When people stop training, their muscles don't get weaker as fast as they shrink — strength sticks around more than size, maybe because the brain and nerves keep working well even as muscles get...

If you gain more muscle and strength when working out, you might also lose more when you stop — your gains and losses seem to go hand in hand.

In untrained young women, doing biceps curls with one arm or both arms at the same time leads to similar increases in biceps muscle thickness after 8 weeks, indicating that the total amount of work and load applied matters more than whether the exercise is done one arm at a time or both together.

Whether you lift your arm weights slowly or with a little swing, your biceps and triceps both get noticeably bigger after eight weeks of training—your triceps grow even more than your biceps.

For guys new to lifting, doing bicep curls with your arms in front of your body works just as well for building arm muscle as doing them with your arms behind you — both give about the same 6% to 9% growth in 10 weeks.

In untrained young women, doing bicep curls with one arm at a time may lead to slightly stronger gains in that arm compared to using both arms together, but does not result in larger muscle growth, suggesting that the nervous system adapts more than the muscle size in response to unilateral training.