A study finds that runners maintain their running economy despite losing speed as they age.
Aging brings about many changes in the tissues and organs of the human body that negatively affect running performance. But these changes do not diminish every dimension of running performance.
The ability to sustain relatively high submaximal speeds over long distances is really a composite ability to which other, more fundamental capacities contribute. These include speed, power, aerobic capacity, and running economy. Among the fundamental capacities that contribute to running performance, running economy appears to be alone in resisting diminishment with age.
This was demonstrated in a 2011 study authored by researchers at the University of New Hampshire. Fifty-one high-level runners representing three separate age brackets were recruited to participate in the study. Eighteen runners were between the ages of 18 and 39, and were classified as “young.” Another 22 runners fell between the ages of 40 and 59, and were labeled “masters.” The remaining 11 runners, all over 60, comprised the “older” group.
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All 51 runners were subjected to a comprehensive battery of tests to measure various running-related physical abilities and characteristics. Their muscle strength, muscle power, muscular endurance, flexibility, and body composition were assessed. On treadmills, their cadence, lactate threshold, VO2 max, and running economy at four different velocities were measured.
If the three age groups were teams and these tests were competitions, the older group would have lost most of them badly. VO2 max declined from 64.1 ml/kg/min in the young group to 56.8 in the masters group to 44.4 in the older group. Maximal heart rate dropped from 197 bpm to 183 to 170. Velocity at lactate threshold fell from 289.7 meters per minute (5:33/mile) to 251.5 m/min (6:24/mile) to 212.3 (7:34/mile). Members of the older group also exhibited significant losses in speed, power, and upper body strength relative to the young and masters groups.
The tests of running economy were the only exceptions to this pattern. At all four velocities, running economy was roughly equal among the three age groups. Runners over age 60 were just as efficient at slow, moderate, and fast running speeds as runner under 40. The authors of the study thus concluded, “The results from this cross-sectional analysis suggest that age-related declines in running performance are associated with declines in maximal and submaximal cardiorespiratory variables and declines in strength and power, not because of declines in running economy.”
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This interesting finding raises the question of why running economy does not decline with age. Similar to running performance itself, running economy is a composite attribute to which other, more fundamental factors contribute. One major factor that contributes to running economy is the capacity of the leg muscles and tendons to capture energy from impact forces and release it back into the ground to propel forward movement. Jumping tests are sometimes used as an approximate way to measure this characteristic, which is often referred to as “leg stiffness” because it has to do with the leg’s ability to quickly stiffen when the foot hits the ground. Runners who can jump higher generally exhibit greater leg stiffness and better running economy.
Jumping tests actually measure leg muscle power more directly than they do leg stiffness, and in this study the older runners exhibited significantly less leg muscle power than young and masters runners. In other words, the older runners were just as economical as the younger runners despite scoring lower in one of the major fundamental contributors to running economy.
This point brings us to the second major contributor to running economy, which is biomechanics. Runners who coordinate their stride movements more effectively run more efficiently. There is no single stride pattern that is most effective for all runners. Differences in body structure create a requirement for each runner to find his or her own most effective way to run. What is universal in the relationship between running biomechanics and running economy is that runners who slow down the least when their feet land and whose feet spend the least time in contact with the ground run most efficiently.
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Biomechanical measurements were not included in this study, but it’s safe to assume that if they had been, the older runners would have exhibited no more braking on impact and no greater ground contact time than the young and masters runners. In fact, the older runners might have scored even better in these measures. After all, the older runners were just as economical as the other groups despite having less power, hence probably less leg stiffness. So they had to be doing something else better than the younger runners, and that something was almost certainly biomechanical, or neuromuscular.
These speculations raise the interesting possibility that runners are able to continue to improve their biomechanics or neuromuscular efficiency throughout life. Something to look forward to!
About The Author:
Matt Fitzgerald is the author of Iron War: Dave Scott, Mark Allen & The Greatest Race Ever Run (VeloPress 2011) and a Coach and Training Intelligence Specialist for PEAR Sports. Find out more at mattfizgerald.org.