Old time strong man (I mean real old time, like late 1800s lifting kettlebells at the circus old) Eugen Sandow used to preach that low weight high repetition workouts built more muscle and endurance than low repetition workouts.
In fact, in between circus show appearances and posing next to the bearded lady, Eugen Sandow used to make a living promoting his lightweight dumbbell system across the globe, and often prescribed his clients follow a routine that used ultra-light dumbbells for sets as high as 100 repetitions per muscle group.
Eugen Sandow was one of the most influential fitness personalities of his day. He and Bernarr Macfadden are often credited as giving birth to the modern fitness industry and for influencing guys like Jack Lalanne, and many other 20th century fitness gurus.
However, despite his overall impact on physical culture, Eugen Sandow and his high rep workouts were largely dismissed by the mainstream fitness industry as bro-science.
That is, until a 2015 study conducted by some of the most influential trainers of the modern era, including Brad Schoenfeld and Bret Contreras confirmed what Eugen Sandow knew all along: low-weight high repetition workouts can be just as effective as high weight low repetition workouts for building muscle.
Here is what the research team found.
The purpose of their 2015 study was to compare the results of low weight high repetition workouts to that of traditional low repetition training.
In the study, subjects were randomly assigned to 1 of 2 experimental groups: a high repetition group where 25-35 repetitions were performed per set, or a low repetition group where 8-12 repetitions were performed per set.
Both groups performed 3 workouts a week, each consisting of 7 exercises. Each group performed 3 sets of each exercise for the prescribed number of repetitions for a total of 8 weeks. Both groups took rest days between each workout.
What the researchers discovered was that participants in the low weight high repetition workout group experienced nearly identical changes in muscle growth, with the high repetition group experiencing slightly greater gains in quadricep size. Additionally, the high repetition workout group also saw the greatest gain in muscular endurance, which was assessed by having each participate complete the bench press at 50% of their 1-rep max to failure.
However, as expected the high weight low repetition group experienced far superior gains in overall strength. So while the study found that low weight high repetition workouts may be as good or slightly superior to low rep workouts for building muscle and endurance, they should not be used by those looking to build raw strength.
Conclusion: Like Eugen Sandow famously preached over 100 years ago, the 2015 study confirmed that light weight high repetition workouts are great for building muscle and endurance. However, while Mr. Sandow might be rolling over in his grave now that science has caught up with his theories on high rep training, the study confirmed his methods might not be ideal for athletes needing to build overall strength.
Schoenfeld BJ, Peterson MD, Ogborn D, Contreras B, Sonmez GT. Effects of Low- vs. High-Load Resistance Training on Muscle Strength and Hypertrophy in Well-Trained Men. J Strength Cond Res. 2015 Oct;29(10):2954-63. doi: 10.1519/JSC.0000000000000958. PMID: 25853914. PubMed.