The general causes for why hamstring injuries occur are the lack of warming up or preparation for any physical activity, overall tightness within the muscles, especially in the lower back and hamstrings, and asymmetrical muscle strength, which can be characterized by the imbalance of strength and weaknesses within the hamstring muscles, quads, and/or hip flexors.
The hamstring is a unique muscle group because all of the muscles are biarticular muscles which means they cross two joints. This means that the muscles of the hamstrings are primary movers while acting on two different joints. So most commonly injuries happen to the hamstring when one part of the muscle is shortening and another part is lengthening simultaneously. I will go more in depth into what exactly I mean below.
To make things easier I will define eccentric contraction which is a muscle contraction when the muscle is lengthening and concentric contraction which is a muscle contraction when the muscle is shortening.
Hamstring injuries occur in three different types of actions. One is before your foot touches the ground, when the foot is pushing off the ground and decelerating. First, before your foot touches the ground in a sprint, and your foot is cycling through, there are moments where the hamstring muscle will be flexing during knee flexion and hip extension. When the foot is about to touch the ground, your body goes through hip extension and knee extension. The hamstring is a biarticular muscle, meaning it is a muscle that crosses two joints, and explains why the hamstring is more susceptible to injury. So, when your foot is about to hit the ground, there’s one part of the hamstring muscle going through flexion(shortening) while the other is going through an extension(lengthening).
Also during deceleration there is a quick transfer of weight either backwards or side to side when cutting. During this, knee and/or hip flexion happens too quickly, which creates an imbalance in your center and can cause hamstring injury. Typically because the hamstring is not adequately prepared either from a strength/range of motion perspective or the muscle is not used to the stress.
Hamstring injuries have different grades, or levels of severity. A grade I injury is most likely a strain, with minimal tearing. You should be able to recover for a grade I hamstring injury in a week or two. A grade II tear is where you will have some degree of actual tearing. This is classified more as a hamstring pull, and it will take more time to recover. You should be able to come back in four to eight weeks. Grade III injuries are a complete tear. This is where your whole muscle is fully ruptured. Because a grade III tear is so severe, it can take you six to eight months to fully recover.
Ways to Resist Hamstring Injuries
- Nordic Hamstring Curls: There have been studies that show how these decrease your chances of having hamstring injuries by up to 51%.
- Deadlifts With A Slight Knee Bend: Having less of a knee bend and putting more stretch will allow you to teach your body how to control itself through eccentric stretches, which will help prevent injuries from occurring.
- Good Mornings: Maintaining a good position in the back and creating more stretch within the hamstring will also help the body control itself and have more range of motion.
- Strengthening Your Lower Back, Glutes, Quads, Hip Flexors, and Core: Strengthening these will have a huge impact because your hamstrings are attached to your pelvis, so being able to control your pelvis will take some pressure off the hamstrings. Also, these muscles have a direct relationship with the hamstring, so having them be strong will help you resist hamstring injuries.
- Deceleration Drills, Sprint Variations, Spring Cycle Drills: You want to prepare your body for the physical exertion that will be replicated during the different types of stretching and deceleration actions.