The Influence of Varied Resistance and Speed of Concentric Antagonistic Contractions on Subsequent Concentric Agonistic Efforts.

Traditionally, near maximal isometric efforts have been used to elicit the beneficial facilitations and inhibitions associated with strength and flexibility improvements using proprio-ceptive neuromuscular facilitation (PNF) and modified PNF techniques. Although concentric reversal of antagonists has been used clinically, there is little evidence regarding the concentric contraction speed and resistance levels necessary to elicit an augmented neuromuscular response. This study addresses the question of speed and resistance specificity and their subsequent PNF effects on strength and power outputs. This was accomplished through the use of a double-acting concentric dynamometer (DACD). Twelve males, aged 18-25 years, participated in this study. Each subject performed a reversal of an antagonist maneuver simulating a horizontal bench pull and bench press, all using combinations of slow speed of contraction, fast speed of contraction, and isometric contraction. Within the limitations of this study, it appears that a low-resistance, fast speed of antagonistic contraction significantly increases both peak and average force during a fast agonistic effort (p < 0.05). Neither maximal isometric nor slow concentric contraction of the antagonist (against heavy resistance) seemed to augment the succeeding concentric effort of the agonist under either slow or fast conditions. (C) 1999 National Strength and Conditioning Association