There are several reasons you want to add the push up to your workouts without weights, if you haven't already. The first is that you are getting a more complete workout then you probably thought you were getting. Because when you workout with push ups you are not just working your chest and your arms. It is also a pretty good shoulder workout too. Working out your front deltoids, your rotator muscles, and your trapezius(shrugs) and your serratus anterior(rib cage to shoulder blade). You use all of these muscles to keep your upper body stiff and rigid when you do your push ups.
But that's not all! You also get a great core workout as well! To do a push up properly, you must maintain correct form. Meaning that your body must stay straight and stiff as you perform the exercise. In order to make this happen you must keep your abs and your glutes contracted the whole time. Brace your abs like you were about to take a punch and squeeze those glutes tight, and you'll be sure to keep good form throughout and get a whole body workout at the same time.
Another reason why I love to do push ups during my workouts without weights is all of the different variations that you can do. From making it easier, to much more difficult, there are enough different ways to do a push up that you should never get bored. Without adding any gym equipment at all I can think of about 14 different variations of the push up.
Here are a few my favorites...
A couple of ways to make push ups easier:
Modified Push Up: Instead of performing the exercise with your legs straight, bend your knees till they touch the ground & cross your ankles behind you. During this modification you are using about 65% of your body weight, as opposed to 75% with the classic push up.
Incline Push Up: Similar to the modified push up, this will lessen the amount of your body weight that you will be pushing. Reducing the stress on the shoulders. To do this, you'll need something that you can lean against that will hold your body weight. This could be a chair, stove, counter top, or even a staircase. Instead of placing your hands on the floor, put them on whatever you chose to use to hold you up. Then just do a regular push up motion, with your body in an incline position.
A couple of ways to make your push up workout more difficult:
Decline Push Up: The exact opposite of the incline push up we talked about earlier. With this exercise you will raise your feet off of the ground onto whatever you've chosen to hold your weight, just like the incline push up. This puts more of your weight onto the upper part of your body working out your chest and shoulders significantly more.
Triple-Stop Push Up: With this method you will assume the normal position and do a standard push up, but with a pause of about 2 seconds at 3 spots along the way. First, about halfway on the way down. Then when your chest is just off of the floor. Finally, as you push back to the starting position, pause just before the point you straighten your arms. Briefly pausing at each point increases strength at that joint angle and 10 degrees in either direction. And also increases the time your muscles are under tension, which stimulates growth. You can even stop again at the halfway point on the way up if you want, making this a 4-stop.
Spiderman Push Up: During this exercise you'll start in the standard push up position. But add in a different movement in the middle of each rep. As you lower your body toward the floor, lift your right foot off the floor, swing your right leg out sideways, & try to touch your knee to your elbow. Then on the way up, reverse the movement back to the starting position. Then on the next rep, touch your left knee to your left elbow. And continue to alternate legs on each rep.
Obviously, there are many more variations of the push up that you can do. But, these are a couple of my favorites that anyone can add to their workouts. No matter what experience or fitness level you are at in your workouts without weights, the push up is definitely a must.