This exact question was answered in a 2012 study by Tim Dorn, & is often quoted by many within running, including ourselves! What they examined in this study was how hard each muscle group worked at increasing running speeds & here are the results: What can we take from these numbers? 🔑 Firstly the soleus (the lower calf muscle does a LOT of work) even at slower speeds they perform upwards of 6.7 times bodyweight of force. 🔑 Generally, the faster the running speed, the more