What causes hamstring injuries? If you read articles on this topic, invariably you will be told that overstretching or forcefully stretching the hamstring can strain or tear the muscle or cause sharp pain, spasm, swelling and bruising. If it hurts to run or if your hamstrings are bruised and tender, the diagnosis is overtraining, muscle tightness and fatigue. If you have pain while walking but not running, the diagnosis is possible low back injury.
You may also read that inflexible hamstrings limit motion and stress the lower back. If you have knee pain, it may be due to hamstring tightness (or weakness) because the knee has to work harder to perform extension movements. Some reports even state that the hamstring injuries are due to excessive strength of the quadriceps or simply an imbalance between the quadriceps and hamstrings.
If these symptoms were indicative of the true causes of injury and if everyone followed the recommendations for fixing them, (that typically include stretching and general strengthening); the number of hamstring injuries should decrease greatly. But we do not see this. Instead, injuries continue to occur, and, in some cases, are even more severe. It appears that once you have a hamstring injury the chances of getting another hamstring injury are increased.
It is rare to find a baseball, football, soccer, lacrosse or basketball team with no hamstring problems! Many teams, including professional ball clubs, continually lose great players for months because of hamstring injuries. It has gotten to the point where most teams now believe that hamstring injuries are “part of the game.” But does it have to be this way? The answer is no if you examine how the hamstrings are involved and how they can best be strengthened in a manner that is specific to the execution of various sports skills.
The problem is in a lack of understanding of how the hamstrings act during the execution of different skills. It is now possible to find reports stating that is the eccentric contraction, or more accurately the forced eccentric contraction, that is the culprit in hamstring injuries. I have been saying this for years (see first edition of Explosive Running published in 2000) so it is heartening to see others now beginning to comprehend this very important role of the hamstrings.
For example, in running or when taking a quick first step, when you drive the knee forward, the hamstring undergoes a forced eccentric stretch at the hip joint. When the shin whips out, there is an even greater eccentric contraction of the hamstrings and tendons at the knee joint. These eccentric contractions are needed to prepare (tense) the hamstrings for the pawback movement, the main force-producing action to drive the leg down and back to make contact with the ground and propel the body forward.
But what happens to the switching of the eccentric-concentric contraction at the hip and knee joints if they misfire when the player has incorrect running technique? For example, when the athlete tries to contract the hamstrings in the pushoff rather than relaxing them as occurs naturally in effective running. This is where it is necessary to pay more attention to see what the athlete does and if it is effective. In other words, it is the improper technique that is creating the problem and causing the injury.
Keep in mind that most injuries have a neuromuscular base. It is not simply a matter of how strong a muscle is. It is the firing of the nervous system and contraction of the muscles that determine how the skill is executed. Most important in regard to the hamstrings is how the muscles and tendons act during the execution of the pushoff in running and cutting. Muscle strength is very important but only in its role the timing and force of the muscle contractions.
Constantly stretching the hamstrings does little if anything to prevent injury, mainly because you do not need a great deal of hamstring flexibility. When you drive the thigh forward, the knee is bent which gives slack at the hip end of the muscle to give you an ample range of motion. Static overstretching creates conditions that do not allow the hamstring to function properly. Recent studies indicate that tighter hamstrings are more conducive to better performance and prevention of injury.
In regard to tight hamstrings causing back problems, I have yet to see a player who has such tight hamstrings that he does not have normal curvature of the spine. In other words, if the spine is held in its normal anatomical position while running, the hamstrings cannot be considered too tight to cause the back to flatten. Any back flattening or slight rounding in the lumbar area that occurs should be when the body is in full support on the ground at which time the hamstring at the hip joint is stretching (hip flexion) and thus, cannot be “too tight.” If you can do a half to three-quarter squat while maintaining normal spinal curvature, you do not have excessively tight hamstrings.
Constantly stretching the hamstrings as many players do is often the cause of many running injuries. Many players are proud of the fact that they can touch their toes when they bend over with straight legs or can raise their leg up onto a rail and then bend over and touch the foot with the fingers. However, in these exercises, because you have a rounded back to reach this far you overstretch the ligaments of the lumbar spine more than you stretch the hamstring. As a result, you end up with a looser back more prone to injury, rather than a safer or stronger back or hamstring muscle.
Athletes need strength with flexibility. Thus, instead of doing mainly static stretches, you should do strength exercises that simultaneously stretch the muscles and connective tissue in the same exercise. For example, doing the good morning exercise stretches the hamstrings eccentrically at the hip joint on the down phase, when you maintain normal spinal curvature. When you rise up, you strengthen the muscle in the concentric contraction. Some athletes prefer doing an analogous exercise on the Yessis Glute Ham Back machine with the legs in motion or with the trunk in motion.
In these exercises you stretch and strengthen the hamstring muscles in the same exercise. If you can not achieve a 90° angle in the hip joint, while still keeping the back in its normal anatomical position, lower the trunk as far as possible. In time you develop the necessary flexibility and strength to go through the full range of motion. This is known as active stretching, the kind that all athletes should practice.