Are calves trainable? Low-intensity calf muscle training with or without blood flow restriction: a randomized controlled trial

Abstract

Abstract Objectives Whether low-load resistance training (RT) without muscle failure, with or without blood flow restriction (BFR), is sufficient to increase strength and muscle growth of calf muscles in trained individuals is still unclear. This study aimed to compare the effects of low-intensity BFR RT vs. traditional low-intensity RT (noBFR) with moderate training volume on strength and circumference. Methods We designed a parallel, randomized controlled trial including 36 RT-trained participants (BFR: 7 females, 32.9 ± 8.8 years, 11 males, 28.4 ± 3.6 years; noBFR; 8 females, 29.6 ± 3.4 years; 10 males, 28.6 ± 4.9 years) who underwent eight weeks of twice-weekly low-load RT with a total of 16 RT sets (30 % of one-repetition maximum [1RM]). RT consisted of bilateral calf raises and seated unilateral calf raises, each conducted with 4 sets (30, 15, 15, 15 repetitions not to failure) of either BFR or noBFR. Outcome measures included calf circumference (CC), leg stiffness (LS), and various strength tests (seated and standing calf raise 1RM, isokinetic strength of plantar- and dorsiflexion). Results There were no significant interactions or group effects for most measures. Both groups showed significant improvements in seated calf raise strength (p=0.046, η 2 p=0.17). Pairwise comparisons indicated moderate to large effect sizes for strength improvements (standardized mean differences: 0.35–1.11), but no changes in calf circumference were observed in either group. Conclusions Low-load RT with and without BFR are useful to increase strength without necessarily affecting hypertrophy. Low-intensity BFR training did not confer additional benefits over traditional low-intensity RT for calf muscle strength or circumference, questioning its general advantage under such conditions.