A new study finds that common stride “improvements” reduce running economy.
Many coaches and experts encourage runners to bounce less and increase their cadence. The objective of making conscious efforts to run with less bounce and a higher cadence is to run with a lower energy cost, or better economy. A team of researchers recently measured the effects of these common running form prescriptions. The results should make coaches and experts think twice about continuing to make them.
Sixteen runners were recruited to participate in the study. They were asked to run at 16 kph (6:02/mile) and their rate of oxygen consumption was measured to assess their running economy. Their stride rates and vertical displacements (or bouncing) were also measured. The treadmill used for the experiment was tricked out with a visual and auditory feedback system for cadence and vertical displacement. The researchers gave each runner a target cadence and vertical displacement to aim for in a second go at running at 16 kph with a breathing mask on. The targets were intended to slightly increase each runner’s stride rate and slightly reduce his vertical displacement from current levels. The runners were able to hit these targets with relative ease with the aid of the visual and auditory feedback provided.
In the initial testing, the researchers found a positive association between natural stride rate and running economy (meaning the most efficient runners tended to take more steps per minute) and an inverse correlation between natural vertical displacement and running economy (meaning the most efficient runners tended to bounce less). These findings gave the researchers some cause to believe that forcing the runners to increase their cadence and reduce their bouncing would improve running economy. However, just the opposite happened. “Alterations led to an increase in metabolic cost in most cases, measured as VO2 uptake per minute and kg body mass,” they confessed.
I don’t know if the researchers were surprised by this finding, but in any case, they should not have been. Past research has generally found that consciously forced changes to running form reduce economy regardless of the specific nature of those changes. This appears to happen for two reasons. First, through training, runners tend to automatically find the most economical way to run for them individually given the present realities of their body structure and biomechanical constraints. Second, as runners become more practiced, they are able to run with less brain activation—that is, more unconsciously. Forcing runners to think about how they are running increases brain activation and reverses the economy-boosting effect of being able to run half-asleep thanks to experience.
This doesn’t mean that runners are always stuck with the running form they have and cannot become more economical. But it does mean that runners have to let these improvements unfold automatically by simply running a lot, running consistently, and running hard.
When I was working on The Runner’s Edge, a book I coauthored with Stephen McGregor, PhD, whose research supports the statements of the preceding paragraph, we came across a runner named Roberto Veneziani, who used a Polar speed and distance device to track his cadence over the course of a full season of training and racing. Then he created a graph that plotted his cadence against his race performances. Between August of one year and February of the next, Roberto’s fitness and race performances improved markedly. His average stride rate in training also increased significantly, from roughly 78 strides per minute to almost 88. But this change occurred without any conscious intervention. Roberto just ran, and let his cadence (and every other dimension of his running form, for that matter) take care of itself.
The authors of the study described above noted, “Mid- and long-term effects of altering…technique should also be studied.” I suppose it’s possible that consciously forced changes to running form that reduce running economy immediately could improve it eventually if insisted upon over weeks or months. But we don’t know that, and in the meantime we do not that just leaving well enough alone and running a lot, running consistently, and running hard does work, so I, for one, will continue doing that.
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.