Does marathon training weaken your feet?

Running can be tough on your feet, and anyone who’s ever finished a race with a black toenail, dealt with plantar fasciitis, or even just hobbled through a long run with painful blisters can attest to that. Marathon running in particular, thanks to the hours of pavement-pounding required to train for and compete in a marathon, can really do a number on your feet. A recent study, published in the Scandinavian Journal of Medicine and Science in Sports, explores exactly what happens to runners’ feet during a marathon and warns runners to take recovery seriously to avoid developing chronic injuries.

The muscles of your feet

There are two main types of muscles in your feet–intrinsic (which means the muscle originates and inserts in the foot) and extrinsic (which means the muscle originates in the lower leg and inserts into the foot through the ankle). Together, these muscles stabilize your arch. The researchers in the study looked specifically at what happens to these intrinsic and extrinsic muscles during a marathon, and how that impacts the arch of the foot.

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The study

The researchers recruited 22 college runners who ran multiple times per week, who had registered for a marathon (in this case, the Mt. Fuji Marathon in either 2019 or 2021). Using MRI technology, the researchers assessed the participants’ feet four times before the marathon, then one, three and eight days after the marathon.

The researchers found that, after the race, several of the intrinsic and extrinsic foot muscles that they assessed before the marathon had weakened significantly and the runners’ arch height had decreased, as well. The researchers noted that the extrinsic foot muscles appeared to show more damage than intrinsic foot muscles. This is likely due to the pressure you put on your ankle joint when running long distances.

The takeaways

If you’ve ever run a marathon, it will not come as a shock to you that marathon running does some damage to your feet. Whether you’re running a marathon or a 5K, this study highlights the importance of prioritizing strength training and recovery strategies that specifically target the muscles in your feet and ankles to avoid injuries. 

“Since more people are now running for their fitness, our findings can provide runners and sports professionals insights on planning better recovery strategies focusing on muscle fatigue and damage to prevent running-related injuries and also improve runners’ conditioning,” says Professor Mako Fukano, one of the authors of the study.

These small muscles are easy to forget about and leave out of your strength and conditioning work, but taking care of them can go a long way in preventing injuries and helping you to run stronger, faster and longer. If you think your feet need some attention, consider booking a visit with a physiotherapist or podiatrist, who can find your areas of weakness and help you create a plan to keep your feet and ankles strong and healthy.