Effect of timing of eccentric hamstring strengthening exercises during soccer training : implications for muscle fatigability

The purpose of this study was to examine the effects of a field-based injury prevention exercise on eccentric hamstring strength during simulated soccer match play. Sixteen semiprofessional soccer players (age 21.3 ± 2.9 years; height 185.0 ± 8.7 cm; body mass 81.6 ± 6.7 kg) completed the Soccer-specific Aerobic Field Test (SAFT90), a multidirectional 90-minute exercise protocol representative of soccer match play. Subjects performed 3 maximal dominant-limb isokinetic contractions at 120°•s-1 for concentric knee extensors (conQ) and flexors (conH), and eccentric knee flexors (eccH) before SAFT90 (t0), at half-time (t45), and immediately after the SAFT90 (t105). After baseline testing, subjects were divided into 2 groups, either performing Nordic hamstring eccentric strengthening exercises during the cool-down (CD) or warm-up (WU) of twice-weekly training sessions. After an 8-week intervention program, the baseline testing was repeated. The WU group displayed a significant increase postintervention in eccH gravity-corrected peak torque (PT) and the functional eccH:conQ ratio at t0 (p < 0.01), a significantly greater improvement compared with CD group (p < 0.05). Conversely, the CD group displayed a significant increase in both eccH PT and the functional eccH:conQ ratio postintervention at t45 (p < 0.05) and at t105 (p < 0.05), which were significantly greater increases compared with the WU group (p < 0.05). These findings indicate that the training intervention had a time-dependent beneficial effect on eccentric hamstring strength and that strength training conducted posttraining significantly reduced the negative influence of fatigue.