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The Running Muscles

Which muscles do we actually use when we run?

by My Finish Line

If someone tries to explain which muscles we use when we run, to save time is it easier to try and think of the ones that we don’t. The heart, obviously, is the most important of them all, but there are dominant muscle groups that play a part in the biomechanical efficiency of running.

The engine of a boat is always in the back in order to propel it forward, and to use that metaphor the glutes and hamstring are quite probably the most crucial body of muscles when we break our strides down in a biomechanical sense. Before you all rush out to perform hamstring curls or glute bridges, breaking down how the body uses these muscles is key in order to understand how we can make little fixes that will make us better.


When our foot strikes the floor, the hamstrings are in an ‘isometric state of contraction’. What that means is you are not extending them (like you would do when kicking a football), or contracting them (like you would do with your arms in a bicep curl), but applying force when they are fully extended, rigid, and against an immovable object (i.e. the earth). What the hamstrings do to the floor when you run is similar to what your arms and shoulders do to a wall if trying to push a house down – that is, apply significant force without neither contraction or extension of the muscle. Of course, this force does go somewhere, and that is into the floor in order to propel you the athlete up and forward. What has been proven is that it is in this isometric state it is best to strengthen a hamstring. Enter Romanian Deadlifts (check out our workout generator) and isometric hamstring exercises of which the internet can provide ample examples. This not only bullet-proofs the hamstring from injury, but also replicates the action of the muscle that it performs when we actually run.

The Illiopsoas

The where? They are more commonly referred to as the hip flexor muscles. It is (they are) composite muscles that you feel at the front of your body at hip level like two huge strong elastic bands* going from your hips to your quads. (*anatomy majors this is your time to wince and/or tut-tut profusely). These muscles are so important for running that cross-sectional analysis of elite runners have found these to be so developed and trained in elite runners as to be twice the size and strength than found in others. To place that into its context, if our hamstrings were twice the size and strength as other people; we would simply never be able to fit into any jeans and if our calves were twice as big we would walk around looking like we had over-sized egg timers for legs. The reason the hip flexors are so developed in elite runners is that the force absorption of top end sprinting (which, by the way can be used to describe the last lap speed capacities of a Paula Radcliffe or Mo Farah as much as normal ‘sprinters’) is so high and the strength demands placed upon the hip flexors so great as far as power and coordination that they become incredibly developed as a by-product of the act of running. Also, strengthening these is a key part of elite running protocol. (see – stair runs / high knee drills etc).

So there we have it. Biomechanics of running in less than 600 words.