OBJECTIVE: This study investigated the effects of an 8-week plyometric training (PT) session on countermovement jump (CMJ) height, take-off velocity, and tensiomyography (TMG) derived contractile parameters in seniors. METHODS: Twenty-three senior adults (age 66.7 +/- 5.2 years) were randomly divided into two groups: PLYO (n = 11) and CTRL (n = 12). Tensiomyography was measured in vastus lateralis (VL), biceps femoris (BF), tibialis anterior (TA), gastrocnemius medialis (GM), and lateralis (GL). Additionally, the electromechanical efficiency (EME) index was calculated in GM as a ratio between amplitudes of peak-to-peak M-wave and TMG (Dm) responses. Biochemical markers of muscle damage and inflammation were evaluated to provide indirect indices of exercise protocol safety. RESULTS: The main effect of time (for take-off velocity p = 0.023; partial eta-2 = 0.236) and group x time interactions (for CMJ, Tc (BF, GM), Dm (BF) and EME p < 0.05; partial eta-2 = 0.136 to 0.236) were observed. Post hoc analysis showed a significant increase in CMJ height and take-off velocity, namely by 14.2% (p = 0.001) and 8.2% (p = 0.01) in PLYO, respectively. Contraction time (Tc) decreased in BF -5.7% (p = 0.001) and GM -9.6% (p = 0.001). Dm decreased only in BF -20.8% (p = 0.001), while the EME index of the GM improved by 22.9% (p = 0.002). There were no differences between groups or assessment time points for c-reactive protein (p = 0.122). CONCLUSION: The present study clearly supports the application of supervised PT exercise in seniors, since explosive power, muscle contractility, and EME of the lower limbs were markedly improved after training.

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