Gym claims: which ones hold up

The first stop takes apart three claims. Muscle grows from the tension that pulls on it, not from the hormone spike after a session; two-joint muscles grew more in a lengthened position in several studies, though the pooled extra is small; and new muscle burns only a few dozen extra kilocalories a day, so building muscle is no fat-loss shortcut.

Light weights build muscle too, as long as sets get close to failure: the nervous system wakes muscle fibers from small to large, and the last reps call up the same fibers either way. Machines and free weights have not been shown to differ for muscle size, while strength rises most on whatever you trained with.

How many sets: more weekly sets mean more growth, but each extra set buys less, and strength levels off sooner. Data above 25 sets a week are still thin, so that range is unclear.

Get the day's protein total first, then split it across meals. A bigger meal pays back less per gram but is not wasted, and the rule that you must eat protein within 30 minutes of training has no basis.

The worry that creatine causes hair loss rests only on a DHT rise in one small study that was never repeated; the only trial that measured hair directly saw no change.

During a heavy lift, blood pressure surges briefly; with regular training, resting blood pressure comes down. For people with hypertension the question is not whether to lift but how, once blood pressure is controlled.

Last, the cost of the shortcut. External testosterone does build muscle, and it shuts down your own testosterone and sperm production; recovery after stopping often takes months to over a year, and in one study, a year after the cycle began, some had still not recovered. SARMs also suppress testosterone and HDL, and products sold online often are not what the label says.