ORIGINAL ARTICLES  EXERCISE PHYSIOLOGY AND BIOMECHANICS 

The Journal of Sports Medicine and Physical Fitness 2009 March;49(1):35-43

Copyright © 2009 EDIZIONI MINERVA MEDICA

language: English

The effects of a plyometric training program on the latency time of the quadriceps femoris and gastrocnemius short-latency responses

Potach D. H. ¹, Katsavelis D. ¹, Karst G. M. ², Latin R. W. ¹, Stergiou N. ^{1, 3}

¹ Nebraska Biomechanics Core Facility University of Nebraska at Omaha Omaha, NE, USA 2 Division of Physical Therapy Education University of Nebraska Medical Center Omaha, NE, USA 3 Environmental, Agricultural and Occupational Health Sciences University of Nebraska Medical Center, Omaha, NE, USA

Aim. The purpose of this study was to determine if a plyometric training program can affect the latency time of the quadriceps femoris and gastrocnemius short-latency responses (SLRs) of the stretch reflex.
Methods. Sixteen healthy subjects (12 female and 4 male) were randomly assigned to either a control or a plyometric training group. Maximum vertical jump height (VJ) and SLRs of both quadriceps femoris and gastrocnemius were measured before and after a four week plyometric training program.
Results. Plyometric training significantly increased VJ (mean±SEM) by 2.38±0.45 cm (P<0.05) and non-significantly decreased the latency time of the quadriceps femoris SLR (mean±SEM) 0.363±0.404 ms (P>0.05) and gastrocnemius SLR (mean±SEM) 0.392±0.257 ms (P>0.05). VJ results support the effectiveness of plyometric training for increasing VJ height.
Conclusion. The non-significant changes in the latency time of the quadriceps femoris and gastrocnemius SLRs seen in the training group suggest that performance improvements following a four-week plyometric training program are not mediated by changes in the latency time of the short-latency stretch reflex.