There are times when you'll pull your hamstring muscle and will have no doubt about the injury. You will feel a surge of pain that forces you to your knees and may require assistance to get you off the track, the field of play or to your couch if you have injured yourself at home. However, there are other times when the pull may not be as severe. You'll be able to save yourself time and pain by taking time off and letting your muscle recover.
Feel for a pull in the back of the hamstring as you break into a jog or a less than full-speed run. This pulling is not normal and could indicate a sprain or a pull in the back of your hamstring. Stop what you are doing and get off the athletic field--this injury is at a critical point. It can heal if you rest it and treat it with ice, but can get severely worse if you try to "tough it out."
Try to pull your leg up towards your chest. If you cannot get your knee past the level of your hip or you feel extreme fatigue as this is happening, you have a pulled hamstring. Your range of motion will be limited when this muscle is strained. Rest the leg and treat it with ice.
Look or feel for swelling in the back of the leg. The swelling may or may not be visual, but it will feel like your hamstring muscle is too thick for your skin if the hamstring is pulled.
Look for discoloration and bruising in the back of the upper leg. This is often a tell-tale sign of a pulled hamstring. In some cases, this may be the result of taking a blow in the back of the leg or it can come from taking a misstep. In the case where the bruise shows up before significant pain or discomfort, it is essential to get off the field of play and ice the injury to reduce the swelling immediately.