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Hamstring injuries are one of the most injured muscles in the lower extremity that plague both elite and recreational athletes alike. The hamstring muscle is extremely susceptible to injury, in activities that require high speed running, jumping, kicking, rapid changes in direction, or lifting heavy objects from ground level. Hamstring injuries heal slowly and tend to recur, inconveniencing athletes again and again.
In a new article by The Journal of Orthopaedic and Sports Physical Therapy, the author has provided the most recent and updated research on hamstring injuries in athletes. I have dissected the new research and broken down why exactly hamstring injuries occur and how we can avoid these stubborn injuries!
But, first let’s take a look at the hamstring’s anatomy and functions:
The hamstring is a muscle complex that is composed of three different muscles: Semitendinosis, semimembranosis, and biceps femoris (the most commonly injured) which has two parts- the long head and short head.
The hamstring originates from the base of your pelvis on the ischial tuberosity (our sit bones) and inserts behind the knee on the tibia or fibula, making it bi-articular, meaning that it crosses two of our joints- the hip and the knee. The primary role of the hamstring is to extend the hip, adduct the thigh, and flex or bend your knee. Your hamstrings are also extremely important for dynamic knee stability, working with the anterior cruciate ligament to prevent the anterior translation of your tibia during heel strike. [2] Without a proper functioning hamstring, athletes have a difficult time controlling how they land during running,. They are unable to get their leg through the entire gait cycle and are unable to bear weight through the leg properly.
Our skeletal muscles consist of two types of muscle fibers, Type I (slow) and Type II (fast). The hamstrings have been found to contain a much higher percentage of Type II fibers, which make the muscle more susceptible to injury [3]. Hamstring injuries commonly occur due to be overstretched or overloaded by taking on more load than the muscle is prepared to handle. Injuries can range from microscopic tears or strains (grade I), moderate or partial tears (grade II), or a severe or complete tear of the muscle (grade III).
What does an injury to the hamstring feel like?
Injury to the hamstring can present in many different ways. Pain that is coming from the hamstring typically presents as posterior thigh pain that increases with bending or straightening your knee, bending forward at the waist, with prolonged sitting, walking, or running. Injured hamstrings normally have soreness or painful spots to the touch along the length of the muscle and are painful with end range stretching and/or resisted testing, meaning that it would hurt to stretch or strengthen it. However, it is extremely important to know that posterior thigh pain may or may not be due to the hamstring. Posterior thigh pain can also be caused by the lumbar spine, hip joint, sacroiliac joint, neural tension, and with posterior hip muscle pathology including the gluteal muscles, piriformis, obturator externus, and obturator internus. All of these tissues refer pain to the posterior thigh and can closely mimic symptoms of a hamstring injury. With that being said, it is important to seek out an evaluation from a physical therapist or an orthopedic physician to properly diagnose the root cause of your posterior thigh pain.
Who is most at risk for injury?
Common risk factors for hamstring injuries [1]:
Previous hamstring injury
Research has shown that with a previous hamstring injury puts individuals at a 2-6x higher rate of re-injury to hamstring! This makes injury prevention of hamstring injuries extremely important! If it’s too late and you have already experienced an injury to your hamstring, have no fear! This is your official sign to get in to see your PT to bullet proof that hamstring to make sure no further injury occurs later.
Increase in age
Athletes over 25 years in age
Decreased muscle fascicle length (We’ll talk about how to improve this later)
High-speed running demands
Altered running or gait mechanics
Studies have shown that hamstrings are active for almost the entire gait cycle with peak activation during the terminal swing phase and early stance phase [3]. Common gait deviations such as over striding or too much anterior pelvic tilt can increase load or stretch of the hamstring muscles
Muscle imbalances
Quadricep to hamstring muscle imbalances have been identified as risk factors in some research, as well as altered trunk and gluteal muscle activity. It can be very common to have under-active gluteal muscles resulting in overactive hamstrings, predisposing them to injury.
Previous ACL injury
The hamstring works in conjunction with our anterior cruciate ligament (ACL) in our knee to help stabilize the knee. If the ACL is compromised, the hamstring automatically has to increase its workload to provide sufficient stabilization of the knee, which can lead to injury.
How can we prevent this from happening?
Strengthen, strengthen, strengthen!
Properly loading the hamstrings through resistive training is extremely important so the muscles can handle the load that is being placed on it during any high-level exercise. Specifically eccentric hamstring strengthening! The research shows that the best way to decrease risk of hamstring injury is to incorporate eccentric hamstring strengthening into strength training. What is this eccentric strengthening that we speak of? An eccentric contraction is when the muscle is lengthening as it is resisting forces. For example, if you are performing hamstring curls, the eccentric contraction is when you are slowly releasing back to a straightened position. Eccentric hamstring exercises help to improve hamstring fascicle length and eccentric hamstring strength. Some of my favorite hamstring strengthening exercises include single leg bridging, Nordic hamstring curls, hamstring curls with slow return to start position (take a full 3-5 seconds to return to start position), and single leg Romanian dead lifts.
Improving motor control
Specific exercises to improve core and gluteal activation during exercise to decrease overactivity of hamstrings as prescribed by a physical therapist or trainer
Proper dynamic warm up before activity
A good warm up before activity plays a huge role in decreasing risk for hamstring injury. Think of your muscles as a batch of noodles. If these noodles are fresh out of the box and not warmed up, they are easily breakable. Once you get the batch of noodles warm, they instantly become much more pliable! The same concept for warming up muscles applies. Properly warmed up muscles improves the extensibility of the muscle which reduces the possibility for injury to the muscle with high impact activities.
Improving hamstring extensibility
Dynamic hamstring stretches and improving hip mobility are key factors to improving hamstring extensibility. Foam rolling or rolling over a lacrosse ball can also be helpful in improving hamstring extensibility. Incorporating these activities before and after training sessions or competitions can improve hamstring flexibility and extensibility. Incorporating eccentric strengthening also helps improve hamstring fascicle length.
If you participate in any activities where hamstring injuries are common, use these prevention tips to keep those hamstrings healthy and strong! An injury to this muscle can be debilitating to anyone’s athletic performance, and we want to keep you active! A physical therapist or strength training professional can help develop an optimal training program. If you unfortunately injure your hamstring or are consistently trying to recover from recurrent hamstring injuries, don't let hamstrings be a pain in your butt! Get in to a physical therapist as soon as possible for evaluation, treatment, and prevention of further injury to get you back to the activities you love!
References:
1. Martin RL, Cibulka MT, Bolgla LA, et al. Hamstring strain injury in athletes. Journal of Orthopaedic & Sports Physical Therapy. 2022;52(3). doi:10.2519/jospt.2022.0301
2. Koulouris G, Connell D. Hamstring muscle complex: an imaging review. Radiographics. 2005 May-Jun;25(3):571-86.
3. Opar DA, , Williams MD, , Shield AJ. and Hamstring strain injuries: factors that lead to injury and re-injury. Sports Med. 2012; 42: 209– 226. https://doi.org/10.2165/11594800-000000000-00000