come back from the body if it achieves the goal, the brain can match the actual sensations received and revise its plan if needed to reduce error. With practice, however, the prefrontal cortex grows quiet; our predictions get faster, more accurate, and the brain becomes more efficient, learning to make decisions sooner.
In just a few sessions of exercise we become stronger, but not because our muscles have suddenly increased in size. The initial gains that take place are neuromuscular adaptations: the brain gets better at communicating with the muscles, using more of them, and using them more efficiently. The brain also learns to tolerate heat, lack of oxygen, and muscle pain. It becomes better at suffering. In essence, the brain is changing.
Neuroplasticity, or brain plasticity, is the process in which your brain’s pathways are altered as an effect of environmental, behavioral, and neural changes. Neuroplasticity occurs as the brain deletes connections that are no longer necessary or useful while strengthening the necessary ones. Which connections are pruned and which are strengthened depends on life experiences and how recently connections have been used. Neurons that grow weak from underuse die off while new experiences and learning new things strengthens others. In general, neuroplasticity is a way for your brain to fine-tune itself for efficiency. To learn new tasks, you need good plasticity.
Neuroplasticity affects both short-term memory (chemical changes) and long-term memory (structural changes). Initial changes in the brain’s structure take place quickly, showing immediate results. These changes are imbedded in short-term memory, but to transfer these changes to long-term memory requires more time (practice). It takes time and repetition for the brain to re-wire new connections, or pathways, that create long-term learning.
Practice is not a new concept for athletes. Distance runners build mileage gradually to teach their bodies to endure long distances, and then we practice these runs until our body transfers the distance to long-term memory. Sir Roger Bannister learned to run the 4-minute mile in the same way. He reduced the race to its simplest common denominator – 400m in one minute or multiples thereof, and trained until running 400m in a minute, 24 km per hour, became automatic.
The third way the brain changes is in function – how and when neurons are activated. Although each of these changes can take place in isolation, chemical, structural and functional changes typically work in concert to facilitate learning.
Fun Fact:Neuroscientist Charles Limb and others have scanned rappers’ brains during a freestyle rap and during a memorized rap. The studies show that during freestyling, there’s a functional change in their neural networks. Through practice, the rappers have reorganized their brain activity, allowing their improvised lyrics to bypass many of the conscious-control portions of the brain, which regulate behavior.
The greatest discovery regarding neuroplasticity is that nothing affects the brain more than our own behavior, and nothing is more effective than practice to help you learn. In fact research shows that increased difficulty, or increased struggle during practice actually leads to more learning and greater structural change in the brain. These studies have also identified the best methods to prepare, or prime the brain to learn include brain stimulation, exercise, and robotics. (33)
The important take-away, something confirmed from cancer treatments and the study of stroke victims, is that the way our brain functions is unique to each person. It goes beyond the fact that we all learn differently. Every human brain processes commands, makes connections, and functions differently. So the common denominator in learning is practice.
Skill athletes (basketball players, dancers, gymnasts, figure skaters) show greater motor cortex plasticity while endurance athletes (cross-country skiers, orienteers, runners) show enhanced plasticity in task-unrelated brain areas.
Motor Cortex Plasticity In Action: Giannis Antetokounmpo’s slam dunk.
In a blatant show of coordination and focus, Antetokounmpo snared the ball mid-air with his right hand while soaring over the head of Knicks’ guard Tim Hardaway Jr. without seeming to notice the obstacle at all – and then slammed the dunk.
THE LIMITS OF HUMAN ENDURANCE
Fatigue refers to the inability to continue exercise at a given intensity. In all sports and exercise training, the onset of fatigue varies depending on a person’s fitness level, exercise intensity, duration, and environmental conditions (e.g., heat and humidity). Fatigue develops over time, but is largely dependent on duration and intensity.
There are two distinct types of fatigue: central and peripheral. Central fatigue (also called Central Nervous System fatigue) involves the brain and spinal cord rather than the muscles. Central fatigue happens in the regions of the brain involved with mood, emotion, and psychological arousal. This is why being psyched, such as during competition, can help performance, but is also why fatigue, like pain, is relative.
With central fatigue, the brain becomes unable to send enough signals to the muscles to maintain optimal muscle activation, resulting in general body fatigue (tiredness, loss of drive, sleepiness, etc.) and reduced muscle force.
Peripheral fatigue results from the muscles becoming fatigued. A lack of resources within the muscle results in the accumulation of lactic acid, causing a burning sensation and fatigue within the muscle. Although both central and peripheral fatigue result in decreased performance of the muscles, they follow different mechanisms.
The question is, how much can you separate the two? It’s hard to distinguish central fatigue (the brain) from peripheral fatigue (the rest of the body) because the brain tends to influence everything, and is in turn influenced by everything.
THE CENTRAL GOVERNOR
Although fatigue produces the belief that our resources are limited, exercise generally ceases before the muscles are depleted. In fact, in all forms of exercise fatigue develops before all skeletal muscles are recruited. Just 35-50% of the active muscle mass is recruited during prolonged exercise (Tucker et al., 2004; Amann et al., 2006), and even during maximal exercise this increases to only about 60% (Sloniger et al., 1997a,b; Albertus, 2008).
Muscle biopsies from cyclers revealed that intramuscular measurements were no different at exhaustion compared to rest, and that these (ATP) levels never dropped below 50% of resting concentrations at any time during the exercise bout, suggesting fatigue causes people to terminate exercise well before muscle energy reserves are depleted (Noakes & Gibson, 2004; Parkin, Carey, Zhao, & Febbraio, 1999).
This supports the updated theory that fatigue is a central (brain) perception – a sensation or emotion – and not a direct physical event. Exercise seems to be regulated in anticipation to insure biological failure never occurs (in healthy humans).
Based on studies done at the time, this new definition of fatigue supported the idea that a central governor reduces the mass of muscle recruited during prolonged exercise gradually to prevent the development of muscle glycogen depletion and muscle rigor, or of hyperthermia leading to heat stroke. In other words, fatigue is one way the brain protects the body and preserves homeostasis by regulating power output – what runners will recognize as pacing.
If fatigue is an emotion, it will (like pain) be perceived differently by different people. Ultimately, the Borg Scale of Perceived Exertion was developed, which matches how hard you feel you are working to a “relative” scale of numbers from 6 to 20. The physical sensation of fatigue increases along the Borg RPE scale as a linear function of exercise duration. Maintaining a strategy that follows this linear increase of effort has been thought to produce the optimum pacing strategy (start slow/easy, finish faster).
The Borg RPE scale has since been described as the manifestation of information about body temperature, oxygen levels, fuel storage, and the more subtle indicators like mood or how much you slept last night. Perceived effort (RPE) gradually increases based on a combination of these psychological and physiological changes. Runners probably don’t consciously correlate pacing to the Borg scale, however, and researchers disagree as to the extent pacing decisions/computations take place consciously and voluntarily or unconsciously and automatically. Where they do agree is on effort: how hard it feels dictates how long you can sustain.
Understanding how we control the feeling of effort is still being studied, especially as it relates to pacing. Two concurrent studies recently looked at pacing methodologies. One uses an effort-based approach where runners increased pace based on self-determined effort rather than the traditional approach of pre-set increments along an increasing scale (start slow/finish faster). The effort-based subjects reached higher VO2 max values. This study, by Alexis Mauger, was co-published in the British Journal of Sports Medicine alongside another study (by Noake’s student, Fernando Beltrami) which used a “reverse” protocol that started fast and gradually slowed. This protocol produced higher than “max” VO2 max values.
Alex Hutchinson aptly summed up these conclusions in his book Endure: Mind, Body, and the Curiously Elastic Limits of Human Performance, ”If you execute a perfectly paced race, that means you effectively decided within the first few strides how fast you would complete the full distance. There’s no opportunity to surprise yourself. . .”
Once exercise begins, pace is continuously modified by continuous feedback to the brain from conscious sources including information of the distance covered (Faulkner et al., 2011) and of the end-point (duration and intensity). Studies show an athlete’s perceived exertion can be positively influenced by knowing the duration of an exercise bout, and that energy is held in reserve and available for an end-spurt regardless of their rating of perceived exertion (RPE). (27) (28).
Other conscious deceptions that improve performance and positively impact RPE include sudden noise, music, seeing the finish line or an encouraging smile, rinsing the mouth with carbohydrate (without actually ingesting the fluid), being provided with inaccurate information by a clock that runs slowly, or the pace of a prior performance that had been deceptively increased by 2%, and a host of psychological factors, including hypnosis.
Interestingly, just swishing a glucose solution in the mouth led to improvements in 1-hour cycling performance, whereas intravenous infusion of glucose did not (Carter, Jeukendrup, & Jones, 2004.) These effects are probably not specific to glucose; recent evidence suggests that simply handling ibuprofen without ingesting it promotes pain relief, for example (Rutchick & Slepian, 2013). Glucose is absorbed almost entirely in the gut, so it would be impossible for glucose briefly swished in the mouth to cause an increase in available blood glucose (Gunning & Garber, 1978). Instead, the presence of glucose in the mouth may simply provide an anticipatory signal of glucose availability, which leads some experts to argue that the body’s glucose resource issue is one of allocation, not of limited supply. (32)
The Greatest Human Strength
RPE prevents the athlete from continuing exercise at a given pace when it might cause bodily harm. This anticipatory regulation, or pacing, balances the desire for optimal performance with the requirement to defend homeostasis. You may not even notice the body’s regulatory reaction at first, but gradually the effort required to sustain a given pace increases. Ultimately, exercise is terminated when the perceived effort reaches a level that is considered higher than the perceived benefit. (25) This conscious decision of whether to maintain, increase or decrease the current workload or indeed to terminate exercise altogether may be the outcome of a balance between motivation and the sense of effort.
One of the most obvious characteristics of human exercise performance is that athletes begin exercise at different intensities, or paces, depending on the expected duration of exercise – a bout of short duration is begun at a much faster pace than one of longer duration. Also, athletes typically run harder in competition than in training. The point is that athletes always show an anticipatory component to their exercise performance that seems to be influenced by neural mechanisms relating to willpower (self-control), motivation and belief.
In 2013, at 64 years old, Diana Nyad set out to be the first person to swim from Havana to Florida without a shark cage. A marathon swimmer can expect chafing, nausea, severe shivering and hypothermia, swollen lips, an irritated mouth, diarrhea, extreme weight loss, and sleep deprivation. At the peak of her strength, age 28, she tried but failed to complete this swim. She later said: “I never had to summon so much will power. I’ve never wanted anything so badly, and I’ve never tried so hard.” Coming back to the sport 30 years later, she claimed, “I thought I might even be better at 60 than I was at 30. You have a body that’s almost as strong, but you have a much better mind.”
Nearly 53 hours after jumping into the ocean in Havana, Nyad finished the 110-mile (180 km) swim; her fifth attempt since 1978 and the fourth since turning 60. In one interview she said, “ — you tell me what your dreams are. What are you chasing? It’s not impossible. Name it.”
Research has suggested that self-control relies on a limited resource – that it unfortunately appears to wane over time similar to a muscle that becomes fatigued with overuse. Humans are less willing to exert effort the longer they have already exerted effort. This so-called ‘ego depletion’ effect has been supported by over 200 separate studies, which show that repeatedly resisting temptation drains your ability to withstand future enticements. With the right motivation, however, it appears you may be able to persevere even when your willpower strength has been depleted.
Motivation combines internal and external factors to stimulate the desire and energy to be continually interested, committed to, or make an effort to attain a goal. It is the result of conscious and unconscious factors such as the (1) intensity of desire or need, (2) incentive or reward value of the goal, and (3) expectations of the individual and of his or her peers. These are the reasons we behave in a certain way. (35)
When motivational arousal is high and must be concentrated within a brief period, the intensity of motivation must also be great. It is the difference, for example, between moving 100 pounds of books one book at a time or all at once, or running an all-out 400m challenge versus enduring a 10,000m race or marathon. Motivation tends to increase as the difficulty of the task increases until the required effort is greater than is justified by the motive – or the required effort surpasses the individual’s skills and abilities. At this point motivational arousal drops. We can see this play out time and again on the marathon course where runners find the reward of finishing the race no longer surpasses the pain of continuing to run.
An increasingly accepted body of exercise physiology has emerged that looks to psychology to understand endurance. This ‘psychobiological model based on motivational intensity’ theory (Brehm and Self, 1989; Gendolla and Richter, 2010) suggests that perception of effort and potential motivation are the central determinants of exercise duration, with people consciously deciding how much or how little effort to apply based on a number of considerations. These new studies suggest endurance is strongly influenced by the manner in which the brains of runners generate the sensations of fatigue.
Remember that fatigue is an emotion entirely self-generated by each athlete’s brain, and therefore unique to each individual – or illusionary. Based on this model, the winning athlete is the one whose illusionary symptoms [of fatique] interfere the least with actual performance.
But psychologists have also found evidence among athletes in what they call “self-efficacy,” or a belief in their own competence and success. This is where self-efficacy converges with the placebo-effect.
Studies repeatedly confirm that interventions such as sugar pills, ice/cold/lukewarm baths, massage, caffeine, beet juice, altitude training, or even a “lucky” ball, in the case of golfers, improve our game. Athletes everywhere swear by them, yet science repeatedly proves the effects are null or ambiguous at best.
Christopher Beedie, a sports psychologist at the Canterbury Christ Church University in England, is among the few scientists who study the placebo effect in athletics. His work often examines how elite athletes perform under intense fatigue when they think they have some kind of performance enhancement.
Beedie recently finished the largest placebo study ever done in athletics—600 subjects in all—and found that the people most likely to respond to placebo were the ones experienced using supplements. Perhaps the previous supplements the athletes had taken primed them to have a placebo response, or maybe athletes who naturally respond to a sports placebo are also likely to have taken performance enhancers. Either way, it suggests that artificially boosted performance and performance boosted from expectation produce similar effects. In some cases, athletes performed better when given a sugar pill than the athletes that were given certain performance enhancing drugs.
Even in the arena of these performance enhancing drugs and placebos, especially for elite athletes, there’s a limit to the benefits of both psychological and pharmacological performance enhancers, so why not just use belief instead? “We’re trying to educate athletes into the idea that the headroom is there to be filled, and drugs are not necessarily the only way of filling that headroom,” Beedie says. “Confidence is the drug of champions.”
In the end, the question we all share is how do we go further/longer/faster; what is the secret of endurance?
Dr. Lara Boyd, Director of the Brain Behaviour Lab, is a physical therapist and a neuroscientist leading the effort to understand what therapies positively alter patterns of brain activity after a stroke. In a research-based TEDx Talk, Boyd describes how neuroplasticity gives you the power to shape the brain you want.
The new discovery is that learning changes our brains differently. My brain will go about learning a new task differently than your brain will learn the same new task. Understanding these differences, these individual patterns, is the future of neuroscience – and possibly sports science as well.
Boyd suggests we understand how we learn. What is it that your brain responds best to? For runners learning to endure, maybe this means experimenting with self-talk, visualization, or forcing yourself to try a new training approach altogether. Coaches are increasingly realizing they can push athletes to new limits just by asking them to do something they didn’t think they could do.
Even when athletes were sufficiently motivated, by monetary rewards or recognition for example, they did not perform as well as athletes who were led to believe they could accomplish the task.
Humans keep doing impossible things. Running a 4-minute mile, running 100 miles, lifting 500 pounds over our head, being an undefeated wrestler with no arms or legs. Each of these things have been accomplished even though public opinion claimed they were impossible at the time. The difference was that in each example these people believed, or were tricked into believing they could do this thing.
The pursuit of endurance is a unique journey for each of us, but it seems science has concluded what athletes have known all along – that there’s more in the tank, if you’re willing to believe it’s there.
A 2017 animal study published in the journal Behavioural Brain Research concluded that a sprint interval training regimen, rather than intensive endurance training regimen has the potential to improve anxiety and depression through a greater increase in (brain-derived neurotrophic factor) contents in the brain.” (10)
A NOTE ON MUSIC: Diversionary techniques to distract the mind, such as listening to music or self-talk, were discussed in a previous post on Pain, and have proven effective in lowering the perception of effort. Music, in particular, can narrow attention and divert the mind from the sensations of fatigue. However, this holds true for low and moderate exercise intensities only; at high intensities, perception of fatique overrides the impact of music. At high intensities, the physiological feedback to the brain regarding things like respiration rate or blood lactate accumulation dominates the conversation, and music fails to divert the mind from the body’s feedback. Listening to music seems to shape how the mind interprets symptoms of fatigue, however, which may enable athletes to perform more efficiently resulting in greater endurance. (16)
Studies demonstrate that running economy significantly changed, along with perceived effort, based on whether the runners knew they were running 20 minutes or whether they did not know the duration, even if they ended up running 20 minutes.
In a recent study published in BMC Medicine, the 64-day ultramarathon TransEurope FootRace Project followed 10 ultra-endurance runners covering about 4,500 km from Bari, Italy to the North Cape, Norway recording a large data collection of brain imaging scans. This study indicates cerebral atrophy among the runners amounted to a reduction of approximately 6% throughout the two months of the race, but was completely reversed within the 6-month follow-up. The results of this unique study, which revealed no brain lesions, gave clues to the effect of extreme fatigue with energy deficits on cortical grey matter volume. Having an understanding of what the brain does during an ultra-marathon event could help refine research on the matter of mind over muscle in determining exercise tolerance in endurance athletes, but may also benefit military personnel involved in physical work over prolonged periods and patients affected by unexplained chronic fatigue syndromes.
A 2011 study (Erickson et al.) demonstrated that 1 year of aerobic exercise increased the volume of the hippocampus by 2% in elderly adults, while controls who underwent 1 year of stretching exercises exhibited a 1.4% decrease in hippocampal volume.
Kids who participated in vigorous physical activity scored three points higher, on average, on their academic test, which consisted of math, science, English, and world studies. (23)
Telling runners they look relaxed makes them burn measurably less energy to sustain the same pace. Giving rugby players a post game debriefing focused on what they did right rather than what they did wrong had effects that continued to linger a full week later. (34)