Lunges and pistol squats are classified as unilateral leg exercises, and both develop your lower body and core muscles. Unilateral exercises can help improve your balance, coordination and proprioception, strengthen your joints to reduce your risk of injury and boost your rate of muscle growth. You can include lunges and pistol squats in your training routine, but consider the pros and cons of each.
Hitting the Lower Body
Both exercises hit all of your lower body muscles -- quadriceps, hamstrings, gluteals and calves, along with your core muscles. However, pistol squats require you to work harder at balancing, so involve the muscles on the inside and outside of your legs -- the adductors and abductors more. You can also change the stride length of your lunges to vary how much work each muscle is doing. Short step lunges will increase quadricep involvement, while long step lunges hit your hamstrings more.
Ease of Performance
If you're just starting training, then neither of these exercises is easy. You should be able to master lunges after a relatively little time training, but pistol squats are a more advanced exercise. Certified kettlebell instructor Steve Cotter, author of "The Complete Guide to Kettlebell Lifting," advises you build up gradually to doing full pistols. Start by simply balancing on one leg, then work up to squatting down to a chair or box, before finally attempting full pistol squats.
Body Weight and Free Weights
You can do lunges and pistols squats using just your body weight or any other form of resistance, such as dumbbells, kettlebells, resistance bands or a weighted vest. You can also use a barbell for lunges, which isn't advisable with pistol squats, due to the risk of falling over with a bar across your shoulders. Lunges can be performed stepping forward or backward, and with your front or back foot on a box, and you can vary the length of your stride. Pistol squats are fairly one-dimensional and don't have nearly as many variations as lunges.
A Gym Staple Vs. a Challenging Newcomer
Both exercises will increase your strength and muscle mass, strengthen your tendons and joints, and reduce your chances of injury when performed correctly. If you're new to training or working out for bodybuilding or strength purposes, then lunges are probably a better choice as a staple exercise in your program. If you don't train in a gym and find lunges too easy, have a desire to become proficient at body-weight exercises or want to impress your friends with a new, extremely challenging exercise, opt for pistol squats.