If you're interested in developing stronger chest muscles, pushups provide one of the very best exercises. Not only do they work your chest with a functional movement you're likely to repeat in real life, they also build strength and endurance in your triceps and shoulders. Pushups also target your core muscles -- your abs and erector spinae, and to a lesser degree your glutes and quads -- because you're basically doing a plank for the duration of the exercise.
Greater Upper Body Strength
Pushups primarily work your chest, triceps and your anterior deltoid, or the front of your shoulders; doing at least one set of eight to 15 repetitions builds muscular strength and endurance. Placing your hands on an elevated surface shifts the focus to the lower part of your chest muscles, but also makes the exercise easier -- so it's a good way of gradually working up to doing full pushups.
Building Functional Strength
Pushups simulate the type of functional movement you might use in everyday life -- for example pushing yourself up off the floor, pushing a heavy bag of groceries across the counter, or holding a giggling baby up in the air.
Of course, most real-life pushing motions aren't going to involve the exaggerated bent wrist you assume during pushups. If you find this position to be uncomfortable, you can do pushups on your fists or using pushup handles to keep your wrists straight. Doing pushups on just one knuckle of each hand -- sometimes called knuckle pushups -- offers no real benefit beyond making your stabilizing muscles work a little harder to keep you steady.
Improved Core Stability
Your entire core works to keep your body steady during pushups, from your abs to your glutes, and even the quadriceps muscles in the front of your thigh. Of course, you only get this benefit if you focus on keeping your body straight from head to heels throughout the motion. If your hips sag down or pike up as you do pushups, you're not getting the full benefit of your workout -- and you might also hurt your back.
Another benefit of doing pushups is their endless variability; shifting your hand position changes which muscles bear the brunt of the effort. Place your hands close together and you'll emphasize the inner fibers of your chest muscles; place them wider apart and you'll emphasize the outer fibers. Or swing your elbows close to your body, hands directly beneath your elbows, to emphasize your triceps. If you start feeling like a particular type of pushup is too easy, you can make it more difficult by simply slowing your pace.