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.

This past week my research led to The Physiology of the World Record Holder for the Women’s Marathon by Andrew M. Jones (originally printed in the International Journal of Sports Science & Coaching). The subject of the paper, referred to only as PR, is of course Paula Radcliffe. Andrew Jones was her physiologist since 1991.

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.

Read more: The Anatomy of a Runner: Muscle