Running Muscles: Which Ones Do You Use Most?

Question
Hi, I was wondering which muscles, in the leg, are used more when running? The thigh muscles or calf muscles?

Answer
The answer depends on how you are running. For instance, sprinting involves a lot more knee lift so thigh muscles would get more work. Slower-paced distance running works the back of the thigh and calf muscles more. Terrain makes a difference, too. Running uphill requires higher knee lift again, exercising the front of the thigh a great deal. These are just general guidelines, but they point out why all these running techniques are used by runners to build up the whole leg.