High-frequency resistance training improves maximal lower-limb strength more than low frequency

This study compared the effects of a weekly lower body resistance-training program divided into low frequency (LOW, one long session) versus high frequency (HIGH, four shorter sessions) in resistance-trained individuals. Twenty-two adults with more than 6 months resistance training experience were randomized to either the LOW or HIGH intervention group. Both groups completed an 8-week training program consisting of four multi-joint exercises targeting the hip and knee extensors. The program progressed from 12-repetition maximum (RM) to 6-RM, with 4-5 sets per exercise performed throughout the intervention. The four exercises were conducted either in one session or four sessions (one exercise per session) per week. 1-RM in the squat, muscle thickness of the vastus lateralis, muscle mass of the lower body (measured using bioelectrical impedance), and jump height were assessed pre- and post-intervention. The HIGH group demonstrated a statistically significant increase in 1-RM compared to the LOW group (7 kg, p = 0.01), while no statistically significant differences were found between the groups for the other outcomes (p = 0.26-0.63). Both interventions resulted in statistically significant increases in 1-RM squat (8 and 15 kg), muscle thickness (2.3 and 2.8 mm), and jump height (1.5 and 1.9 cm) from pre-to post-test. There were no statistical changes in lower-body muscle mass for either group (p = 0.16-0.86). In conclusion, a weekly training protocol of four multi-joint lower-limb exercises distributed over four sessions resulted in greater increases in maximal strength compared to one session in resistance-trained adults. Both frequencies were similarly effective in improving muscle hypertrophy and jump height. Both high and low resistance training frequencies are viable options for increasing maximal strength, hypertrophy, and jump height. High resistance training frequency seems to favor lower limb muscle strength in trained adults. High and low resistance training frequencies lead to similar improvement in muscle hypertrophy and jump height in trained adults.