Velocity-specific training in elbow flexors

The purpose of this study was to show that velocity-specific training may b e implicated in modifications in the level of coactivation of agonist and a ntagonist muscles. Healthy males (n = 20) were randomly placed in to two gr oups: one group trained using concentric contractions (n = 12), the other w as an untrained control group (n = 8). The training group underwent unilate ral resistance training at a level of 35 (5)% of a one-repetition maximal c ontraction of the elbow flexors, executed at maximal angular velocity. Trai ning sessions consisted of six sets of eight consecutive elbow flexions, th ree times per weak for a total of seven weeks. The velocity of the ballisti c movements executed during training were measured using an optoelectronic measuring device (Elite), both at the beginning and at the end of the train ing period. Subjects were tested pre- and post-training during isokinetic m aximal elbow flexions with constant angular torque (CAT) at 90 degrees (0 d egrees = full extension), and at different velocities (60, 120, 180, 240 an d 300 degrees . s(-1)) for concentric actions, and -60 and -30 degrees . s( -1) for eccentric and isometric contractions at 90 degrees. In order to ver ify the levels of activation of the agonist biceps brachii (BB) muscles and antagonist triceps brachii (TB) muscles during maximal voluntary activatio n, their myoelectrical activities were recorded and quantified as root mean square (RMS) amplitudes, between angles of 75 and 105 degrees. The results show that mean angular velocities between elbow angles of 75 and 105 degre es were similar before [302 (32)degrees . s(-1)] and after [312 (27)degrees . s(-1)] the training period. CAT significantly increased measures at angu lar Velocities of 240 and 300 degrees . s(-1) by 18.7% and 23.5%, respectiv ely. The RMS activity of BB agonist muscles was not significantly modified by training. Post-training normalized RMS amplitudes of TB antagonist muscl es were inferior to those observed at pre-training, but values were only si gnificantly different at 300 degrees . s(-1). In conclusion, in this study we attempted to show that an increase of CAT to 240 and 300 degrees . s(-1) , though velocity-specific training, may be due, in part, to a lowering of the level of coactivation.