Stepwise Load Reduction Training On Muscle Thickness And Walking Speed In Middle-aged And Older Individuals

PURPOSE: To examine the effects of stepwise load reduction training (SLRT), using multiple loads within a set, on muscle strength, muscle thickness, walking speed and power in middle-aged and older individuals. METHODS: Forty-five healthy middle-aged and older individuals (mean age: 54.7 ± 11.5 years: dropout, n = 9) were randomly assigned to either SLRT group (n = 17: 2 sets of 2 repetitions (reps) at 85% 1RM, 3 reps at 70% 1RM, and 6 reps at 55% 1RM) or low-load group (LL: n = 19: 4 sets of 6 reps at 55% 1RM). Rest intervals between sets were 3 minutes for both groups. Participants trained twice a week for 6 weeks. Exercises included parallel squats, bench presses, lat pull-downs, Romanian deadlifts, back lunges, and kettlebell swings, with protocols applied only to parallel squats. Participants were instructed to "lift as quickly as possible" during the squat. Measurements for muscle thickness (rectus femoris + vastus intermedius), time to 5-m walk (T5), isometric maximal voluntary contraction (MVC), and maximal concentric velocity (V0) were taken at baseline and post-intervention. Blood lactate (La) concentrations were measured after the first session. RESULTS: La was significantly higher in SLRT (4.2 ± 1.5 mmol/L) than that in LL group (2.7 ± 0.7 mmol/L) after each exercise (p < 0.001). Muscle thickness increased significantly (group × time; p = 0.04, time; p < 0.001, group; p = 0.53), with a greater increase in the SLRT (7.5 ± 5.3%, p = 0.04) compared to the LL group (3.9 ± 5.7%). For T5 and V0, a significant main effect of time was observed (p < 0.05, T5: SLRT = 0.2 ± 11.3%, LL = −6.4 ± 10.3%, V0: SLRT = 7.9 ± 12.8%, LL = 13.4 ± 14.2%). MVC did not change significantly over time. CONCLUSION: Multiple loads within a set of resistance training sessions improved muscle hypertrophy, but did not improve walking speed or maximal concentric velocity.