That’s what a new study at Loughborough University, in Britain, set out to test (abstract here, press release here). They put 97 runners with 10K season-best times ranging from 29:32 to 56:49 through a series of treadmill tests while using 3-D motion capture to analyze 24 different variables related to the motion of various body parts. Then they analyzed the results from a range of speeds between 8:00 and 9:36 per mile (which all the runners in the study could sustain comfortably during testing) to look for patterns.
The first thing that pops out in the results is the high level of variability: For most of the biomechanical parameters, there was a huge range in how people ran. Some runners had twice as much vertical oscillation (how much up-and-down bounce there is in your stride, basically) as others; some had almost three times more “braking” when their foot hit the ground than others.
There was also a huge range in racing performances (as noted above) and in running economy, a measure of how much energy you burn to sustain a given pace. Again, some runners burned almost twice as much energy to cover a given distance compared to others, when resting metabolism was subtracted.
The key question, then, was whether the differences in biomechanics were related to the differences in speed and efficiency. And the answer was yes. In fact, 19 of the 24 biomechanical variables were significantly correlated with running economy, and 11 with seasonal best racing times.
In a sense, that’s not a very useful result. If everything matters, then you don’t get any guidance on what matters most. But many of the biomechanical variables were actually measuring similar things. For example, to measure vertical oscillation, should you look at where your center of mass is, or how much a core point on your body like the pelvis moves? And should you measure oscillation during the whole stride, or just when your foot is on the ground?
So the researchers then used statistical techniques to figure out which combination of variables offered the best independent predictions of running performance and economy.
For running economy, three variables stood out: vertical oscillation (measured by the up-and-down motion of the pelvis; less is better); how bent your knee is when your foot hits the ground (more bent is better); and braking (also measured by looking at the motion of your pelvis; less slowdown as your foot hits the ground is better).
Overall, these three variables explained 39.4 percent of the individual differences in running economy—and the vast majority of that (27.7 percent) came from vertical oscillation.
For running performance, four variables stood out: braking (as above); the angle of the shin when your foot hits the ground (closer to vertical is better); duty factor (basically a measure of how long your foot stays on the ground relative to your overall stride; quicker is better); and the forward lean…