A novel approach to identify the end of the concentric phase during ballistic upper-body movements.

Using an indirect means to identify the end of the concentric phase during a ballistic effort may over/underestimate calculations requiring an accurate definition of this position. Thirty men performed 4 ballistic bench press repetitions at 6 relative loads. Kinematic and kinetic data were acquired with a position transducer and portable force plate, respectively. Two pressure switches were fastened to the underside of the barbell, connected in parallel and wired such that their voltage would be zero until contact was lost. The point of release was defined as the position at which (a) the vertical force dropped below zero, (b) the load was held before initiating eccentric movement, and (c) the voltage of the switches rose above 1 V. Height thrown, as calculated by the position data, was significantly higher than both other analysis strategies at all loads (0.040-0.140 and 0.080-0.130 m greater than the switch and force methods, respectively). No significant differences were found between the switch and force, with the exception of the 15% 1 repetition maximum load. A direct method of measurement may be the most appropriate way to provide an accurate assessment of the means or temporal variables of any ballistic movement.