Effects of Lift Velocity on Muscle Activation During Leg Extension

摘要

It is not known if manipulating velocity within a prescribed resistance training mode will improve muscleactivation. Muscle activations of the Rectus Femoris (RF), Vastus Lateralis (VL), Vastus Medialis (VM) and BicepFemoris (BF) were examined during a leg extension exercise at 3 different velocities on 15 subjects (10men, 5 female,Age = 21.5 ± 1.8 yrs, Height = 171.2 ± 12.5 cm, Mass = 75.5 ± 16.3 kg). Trials of 1 set of 10 repetitions at 60% of 1RM,were performed at 15, 30 and 60o/s. Bipolar surface electrodes were placed over the BF, RF, VL, and VM. Micro-switcheswere utilized to identify the concentric (CON) and eccentric (ECC) phases of the lift. Data were sampled at 1024 Hz,filtered, rectified and the mean, integrated EMG calculated. One 2 x 4 x 3 (action x muscle x velocity) ANOVA withbonferonni adjustment was run and significance was followed by Tukey HSD post hoc analysis. Results indicatedsignificantly greater activation of the VL, RF and VM for ECC extension at 60o/s compared to 15o/s. While 60o/s was alsogreater than 30o/s for the VL and VM during ECC. While comparing muscle action, CON VL, VM and RF were greaterthan ECC at 30o/sec, meanwhile VM CON was also greater at 15o/sec. No differences in muscle activation at any velocityor muscle action for BF were identified. We conclude that muscle recruitment while training with a 60% 1RM load ismaximized at a velocity of 60o/s during ECC activity and 15 or 30o/sec during CON.