Because the warm-up, cooldown, and travel between circuit training stations is leg-intensive, you don’t need to include a lot of leg-strengthening exercises in your circuit routine.
If you have a weight bench with attachments at your disposal, you can add leg extensions, leg curls, leg presses, and any other exercises the machine supports.
Step-ups: Step-ups work nearly every muscle in your leg, as well as your butt muscles. To do this exercise, you need a step — one of the steps on the bottom of a stairway can work well. However, buying a step-aerobics platform and placing two sets of risers underneath the platform (to a height of 10 to 12 inches) may be more convenient (because it’s portable). You simply keep walking or running up and down the one step. Step up on one step and then bring the other leg up on that step, too. Then step back down, following with the other leg. Then up the step again, then back down, and so on.
Single-leg squats: Single-leg squats work your butt and upper legs and help develop balance. Stand on your right leg at the edge of the step, so that the instep of your right foot comes right to the edge of the step and your left leg is dangling off the step. Pull in your abdominals and bend your right leg on the step at the knee as you push your hips back, sinking into your right heel, until the heel of your left leg just touches the ground. Lead with your right heel, not your toes; straighten the leg on the step. Repeat. On the second circuit, use the other leg.
The heels of both feet should be along the same horizontal line. Also, you may need to hang on to something (perhaps a railing) to keep yourself from falling.
Standing calf raise: Standing calf raises work your calves and shins and help develop balance. Stand on the edge of a step or, if you have a step-aerobics platform, place two sets of risers underneath the platform. Stand tall with your abdominals pulled in, the balls of your feet firmly planted on the step, and your heels hanging over the edge. Rest your hands against a wall or a sturdy object for balance. Raise your heels a few inches above the edge of the step so you’re on your tiptoes. Hold the position for a moment, and then lower your heels below the platform, feeling a stretch in your calf muscles. Repeat. On the second circuit, use the other leg.
If you find one-legged calf raises too challenging at first, try doing this exercise with both legs.