Running economy is the runner’s equivalent of automobile gas mileage. The less oxygen your body consumes at any given pace, the more economically you run. A high running economy is beneficial in two ways. With it you can run faster before reaching your maximum rate of oxygen consumption and you can also run farther before running out of muscle fuel.
There is a key difference between running economy and gas mileage, however. Cars get the same gas mileage regardless of whether the tank is full, half-full, or three-quarters empty. But runners actually lose economy as they become progressively fatigued. The reason seems to be that running form changes with fatigue, becoming sloppier and more wasteful. One way to improve your performance in races is to train specifically to delay and attenuate this “falling apart” of the stride.
How is this done? A study from England’s Northumbria University performed last year begins to answer the question. The purpose of the study was to investigate the relationship between muscular endurance and fatigue-related loss of running economy. Muscular endurance is the capacity of individual muscles to maintain their force output through sustained hard work. When you contract a muscle as hard as you can and hold that contraction for an extended period of time, the force of the contraction will steadily decrease as the muscle fatigues. But this loss of force will occur more slowly in a muscle that has high endurance than in one that has low endurance. The authors of this new study hypothesized that runners who exhibited high endurance in their quads and hamstrings in muscular endurance tests would also exhibit a smaller fatigue-related loss of economy when running.
Ten well-trained male runners participated in the study. All ten were asked to do two separate treadmill runs. In one run they simply went for a long time at a steady, moderate pace. In the other run they did the same thing, except in the middle they had to run 4 minutes at VO2max pace (i.e. very high-intensity). The purpose of these 4 minutes was to accelerate fatigue and the loss of running economy that comes with it.
The researchers measured running economy throughout both runs. As expected, they found that running economy decreased significantly after the 4-minute burst of high-intensity running compared to the latter half of the other run. This confirmed that fatigue spoils running economy. But not all ten runners experienced the same level of economy loss. Those who exhibited the highest levels of muscular endurance in separate tests experienced a smaller loss of economy than those who had poorer muscular endurance. These results suggest that boosting local muscular endurance is an effective way to minimize the loss of running economy that occurs toward the end of a run.
Running itself boosts local muscular endurance. But the authors of this study suggested that runners might benefit further by supplementing their running with the performance of exercises specifically designed to enhance muscular endurance. These include high-repetition strength exercises such as 20 repetitions of stability ball hamstrings curls and long-hold isometric exercises such as a reverse plank held for 30 seconds.
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.