Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
5709487 | Journal of Electromyography and Kinesiology | 2017 | 39 Pages |
Abstract
The study was aimed at assessing possible correlations of the electromechanical delay components during muscle contraction (DelayTOT) and relaxation (R-DelayTOT), with muscle-tendon unit (MTU), muscle, and tendon stiffness before and after static stretching (SS). Plantarflexor muscles' maximum voluntary torque (Tmax) was measured in 18 male participants (age 24 ± 3 yrs; body mass 76.4 ± 8.9 kg; stature 1.78 ± 0.09 m; mean ± SD). During Tmax, surface electromyogram (EMG), mechanomyogram, and force signals were detected. DelayTOT and R-DelayTOT with their electrochemical and mechanical components were calculated. Passive torque and myotendinous junction displacement were assessed at 0°, 10° and 20° of dorsiflexion to determine MTU, muscle and tendon stiffness. The same protocol was repeated after SS. DelayTOT, R-DelayTOT and their mainly mechanical components correlated with MTU, muscle and tendon stiffness, both before (R2 from 0.562 to 0.894; p < 0.001) and after SS (R2 from 0.726 to 0.955; p < 0.001). SS decreased Tmax (â14%; p < 0.001) and lengthened almost all the DelayTOT and R-DelayTOT components (from +5.9% to +30.5%; p < 0.05). Correlations were found only between stiffness and the mechanical components of DelayTOT and R-DelayTOT. Correlations persisted after SS but delays increased to a higher extent than stiffness, indicating a complexity of the relationship between stiffness and delays that will be discussed in the manuscript.
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Authors
Stefano Longo, Emiliano Cè, Susanna Rampichini, Michela Devoto, Massimo Venturelli, Eloisa Limonta, Fabio Esposito,