If young women do light weightlifting while wearing special bands that squeeze their arms or legs, they can get stronger and their muscles can grow bigger in just four weeks—without lifting heavy weights at all.

If you do light weightlifting with a band around your arm to restrict blood flow, whether you're pushing or lowering the weight doesn’t seem to matter—both ways make your muscles stronger and bigger about the same amount in four weeks.

If young women do light weightlifting with a special band that restricts blood flow for four weeks, their muscles get stronger and bigger—even after just two weeks—without having to lift heavy weights.

When young women do light weightlifting with bands that squeeze their arms or legs, their muscles don’t get better at receiving signals from their brain—but they still get stronger. This means something else, like muscle swelling or chemical changes, must be making them stronger.

If you lift heavy weights with a special band that cuts off some blood flow, it doesn’t make your muscles stronger or bigger than just lifting heavy weights alone—even though your muscles feel more burned.

If you can't lift heavy weights because of an injury or illness, doing light weight exercises while squeezing your limbs tight might still help you get stronger — and that could be a good option for people in rehab.