The role of maximal strength and load on initial power production.
OBJECTIVE
The influence of maximal strength, as measured by the maximal load lifted for one repetition (1RM), on power production in the initial 200 ms of the concentric phase for both rebound and nonrebound movements was investigated. We also investigated the effect of external load upon this relationship.


METHODS
Twenty-seven male subjects (21.9 +/- 3.1 yr, 89.0 +/- 12.5 kg) were separated by previously determined bench press IRM into high (100.88 +/- 7.24 kg) and low (72 +/- 6.61 kg) RM groups. Concentric only bench presses and rebound bench presses were compared between and within groups to note the effect of RM across external loads of 40%, 60%, and 80% 1RM, on instantaneous, mean, and peak power output.


RESULTS
The results of this study clearly indicated the enhancement of concentric motion by prior eccentric muscle action (336-1332% enhancement in the first 20 ms). Possessing a high RM augmented power production in the initial 200 ms of stretch-shorten cycle activity, across all the external resistances tested (P < 0.05). The temporal characteristics of this enhancement, however, differed across loads. That is, 80% IRM loading showed a later time to peak enhancement (80 ms vs 20 ms). Interestingly, the influence of RM on concentric only motion in the initial 200 ms across the external resistances tested was found to be nonsignificant.


CONCLUSIONS
The results suggest that the role of maximal strength during initial power production between concentric and stretch-shorten cycle activity differs, which has important implications for the training of athletes.
Cronin
J B
JB
Sport Performance Centre, School of Physiotherapy, Auckland University of Technology, New Zealand. john.cronin@aut.ac.nz
McNair
P J
PJ
Marshall
R N
RN
D000328:Adult; D006801:Humans; D008297:Male; D009068:Movement / Q000502:physiology*; D009119:Muscle Contraction / Q000502:physiology*; D016474:Weight-Bearing / Q000502:physiology*