We have all seen the claims on blogs, in articles and on places like You Tube that running shoes weaken muscles and that is why we should not be using the big bulky motion controlling running shoes. The claims are made quite regularly and with a certain amount of assertiveness that you would have to believe that those making the claims actually have some evidence to back up the claims, but they don’t. Don’t you think that the onus is on those making the claims to come up with the evidence? Have you noticed that they never do?
Do running shoes weaken muscles? Consider these points:
- There is no evidence that they do
- If a non runner starts running tomorrow in the most bulky motion controlling running shoe, surely their muscles are going to get stronger and not weaker? How is that shoe actually going to weaken the muscles if they are using the muscles more by running?
- Critics of the big bulky motion control running shoes like to point out that the evidence shows that, in general, they do not really control motion (and they are right; I will do a future article on that). If the shoes are not controlling any motion, then the foot must be moving, so how is that going to weaken the muscles? Do you see the hypocrisy of having this one both ways?
- As discussed here a paper presented at the 2012 ACSM meeting that showed that: “ barefoot running does not result in greater activation in these muscles compared to running shod. This suggests that barefoot running may not result in strengthening of the foot intrinsic muscles“, so if there is no difference in muscles activation, how do shoes weaken the muscles?
- The most motion controlling footwear are probably ski boots; no one is raising concerns nor is anyone seeing an epidemic of weak feet in skiers!
- If it was the case, then you would expect to see more pronated/flat feet in runners compared to the general population. There is no evidence nor are there any reports of more flat/pronated feet in runners compared to the general population.
- Three studies have looked at foot orthotics and muscle strength. Two have shown an increase and one no change, so the evidence is that foot orthotics do not weaken the muscles. As running shoes are allegedly less supportive than foot orthotics and if foot orthotics don’t weaken the muscles than how do running shoes do it?
I have no doubt that barefoot or minimalist running does strengthen some muscles more than running in shoes, but that does not mean they were weak to start with and neither does it mean that running shoes weaken muscles. In fact, it has been shown that the anterior tibial muscle is less active in forefoot striking, so that means that this muscle will get relatively weaker in those who forefoot strike while barefoot or minimalist running. Some muscles are used more to forefoot strike and some are used less, so this makes a mockery of the blanket claim that barefoot running strengths the muscles, when some muscles are used less!
What does the evidence say about running shoes and muscle strength? We now have this study:
Athletic training with minimal footwear strengthens toe flexor muscles
Jan-Peter Goldmanna, Wolfgang Potthast & Gert-Peter Brüggemann
During the propulsive phase of human locomotion, long and short toe flexor muscles (TFM) are exposed to mechanical stimuli caused by ground reaction forces. Further, flexible footwear seems to facilitate increased loading on foot structures. The purpose of the study was to evaluate the effects of high intensity athletic training with minimal footwear on TFM strength. Forty-seven female sport students participated and were randomly divided in three groups: the experimental group (EG; n = 18; 25 ± 5 yrs, 59 ± 6 kg) and the training control group (TG; n = 18; 23 ± 2 yrs, 64 ± 6 kg) performed high intensity athletic training (3 weeks, 5 times per week, 30 min per session) on the forefoot. The EG wore a minimal shoe, the TG performed the exercises with traditional training shoes. The basic control group (CG; n = 11; 27 ± 5 yrs, 63 ± 7 kg) participated in no training programme. To evaluate the training effects on TFM strength, maximum metatarsal phalangeal joint (MPJ) plantar flexion moments during maximal voluntary isometric contractions (MVIC) at 0° and 25° MPJ dorsal flexion were measured in a custom made dynamometer before and after the training intervention. The results showed that (1) in 0° MPJ dorsal flexion, MPJ moments were significantly increased in the EG (p < 0.01) and TG (p < 0.05) and differed significantly to the CG (p < 0.05); (2) in 25° MPJ dorsal flexion, TFM strength was significantly increased in the EG (p < 0.01), but not in the TG and CG (p > 0.05). In this joint angle position the EG significantly differed from the TG and CG (p < 0.05). The results of the study show that athletic exercises with minimal footwear strengthen TFM after three weeks intensive training.
This study compared toe flexion strength in a control group, a traditional shoe group and a minimalist group. They claimed that the study showed that the minimalist group got stronger than the traditional shoe group and the control group. Note that the strength in the traditional running shoe group did not go down (it actually went up!), so we have some evidence that running shoes do not weaken muscles and strengthens them! (which supports the points I made above). The results in the paper claim that the minimalist group did get stronger, but the results are not as clear as stated as the authors used repeated measure t-tests (rather than an ANOVA) to do within groups comparisons which is not how you are supposed to analyze a randomized controlled trial. They should have done a between groups comparison (which is what the CONSORT statement and how every textbook on randomized controlled trials says you should do). Until we see the results of a between groups analysis the claims in the paper can not be verified as the minimalist group actually doing statistically significantly better, but they probably did. However, the study showed in the within groups analysis that the traditional running shoe group did not get weaker and got stronger which is evidence that contradicts all the unsupported claims that we see and hear on running shoes weakening muscles.
As always, I go where the evidence takes me until convinced otherwise, and the evidence tells me that running shoes do not weaken the muscles.
Goldmann, J., Potthast, W., & Brüggemann, G. (2013). Athletic training with minimal footwear strengthens toe flexor muscles Footwear Science, 5 (1), 19-25 DOI: 10.1080/19424280.2012.744361