Comparison of Performance Variables and Muscle Activity During the Squat and Box Squat

• Published in: Journal of strength and conditioning research 2011-03, Vol.25, p.S21
• Main Authors: Skinner, J W, McBride, J M, Kirby, T J, Schafer, P C, Haines, T L
• Format: Article
• Language: English
• Subjects: Legs; Muscular system
• ISSN: 1064-8011; 1533-4287
• DOI: 10.1097/01.JSC.0000395610.80262.25

PURPOSE: The purpose of this investigation is to determine the difference in performance variables and muscle activity between a squat with or without (box squat) a stretch-shortening cycle or coupling phase. A box squat removes the coupling phase by requiring the lifter to lower the weight, sit on a box and then raise the weight. This may allow the lifter to focus on concentric phase muscle activity by removing the stretch-shortening cycle. METHODS: Eight resistance-trained males (Height: 179.61 ± 13.43 cm; Body Mass: 107.65 ± 29.79 kg; Age: 24.77 ± 3.22 years; 1RM: 200.11 ± 58.91 kg) with at least 3 years of experience performing the back squat with no prior injuries within the last year prior to participating in the study. Subjects were asked to perform two trials of a squat (S) and box squat (BS) at 60%, 70%, and 80% of their one their repetition maximum (1RM) in a randomized fashion. Each trial of the S and BS was performed with the subject standing on a force plate with a bar attached to two potentiometers. Squat performance was determined by calculating peak force (PF), peak power (PP), and peak velocity (PV). Muscle activity was monitored through electromyography (EMG) for all squats for the vastus lateralis (VL), vastus medialis (VM), biceps femoris (BF), and longissimus (L1) muscles. RESULTS: Muscle activity was significantly higher for BF during the concentric (0.15 ± 0.067; 0.0289) and eccentric (0.03 ± 0.007; 0.0262) phase of S when compared to BS at 60% of 1RM. Muscle activity was significantly higher for VL (0.472 ± 0.158; 0.005) in the concentric phase of the S when compared to the BS at 70% of 1RM. Muscle activity was also higher at VL (0.313 ± 0.084; 0.041) and L1 (0.167 ± 0.090; 0.009) during the eccentric phase of the S compared to the BS at 80% of 1RM. CONCLUSIONS: Muscle activity was generally higher in the S with several significant differences noted in comparison to the BS. It does not appear that the BS, which removes the coupling phase, increases muscle activity in either the eccentric or concentric phase. PRACTICAL APPLICATIONS: The box squat does not appear to be a viable alternative to squatting due to a decrease in muscle activity, which would not optimize training adaptations. [PUBLICATION ABSTRACT]