When women who lift weights do squats with 80% of their max weight, their butt muscles work way harder compared to their hamstrings — more than with lighter or heavier weights.

When women who lift weights do squats with a light weight (about 40% of their max), their butt and hamstring muscles work together in perfect balance as they lower down.

When women who lift weights do squats with different levels of heavy weights, the way their thigh and butt muscles work together stays the same — no matter how heavy the weight is.

When women who lift weights do squats with a really heavy weight (close to their max), their leg and butt muscles have to work a lot harder than when they use lighter weights.

For women who lift weights regularly, squatting with 80% or 90% of your max weight activates your muscles about the same — going heavier doesn’t seem to turn on more muscle once you hit that range.

Doing hip thrusts or squats for nine weeks, with the same total amount of work, makes your butt muscles grow just as much—so neither exercise is clearly better for building glutes if you're new to lifting.