Resistance Training Frequencies of 3 and 6 Times Per Week Produce Similar Muscular Adaptations in Resistance-Trained Men.
Level 2 - randomized trial
Randomized controlled trial comparing two training frequencies under volume-equated conditions
PubMed 30363041 · doi:10.1519/JSC.0000000000002909
What was done
Twenty-seven resistance-trained men were randomized to train either 3 times per week (RT3, n = 14) or 6 times per week (RT6, n = 13) for a 6-week supervised, volume-equated resistance training program. Upper- and lower-body strength (1-repetition maximum), muscular endurance (repetitions to failure at 60% 1RM), and muscle thickness of the elbow flexors, elbow extensors, rectus femoris, and vastus intermedius were assessed before and after the intervention.
What was found
Both groups showed similar strength increases with no significant between-group differences: upper-body strength increased +4% in RT3 and +6% in RT6, while lower-body strength increased +22% in RT3 and +18% in RT6. Muscular endurance did not significantly increase in either group. Muscle thickness increased similarly in both groups for elbow extensors (RT3: +14%, RT6: +11%), rectus femoris (RT3: +5%, RT6: +6%), and vastus intermedius (RT3: +10%, RT6: +11%). Elbow flexor thickness significantly increased only in the RT3 group (+7%).
Why it matters
When total weekly training volume is matched, splitting workouts across 3 versus 6 days per week yields comparable adaptations in muscle size and strength, allowing individuals flexibility to choose schedules that best fit their preferences.
Limits
The study had a small sample size (n = 27), a short intervention duration (6 weeks), and included only young, resistance-trained men, limiting generalizability to women, older adults, or longer training cycles.
Cited by
- supports A study comparing volume-matched resistance training performed over three days versus six days in young men showed greater biceps growth in the three-day group and no difference in other muscle groups.