Abstract
The purpose of this study was to compare the effects of a protocol employing a combination
of loading zones vs. one employing a constant medium-repetition loading zone on muscular
adaptations in resistance-trained men. 19 trained men (height=176.9±7.0 cm; body mass=83.1±11.8 kg;
age=23.3±2.9 years) were randomly assigned to 1 of 2 experimental groups: a constant-rep
resistance training (RT) routine (CONSTANT) that trained using 8–12 RM per set, or
a varied-rep RT routine (VARIED) that trained with 2–4 RM per set on Day 1, 8–12 RM
per set on Day 2, and 20–30 RM on Day 3 for 8 weeks. Results showed that both groups
significantly increased markers of muscle strength, muscle thickness, and local muscular
endurance, with no differences noted between groups. Effect sizes favored VARIED over
CONSTANT condition for elbow flexor thickness (0.72 vs. 0.57), elbow extensor thickness
(0.77 vs. 0.48), maximal bench press strength (0.80 vs. 0.57), and upper body muscle
endurance (1.91 vs. 1.28). In conclusion, findings indicate that both varied and constant
loading approaches can promote significant improvements in muscular adaptations in
trained young men.
Key words
loading zones - repetition range - muscle hypertrophy - maximal strength - muscular
endurance
