Doing leg curls with your foot pointed up or down leads to the same muscle growth and strength gains over 10 weeks. This means your starting leg position doesn't change how much your muscles grow or...

After 10 weeks of leg curls, it doesn’t matter if your foot is pointed up or down—you’ll get the same muscle growth and strength gains either way.

When doing leg curls, keeping your toes pointed up lets you lift more total weight over time than pointing them down, even though both positions build muscle and strength equally. This extra volume might happen because one position is easier on your muscles or more mechanically efficient.

Doing leg curls with your toes pointed down builds the same amount of hamstring muscle and strength as pointing them up, but you can do it in less time. This means you might get the same results faster by simply changing your foot position.

People did more total reps with their foot pointed up, but that didn’t make their muscles grow bigger or stronger than the leg with the foot pointed down.

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.