The Claim
Resistance training performed twice weekly for 10 weeks increases leg press and biceps curl one-repetition maximum strength by approximately 20–25% and muscle cross-sectional area of the vastus lateralis and biceps brachii by 15–17% in untrained adults aged 18–40.
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.
Untrained adults aged 18–40 who perform resistance training twice a week for 10 weeks experience a 20–25% increase in maximum strength for leg press and biceps curl exercises and a 15–17% increase in the size of the thigh and biceps muscles.
See the scientific wording
Resistance training performed twice weekly for 10 weeks increases leg press and biceps curl one-repetition maximum strength by approximately 20–25% and muscle cross-sectional area of the vastus lateralis and biceps brachii by 15–17% in untrained adults aged 18–40.
When someone lifts weights, their muscle fibers experience tension that triggers the addition of new nuclei from nearby cells, allowing the fibers to make more protein and grow thicker. At the same time, the brain and spinal cord learn to activate more muscle fibers at once and reduce signals that hold back force, making each contraction stronger. These two changes — thicker muscles and better nerve control — happen together and cause both bigger muscles and greater strength.
What the research says
1 studyThis study found that people who didn’t lift weights before got about 20–25% stronger and their arm and thigh muscles grew by 15–17% after doing weight training twice a week for 10 weeks — exactly what the claim says.
Score breakdown, mechanism chain, raw evidence, ideal studies needed & 1 supporting studies
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.