Air squats, also known as body weight squats are a staple beginner move for working the lower body. When you want to ramp up the intensity however, air squats can be a little too basic, meaning you need to switch things up and start performing regular squats with weight. This doesn't mean that air squats become redundant in your training, just that you need to find a way to make them a little more challenging.
Mastering the Techniques
For air squats, stand with your feet slightly wider than shoulder width apart and your knees and toes facing straight ahead. Squat down in the same way you'd sit into a chair -- by pushing your hips back, then bending your knees. Go as low as you can without your heels coming off the floor or your back rounding, then push back up again. (Ref 1) Weighted squats are performed in exactly the same way. You can do this by holding a barbell across your upper-back or by holding weights at your sides. (Refs 2 & 3)
The Learning Curve
Don't run before you can walk. If you're new to weight training, the air squat is the best way to learn correct squatting technique, as if you have any form issues, it's better to fix them before you look to add weight. Common errors when performing air squats include dropping your shoulders forward, rounding your lower-back and not going low enough, according to coach Colin Struckert of The Training Box. (Ref 4)
Strength and Power
For building sheer strength and power in your legs, you can't beat the squat. Barbell squats are essential exercises in any powerlifting or Olympic weightlifting program. Getting stronger in the squat will make you run faster and jump higher, increase your mobility and decrease joint pain, improve your athletic performance an strengthen your core, says strength coach Charles Poliquin. (Ref 5)
The Final Decision
Both air squats and weighted squats have their advantages and disadvantages. Air squats are a must if you train at home with no equipment and still want to build your legs. You can make them harder by increasing the number of repetitions you do, going lower or slowing down the tempo and performing them slowly. If you want to get stronger though, adding weight is essential -- you need progressive overload in the form of heavier weights, so hit the gym, grab a barbell or pair of dumbbells and go to town.