Gesel, FJ, Morenz, EK, Cleary, CJ, and LaRoche, DP. Acute effects of static and ballistic stretching on muscle-tendon unit stiffness, work absorption, strength, power, and vertical jump performance. J Strength Cond Res 36(8): 2147-2155, 2022-The purpose of this study was to evaluate the effects of static and ballistic stretching on muscle-tendon unit (MTU) stiffness, work absorption (WA), strength, power, and countermovement vertical jump (CMJ) performance. Using a within-subject design, 22 subjects performed 3 separate experimental conditions: no-stretching, ballistic stretching, and static stretching for the quadriceps, hamstrings, gluteus, and plantarflexor muscle groups. After each condition, plantarflexor MTU stiffness, WA, isometric strength, and power were measured, followed by a CMJ on a force plate to obtain peak center of mass velocity, peak power, rate of force development, peak force, work, and vertical jump height. Repeated measures analysis of variance with Bonferroni corrected post-hoc tests were used to detect differences between conditions for plantarflexor and CMJ measures. An acute bout of static stretching significantly reduced WA by 12% ( p = 0.049) and isokinetic power by 8% ( p = 0.047) compared with the control condition but ballistic stretching did not ( p = 0.624, p = 0.692, respectively). Significant positive correlations existed between MTU stiffness, WA, strength, and power ( r = 0.64-0.77, p < 0.001). Despite significant positive correlations between MTU stiffness, WA, and CMJ performance measures ( r = 0.40-0.72, p < 0.001), neither static nor ballistic stretching affected CMJ performance ( p > 0.05). These data show that stiffer MTU that absorb more work (energy) are associated with greater muscle force, power, and CMJ performance. Although an acute bout of static stretching impaired MTU passive-elastic properties and power production, neither static nor ballistic stretching impaired isometric strength or CMJ performance.
