If young guys who haven't worked out in a while do different leg exercises for 9 weeks, their upper outer thigh muscles grow more than the middle part — even with exercise variety, growth isn't even.

If you switch up your leg exercises during a workout routine, you might build more muscle in certain parts of your thigh—like the upper side—compared to sticking with the same moves.

If young guys who haven’t worked out in a while switch up their strength exercises for the same muscles, they’ll likely build muscle more evenly across their thighs and arms over nine weeks compared to doing the same moves every time.

If young guys who used to work out take a break and then do the same strength exercises over and over for about two months, some parts of their muscles might not grow much — especially on the side of the thigh and upper arm — which means doing the same routine might not help all muscles grow equally.

If you mix up your strength workouts for the same muscle, it might help it grow more evenly from top to bottom, especially if you haven’t been training for a while.

Even if you do a lot of leg workouts, your thigh muscles grow about the same amount whether you do 20 or 50 sets a week—just doing any consistent training makes them bigger.