In healthy young men, both intense weight training and intense weight training with restricted blood flow lead to measurable thickening of the connective tissue surrounding the thigh muscle,...

In healthy young men, performing intense weight training with or without restricted blood flow to the leg leads to measurable thickening of the connective tissue surrounding the main thigh muscle after six weeks.

In healthy young men, two different types of weight training programs—high-intensity lifting and high-intensity lifting with blood flow restriction—produce similar increases in thigh muscle size after six weeks, suggesting that pushing muscles to fatigue with the same number of sets each week matters more for growth than how heavy the weights are.

In healthy young men, two different resistance training methods—training until muscle failure or using blood flow restriction with mixed intensities—produce similar increases in thigh muscle size after six weeks, suggesting that reaching muscle failure may matter more for muscle growth than how heavy the weights are or how much total work is done.

If you're a young man who already trains regularly, doing more sets with lighter weights for 6 weeks can make your thigh muscle grow a little bigger — but doing fewer sets with heavier weights won't make it grow at all.

Lifting weights twice a week for six weeks — whether using heavier or lighter weights — helps young, healthy guys build leg muscle just about the same amount, compared to not training at all.