Effects of Weekly Set Volume on Muscle Adaptation

BACKGROUND: The progressive loss of strength and muscle mass is a natural process of aging, with direct implications for functional capacity. Resistance training (RT) is considered the main intervention to counteract this decline. Although RT guidelines are well established, the ideal weekly volume of sets to maximize strength and hypertrophy gains in older adults remains unknown. PURPOSE: To investigate the effects of different weekly RT volumes on lower limb muscle strength and hypertrophy (quadriceps femoris) in older adults. METHODS: Fifty-seven older adults of both sexes will be matched for maximum dynamic strength (one repetition maximum - 1RM) and randomly divided into 03 groups: \[Low Volume (LV = 6 sets/week, n = 19), Moderate Volume (MV = 18 sets/week, n = 19) and High Volume (LV = 30 sets/week, n = 18)\]. All participants will undergo a 10-week resistance training protocol (3x/week), consisting of 8 exercises: bench press, leg press, seated row, leg extension, bicep curl, leg curl, triceps pulley, and seated calf raise. Only the leg extension and leg press exercises will be performed with different volumes of sets (VB = 1 set/exercise; VM = 3 sets/exercise; VA = 5 sets/exercise). The number of repetitions per set will be 8-12, and the training load will be adjusted every two weeks based on the maximum number of repetitions performed in the last training session. The following dependent variables will be analyzed before and after the training program: (1) maximum dynamic strength (1RM) and (2) maximum voluntary isometric contraction (MVIC) in the leg extension exercise, (3) muscle hypertrophy (thickness) of the quadriceps muscle and rectus femorisusing ultrasound images, and (4) rating of perceived exertion (RPE) and (5) affective responses (pleasure and displeasure) after training sessions. Data will be tested for normality and homogeneity using the Shapiro-Wilk's and Levene's tests, respectively. Changes over time and between groups will be analyzed with two-way repeated measures ANOVA tests. Violation of sphericity was corrected using the Greenhouse-Geisser method. When significant differences will be confirmed with the ANOVA, multiple comparison testing will be performed using the Bonferroni post hoc correction to identify these differences. Values will be expressed as mean (standard deviation and 95% confidence interval). The significance level was set at p \< 0.05.