Changes in Spinal-Reflex Excitability during Static Stretch and/or Explosive Contraction

To examine individual or combined effects of static stretch and explosive contraction on quadriceps spinal-reflex excitability (the peak Hoffmann’s reflex normalized by the motor-response) latency times motor-response. Fourteen healthy young males randomly experienced four conditions (stretch, contraction, + control—no intervention). For condition, three sets a 30 s hold using modified Thomas test each leg were performed. trials maximal countermovement vertical jump Quadriceps latent period value right compared at pre- post-condition. All measurement values across not changed any time point (condition × time) in (F6,143 = 1.10, p 0.36), 0.45, 0.84), motor-response 0.37, 0.90), heights (F2,65 1.82, 0.17). A statistical trend was observed condition that increased 42% (effect size: 0.63). Neither nor excitability, reflex, Since our protocol did affect jumping performance induced post-activation potentiation effect, either could be used as pre-exercise activity.