If the goal is to rebuild muscle you can actually use, standing exercises usually give your legs a better challenge. Recommended Sets and Reps: Perform 3 sets of 8 to 12 reps. Rest for 60 to 90 seconds between sets. A clean set of moderate deadlifts can do plenty to rebuild strength in your hips, legs, and back. Recommended Sets and Reps: Perform 3 sets of 10 to 15 reps. Rest for 60 to 90 seconds between sets. Restoring leg muscle after 55 doesn’t have to mean living on leg machines.