Even if you lift the same weight every time without making it heavier, your arms can still get noticeably bigger in just two months — at least when you're just starting out and you're a young woman.

Even if you don’t lift heavier weights over time, just doing regular arm workouts for 8 weeks can make your triceps muscles noticeably bigger—way more than just sitting around.

If you're a young woman just starting weight training, slowly lifting heavier weights over time will make your triceps (the back of your arms) grow about twice as much as just doing the same workout over and over.

If you're someone who regularly lifts weights, doing more triceps exercises each week might help your triceps muscles get a little bigger—but only a little, and not as much as it helps your biceps.

Both kinds of weight training—whether you do one hard set or three regular ones—made young men’s triceps bigger and stronger after six weeks.

Even lifting light weights really slowly until you can't do another rep can make your muscles bigger, just like lifting heavy weights.