The effects of acute static and dynamic stretching on spring-mass leg stiffness

Abstract

Objective: This study investigated the effect of brief static and dynamic stretching on spring-mass leg stiffness in a vertical bilateral hopping task. Method: 38 men and 18 women were randomly assigned to either a natural (NAT; n = 27), or maximal (MAX; n = 29) hopping group. NAT bounced at their self-selected stiffness and MAX were instructed to bounce as stiffly as possible. Hopping was performed at 2.2 Hz on a force plate. After each of four treatment conditions (no stretch, 30 s stretch, multiple (4 ) 30 s stretch, and dynamic stretch), subjects completed three  30 s bouts (2 minute rest periods) of hopping, in a counterbalanced crossover design. Stretches were performed on: gluteals, hamstrings, quadriceps and calves. Spring-mass leg stiffness was calculated as the ratio of peak vertical force to vertical displacement during ground contact. Results: The results revealed that men displayed greater leg stiffness than women (mean difference: 6.04 kN•m-1 ; 95% likely range: 1.94-10.13 kN•m-1), and that MAX produced higher stiffness values than NAT (mean difference: 10.93 kN•m-1 ; 95% likely range: 6.84-15.03 kN•m-1). Although there were no significant effects of treatment (p = 0.85) or time (p = 0.54) on leg stiffness, there was a significant treatment × time interaction (p = 0.015). Nevertheless, post hoc analyses were unable to identify where those differences were. Conclusion: Relative to control, the results of this study showed that brief static stretching or non task-specific dynamic stretching does not affect spring-mass leg stiffness during vertical bilateral hopping.

Dynamic and static stretching on hamstring flexibility and stiffness: A systematic review and meta-analysis

“…In two studies, the intervention methods were not clearly defined and were excluded [ 36 , 37 ]. The outcomes of 3 studies did not meet the inclusion criteria and were excluded [ [38] , [39] , [40] ]. One study had unclear outcome indicators, so it was excluded [ 41 ].…”