Examining the Impact of Supramaximal Eccentric and Long-Lever Isometric Training Protocols on Isometric Hamstring Strength, Nordic Hamstring Performance, and Sprint Speed

Abstract

The aim of this study was to compare the effects of a 6-week higher-volume eccentric training protocol with a combined lower-volume eccentric and long-lever isometric protocol on posterior chain strength and sprint performance. Thirty-three NCAA Division II soccer players (men: n = 17, age = 19.7 ± 1.2 years, height = 178.9 ± 6.6 cm, body mass 79.8 ± 8.1 kg; women: n = 16, age = 20.1 ± 0.9 years, height = 166.7 ± 5.2 cm, body mass = 67.0 ± 12.1 kg) were allocated to either group via exhaustive minimization. Nordic hamstring exercise break-point angle (NBPA), rapid isometric hamstring strength (LLB), 20m sprint performance, and continuous angular knee extension velocity waveforms were assessed pre- and post-intervention, and following a 2-week detraining period. A significant main effect of time was observed for sprint, NBPA, and rapid isometric strength (p < 0.05); however, Bonferroni-corrected within-group comparisons reached significance only for sprint performance in both groups, with no significant between-group differences for any outcome. Equivalence testing supported comparable sprint adaptations between protocols but could not be established for eccentric or isometric hamstring strength. All discrete outcome measures were largely maintained or continued to develop following the detraining period though range-specific eccentric strength appeared more sensitive to the training cessation. A combined low-volume eccentric and isometric training approach may represent a viable alternative to higher-volume eccentric programming for hamstring strength and speed development, although this should be approached cautiously to preserve neuromuscular qualities relevant to hamstring injury risk mitigation.