A number of relevant studies a have been published in the last few days. Rather than add them to that massive backlog of papers I need to write about, I am trying to knock them out quickly. The first one showed no injury differences between barefoot and shod runners; the next one showed no differences in injuries and performance between heel and midfoot/forefoot strikers. Now we have one on the effects of barefoot and shod running on muscle kinetics:
Barefoot and shod running: their effects on foot muscle kinetics
The Foot and Ankle Online Journal 8 (2): 2
Running shoe technology has advanced significantly in the last 50 years, although the overall injury rate has yet to decrease. Barefoot (BF) running has become increasing more popular in the last 10 years. The current investigation aimed to explore differences in the forces produced by the foot muscles during BF and shod (SH) running. Fifteen male participants ran at 4.0 m.s-1 (± 5%). Kinematics were measured using an eight-camera motion analysis system alongside ground reaction forces. Peak and average stance phase forces from the flexor digitorum longus (FDL), flexor hallucis longus (FHL), peroneus longus (PL), extensor digitorum longus (EDL) and extensor hallucis longus (EHL) muscles were obtained using OpenSim v3.2. Peak and average forces of the FDL, FHL and PL muscles were significantly larger when running BF, whereas peak and average forces of the FHL and EHL muscles were significantly larger when running SH. This study supports the conjecture that the plantar muscles are required to work harder when running BF in relation to SH, indicating that BF training may serve to strengthen the foot musculature.
This study collected kinematic and kinetic data on 15 runners who ran barefoot and in the New Balance 1226. The runners were not habituated to barefoot running, so the results need to be considered in that context. The data was then analysed in a simulation program to determine forces generated by different muscles. Obviously, this is a simulation and not a direct measure of the forces generated.
What did they find:
Forces from flexor digitorum longus (FDL), flexor hallucis longus (FHL), peroneus longus (PL) were higher when barefoot running.
Forces from extensor digitorum longus (EDL) and extensor hallucis longus (EHL) were higher when running in the shoes.
This is consistent with other work and theoretically makes sense if you consider what muscles would theoretically work harder when barefoot running or midfoot/forefoot running. This is consistent with what I been banging on about for years: Its six of one and half a dozen of the other: Rearfoot vs Forefoot striking when running.
Where I am going to disagree with the author is one of the concluding lines: “indicating that BF training may serve to strengthen the foot musculature“. Well, yes, that is right, but the opposite could be said about using running shoes to strength EDL and EHL.
What do I take from this:
Barefoot running increases the load and exposes structures associated with FDL, FHL and PL to increased injury risk
Barefoot running can be used to help strength FDL, FHL and PL.
Shod running increases the load and exposes structures associated with EDL and EHL to increased injury risk.
Shod running can be used to help strength EDL and EHL.
This study also confirms that running shoes do not weaken muscles. The fan boys like to liken running shoes to ‘foot coffins’ that weaken the muscles. Based on the above data, barefoot running is going to “weaken” EDL and EHL …. wearing running shoes is going to strengthen them. Additionally, just because FDL, FHL and PL generate higher force when barefoot does not mean that they are being weakened in running shoes (which is what the fan boys will interpret this study as showing). Just the mere fact that you are ‘running’ and being active is going to strengthen those muscles compared to non-runners.
As always, I go where the evidence takes me until convinced otherwise …. barefoot running is not better than shod running; it is just different.