Foot strike has been a hotly debated topic of late, with some sources indicating it makes no difference to performance, and others emphasizing its importance for running form. A study in the Journal of Strength and Conditioning Research closely examined foot striking during an ultra-marathon to find answers.
The researchers analyzed various checkpoints along a 161km ultra-marathon and took samples from several thousands of participants. The researchers examined foot strike, stride length, stride frequency, and even took blood samples.
Creatine Kinase Levels
Most of the participants were heel strikers. The heel striking tendency increased by about nine percent at the beginning of the race and then dropped to four percent during the race. When they analyzed the blood samples, the researchers found greater creatine kinase activity in midfoot and forefoot strikers as the race went on, which is a possible explanation for this effect.
Creatine kinase is a blood marker for muscle damage. In this case, muscle damage is essentially equivalent to muscle exertion. Since creatine kinase was higher in those who didn’t run with a heel strike, and since heel striking became more prevalent during the race than it was at the start, it’s safe to say that heel striking required less muscular effort to maintain.
Elite Runners and Foot Strike Patterns
Don’t abandon your attempts at mid- or forefoot striking just yet, however. Although non-heel strikers did experience a greater need for muscular control, and perhaps even a slightly greater cost of energy as a result, non-heel striking may have helped to make the top runners elite. By the final checkpoint where foot strike patterns were analyzed, thirty percent of the top twenty runners (six total), were using a forefoot or midfoot strike instead of a heel strike. Although there seemed to be no relationship between foot strike and speed, when you look at all the runners together, you see the fastest were more likely to be midfoot and forefoot strikers.
Elite runners are more likely to spend time on their running form, and thus might be more willing to spend the time on a different sort of foot strike. This could be a confounding factor in the results of elite foot striking patterns. They would also be better able to handle the physical demand of the different foot strike.
This fact seems true when looking at the other data in this study. The top twenty finishers had more stable stride rates and stride lengths. Stride length in particular didn’t change much at all and would be a critical part of their form. By contrast, the other finishers experienced greater changes, including an increasing stride frequency throughout the race and a reduced stride length.
The Uphill Factor
It’s important to note this was a hilly course, and hills increase the technical demands of distance running. For example, when running uphill, the ground meets the front of your foot faster than the back, increasing the prevalence of forefoot striking. Enough uphill running might cause a preference for that type of foot strike, even once the road flattens. The opposite may be true for downhill running, which is more technically demanding for a non-heel striker.
The researchers concluded that both harmful impact and muscular damage should be avoided during an ultramarathon. Since heel striking reduces damage, while non-heel striking reduces impact, they deemed foot strike a variable that should progress naturally. However, since elite runners have more stable form, and thus less muscle damage, I’d recommend not taking the researchers’ advice. Reducing impact is more important when developing the conditioning to handle the race length you like. I would advise ultrarunners to develop a more technical foot strike, rather than heel strike.
References:
1. Mark Kasmer, et. al., “Foot Strike Pattern and Gait Changes During a 161-km Ultramarathon,” Journal of Strength and Conditioning Research, 28(5), 2014
Photo courtesy of Shutterstock.
