The Physiology of Elite Runners

Competitive running can be thought of as the time taken to run a specific distance, with the baseline measure of performance being the time on the clock as an athlete crosses the finish line. At the elite level, Olympic disciplines range from 100 metres to a marathon, with anything beyond that classed as an ultramarathon.

These individual events are designed to determine the fastest athletes in the world. However, such variation in racing distance and duration results in unique event demands and associated determinants of performance. Here we look at the physiology of running, with a particular focus on the physiological demands of marathon running and the kinematic (movement) variables associated with elite endurance runners and sprinters.

Endurance Runners

The key physiological demands of marathon running have been documented as: 

• Maximal oxygen uptake (VO2 max) – the maximum amount of oxygen uptake and utilisation per minute, per kilogram of body mass.
• Lactate threshold – the point at which blood lactate increases above baseline levels and running economy.
• The energy demands for a given running speed⁽¹⁾.

Oxygen Consumption

During endurance running, oxygen is taken into the body to facilitate aerobic energy production and exercise performance. As the intensity of exercise increases, so too does the volume of oxygen consumption required to maintain performance levels. The trend continues until a maximal point is reached, at which the volume of oxygen  consumption cannot increase further with increases in exercise intensity. This point defines VO2 max and represents the maximum volume of oxygen the body can take up and utilise during exercise. 

Expressed as millilitres of oxygen consumed per kilogram of bodyweight per minute (ml/kg/min), the VO2 max values of elite endurance athletes have been reported at between 70 and 85 ml/kg/min (2,3), compared to 43.5 ± 7.0 ml/kg/min in untrained runners⁽⁴⁾. These high VO2 max values support faster running speeds during long-distance racing and result in winning performances.

Lactate threshold

The second physiologic demand of marathon running is lactate threshold, which can be expressed as a percentage of VO2 max and relates to the first increase in blood lactate above baseline levels. Increases in lactate threshold typically result in improved endurance running performance⁽¹⁾.

In elite athlete populations, lactate threshold can be 82.0±6.6% of VO_2max, compared to 76.6±6.4% in untrained populations ⁽⁴⁾. In combination with a high absolute VO_2max, the ability to perform for extended periods of time at a high percentage of VO_2max results in an endurance runner who can sustain fast running speeds.

In elite endurance runners, with similar VO_2max, running economy is a better predictor of performance ⁽⁵⁾.

Energy demands

Defined as the energy demands for a given running speed, athletes with good running economy expend less energy compared to athletes with poor running economy at the same speed ⁽⁵⁾. Expending less energy and therefore using less oxygen, at a given running speed, results in a more efficient elite endurance runner.

A number of variables interact to determine running economy, these can be categorised as: training factors, environmental, physiological, biomechanical and anthropometry; shown below. Endurance runners who can combine a high VO_2max with good running economy are likely to perform the best in race situations and cross the finish line first.

Sprinters

The 100m final is often viewed as defining the so-called fastest athlete on the planet (6). The physiology of running and kinematic factors combine to result in the sprinting speeds needed to run 100m in under 10 seconds. The predominant physiological factor displayed across sprinters is a high percentage of fast twitch muscle fibres, up to 75% in elite sprinters ⁽⁶⁾.

Fast twitch muscle fibres produce force at a high rate, allowing sprinters to generate higher power outputs per step. The resulting metabolic power per ground contact time and mechanical output sees elite level sprint performances close to the limits of human performance ⁽⁶⁾.

The two key kinematic variables that define sprint speed are stride length and stride frequency ⁽⁷⁾. An optimal ratio of these two variables will result in the highest speed an individual sprinter can achieve. As the relationship between these two is mutually dependent, an increase in one has the potential to improve sprint performance. 

However, with these being dependent factors, increasing stride frequency decreases stride length and increasing stride length decreases stride frequency. When looking to improve one of these variables and overall sprint performance, an improvement will only be seen if the other variable does not undergo a proportional or greater decrease. An analysis of elite 100m performances reported stride frequencies of 4.25 Hz and stride lengths of 2.44 metres, resulting in running velocities of 10.38 m/s and 100m times of 9.63 seconds ⁽⁷⁾.

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References

1. Midgley, A. W., McNaughton, L. R., & Jones, A. M. (2007). Training to enhance the physiological determinants of long-distance running performance. Sports Medicine, 37(10), 857-880.
2. Joyner, M. J., & Coyle, E. F. (2008). Endurance exercise performance: the physiology of champions. The Journal of physiology, 586(1), 35-44.
3. Billat, V. L., Demarle, A., Slawinski, J., Paiva, M., & Koralsztein, J. P. (2001). Physical and training characteristics of top-class marathon runners. Medicine & Science in Sports & Exercise, 33(12), 2089-2097.
4. Caputo, F., Mello, M. T., & Denadai, B. S. (2003). Oxygen uptake kinetics and time to exhaustion in cycling and running: a comparison between trained and untrained subjects. Archives of physiology and biochemistry, 111(5), 461-466.
5. Saunders, P. U., Pyne, D. B., Telford, R. D., & Hawley, J. A. (2004). Factors affecting running economy in trained distance runners. Sports Medicine, 34(7), 465-485.
6. Beneke, R., & Taylor, M. J. (2010). What gives Bolt the edge—AV Hill knew it already!. Journal of biomechanics, 43(11), 2241-2243.
7. Krzysztof, M., & Mero, A. (2013). A kinematics analysis of three best 100 m performances ever. Journal of human kinetics, 36(1), 149-160.

Written By

Ben Samuels

Ben is a Performance Nutritionist at Science in Sport