Hypertrophic adaptations to a 6-week in-season barbell vs. flywheel squat added to regular soccer training

BACKGROUND: The aim of this study was to compare the hypertrophic adaptations to barbell or flywheel squat exercise added to regular in -season soccer training. METHODS: Quadriceps' (rectus femoris [RF], vastus medialis [VM] and vastus lateralis [VL]) cross-sectional area (CSA) in its portions (proximal [PROX], middle [MID], and distal [DIST]) was measured on both legs before and after a 6-week barbell (80 to 90% one-maximum repetition; N.=7) or flywheel (0.0611 to 0.0811 kg center dot m2; N.=7) in an U19 professional soccer team using a 3T magnetic resonance imaging. Both groups underwent 5 sets x 6 reps per session of squat separated by 3-min rest, while controlling the time under tension (within 0.5 and 0.8 s). RESULTS: The barbell squat group experienced moderate CSA increments in the VMMiD and the VLDiST of the right leg (d=0.98-0.99). Addition-ally, the flywheel group experience large CSA increments in the RFMiD, VLPROX and VLMiD of the right leg (d=1.00-1.84). On average, flywheel squat training largely produced greater force during exercise compared to the barbell squat training (29.2 vs. 12.2 N center dot kg-1; d=5.95), whereas the barbell squat training produced moderately greater power output (10.5 vs. 9.7; d=0.52). CONCLUSIONS: Barbell squat training seems to be more effective for VM hypertrophy whereas flywheel squat triggers greater RF and VL hypertrophy as complementary to regular field-based soccer practice and competition within a short range of time (6 weeks) during the in-season. These findings can be considered also from either strength or reconditioning perspective based on the increase in the quadriceps muscles' CSA as mechanism underlying strength/power adaptations. (Cite this article as: Filetti C, Ruscello B, Leo i, Porta M, Chiari A, Miranda C, et al. Hypertrophic adaptations to a 6-week in-season barbell vs. flywheel squat added to regular soccer training. J Sports Med Phys Fitness 2023;63:60-8. DOI: 10.23736/S0022-4707.22.13793-X)