This study compared kinematics and electromyography (EMG) in the lower extremities during different phases of the last repetition, when performing the squat of different repetition maximums. Thirteen strength trained men performed a 1-, 3-, 6-, and 10-RM squat, in a randomized order. The main findings were that kinematics was very similar, except for a smaller inclination of the trunk at V0 in the 1-RM compared to other repetitions, and at Vmax1 compared to 10-RM. Furthermore the 1-RM revealed significantly higher EMG amplitude in the vastus lateralis in the sticking- and post-sticking region when compared to 10-RM. It was concluded a 10-RM may fatigue the vastus lateralis, explaining the lower EMG amplitude, accompanied with a greater inclination of the trunk, which is possibly a compensatory strategy of the body to reduce knee-extensor torque.
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