Leg pain pain is a common complaint, especially for people who run a lot. Although running is a great exercise it asks a lot of the muscles in the thigh and hip, and when we have been sedentary for a lot of the day sitting at desks this can be a lot for the body to cope with. A common area for people to experience pain is at the top of the thigh near the pelvis. It often goes with rest only to return as soon as we start training again.
In order to understand what causes this problem we need to know little bit about the muscles around this area. The four main muscles in the thigh (Quadriceps) are mainly concerned with straightening the leg. One of the muscles also helps in assisting the hip flexors which bring the thigh to the front again so we can take the next step forward. However the main hip flexor is a little know muscle called psoas (it’s a silent ‘p’ if you want to impress your friends!). It attaches to the lower back and the inner thigh and can therefore cause problems in both these areas. If this muscle becomes chronically short, for example if we sit a lot, then it can’t operate at its full potential and struggles when we ask it to work hard when we’re running and sprinting.
The reason for the pain at the top of the thigh is often not the psoas muscle itself as this is often working at below full potential, but the small muscle of the quadriceps I mentioned in the previous paragraph. As this assists in flexing the thigh it gets recruited when the psoas isn’t working correctly, and so becomes prone to injury and therefore pain and tenderness. We therefore experience thigh pain from the smaller accessory muscle at the top of the thigh, but it's not because this muscle isn’t working well, it's because it’s working too hard!
To address the problem we need to treat the local inflammation but most importantly the shortened hip flexors. Just treating the injured muscle doesn’t address the root cause and so the injury keeps returning.