Sprint Acceleration Mechanics: The Major Role of Hamstrings in Horizontal Force Production

Abstract

Recent literature supports the importance of horizontal ground reaction force (GRF) production for sprint acceleration performance. Modeling and clinical studies have shown that the hip extensors are very likely contributors to sprint acceleration performance. We experimentally tested the role of the hip extensors in horizontal GRF production during short, maximal, treadmill sprint accelerations. Torque capabilities of the knee and hip extensors and flexors were assessed using an isokinetic dynamometer in 14 males familiar with sprint running. Then, during 6-s sprints on an instrumented motorized treadmill, horizontal and vertical GRF were synchronized with electromyographic (EMG) activity of the vastus lateralis, rectus femoris, biceps femoris, and gluteus maximus averaged over the first half of support, entire support, entire swing and end-of-swing phases. No significant correlations were found between isokinetic or EMG variables and horizontal GRF. Multiple linear regression analysis showed a significant relationship (P = 0.024) between horizontal GRF and the combination of biceps femoris EMG activity during the end of the swing and the knee flexors eccentric peak torque. In conclusion, subjects who produced the greatest amount of horizontal force were both able to highly activate their hamstring muscles just before ground contact and present high eccentric hamstring peak torque capability.

Kinetic demands of sprinting shift across the acceleration phase: Novel analysis of entire force waveforms

“…A smaller touchdown distance and lower horizontal velocity of the foot (relative to the ground) are considered to be mechanisms to reduce braking impulse, by creating a more “active touchdown” . In a previous study by Morin et al, an athlete's ability to activate their hamstring muscles during late swing phase along with the capacity to produce high eccentric hamstring torques was associated with higher average antero‐posterior forces during the stance phase. Moreover, energy absorption at the knee during late swing (presumably involving work carried out by hamstrings) was previously suggested to be responsible for continuing acceleration at near maximal velocities, which could be linked to a decrease in forward horizontal foot velocity prior to touchdown and a more active touchdown.…”

Sprint versus isolated eccentric training: Comparative effects on hamstring architecture and performance in soccer players

“…In addition to its potential role in preventing posterior thigh muscle strains, hamstring muscle strength has been suggested as an important factor to improve sprinting performance in soccer as a horizontal force producer [15,16]. During the acceleration phase of sprinting, forward orientation of ground reaction force (GRF) has been shown to be the most powerful determinant of field sprint performance compared to the overall magnitude of vertical or resultant GRF [17]. Recently, Morin et al [17] have shown that hamstring EMG activity during the swing phase and eccentric knee flexor peak torque were related to the amount of horizontal GRF produced during treadmill sprint accelerations converting the hamstrings as a key muscular determinant of sprint acceleration performance.…”

“…During the acceleration phase of sprinting, forward orientation of ground reaction force (GRF) has been shown to be the most powerful determinant of field sprint performance compared to the overall magnitude of vertical or resultant GRF [17]. Recently, Morin et al [17] have shown that hamstring EMG activity during the swing phase and eccentric knee flexor peak torque were related to the amount of horizontal GRF produced during treadmill sprint accelerations converting the hamstrings as a key muscular determinant of sprint acceleration performance. These results suggest that the conjunction of hip extensors (hamstrings in particular) torque capability and degree of activation during the swing phase, is a key muscular determinant of sprint acceleration performance [17].…”

“…Recently, Morin et al [17] have shown that hamstring EMG activity during the swing phase and eccentric knee flexor peak torque were related to the amount of horizontal GRF produced during treadmill sprint accelerations converting the hamstrings as a key muscular determinant of sprint acceleration performance. These results suggest that the conjunction of hip extensors (hamstrings in particular) torque capability and degree of activation during the swing phase, is a key muscular determinant of sprint acceleration performance [17]. This important role of the posterior thigh muscles during sprinting could partly explain the altered capability to produce horizontal force at low speed during the first meters of the acceleration phase shown by soccer players after return to sport from a hamstring injury [18].…”

Commentary: Tensiomyographic Markers Are Not Sensitive for Monitoring Muscle Fatigue in Elite Youth Athletes: A Pilot Study

“…Therefore, the measures that Wiewelhove et al implemented to assess peripheral muscle fatigue (lower limb muscle soreness and CMJ height) likely reflect significant fatigue of other muscles, but not the RF. This is not surprising as many other hip/knee extensor and flexor muscles are involved in sprint-related exercises (Morin et al, 2015). If these other muscles were tested with TMG we argue that TMG markers would have been sensitive enough to detect peripheral muscle fatigue.…”