Progressive Resistance Training Volume: Effects on Muscle Thickness, Mass, and Strength Adaptations in Resistance-Trained Individuals

Aube, D, Wadhi, T, Rauch, J, Anand, A, Barakat, C, Pearson, J, Bradshaw, J, Zazzo, S, Ugrinowitsch, C, and De Souza, EO. Progressive resistance training volume: effects on muscle thickness, mass, and strength adaptations in resistance-trained individuals. J Strength Cond Res 36(3): 600-607, 2022-This study investigated the effects of 12-SET, 18-SET, and 24-SET lower-body weekly sets on muscle strength and mass accretion. Thirty-five resistance-trained individuals (one repetition maximum [1RM] squat: body mass ratio [1RM: BM] = 2.09) were randomly divided into 12-SET: n = 13, 18-SET: n = 12, and 24-SET: n = 10. Subjects underwent an 8-week resistance-training (RT) program consisting of 2 weekly sessions. Muscle strength (1RM), repetitions to failure (RTF) at 70% of 1RM, anterior thigh muscle thickness (MT), at the medial MT (MMT) and distal MT (DMT) points, as well as the sum of both sites (sigma MT), along with region of interest for fat-free mass (ROI-FFM) were measured at baseline and post-testing. For the 1RM, there was a main time effect (p <= 0.0001). However, there was a strong trend toward significance (p = 0.052) for group-by-time interaction, suggesting that 18-SET increased 1RM back squat to a greater extent compared with 24-SET (24-SET: 9.5 kg, 5.4%; 18-SET: 25.5 kg, 16.2%; 12-SET: 18.3 kg, 11.3%). For RTF, only a main time-effect (p <= 0.0003) was observed (24-SET: 5.7 reps, 33.1%; 18-SET: 2.4 reps, 14.5%; 12-SET: 5.0 reps, 34.8%). For the MMT, DMT, sigma MT, and ROI-FFM, there was only main time-effect (p <= 0.0001) (MMT: 24-SET: 0.15 cm, 2.7%; 18-SET: 0.32 cm, 5.7%; 12-SET: 0.38 cm, 6.4%-DMT: 24-SET: 0.39 cm, 13.1%; 18-SET: 0.28 cm, 8.9%; 12-SET: 0.34 cm, 9.7%-sigma MT: 24-SET: 0.54 cm, 6.1%; 18-SET: 0.60 cm, 6.7%; 12-SET: 0.72 cm, 7.7%, and ROI-FFM: 24-SET: 0.70 kg, 2.6%; 18-SET: 1.09 kg, 4.2%; 12-SET: 1.20 kg, 4.6%, respectively). Although all of the groups increased maximum strength, our results suggest that the middle dose range may optimize the gains in back squat 1RM. Our findings also support that differences in weekly set number did not impact in MT and ROI-FFM adaptations in subjects who can squat more than twice their body mass.

Automated summary

This study investigated the effects of different resistance training volumes on muscle strength and mass accretion in resistance-trained individuals. The results suggest that a moderate training volume may optimize gains in squat strength. Additionally, differences in weekly set number did not impact muscle thickness and fat-free mass adaptations in individuals who can squat more than twice their body weight.