When most think of strength training, they immediately envision dumbbells, barbells and other weighted implements. Weighted implements provide the resistance that your muscles must overcome, and thus are the stimulus for causing increases in muscular strength and size. Bodyweight exercises, however, are activities that also develop muscular strength and size, but without any use of weights. Instead, your own body weight provides the resistance that your muscles must overcome.
There are a number of benefits to performing body weight exercises. The first obvious advantage is that no additional equipment is required, which means you don't need access to a gym and can perform the exercises anywhere. Most importantly, however, is that bodyweight exercises require a greater level of balance and coordination to complete, which means that not only will an exercise develop the primary muscles it targets, but will simultaneously recruit surrounding stabilizing muscles.
Bodyweight exercises are appropriate for beginners and can be easily adapted for more advanced lifters. For those starting out with strength training, performing workouts that consist of bodyweight exercises will allow them to develop a baseline level of overall strength before they increase the intensity of their workouts with weighted implements.
You can develop all of the major muscle groups with bodyweight exercises. The following are the most common of bodyweight exercises, as well as a bit of information on how you can adapt them to increase or decrease their difficulty.
Push-ups
Push-ups develop the chest, shoulders, triceps and abdominals. You can increase the stress on the chest by widening your hand placement, or increase the stress on your shoulders and triceps with a more narrow hand position. For those who are unable to perform push-ups from their feet, modified push-ups can be completed from the knees. Those looking to increase the difficulty of the push-up can complete the exercise using a diamond-hand placement, where the hands are placed on the floor together and directly underneath the center of the chest, with the fingers creating a diamond shape.
Dips
Dips also target the chest, shoulders and triceps, but the load is distributed differently. During push-ups, the chest is the primary muscle handling the load, but during dips, it's the shoulders and triceps. If you're unable to perform a dip, try a bench dip. Sit on the edge of a bench or chair with your hands placed on the edge of the bench on either side of your hips. Extend your legs out onto the floor in front of you. Hold your body weight with your hands and slide your hips forward so that they clear the bench and then lower them down to the floor by bending your elbows. To increase the difficulty of the regular dip, hold a weighted implement between your knees.
Pull-ups / Chin-ups
The pull-up and chin-up primarily develop the latissimus dorsi, which is the largest muscle in the back, but the biceps, trapezius and abdominals also contribute. The more narrow your hand placement on the bar, the more effective your biceps are, and the easier the exercise becomes. Chin-ups, with your hands twisted so that they're facing you, increase the recruitment of the biceps even further and are thus even easier to complete. If you currently lack the strength to perform pull-ups or chin-ups, place your feet on a chair. This allows you to take some of the weight off your arms. To increase the difficulty of the exercise, hold a weighted implement between your knees or feet.
Squats
Squats are such a quality exercise, because they single-handedly develop all of the major muscles in the legs. The glutes, quadriceps, hamstrings and calves are all required to perform the squat. If you have difficulty with the squat, practice squatting down onto a chair and then standing back up just using your legs. If you're looking to increase the difficulty, hold weighted implements in your hands or on the back of your shoulders.
Lunges
Lunges also recruit all of the major muscles in the legs, but it's a unilateral exercise, meaning one leg works at a time. This is beneficial because during squats, your dominant leg can take on more than half of the work load, allowing your non-dominant leg to take it easy. During lunges, however, each leg has to hold its own. Those who cannot lower all the way down into a lunge can perform quarter lunges. Those looking to kick the difficulty up a notch can hold weighted implements in their hands or on the back of the shoulders.
Front Planks
Planks develop strength in your abdominals, obliques and hip flexors. They're unlike all of the other listed exercises because they require you to get into a position and hold it over time, rather than perform for repetitions. However, if you cannot hold the front plank for more than five seconds at a time, it's okay to perform the exercise for reps. Get into the plank and then lower back down. Repeat this over and over until you develop adequate strength. To increase the difficult of the plank, you can alternative lifting your feet inches up off the floor.
Burpees
I've saved the most difficult exercise for last. Burpees are challenging, but so incredibly effective because they are a full-body workout in themselves. They hit your chest, shoulders, triceps, abdominals, glutes, quadriceps, hamstrings and calves. If you have trouble, perform the exercise without the push-up. Although there won't be many looking to increase the difficulty of the burpee, if you are looking for a challenge, you can perform the exercise while holding a medicine ball. Do the push-up component with your hands on the ball, and then hold onto it when you jump.