Experimental chronic low‐frequency resistance training produces skeletal muscle hypertrophy in the absence of muscle damage and metabolic stress markers

Muscle growth occurs primarily due to mechanical tension during resistance training, while factors like metabolic stress, hormone changes, and muscle swelling do not play a major role.

Scientists aren't sure if the burning feeling you get during a tough workout (called metabolic stress) actually helps your muscles grow, because it's always happening at the same time as the physical pulling on muscles—and we can't separate the two in people.

Rats that performed low-frequency resistance training had 24% less TNF-α protein in their soleus muscle compared to rats that did not exercise.

When rats do low-frequency weightlifting, their blood doesn't show signs of muscle soreness or energy stress, meaning this kind of exercise doesn't hurt or tire their muscles.

When rats do light weight training twice a week for three months, their calf muscles get about 12% bigger—even though they’re not lifting heavy weights—so maybe you don’t need to lift heavy to build muscle.

When rats do resistance exercises less often, their blood doesn't show signs of muscle damage or stress—so this kind of workout seems gentle on their bodies.