Current research finds that you don’t need to lift heavy weights like the beefiest guy at the gym to get bigger muscles. A 2022 umbrella review of 14 meta-analyses reported that training volume and frequency may matter more than how heavy you lift.
Volume
When other variables are held constant, higher volume increases time-under-tension, which the researchers Bernárdez-Vázquez et al. proposed as a key driver of muscle hypertrophy. They wrote that doing two to three sets elicits 40% more hypertrophy compared to a single set, while no differences were observed when comparing two to three sets vs. four to six sets. This may be because higher volume places the body until high metabolic stress, which stimulates higher protein synthesis.
They added that “at least 10 weekly sets per muscle group is necessary to maximize increases in muscle mass.” However, they cited a 2017 study that showed low-volume protocols (four weekly sets or less per muscle group) “could be enough to get substantial gains in muscle hypertrophy.”
Frequency
Bernárdez-Vázquez et al. reported that frequency doesn’t significantly affect muscle hypertrophy much when volume is the same across comparison groups. They wrote that spreading a fixed volume across more sessions per week allows each session to be less taxing, which optimizes recovery and maintains training intensity.
However, Bernárdez-Vázquez et al. cautioned that combined high intensity and high frequency training can lead to overtraining. Also, the included studies primarily focused on leg and arms muscles, so the authors could not be extrapolated to other muscle groups nor could multi-joint and single-joint exercises be compared.
Intensity
Intensity is still an important factor in muscle hypertrophy. Bernárdez-Vázquez et al. wrote that traditionally, using high loads with a moderate number of reps, such as 80% of one-rep max for eight to 10 sets, “[allows] the recruitment of high-threshold motor units, which is not possible with the high repetition range.”
“However, there is a lack of evidence to objectively establish the balance between external load, metabolic stress and hypertrophy responses,” they wrote.
Bernárdez-Vázquez et al. wrote that low loads (under 60% of one-rep max) and high loads (65% and higher) produce comparable hypertrophy results, provided sets are taken to or near muscular failure. This is based on a 2016 meta-analysis that used untrained participants.
But a 2017 meta-analysis found low-load training yielded similar results as high-load training. Bernárdez-Vázquez et al. wrote that the suggested that training with low loads “implies a higher level of discomfort, although this did not imply a lower adherence to it compared to that reported in programs with high loads.”
The authors also reported a “95% confidence and prediction intervals,” indicating the evidence remains uncertain and further research is needed.
Citing a 2020 systematic review, Bernárdez-Vázquez et al. reported this study “non-significant differences” in hypertrophy when comparing the effects of low-load versus high-load training between type I and type III muscle fibers.
They pointed out that most of the data is based on untrained people, so not much is known about training intensity for trained people, such as athletes.
Contraction type
While eccentric muscle contractions (elongation of muscle fibers under tension) has been touted as being superior to concentric contractions (shortening of muscle fibers), Bernárdez-Vázquez et al. cited that a 2017 systematic review that found concentric contractions can also significantly increase muscle hypertrophy. According to that study, the difference between eccentric and concentric contractions is small: 10% versus 6.8%, respectively.
Bernárdez-Vázquez et al. wrote that eccentric contractions place a higher load on muscles than concentrics. “These differences could be explained because of the higher force and mechanical load generated during eccentric training compared to concentric when the same repetitions number is performed,” they wrote.
Based on the same 2017 study, Bernárdez-Vázquez et al. wrote that concentric contractions may affect higher hypertrophy gains in the middle of the muscle while eccentric contractions affect higher on the distals ends of the muscle.
Finally, the author cited a 2020 meta-analysis that found eccentric training may stimulate greater growth in type II muscle fibers compared to concentric training. A likely reason is that eccentric contractions tend to activate high-threshold motor units, which are predominantly composed of Type II fibers. “However, the mechanism by which such a fiber type preference exists is not clear,” they wrote.
Repetition duration
How quickly or slow you lift can also affect muscle hypertrophy. Bernárdez-Vázquez et al. reported that slowing the lift increases mechanical tension at 80% to 85% of one-rep max. They cited a 2015 systematic review that found reps that last 0.5 to 8 seconds to be effective. However, very slow tempos around 10 seconds per rep may be counterproductive, likely because they fail to adequately recruit high-threshold motor units.
“From a practical perspective, a wide range of repetition durations can be used to stimulate hypertrophy, however, very slow repetitions should be avoided,” they wrote.
Overall, the authors ranked the meta-analysis quality as “moderate” or “high.”
Details of the 2022 umbrella review.
Nick Ng, BA
Nick Ng is the editor of Massage & Fitness Jounal and the managing editor for My Neighborhood News Group.
An alumni from San Diego State University with a bachelor’s degree in graphic communications, Nick had also completed his massage therapy training at International Professional School of Bodywork in San Diego in 2014. In 2021, he earned an associate’s degree in journalism at Palomar College.
When he gets a chance, he enjoys weightlifting at the gym, salsa dancing, and exploring new areas in the Puget Sound area in Washington state.
