Energy Cost From Squats With Matched Work But Varying Contraction Intensities And Loads

Abstract

PURPOSE: Explosive contractions increase the energy cost of resistance exercise, but being explosive for entire sets is exhausting and unfeasible for many. Therefore, we examined whether compound sets of squats would increase energy expenditure compared to recreational squats. Compound sets included explosive squats followed by heavy squats. METHODS: Eight healthy men (23±3 yrs; 83±22 kg; 174±7 cm) performed three protocols, one each week, designed to compare energy expenditure between four sets of squats performed with either recreational contractions (neither deliberately explosive nor slow) with 65% of 1RM (REC), compound sets with two explosive followed by eight heavy squats using 68.75% of 1RM (2/8), and four explosive followed by six very heavy using 75% (4/6). All explosive squats for 2/8 and 4/6 used 50% of 1RM. Subject’s 1RM was determined using a plate-loaded squat machine, and each protocol was randomly assigned in a counterbalanced order. In addition to the standardization of repetition speed, ROM, and rest intervals, total work performed (reps x sets x load) was identical across protocols. Expired air was collected continuously before (15 m), during (20 m), and after (30 m) each exercise protocol using a metabolic cart. Data were analyzed using a two-way repeated measures ANOVA with Fisher’s least significant difference (LSD) post hoc analyses. We hypothesized that 4/6 squats would increase energy expenditure significantly compared to recreational squats. RESULTS: Rates of energy expenditure (kcal·min-1) were not significantly different (p≤0.05) among protocols (see Table). Total energy expenditure (kcal) was not different between REC (51±15.7), 2/8 (57±15.8), and 4/6 (61±17.6). CONCLUSIONS: Compound sets of squats beginning with two and four explosive reps followed by heavy and very heavy recreational reps, respectively, did not significantly increase the energy cost of resistance exercise.