Poor Running Mechanics
Learning proper running skills to identify errors in running mechanics. For example, when sprinting, anteriorly rotating the pelvis during acceleration increases tension on the hamstrings, and this tension could result in a hamstring pull.
If you want to learn proper running and don’t have a working background in biomechanics, find an accomplished sprint coach who can teach you how to teach running. A great print resource is Running: Biomechanics and Exercise Physiology in Practice by Frans Bosch and Ronald Klomp (Churchill Livingston, 2005). It’s 424 pages of heavy reading, but it also comes with an excellent DVD that shows how to put the information into practice.
I’ll also mention here that sprinters should avoid running on treadmills – even the fancy high-speed treadmills that many professional sports teams use. Running on a treadmill increases the risk of hamstring injuries because such training decreases the hip extensor function of the hamstrings.
Inadequate Warm-up and Cooldown
Improperly designed workouts can cause hamstring injuries. A proper warm-up is needed to prepare the muscles for sprinting. For example, rather than static stretching, a series of dynamic stretches will more properly prepare the muscles and nervous system for the hard work ahead. Likewise, what you do after a workout is important. After a sprint session, muscles often have a high level of tension – the best time to perform static stretching to relax the muscles is immediately after the cooldown, not several hours later. The "Crossfit" system is designed for this.
It takes years to work up to a high volume of training, and even then athletes must make careful choices in their lifestyles, nutrition and supplementation to safely handle such training methods. So if an athlete is working full-time at a stressful job and walking on concrete all day, then they probably will not be able to train like an Olympian or competitive athlete.
Not Working All Functions of the Hamstrings
The hamstrings have two primary functions: to extend the hip and to flex the knee. One effective exercise to develop both functions is the glute-ham raise. It also can help resolve structural imbalances between the medial hamstrings (semitendinosus and semimembranosus), which rotate the foot inward, and the lateral hamstrings (biceps femoris), which rotate the foot outward. For example, if an athlete runs with their feet turned excessively outward, I would have them perform the glute-ham raise with their feet turned slightly inward. If they run with their feet turned excessively inward, I would have them perform the exercise with their feet turned slightly outward.
Most Chiropractors and physiotherapists will recommend a hamstrings-to-quadriceps ratio of 66 percent, meaning that your hamstrings should be able to produce 66 percent of the force of the quadriceps.
Is there a simple field test to determine your hamstrings to quad ratio? The following field test is correlated to low levels of hamstrings pulls: simply compare your maximal front squat to your back squat. If your front-squat strength is less than 85 percent of your back squat, then you have a structural imbalance. That is of course, assuming that range is FULL, ass-to-grass type of squats.
Further, it’s important to have structural balance not just between the quadriceps and the hamstrings, but between each leg. The strength of the right hamstring should be equal to the strength of the left – this is why it is important to always include unilateral leg exercises such as split squats and step-ups in the workouts for athletes to correct those deficiencies before performing a squat program.
Lack of Eccentric Loading in Strength Workouts
The most commonly injured hamstring muscle is the biceps femoris, so it’s wise to include eccentric training protocols when working this muscle. For example, to increase eccentric loading during a leg curl, you could lift the weight with both legs, and then lower it with just one. Eccentric loading is useful in helping improve sprint performance.
Inappropriate Loading Parameters
One of the primary reasons athletes have weak hamstrings is they use the wrong rep schemes and perform an insufficient volume of work. The hamstrings, especially the biceps femoris, are primarily fast-twitch fibers and respond better to high-intensity exercise. Inappropriate loading parameters that impose insufficient loads will make these fibers more susceptible to injuries during high levels of athletic performance.
Adhesions and Scar Tissue
Adhesions and scar tissue in the hamstrings and associated muscles not only can affect sprinting performance but also are associated with excess tightness that can contribute to hamstring injury. One of the most effective methods of treating this type of soft-tissue problem is with Active Release Techniques Treatment® (ART), which was developed by Dr. Mike Leahy. ART is especially effective in restoring normal muscle function because the area being treated is moved through its optimal range of motion. Often a single treatment can completely restore muscle function, but of course the number of treatments is determined by a variety of factors, including the seriousness of the injury. Personally working under Dr. Leahy and taking ART courses, I have seen the effectiveness of this treatment. Also, implementing into my practice has produced amazing results.
Improper Use of NSAIDS
NSAIDs, an acronym for nonsteroidal anti-inflammatory drugs, are often used to deal with the pain and inflammation associated with hamstring pulls. One problem with using NSAIDs is that they can interfere with the healing of the tissues. Rather than using NSAIDS, there are many effective nutraceuticals that act like drugs without producing many of the side effects associated with drugs. For example, to deal with inflammation, consider effective nutraceuticals such as omega 3 fish oil, vitamin D3 and probiotics.
There are many other possible causes of hamstring sinjuries, but by addressing these issues you’ll greatly reduce your risk of a hamstring injury