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Influence of Strength on Magnitude and Mechanisms of Adaptation to Power Training


Medicine & Science in Sports & Exercise: August 2010 - Volume 42 - Issue 8 - p 1566-1581
doi: 10.1249/MSS.0b013e3181cf818d
Applied Sciences

Purpose: To determine whether the magnitude of performance improvements and the mechanisms driving adaptation to ballistic power training differ between strong and weak individuals.

Methods: Twenty-four men were divided into three groups on the basis of their strength level: stronger (n = 8, one-repetition maximum-to-body mass ratio (1RM/BM) = 1.97 ± 0.08), weaker (n = 8, 1RM/BM = 1.32 ± 0.14), or control (n = 8, 1RM/BM = 1.37 ± 0.13). The stronger and weaker groups trained three times per week for 10 wk. During these sessions, subjects performed maximal-effort jump squats with 0%-30% 1RM. The impact of training on athletic performance was assessed using a 2-d testing battery that involved evaluation of jump and sprint performance as well as measures of the force-velocity relationship, jumping mechanics, muscle architecture, and neural drive.

Results: Both experimental groups showed significant (P ≤ 0.05) improvements in jump (stronger: peak power = 10.0 ± 5.2 W·kg−1, jump height = 0.07 ± 0.04 m; weaker: peak power = 9.1 ± 2.3 W·kg−1, jump height = 0.06 ± 0.04 m) and sprint performance after training (stronger: 40-m time = −2.2% ± 2.0%; weaker: 40-m time = −3.6% ± 2.3%). Effect size analyses revealed a tendency toward practically relevant differences existing between stronger and weaker individuals in the magnitude of improvements in jump performance (effect size: stronger: peak power = 1.55, jump height = 1.46; weaker: peak power = 1.03, jump height = 0.95) and especially after 5 wk of training (effect size: stronger: peak power = 1.60, jump height = 1.59; weaker: peak power = 0.95, jump height = 0.61). The mechanisms driving these improvements included significant (P ≤ 0.05) changes in the force-velocity relationship, jump mechanics, and neural activation, with no changes to muscle architecture observed.

Conclusions: The magnitude of improvements after ballistic power training was not significantly influenced by strength level. However, the training had a tendency toward eliciting a more pronounced effect on jump performance in the stronger group. The neuromuscular and biomechanical mechanisms driving performance improvements were very similar for both strong and weak individuals.

1School of Exercise, Biomedical and Health Sciences, Edith Cowan University, Perth, AUSTRALIA; 2New Zealand Academy of Sport North Island, Auckland, NEW ZEALAND; and 3Institute of Sport and Recreation Research New Zealand, Auckland University of Technology, Auckland, NEW ZEALAND

Address for correspondence: Prue Cormie, Ph.D., School of Exercise, Biomedical and Health Sciences, Edith Cowan University, 270 Joondalup Dr. Joondalup, WA 6027, Australia; E-mail:

Submitted for publication September 2009.

Accepted for publication December 2009.

©2010The American College of Sports Medicine