Low or High Reps - Which is better for Muscle Mass development?

The Muscle Mass Debate: High vs Low Reps for Muscle Growth

If you look at many fitness websites, you will see such programs as “100-Reps Hell” or the “3 Minute Set” programs being advocated at the ultimate program for muscle size. Some bodybuilders advocate high reps for muscle growth where others advocate low repetitions, but there is little research to prove which repetition scheme works the best for muscle growth. Results of these studies are conflicting, with some studies finding superiority for heavier load training and others showing no significant differences between high repetition protocols taken to fatigue compared to lower repetitions taken to fatigue. The case for heavier weight lifting is based that on the fact that type II fibers display an approximately 50% greater capacity for growth compared to type I fibers. Type II fibers are activated with a weight in excess of 70-80% 1RM is required to recruit the largest units.

Researchers examined 18 young men experienced with resistance training experience, they were matched according to baseline strength, and then randomly assigned to 1 of 2 experimental groups:

-A low-load resistance training routine where 25-35 repetitions were performed per set per exercise, or

-A high-load resistance training routine where 8-12 repetitions were performed per set per exercise.

The resistance training protocol consisted of 3 sets of 7 exercises per session targeting all major muscle groups of the body. The exercises performed were: flat barbell press, barbell military press, wide grip lat pull-down, seated cable row, barbell back squat, machine leg press, and machine leg extension. During each session, subjects in both groups performed three sets of 7 different exercises representing all the main muscles. Training was carried out three times per week on non-consecutive days, for eight total weeks. All other resistance training variables (e.g., exercises performed, rest, repetition tempo, etc.) were held constant. The training interventions lasted eight weeks with subjects performing three total body workouts per week. The subjects all consumed a whey protein isolate drink post exercise to ensure optimal recovery. The researchers measured muscle hypertrophy and strength from both protocols.

Low Repetitions vs High Repetitions for Muscle Growth: Which is Better?

At the end of eight weeks, when the researchers crunched all the data, both routines increased muscle growth similarly with no significant differences between the two groups. These results run contrary to accepted hypertrophy training guidelines, which profess that loads of at least 65% are necessary to stimulate muscle growth in well-trained individuals.

In terms of strength, although LL did increase maximal muscle strength, the heavier weight, lower rep routine resulted in greater increases in strength. It should be noted that the greater increase in bench-press strength for the high load method led to their lifting slightly higher mean loads (~2 kg) compared with low weight. 1RM bench press increased by 6.5% vs. 2.0% for the low load routine.