Research Blog

Running Economy: Does it matter what part of your foot strikes the ground first?

runner on road demonstrates heel strike.

A study looks at the efficiency dynamics of forefoot and rear-foot running strikes.  What they find is contradictory to conventional running wisdom. The runner on the right is clearly a heel striker.

A major part of running form is the part of the foot that strikes the ground first. Runners can either strike the ground with the ball of the foot first (fore foot strike) or the heel of the foot first (rear foot strike). Virtually all novice runners run as heel strikers according to a recent study (Footstrike patterns among novice runners wearing a conventional, neutral running shoe, 2013.  Bertelsen, et al.).  However, many runners convert over to fore foot strike running at some point in their running career due to natural changes in running form or because of encouragement from coaches or the media. A study by a team at Harvard has put a lot of focus on the benefits of running barefoot and forefoot striking; however, the study received an undisclosed amount of funding from Vibram, the shoe company that makes the popular barefoot running FiveFinger shoes.  So what is better? For preventing injury, forefoot running has an advantage because it reduces the body's impact with the ground. However, a study published this month in the Journal of Applied Physiology found no difference in running economy between natural heel strikers and forefoot runners (Economy and rate of carbohydrate oxidation during running with rear foot and forefoot strike patterns, 2013. Gruber, et al.).

In the study, the researchers analyzed running economy using two measures: VO2 and %CHO. VO2 is a measure of oxygen consumption and can be used as a gauge of total energy output during aerobic work. %CHO is the percent of total energy that comes from carbohydrates. As the intensity of exercise increases, the body relies on carbohydrates to supply a greater proportion of energy (as opposed to fats, which take longer to breakdown). Thus, %CHO can be used a rough barometer of of exercise intensity. The study used 37 runners, some of which were habitual forefoot runners and others who were habitual rear foot runners. The habitual rear foot runners and forefoot runners were tested for VO2 and %CHO on a treadmill at three set speeds: slow, medium and fast.  Interestingly, no significant differences were observed in running economy as measured by VO2 between the habitual forefoot runners and habitual rear foot runners. Yet, rear foot runners appear to have an advantage with carbohydrate utilization. Saving precious glycogen stores is critical in endurance races; exhausting the muscle and liver glycogen stores is what causes marathon runners to "hit the wall". The data is depicted in the figure below.

 Group mean net mass-specific rate of oxygen consumption (V̇o2; A) and relative rate of carbohydrate oxidation to total energy expenditure (%CHO; B) for the rearfoot (RF) and forefoot (FF) groups performing their habitual footstrike pattern at each speed.

The study had each group run in the striking pattern that they were not naturally accustomed to. It would be expected that running economy would decrease in the short-term while running in a form one is not accustomed to.  This is because muscles that are not typically activated are needed to adapt to the new form. Habitual rear foot strikers saw a decrease in running economy when they switched over to forefoot running at slow and medium speeds when assessed with VO2. On the other hand, habitual forefoot runners saw no significant change in running economy at any speed when they switched to rear foot running. This might suggest that if you are a habitual rear foot runner, you don't want to switch to forefoot running on race day. This data can be seen in the figure below.

Group mean net mass-specific rate of V̇o2 (A) and relative %CHO (B) of the RF and FF groups performing the RF and FF strike patterns at each speed. Error bars indicate +1 SD. *Significant difference between footstrike patterns within the indicated group (P < 0.05). †Significant difference between groups when performing the FF strike pattern (P < 0.05). ‡Significant difference between groups when performing the RF strike pattern (P < 0.05). §Significant difference between footstrike patterns when the data were collapsed across group (P < 0.05).

The study looked at some other interesting kinematics. No difference in contact time with the ground was observed between groups. Only small differences in stride length were observed. The message here is do what feels good for you.  

A researcher at BYU created slow motion videos of elite runners' foot strikes while racing at the US Olympic Trials. In the videos, there are a myriad of different foot striking patterns. It would be expected that the elite distance runners would share a striking pattern if one form of running was innately better. Rather, running foot strikes appears to be an individualized decision.

Neither of the studies discussed on this blog entry addressed injury prevention.  There may be some merit to the claim that forefoot running can reduce overuse injury, but this is speculative. We are not aware of any research that definitively backs up this claim.

Copyright © 2016  All rights reserved.