The Claim
In recreationally active men, a 12-week high-intensity, low-volume concurrent training program increases type I and type IIa muscle fiber cross-sectional area by approximately 12.9% and 12.7%, respectively, while no such increase in type I and type IIa muscle fiber cross-sectional area occurs in recreationally active women undergoing the same training program, despite comparable gains in strength and lean body mass.
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.
After 12 weeks of high-intensity, low-volume concurrent training, recreationally active men experience a 12.9% increase in type I muscle fiber size and a 12.7% increase in type IIa muscle fiber size, while recreationally active women do not show similar increases in these muscle fiber sizes, even though both groups gain equal strength and lean body mass.
See the scientific wording
In recreationally active men, a 12-week high-intensity, low-volume concurrent training program increases type I and type IIa muscle fiber cross-sectional area by approximately 12.9% and 12.7%, respectively, but no such hypertrophy occurs in women despite similar gains in strength and lean body mass.
In men, intense resistance and sprint training creates strong mechanical forces in muscle fibers that turn on a growth pathway called mTORC1, which tells the cell to build more muscle proteins, making the fibers bigger. Women experience the same training and same strength gains, but their muscle fibers do not turn on this growth pathway, so their fibers do not get larger.
What the research says
1 studyMen who did this specific workout got bigger muscle fibers in their thighs, but women doing the exact same workout didn’t — even though both got stronger and gained the same amount of lean muscle. The study proves this difference actually happened.
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.