The fourth in a series of posts about what makes runners uniquely equipped to run. This post is a comprehensive review of the knee, including function, injuries, recovery and strengthening specific to runners.
The knee is a complex synovial joint that flexes, extends and twists slightly from side to side. It joins the thigh bone (femur) to the shin bone (tibia). When we’re sitting, the femur and tibia barely touch; standing they lock together to form a stable unit.
Two groups of muscles support the knees, including the hamstrings, which are the muscles on the back of the thigh. They run from the hip to just below the knee and work to bend the knee. The other are the quadriceps, which are the four muscles on front of the thigh that run from the hip to the knee and straighten the knee from a bent position.
Webmd.com defines knee conditions not covered in this post, such as ACL strains or tears which leads to the knee “giving out,” damage to a meniscus – the cartilage that cushions the knee, which often occurs with twisting the knee, rheumatoid and knee osteoarthritis, bursitis, and gout (also a form of arthritis).
A common sporting injury is pulling or straining the hamstring tendons, two groups of string-like connective tissues at the back of the knee and thigh that connect some of the major muscles of the knee.
Knee injury symptoms include pain, tenderness, swelling, locking, “giving way,” snaps, crackles, or pops.
For this discussion we’ll focus on the most common runner’s knee injuries, which fit into two categories – they rarely occur together:
1. pain on the side: iliotibial band syndrome (ITBS)
2. pain on the front: patellofemoral syndrome (PFPS)
PFPS affects the kneecap and surrounding area, where ITBS definitely affects the side of the knee (the side facing outwards).
Iliotibial Band Syndrome (ITBS)
The iliotibial band (IT band) is a band of fibrous tissue that runs along the outside of the thigh, from just above the hip to just below the knee, (like a cowboy’s chaps).
The IT band is made up of fascia, an elastic connective tissue found throughout the body.
Fascia is a sheath that encloses muscles, connects muscles to bone and compartmentalizes muscles that serve a similar function. The IT band is the largest piece of fascia in the human body.
It has traditionally been understood that the IT band provides stability to the knee and hip, and helps prevent dislocation of those joints. Hold that thought.
Understanding the IT Band
Opinions regarding the IT band, its definition, function, injuries and recovery, have evolved. In fact, precise descriptions of the IT band – which muscles attach to it and where – have been all but non-existent leaving this part of the anatomy perhaps one of the most controversial of all.
An injury of the iliotibial band, Iliotibial Band Syndrome (ITBS), was first identified in the 1970s and was thought to be the result of the IT band becoming tight or shortened, thus the recommended treatment of stretching.
Researchers at the University of Kentucky compared runners with IT band syndrome to healthy runners, however, and found that the injured runners actually had longer IT bands on average, but weaker hip muscles, indicating that strengthening the hip muscles may be more effective – not only for rehab, but for preventing the injury in the first place.
New studies have set out to prove that the iliotibial band moves, which also gave way to a new name for its injury: Iliotibial Band Friction Syndrome, or ITBFS – except that this entire study contradicts other studies that have concluded motion of the IT Band is simply an illusion.
One of the more recent studies, reported in the Harvard gazette (August 2015) examined whether the iliotibial band actually stores and releases elastic energy to make walking and running more efficient (similar to an elastic band – as with the Achilles’ tendon).
To understand what role the IT band plays in locomotion, the researchers developed a computer model to estimate how much it stretched during walking and running ― and by extension, how much energy it stored. Then, using a custom-built frame, Carolyn Eng, the first author of these studies, manipulated human and chimpanzee cadaver limbs measuring how much the IT band changed in length for each shift in joint angle.
The study concluded that part of the IT band stretches as the limb swings backward, storing elastic energy. That stored energy is then believed to be released as the leg swings forward during a stride.
Computer simulation of a human leg running (Credit Carolyn Eng)
The view that the IT band acts as a ‘spring’ contradicts all previous understanding that its primary function is to stabilize the hip, but then it seems almost everything we thought we knew about ITBS is subject to change – and then change again.
Why it hurts: ITBS is no longer thought to be a tightening of the iliotibial band, but instead a layer of tissue under the iliotibial band that becomes inflamed (possibly causing a layer of fat and loose connective tissue to become pinched between the iliotibial band and the knee, causing ITBS).
What we do know is that ITBS is an overuse injury most common in runners and cyclists where the overuse creates stress the body cannot repair, and soft tissue breakdown occurs – the result of weak hips, running only on one side of a crowned road, or only one way around a track. Studies also demonstrate that weakness or inhibition of the lateral gluteal muscles can be a factor.
Training errors can also cause iliotibial band issues – too much too soon or abrupt changes to intensity, as well as anatomical issues, such as leg length discrepancies, high arches, supination of the foot, excessive foot-strike force, knees that lean inward, and muscular imbalances within the hip.
And ITBS can be a common injury in activities such as gardening, hiking, treading water, running up and down stairs, excessive up-hill and down-hill running, and is increasingly recognized in other sports including soccer, weightlifting, and skiing. In other words, there are a plethora of causes for ITBS.
A good discussion of IT band pain can be found on runireland.com and at painscience.com.
Note: Up to 50 percent of cyclists experience knee pain. In one observational study of 254 cyclists over six years, 24 percent of the cyclists presenting to a sports medicine clinic for knee pain were diagnosed with ITBS.
Cyclists can develop ITBS if the saddle is too high, too far back, or if there is excess internal rotations (toed-in) of the lower leg – all of which put additional stress on the iliotibial band.
Where it hurts: An injured IT band can cause pain on the side of the hip, down the outside of the leg, and eventually on the outside of the knee, which is then considered IT band Syndrome (ITBS).
The epicentre of ITBS pain is on the outside of the knee – specifically the spot on the side of your knee, around the most sticky-outy bump (a technical term I’ve recently discovered), that is sensitive to pressure, while the kneecap is not particularly sensitive when pushed firmly straight into the knee.
- It really hurts to go down stairs (or downhill running) but not so much going upstairs.
- Doing a deep knee bend doesn’t necessarily hurt.
- The onset of pain happened rather quickly – over a few hours rather than days.
- Pain is worse after sitting for long periods of time.
- Left unchecked, ITBS will produce a pain so great that running is impossible – bringing the body’s largest joint to its knees (so-to-speak).
First, the recovery steps that are not controversial:
- Rest & Ice to reduce inflammation;
- Stop the perpetuating factors that caused the irritation;
- Sleep with a pillow between the knees to decrease tension on the IT band through recovery;
- Add strengthening exercises for the hips to your exercise program.
Massage vs Stretch: for many years IT band stretches were suggested to relieve the pain associated with ITBS and to reduce the tightening of the fascia.
It is unclear that the IT band itself will stretch, however, leading some experts to suggest it is most effective to stretch and strengthen the surrounding gluteal, quadriceps and hamstring muscles, which can cause tension on the IT band.
(A February 2017 study says the iliotibial band tensor fascia lata complex (ITBTFLC) “is capable of tissue elongation under normal physiologic loads that simulate a clinical stretching protocol. It is uncertain whether this “stretch” translates into sustained, clinically meaningful tissue elongation.”)
While some physiologist swear stretching the IT band is 100% ineffective in treating ITBS, my research took a significant turn when a post on LinkedIn caught my attention, “Ilio-tibial Band: Please do not use a foam roller!” , which suggests it is actually massage that should be avoided at all costs – and it was in the comments readers wrote in response to this LinkedIn post that I discovered even more controversial thoughts on ITBS.
I would suggest, in the absence of a more direct and agreed upon plan of action, that we all do what works best for us as individuals (remember N=1). I dealt with ITBS for several years before learning what worked best for me, which includes massage of the IT band (from the hip all the way to the outside of the knee) to relieve the soreness and relax the tendon (or whatever it is that’s sore), strengthening of the hips, and prevention.
Stretching the band provides temporary relief from the pain, but deep massage will relax and release the tension on the band (it can feel like a guitar string just under the skin). Massage can be uncomfortable at first so you want to be careful that you don’t make the soreness even worse: start with a minute and work up to 3 – 4 minutes at a time working (or using a foam roller, if you dare) up and down the outside of your thigh.
Massaging the band whenever it becomes sore will effectively prevent the progression of ITBS and the resulting pain in the knee, although it is important to understand what is creating the injury in the first place.
Running can be maintained during ITBS recovery only to the point the pain returns (i.e., if the pain returns after 3 miles of running, reduce your daily mileage to less than 3 miles so the entire run can be finished pain free). In my worst case of ITBS, I discovered I could run exactly 18 minutes before the pain returned, so I stopped at 17 minutes regardless of how much distance had been covered.
In some cases, the IT band has become so severely injured that running is impossible, and recovery and strengthening efforts only exacerbate the problem. In this case, total rest is recommended. Cross training may be considered, keeping in mind that some sports, such as hiking and cycling, may be counterproductive.
Runner’s Note: A review in the National Institutes of Health states that biomechanical studies have shown that faster-paced running is less likely to aggravate ITBS, and faster strides are initially recommended over a slower jogging pace.
Patellofemoral Pain Syndrome (aka runner’s knee):
Although pain in or around the center of the knee has become known as runner’s knee, it can affect almost anyone – athletes and sedentary folks alike. Some say runner’s knee isn’t a specific injury but rather a broad term that describes the pain you feel if you have one of several knee problems.
Wikipedia says, “The diagnosis of patellofemoral pain syndrome is made by ruling out patellar tendinitis, prepatellar bursitis, plica syndrome, Sinding-Larsen and Johansson syndrome, and Osgood–Schlatter disease.”
Why it hurts: The medical cause of PFPS is thought to be increased pressure on the patellofemoral joint, although it is generally accepted that PFPS is brought on by many of the same issues, such as weak hips or muscle imbalances, training that progresses too fast too soon, extensive periods of sitting, a tilted patella, and other factors that place extra stress on the bone including flat feet, abnormal rotation of the hips, and tightness of the IT band or hip flexors, and wearing down, roughening, or softening of the cartilage under the kneecap. Obesity can also play a role in causing PFPS.
Where it hurts: The epicentre of PFPS pain is somewhere under or around the kneecap. It’s uncomfortable pushing your kneecap straight into your knee, but there is no particularly sensitive spot on the outside of the knee.
- A deep knee bend definitely hurts.
- The onset of pain happened slowly, possibly while ascending stairs or running uphill,
- it definitely hurts when going upstairs, but may hurt going up and down.
- Sitting with bent knees hurts, and hurts worse after standing up.
Recovery efforts begin with R.I.C.E. to “quiet the knee” followed by identifying any irregularities, such as pronation or supination. A physician should be consulted sooner rather than later to make a proper diagnosis and treatment plan.
Note: Chondromalacia Patellae and Patellofemoral Pain Syndrome/Runners Knee are terms often used interchangeably to describe anterior knee pain regardless of the cause of the pain. Although PFPS/Runners Knee may lead to Chondromalacia Patellae, the latter is a chronic degenerative condition affecting the articular cartilage on the under surface of the kneecap (although this too is different from the degeneration of knee osteoarthritis).
Does Running Cause Knee Problems and Eventual Arthritis?
A 2006 study measured the changes in the cartilage volumes in the tibia, patella and medial and lateral meniscus (the cartilaginous tissues that provide structural integrity to the knee) after the extreme dynamic loading that occurs in long-distance runners. It also examined the rate of recovery from the alterations occurring at the knee joint due to loading during distance running. This study revealed that after 1 hour of rest no significant reduction of cartilage volume was measured for the patella, the tibia or the lateral and medial meniscus.
Although there were significant changes after a 5, 10 and 20 km run, the conclusion on the basis of the study was that the cartilage is able to adapt well to the loads caused by running and that the articular structures were found to recover rapidly so that exercise could be continued after a short rest without reservation.
Every source seems to agree on several things we can do to help prevent long term damage to our knees due to injury and/or prevent the onset of osteoarthritis regardless of our chosen sport.
Avoid Carrying Extra Weight: Increased body weight, which adds stress to lower body joints, is a well established factor in the development of osteoarthritis. Your knees, which carry the brunt of your weight, are particularly at risk. For every pound you gain, you add 4 pounds of pressure on your knees and six times the pressure on your hips.
Research shows that excess body fat produces chemicals that travel throughout the body and cause joint damage, which would mean obesity plays a systemic, not just a mechanical, role in osteoarthritis onset.
A two-year study of overuse running injuries among 300 recreational runners found knee stiffness to be the significant predictor of injury; even more so than compared to issues related to flexibility, quadriceps angle, arch height, rearfoot motion, strength, footwear, and previous injury.
Knee stiffness (a measure of how much the knee bends when a given force is applied) is more common in runners with higher body weights (≥80 kg), and significantly increases the odds of sustaining an overuse running injury.
Avoid Overuse/Injury: While running itself doesn’t increase the risk of osteoarthritis, running injuries can – especially when you delay treatment or rush recovery. If an injury is not properly cared for, the non-healing of it can cause the degenerative process of arthritis to start in the joints.
Train smart: don’t ramp up too quickly, don’t train if you’re injured.
Be Strong: Studies show that weakness of the muscles surrounding the knee is associated with osteoarthritis, especially in women, and makes the pain and stiffness worse after onset. Strengthening exercises for thigh muscles are also important in reducing the risk.
Strengthen the Knee
Minor increases in the strength of the quadriceps has been shown to help reduce the risk of knee osteoarthritis and its progression as well as reduce pain. Those suffering from arthritic knee pain can also benefit from exercise due to the support it provides to the joint area.
This post is meant for informational purposes only. Please consult a physician to discuss your specific injuries.
Other Posts in this Series:
The Anatomy of a Runner: it’s all about that bass (the Upper Leg & Glutes)
The Anatomy of a Runner: be still my beating heart