If you do weight training to build muscle mass, you may as well use weights that you can do 30 reps with instead of weights that you can only manage 10 reps with, American sports scientist Brad Schoenfeld discovered. But if your aim is strength gain, high reps resistance training is less suitable.
Schoenfeld did an experiment with 18 young men, who had been doing weight training on average for over three years.
Strength training with high reps great for building muscle mass, not for building strength
Schoenfeld divided the men into two groups, all of whom did a full body workout three times a week for eight weeks. The subjects did seven basic exercises: bench-press, military-press, lat-pulldown, cable-row, squat, leg-press and leg-extension. They did to-failure sets.
Half of the subjects trained using weights that were 70-80 percent of the weight at which they could just manage 1 rep [1RM]. Their sets consisted of 8-12 reps. [High load]
The other half of the subjects trained using weights that were 30-50 percent of the weight at which they could just manage 1 rep. Their sets consisted of 25-35 reps. [Low load]
At the end of the eight weeks both groups had gained the same amount of muscle mass. Apparently for muscle mass it makes no difference whether you train with relatively heavy or light weights.
The weight with which the subjects could just manage 1 rep [1RM] increased by more in the High load group than in the Low load group. The increase in 1RM for the bench press in the Low load group was not even statistically significant.
But by the end of the experiment the subjects in the Low load group were able to perform more reps when they did bench presses with 50 percent of their 1RM. The figure above shows that the total number of kilograms that the subjects in the High load group were able to shift in a to-failure set with 50 percent of their 1RM actually decreased a tiny amount – but not significantly.
“Low-load training can be an effective method to increase muscle hypertrophy of the extremities in well-trained men”, Schoenfeld concluded. “The gains in muscle size from low-load training were equal to that achieved with training in a repetition range normally recommended for maximizing muscle hypertrophy.”
“Provided that maximal hypertrophy is the primary outcome goal irrespective of strength increases, these findings suggest that a new paradigm should be considered for hypertrophy training recommendations, with low-load training promoted as a viable option.”
“On the other hand, if maximizing strength gains is of primary importance, then heavier loading should be employed at the exclusion of lower load training.”
Effects of Low- vs. High-Load Resistance Training on Muscle Strength and Hypertrophy in Well-Trained Men.
The purpose of this study was to compare the effect of low- versus high-load resistance training (RT) on muscular adaptations in well-trained subjects. Eighteen young men experienced in RT were matched according to baseline strength and then randomly assigned to 1 of 2 experimental groups: a low-load RT routine (LL) where 25-35 repetitions were performed per set per exercise (n = 9) or a high-load RT routine (HL) where 8-12 repetitions were performed per set per exercise (n = 9). During each session, subjects in both groups performed 3 sets of 7 different exercises representing all major muscles. Training was performed 3 times per week on nonconsecutive days, for a total of 8 weeks. Both HL and LL conditions produced significant increases in thickness of the elbow flexors (5.3 vs. 8.6%, respectively), elbow extensors (6.0 vs. 5.2%, respectively), and quadriceps femoris (9.3 vs. 9.5%, respectively), with no significant differences noted between groups. Improvements in back squat strength were significantly greater for HL compared with LL (19.6 vs. 8.8%, respectively), and there was a trend for greater increases in 1 repetition maximum (1RM) bench press (6.5 vs. 2.0%, respectively). Upper body muscle endurance (assessed by the bench press at 50% 1RM to failure) improved to a greater extent in LL compared with HL (16.6 vs. -1.2%, respectively). These findings indicate that both HL and LL training to failure can elicit significant increases in muscle hypertrophy among well-trained young men; however, HL training is superior for maximizing strength adaptations.
PMID: 25853914 DOI: 10.1519/JSC.0000000000000958 [PubMed – indexed for MEDLINE]