Conceptual framework for strengthening exercises to prevent hamstring strains

High-speed running accounts for the majority of hamstring strains in many sports. The terminal swing phase is believed to be the most hazardous as the hamstrings are undergoing an active lengthening contraction in a long muscle length position. Prevention-based strength training mainly focuses on eccentric exercises. However, it appears crucial to integrate other parameters than the contraction type. Therefore, the aim of this study is to present a conceptual framework based on six key parameters (contraction type, load, range of motion, angular velocity, uni-/bilateral exercises, kinetic chain) for the hamstring's strength exercise for strain prevention. Based on the biomechanical parameters of sprinting, it is proposed to use high-load eccentric contractions. The movement should be performed at a slow to moderate angular velocity and focused at the knee joint, while the hip is kept in a large flexion position in order to reach a greater elongation stress of the hamstrings than in the terminal swing phase. In this way, we believe that, during sprinting, athletes would be better trained to brake the knee extension effectively in the whole range of motion without overstretch of the hamstrings. Finally, based on its functional application, unilateral open kinetic chain should be preferred

Optimising Hamstring Strength and Function for Performance After Hamstring Injury

Hamstring strain injury often results in neuromuscular performance deficits that persist beyond rehabilitation and the return to full training and competitive sport. It seems appropriate to address these deficits as a part of a sport-specific training program which primarily aims to enhance performance. Prolonged deficits in horizontal ground reaction forces in sprinting, repeat sprint performance, knee flexor eccentric strength and biceps femoris long head fascicle lengths have been observed in multiple studies of hamstring strain injury. Why such deficits persist beyond the return to sport is not known, although persistent neuromuscular inhibition of the injured muscles has been proposed. There is limited and mixed evidence for sprint running kinematic (technique) differences between previously injured and uninjured limbs or athletes, although more work in this area seems warranted. While there is some uncertainty about the optimal mix of methods for addressing the aforementioned deficits, sport-specific running programs in conjunction with continued monitoring of acceleration phase sprint performance and repeated sprint ability seem appropriate. Heavy strength training with at least some eccentrically biased exercises is also recommended to address deficits in eccentric strength and muscle fascicle lengths