Upper Extremity Muscle Activity During The Lacrosse Shot

Abstract

PURPOSE: To determine if lacrosse shaft stiffness influenced upper extremity muscle activity and/or shot velocity. METHODS: Muscle activity of the biceps brachii, triceps brachii, flexor carpi radialis, and extensor carpi radialis of the arm closer to the head of the shaft was measured (EMG, 1500Hz). Subjects (n=5; 20±2.4 years, 79.8±6.87 kg, 177±4.52 cm) with 4.5±2.96 years of lacrosse experience completed shots using four shafts of different stiffnesses. Subjects and research team were blinded to shaft stiffness. Subjects shot 5 times per shaft with order of shaft randomized. Subjects were instructed to shoot with maximum effort from a stationary position (i.e., one step forward with the front foot; the back foot remained on the ground). Subjects were given time to warm up with practice shots on net. A video camera was used to record discrete kinematic events of the shot. Shot velocity was recorded for each shot and averaged across the 5 trials per condition. Video data was visually inspected and the time of occurrence of maximum elbow flexion, ball release, and maximum elbow extension were identified. EMG data were processed by removing any zero offset, full-wave rectifying the data and averaging across two phases defined by the kinematic discrete events. Muscle activity for each phase and shot velocity was compared between shafts using a repeated measures ANOVA (α=0.05). RESULTS: Neither muscle activity for any muscle analyzed nor shot velocity were influenced by shaft stiffness (p>0.05). CONCLUSION: Having a high shot velocity can be advantageous to a lacrosse player. Besides the player ability, lacrosse equipment may be a factor in determining shot velocity. However, in this experiment, shaft stiffness did not have an influence on muscle activity or shot velocity.