Relevance of evaluating the rate of torque development in ballistic contraction of submaximal amplitude

OBJECTIVE: The neuromuscular quickness capacity can be assessed by calculating the rate of torque development (RTD) during ballistic contractions of maximal (RTDmaximal) or submaximal (RTDsubmaximal) amplitudes. In a series of ballistic contractions of submaximal amplitudes, the RTD scaling factor (RTD-SF) represents the slope of the linear regression between achieved peak torques and the corresponding RTD. First we investigated whether the RTD-SF contributes to the prediction, together with maximal voluntary torques (MVT), of the RTDmaximal. Then, we evaluated the agreement between the z-scores of RTDmaximal and RTDsubmaximal. APPROACH: The MVT was obtained for the quadriceps and hamstrings muscles of 22 elite young soccer players. RTD-SF was quantified in a series of ballistic contractions of submaximal and maximal amplitudes. RTDsubmaximal was estimated from the regression relationship between the peak torques and the corresponding RTD. MAIN RESULTS: MVT, RTD-SF and y -intercept in total accounted for 76.9 and 61.2% of the variance in RTDmaximal in quadriceps and hamstrings, respectively. Specifically, RTD-SF accounted for 13.7% and 18.7% of the variance in RTDmaximal, respectively. Generally, the agreement between the z-scores of RTDmaximal and RTDsubmaximal was poor both in quadriceps and hamstrings. SIGNIFICANCE: These results suggest that RTD-SF may have a functional relevance in the relationship between MVT and RTDmaximal and influence the amount of torque that can be achieved in a quick muscle contraction. Moreover, evaluating the RTDsubmaximal does not provide results that are interchangeable with RTDmaximal. Thus, evaluating the RTD across the whole range of torque could provide additional meaningful information about neuromuscular quickness.