Exploring the Upper Limits of Resistance Training Volume for Muscle Hypertrophy and Strength in Trained Athletes

Purpose The study examined the effect of high resistance-training (RT) volumes on muscle strength and hypertrophy in trained male athletes. The aim was to determine whether ~60 sets per week would be beneficial compared to lower volume and whether increased volume can affect non-responsiveness. Methods Twenty-seven strength-trained male athletes completed a 10-week RT intervention, followed by a 7-week experimental phase, in which they were split into normal (NOR, n = 12) and extra volume (XTR, n = 15) groups, with XTR performing 1.5 times more weekly sets. Muscle thickness in the vastus lateralis (VL) and biceps femoris (BF) was measured via ultrasound, and strength through back squat (BS), deadlift (DL), isometric squat, broad jump, and peak power. Results VL and BF thickness increased significantly during the initial 10-week RT (pre to mid: VL: 7.0% ± 9.8%, P = 0.003; BF: 8.6% ± 10.3%, P < 0.001, pre to post: VL: 6.1% ± 11.8%, ns.; BF: 4.2% ± 8.0%, P = 0.050), along with substantial improvements in strength (BS: 19.1% ± 10.95%; DL: 12.5% ± 8.3%, both P < 0.001). Over the final 7 weeks, no significant group differences in muscle size were found between XTR and NOR in the whole group or in non-response participants (< 2 × typical error in VL thickness during the first 10 weeks). For strength, only DL showed a difference between groups, favouring less volume ( P = 0.043). Conclusions Substantially increasing RT volume did not enhance muscle hypertrophy or strength in athletes. Furthermore, non-response was unaffected by increased RT volume.