Air squats are an amazingly simple, safe, inexpensive, effective form of exercise. Air squats are simply squats done without additional weights, just using one's own body weight for resistance.
They can be done by people of all ages and in virtually any location. I currently have an 82-year old female client who is doing her squats holding onto the door knobs on her bedroom door for balance.
Air squats utilize all the big muscles in your lower body including the quadriceps, hamstrings, adductors and the gluteal muscles in the buttocks. Strengthening these muscles will provide a lifetime of benefit. This is especially important for the elderly because strength in these muscles helps prevent falls and subsequent injuries.
There is another benefit from air squats that gets overlooked. Squats are a great weight-loss technique. I encourage my clients who want to lose weight to do 20 or 30 air squats about 10 minutes before each meal. Activating all the muscles in the legs and buttocks delivers more blood, oxygen and nutrients to all these cells. Then after eating, much more of the blood sugar from a meal gets delivered to these big muscles where it gets utilized for energy rather than getting converted to triglycerides and stored as fat. Yes, just doing squats for a couple of minutes before a meal will help you avoid storing the calories from a meal as body fat.
Here is a link to a site that provides air squat instructions and a short video that demonstrates the correct form for air squats: