Managing Hamstring Tendon Stiffness for Athletes

Hamstring injuries, especially to the biceps femoris long head, remain a leading cause of time-loss in elite soccer. Our understanding of how hamstrings behave across different running tasks and during targeted strength exercises provides critical insights for injury mitigation and rehabilitation strategies. Running Mechanics; Speed & Direction Matter: -       As running speed increases, hamstring EMG activity rises, especially in late swing, peaking over 120% MVIC in some individuals. -       The BFlh is highly active and susceptible to strain as it lengthens under load during late swing. -       Crucially, EMG patterns are highly individual yet consistent across speeds, highlighting the importance of personalized rehab and neuromuscular retraining. -       Turning at speed introduces asymmetrical hamstring loading. -       The outside leg exhibits more braking and greater horizontal forces; the inside leg produces more vertical force with altered joint kinematics. -       Curved sprinting increases lateral trunk lean, pelvic rotation, and ground contact time differences—factors that affect hamstring load distribution and injury risk. -       Rehab must include multiplanar, directionally specific sprint exposure. Exercise Selection Matters: Nordic Hamstring Curl - Produces the highest peak hamstring forces - Causes the greatest fascicle lengthening, especially in the semimembranosus and short head of the BFlh - Highly effective for eccentric strength and increasing fascicle length - Unmatched for eccentric overload and fascicle lengthening, making it ideal for fascicle remodeling. Single-leg Roman Chair - Produces moderate peak forces - Mimics quasi-isometric contraction during late swing phase - Targets BFlh long head and semimembranosus more effectively - Suitable for mid-stage rehab and controlled load progression (transition phases and load tolerance) Single-leg Deadlift - Produces lower peak forces, but with greater range of motion - Leads to the highest mean fascicle length, promoting hip-dominant adaptation - Engages the glutes more while still loading hamstrings - Ideal for late-stage rehab, reconditioning, and return-to-play prep - Support hip-dominant mechanics, useful for terminal rehab and reconditioning. Applied Takeaways: - Rehab Progressions Must Reflect Individual EMG Profiles: Each athlete displays unique activation patterns—assess and program accordingly - Introduce Running Early: Submaximal running can help restore neuromuscular patterns without overloading healing tissue - Don’t Neglect Curved Sprinting: Prepare hamstrings for multidirectional force vectors seen in match play—especially in fullbacks and wingers https://lnkd.in/g_9dxske https://lnkd.in/gyuGnCpv https://lnkd.in/gt23Enza

Participation in athletics provides many benefits for an athlete’s health and athletic performance but is also associated with the unfortunate consequence of potential injury. Soft tissue injuries can be very frustrating to the athlete. This is especially true of hamstring injuries. Fascicle (a bundle of muscle fibers surrounded by connective tissue that make up skeletal muscle) length is a significant indicator of muscle’s capacity for force generation. When injured, the soft tissue damage results in the consequential shortening of fascicles due to the ensuing healing process of the body. Therefore, a component of the athlete’s sports rehabilitation should include the re-establishment of fascicle length. Fascicle lengthening transpires via the application of appropriately prescribed exercise. Exercise results in an adaptation of the muscle to increase in the number of sarcomeres in series within the fascicle, resulting in a longer fascicle (muscle). One method to achieve fascicle length is through the application of eccentric exercise to strengthen the muscle in a lengthened position (Tyler 2014, Schmidt 2012). An increase in fascicle length brings about, (a) improved athletic performance as longer fascicles can enhance the muscle’s ability to store elastic energy thereby improving high velocity performance in activities such as jumping and sprinting, and (b) assists in injury prevention as the lengthened muscle is now working more efficiently while averting overstrain (overstretching of the fascicles/muscle) during athletic performance. One effective method to initiate hamstring fascicle lengthening is through the utilization of a cable column for eccentric exercise execution (see attached video). The athlete is positioned on their back at an appropriate distance from the cable column with the hip flexed at 90°.  With an ankle cuff attached to both the athlete and the cable, a partner passively flexes the knee to 90°. The athlete then actively and slowly extends (eccentrically) their knee with a suitably prescribed cable column weight intensity until achieving full knee extension. The athlete briefly maintains this weight loaded fully extended position followed by the partner passively returning the lower extremity to 90° of knee flexion to repeat the exercise for the prescribed number of repetitions. It may be necessary to initiate the eccentric cable exercise with a hip flexion position of less than 90° (i.e. 70° or 80°) to (a) conservatively introduce the exercise to the athlete, (b) assess the athlete’s tolerance during the eccentric exercise execution (i.e. pain or discomfort), and (c) eliminate the concern (fear) of performing the exercise with the injured extremity. The eccentric exercise is then appropriately progressed over time to be executed at 90°, 100°, and 110° of hip flexion respectively for continued enhancement of fascicle lengthening.

In-Season Hamstring Prep: Building Braking Capacity Most hamstring issues in-season are not caused by a lack of strength. They occur when the hamstrings cannot tolerate or coordinate high-velocity eccentric braking during sprinting—especially late swing. This in-season prep series is designed to maintain force tolerance, timing, and stiffness in the exact positions where hamstring injuries occur, without accumulating soreness or residual fatigue. The progression moves from long-lever isometric force acceptance to rapid limb switching and braking, mirroring the demands of max-velocity sprinting. Supine Long Lever Hamstring Bridge PIMA This is the foundation of the series. With the knees near extension, the hamstrings are placed at long muscle lengths while producing high isometric force through the posterior chain. Key qualities developed: • Long-length force tolerance • Posterior pelvic control • Reduced reliance on lumbar extension Sprint relevance: Late swing occurs with the knee nearly extended and the hamstrings under maximal strain. This drill restores confidence and capacity in that position without the cost of eccentric soreness. Single-Leg Supine Long Lever Hamstring Bridge PIMA Now we introduce asymmetry and limb specificity. Single-leg loading increases: • Relative force demands • Pelvic control requirements • Limb-to-limb accountability Why this matters: Sprint mechanics are unilateral. This drill exposes deficits that bilateral work can hide, ensuring each hamstring can tolerate long-length force independently. Supine Double-Leg Hamstring Catches This is where the series transitions from static capacity to dynamic braking. The athlete rapidly accepts load into knee extension and “catches” the position, emphasizing: • Fast eccentric deceleration • Posterior chain stiffness • Controlled energy absorption Sprint transfer: This closely mirrors the rapid braking action required during late swing as the foot prepares for ground contact. Single-Leg Supine Hamstring Catches Here we narrow the focus to unilateral eccentric braking. Single-leg catches demand: • Faster force acceptance • Greater pelvic stability • Precise timing at high strain rates Why it’s critical in-season: Most hamstring injuries occur during unilateral sprint actions, not symmetrical positions. This drill builds tolerance without excessive volume or fatigue. Single-Leg Supine Hamstring Switches This is the most sprint-specific element of the prep. Rapid alternating catches and releases introduce: • High-speed limb switching • Coordinated eccentric-to-concentric transitions • Trunk and pelvis stability under speed Sprint relevance: This closely resembles stride-to-stride transitions at max velocity, where timing errors—not strength deficits—lead to tissue overload. How I Use This In-Season • Pre-practice: prime braking capacity before sprint exposure • Intra-lift: paired with speed or power work • Micro-dose sessions: high-velo non-lift days