Using Acceleration as a Tool for Hamstring Rehabilitation
Over the course of the last three years we’ve worked with a ton of high level basketball players as you may have seen. I’ve talked in detail about the negative ramifications of high level basketball players playing in so many games, practices, and skill sessions.
This includes (but not always) over extended anterior pelvic tilts, upper compression of anterior ribs, knee pain, and QL pain. Obviously all connection points based on the demands of their sport. A majority of the time is spent in late stance push off in gait which can cause all of the aforementioned pathologies. There’s been a resurgence in popularity in PRI and the likes in helping solve and rehabilitate pain. However, due to the lack of knowledge I don’t see a ton of talking points on acceleration to be used as a means of rehabilitating and restoring proper gait mechanics to limit the chances of chronic hamstring injuries.
For the most part, rehabilitation professionals must return athletes to the activities required for their sport, particularly at the intensities required to be competitive. Thus, it follows that running and sprinting should be fundamental components of that return-to-play process. Because of the numerous qualities displayed in running and sprinting—high-velocity recruitment, significant force production, eccentric control, timing, coordination, active range of motion, and specific endurance requirements—it not only serves as a highly effective means of preparing athletes for the demands of their sport, but also a very useful screening tool to assess their competence across a broad spectrum of physical and neurological qualities.
Your body can’t go where it already lives. For example, if you are an individual who lifts a ton of weight consistently over time, you probably live in a state of extension, externally rotated femurs, nuated sacrums, and lumbar extension of the low back. In order to generate more force we must pull these individuals back into positions from which they can run/produce power at high velocities.
So When Can Hamstring Injuries Occur?
The most common scenario for running-based hamstring strains is when an athlete is either transitioning to upright high-speed running or trying to maintain upright sprinting posture while running at or near top speed. The position of the upright sprinting stride creates a greater opportunity for rapid lengthening of the hamstrings under tension, eccentrically loading the hamstrings to a point of potential injury. The late-swing phase of upright sprinting creates a significant eccentric load on the hamstrings prior to ground contact. The combination of rapid lengthening and force production on ground contact can cause the hamstrings to strain.
Furthermore, working with basketball players who have longer femurs, longer tibias, and are more fast twitched in nature, it’s especially important to reinforce acceleration mechanics to reduce longer phases of eccentrically loaded hamstrings given how much torque and force is produced so quickly.
As mentioned previously, upright sprinting—even at submaximal velocities—places a significantly greater eccentric stress on the hamstrings. Acceleration, on the other hand, involves greater knee flexion on ground contact, limiting the eccentric stress on the hamstring. The hamstring is still involved in the production of force and the stabilization of the knee joint, but it is not exposed to the same high-risk lengthening experienced in upright sprinting. Thus, an athlete can still benefit from the strengthening forces produced during acceleration through an activity that approaches, but doesn’t duplicate, the mechanics of maximum-velocity sprinting.
Touchdown of the foot plays an important role in relation to one's center of mass in motion. For example, the hamstring is under the most recruitment at 90 degrees of hip flexion. If the foot is in front of the hip (the fulcrum) a greater eccentric load is placed on the hamstring. Whereas, if the foot placement is behind the hip there is more concentric action of the hip and knee and less load on the hamstrings.
While it is common to attribute muscle strains to a strength deficiency, it is often a much more complicated scenario. While it is a good thing to make an athlete strong, it is also very important to combine strength with skill when it comes to muscle recruitment, particularly at high velocities. High-speed sprinting involves a complex arrangement of muscle-firing patterns with a high level of dissociation between the three muscles that make up the hamstring group.
Strength is just force potential.
The technical abilities that we create are the expression of one’s strength and torque abilities. The Neuro muscular and nervous system also must adapt in order to make lasting changes in the brain. Working with youth and professional athletes - the principles and process are the same although the means might be different.
In their 2014 study, “Biceps Femoris and Semitendinosus – Teammates or Competitors? New Insights into Hamstring Injury Mechanisms in Male Football Players: A Muscle Functional MRI Study,” Schuermans et al. examined this concept in greater depth. They found that injured hamstrings demonstrated more symmetrical muscle activation patterns, causing the hamstring muscle bellies to contract less efficiently. They determined that the biceps femoris muscle compensated for the functions of the semitendinosus. Knowing that 83% of running-related hamstring injuries occur in the biceps femoris, we can infer that specific muscle groups are not firing at the correct time during the running gait cycle, creating greater risk to other structures within the hamstring complex.
Most athletes you work with will possess high levels of force due to the nature of their sport or training experience. Biomechanically if these individuals are not working in unison in regards to the entire lower extremity structure - you run into desynchronization of the neuromuscular system. Somewhere down the chain something's gotta give (in sprinting) the hamstrings usually take the cake.