As it turns out, our muscle mass typically peaks in our early 40s. After that, our muscles can start to gradually deteriorate (something called sarcopenia), which can lead to falls and other troubling health issues down the road. (Especially if you stop working out.)

While more research is needed to fully understand how to counter this process, there are precautions you can take now to slow its progression and perhaps even prevent the loss of muscle mass in the future. 

The good news: Strength-training moves may help you improve and maintain your muscle mass and tone. If your goal is to strengthen and tone your legs specifically, then the one move you need is the chair squat. 

"The chair squat targets the glutes, hamstrings, and quadriceps effectively and efficiently," says personal trainer Daphnie Yang.

Yang says that while certain lower-body exercises are only able to target one muscle group at a time, the chair squat effectively targets multiple lower body muscles at once.

When doing this move, be sure to keep your knees in line with your ankles. Keep your weight in your heels and try to keep the core engaged to keep your lower back safe.

Perform this chair squat 2 to 3 times a week every other day to strengthen and tone your legs. Yang recommends starting with 2 sets of 20 and then working your way up to 3 sets of 20. And try this exercise barefoot so that you can feel your feet grounding into the floor. 

Step 1: Begin by sitting on the edge of a sturdy chair with your feet hip-width apart. Keep your knees in line with your ankles, and keep your abs engaged.

Step 2: Reach your arms straight out in front of you, keeping your triceps tight. 

Step 3: Stand up, squeeze your glutes, and push your arms behind you.

Step 4: Slowly return to the starting position and make sure your weight is in your heels. 

Step 5: Let your glutes graze the edge of the chair, and immediately repeat the exercise.