---
title: "Running long distances changes the shape of your feet"
published: 2016-02-08
updated: 2026-08-04
category: "Ciencia"
source: "https://dev-abp.massivoai.com/en/articles/correr-largas-distancias-cambia-la-forma-de-los-pies"
---

# Running long distances changes the shape of your feet

**With each stride we take, our body's weight falls on one of our feet. When we walk or simply when we stand, the same thing happens, but when running the force of impact is much greater and the foot undergoes transformations after long training sessions**.

Blisters, black toenails, and other injuries we suffer especially on those long-distance days can be caused by changes in the shape of the foot while we run. A [recent study](http://www.mdpi.com/2411-5142/1/1/30/htm) analyzed the shape of the right foot of 22 athletes before and after running a 35-kilometer race. The researchers found that after the long training session the shape of the foot had changed in several aspects. 

The arch of the foot, for example, became deformed due to the repetitive loads the foot received during the nearly two hours it took athletes on average to complete the distance (they were elite athletes). The researchers believe that muscle fatigue and changes in the soft tissues of the foot also influence foot deformation after such long training sessions.

Another very relevant discovery from the study was that foot volume decreased after the 35 kilometers, which could negatively affect the comfort and proper fit of running shoes and cause skin injuries. Athletes tie their laces based on the shape of their foot before they start running, but later, when the shape and volume of the foot change, it is not usual to stop and make adjustments, which could cause injuries such as blisters, bruises, or black toenails.

Some studies have found that up to 39% of marathon runners approach medical tents to address blister-related problems, making it a very common issue. The cause of so much discomfort could be in that small "gap" or void that forms when the foot volume decreases after so many kilometers.

The researchers' advice, curiously, is directed at shoe manufacturers and not at athletes. It is unlikely, after all, that runners would stop mid-race to readjust their shoes. The researchers suggest that manufacturers take into account these changes in foot shape so they can design shoes that fit better after many kilometers.

A Buen Paso uses [Massivo](https://massivoai.com), the event-registration platform that powers this article.