Pushups and their many variations increase your upper-body strength by primarily targeting your pushing muscles. They don't work your pulling muscles and have a negligible effect on your legs. Pushups have no cardiovascular benefits and don't burn fat unless they are part of a circuit including other exercises. A pushup-only workout has a limited effect on your overall fitness. For a comprehensive workout program, you need to add exercises that address the elements pushups lack.
Upper-Body and Core Strength
Pushups strengthen and tone your chest, anterior deltoids -- front of your shoulders -- and triceps. Pushups also strengthen your core muscles, according to strength coach Nick Bromberg, writing for The Post Game. As you crank out your reps, your abs and obliques isometrically contract to help keep your body straight. The erector spinae of your lower back and your quadriceps also work to stabilize your body. Do three sets of 20 to 25 reps. Increase your reps as you get stronger.
Variety is King
Increase your intensity with one-arm pushups and clap pushups. To do one-arm pushups, keep your legs slightly more than hip-width apart to maintain your balance, and place your other arm behind your back. Clap pushups increase explosive strength. On the upward motion, push off with your arms and legs, propel your body into the air, clap, land in the pushup position, and repeat. For an easier version, keep your feet on the floor as you clap. Pushup variations shift the focus onto other upper-body muscles. For example, triangle pushups, with your hands close together, accentuate your triceps. Handstand pushups, with your legs straight up in the air, your feet braced against a wall, and your body upside-down, work your shoulders intensely. Do two sets of 10 to 15 reps of each exercise.
A Taste of India
The Hindu pushup works your pushing muscles and stretches your lower back. To perform the exercise, place your hands approximately shoulder-width apart on the floor and your legs behind you with feet shoulder-width apart. With your weight balanced on your hands and toes, push your butt up in the air so your body forms an inverted V, with your head between your straight arms. This is the Downward-Facing Dog starting position in yoga. Drop your hips to the floor and bend your elbows, and in a fluid motion arch your back by straightening your arms so your chest is facing forward and your head up. Repeat. Do three sets of 12 to 20 reps.
Push, Pull, Squat and Crunch
Increase the effectiveness of your pushup workout by including other body-weight exercises such as pullups, body-weight squats and crunches. Pullups work the pulling muscles of your upper back and biceps, and body-weight squats target your legs. Increase your intensity by doing the exercises back-to-back with no rest between sets. Do 15 to 20 pushups, eight to 12 pullups, 15 to 20 body-weight squats, and 20 to 25 crunches.
Strengthen your heart and lungs and burn fat with a cardiovascular routine. Do 30 to 45 minutes of steady-state moderate-intensity activities such as swimming, bicycling, brisk walking or running. Increase your intensity by incorporating short intense intervals into these activities. For example, bicycle at a sedate pace for two minutes, then sprint for one minute. According to the American Council on Exercise, intense intervals significantly increases your fitness.