CONTRIBUTION OF SELECTED MUSCLES TO BASKETBALL SHOOTING

Abstract

INTRODUCTION Release speed impulse generation requirements with respect to distance in basketball shooting are non-linear (e.g. Miller and Bartlett, 1996). Information as to the mechanisms by which impulse is generated may be useful in developing sport-specific training routines. This study sought to examine the changes in muscular activation in basketball shooting of selected upper body muscles with respect to shooting distance. METHODS Thirteen accomplished male basketball players participated in the study. EMG traces (1 000 Hz) were collected from 4 muscles (bicepdtriceps brachii [BBm], flexorlextensor carpi radialis [FCPIECP]) for shots from distances of 2.74 m, 4.57 m and 6.40 m until five successful shots had been made. Mean values were calculated for contraction time (TC), average rectified emg (AEMG) and median frequency (MF). The positive relationship between TC and shooting distance for TB was inverted for its antagonist muscle (BB). While this may suggest an increasing contribution by TB, the total muscle activity (TC x AEMG) only increased between 2.74 m and 6.40 m, as was the case for ECP. While AEMG also showed consistent increases between 2.74 m and 6.40 m shots, 4.57 m shots did not conform to this trend. This may have been due to the latter shots being free throws in which ground contact is maintained. Median frequency, purported to reflect force generation, remained relatively consistent for all shooting distances. This may be interpreted as suggesting consistency of number of fibres recruited for all shooting distances or that, if extra fibres were recruited, their threshold frequencies were similar to those previously active. The magnitude of changes in AEMG may indicate that the latter explanation is the more plausible. CONCLUSIONS The increase in total activity of the agonists at the elbow and wrist joints between 2.74 m and 6.40 m may not indicate an increased contribution to ball release speed, as net joint torque also depends on antagonist muscle contributions, which also increased over the same distances. While increases in agonist torques may outweigh those in antagonists, it is likely that the required increases in ball release speed were also generated by increased torques at other joints. MF and AEMG data suggest that extra fibres of similar threshold frequencies to those already active were recruited to increase agonist/antagonist torques. REFERENCES Miller, S.A. and Bartlett, R.M. (1996). J. Sp. Sci., 14,243-253.