The Claim
Hypertrophy of both slow-twitch and fast-twitch muscle fibers is similar between low-load/high-repetition and high-load/low-repetition resistance training when performed to volitional failure.
What the research says
Supports is higher
Support is ahead, but a single strong opposing study can change this.
These are independent scores, not a percentage. Higher-grade studies count more, so a single strong opposing study can outweigh several weaker ones.
When resistance training is performed to muscle failure, low-load with many repetitions produces the same amount of muscle fiber growth as high-load with few repetitions.
See the scientific wording
Hypertrophy of both slow-twitch and fast-twitch muscle fibers is similar between low-load/high-repetition and high-load/low-repetition resistance training when performed to volitional failure.
When muscles are worked until exhaustion, the body recruits all muscle fibers, slow and fast, by first fatiguing the easy-to-use fibers and then forcing the powerful ones to kick in. This full activation creates enough stress to trigger satellite cells to multiply and donate new nuclei to muscle fibers, allowing them to build more protein and grow larger. The same process happens whether the weight is light or heavy, as long as the effort pushes the muscle to its limit.
What the research says
4 studiesWhen you lift light weights until you can't do another rep, or heavy weights until you can't do another rep, your muscles grow about the same amount—both ways work if you push yourself to the limit.
This study showed that lifting very light weights with restricted blood flow until you can't do another rep can make your muscles grow just as much as lifting heavy weights — even in both slow and fast muscle fibers.
When you lift light weights with lots of reps or heavy weights with few reps — as long as you push until you can't do another rep — your muscles grow about the same amount. This study found no clear difference between the two methods.
When you lift light weights with lots of reps or heavy weights with few reps — as long as you push until you can't do another rep — both ways make your muscles grow about the same, according to this big review of studies.
Related videos
Score breakdown, mechanism chain, raw evidence, ideal studies needed & 4 supporting studies
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.