The pushup is a benchmark of fitness for many entities, including law enforcement and the military, pictured above.

The Pushup

Have two hands? Check. A relatively flat surface? Check. Great, because that is all you need to perform one of the most versatile, effective and useful exercises available. Pushups are great for building strength and stability across several muscle groups, and can be performed anywhere with ease. A benchmark of fitness for law enforcement and military agencies everywhere, let's take a look at what makes it the best bodyweight exercise.

Muscles Used

Pushups are awesome exercises to perform due to the range of muscles used each repetition. In order to keep the body aligned, the abdominals act as a stabilizing muscle and are constantly contracted during a proper rep. The pectoralis major, often abbreviated as "pecs", runs from the top of the arm to the cent of the chest on both sides of the body. These chest muscles work to move the upper arms toward the chest in the upward portion of the movement.

Performing the same function but located on the opposite plane of the body, the anterior deltoid muscles also control the speed of the downward portion of a pushup. Additionally, the  triceps brachi play a large role in the workings of the move. The triceps power the elbow joints to extend the arms during the upward phase of the exercise, as well as control the speed of flexion during the downward movement. 

The legs and several other muscles also work during the repetition of pushups, but none are as significant as the aforementioned muscle groups.

Proper Pushup Form

Proper form is primarily concerned with maintaing alignment from the neck down to the legs. Laying flat on the floor, bodyweight should be placed on the palms of the hands and the tips of the toes. Focus your gaze on the floor below you, and make sure your neck is aligned with your torso. Hands should be spaced slightly wider than shoulder-width, and arms should align with the middle of the chest. Moving down the body, a straight line should be formed from the neck, down the back and through the hips and legs. 

Keeping the shoulders and back stable, and maintaining a straight alignment, lower your torso until a full range of motion is completed. During the upward phase, place pressure on the outside of the hands and avoid stressing the wrists. If you have pain or too much discomfort in your wrists when performing a pushup, I suggest using dumbbell handles to push off of. Also, you could consider purchasing an ergonomic aid, such as the Perfect Pushup. Tools like this are a great way to reduce the negative stress of pushups.

Perfect Basic Pushup
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Pushup Variations

One of the greatest feats of pushups are the amount of variations that can be performed. It is possible to get a great and varied chest workout from using several types of the exercise. Different methods work the activated mucles in different ways and place stress on varying areas, changing the exercise's effect. 

Elevated repetitions can be done with the feet resting on an elevated surface, such as a bench, chair or swiss ball. 

Backhanded and knuckle pushups are performed with the weight resting on the back of the hands and on closed fists, respectively.

Diamond or tricep variations are done with the palms close together towards the center of the chest, placing more emphasis on the triceps.

Explosive reps involve explosively pushing yourself off the floor with each upward phase.

In addition to these, there are a large number of pushup variations that work the body in many different ways. Be sure to try out the basics, and don't be discouraged if you can't do some of the more exotic alternatives. With practice and patience, performing correct pushups should lead to a great improvement in posture and overall fitness level.