When people lift lighter weights many times (12 reps max), their muscles get bigger and that's why they get stronger. But when lifting heavier weights fewer times (4-8 reps max), their strength comes more from their brain and nerves learning to use muscles better, not from bigger muscles.

When people lift weights in a way where they can do 12 reps max, getting stronger is closely tied to getting bigger muscles. But this link isn't seen when lifting for only 4 or 8 reps max.

When beginners lift weights for 10 weeks, doing fewer reps with heavier weights (like 4 or 8 reps max) builds more strength than doing more reps with lighter weights (12 reps max), even if the total work is the same.

When men lift weights, doing more reps with lighter weights (like 12 reps max) gives less strength improvement than doing fewer reps with heavier weights (like 4 or 8 reps max), even if the total workout effort is the same.

Getting stronger from lifting weights doesn’t always mean your muscles are getting bigger—and vice versa. Strength and size don’t go hand in hand.

Getting stronger from lifting weights doesn’t always mean your muscles are getting bigger—and vice versa. Strength and size don’t go hand in hand.