The push-up is a widely recognized bodyweight exercise used to build strength and endurance in the upper body. Unlike exercises using free weights, the resistance comes from supporting a portion of your own mass against gravity. This reliance on body mass often leads to the question of exactly how much weight the muscles are actively pressing. Quantifying the specific percentage of body weight supported by the hands is rooted in biomechanical analysis, which helps gauge the training load and make informed adjustments.
The Body Weight Percentage in a Standard Push Up
A standard push-up, performed with the hands shoulder-width apart and the body held straight, does not require pressing 100% of the body weight. Biomechanical studies using force platforms show the average load supported falls into a specific range. For most individuals, the hands support approximately 64% of the total body mass when the arms are fully extended at the top of the movement.
The resistance changes dynamically throughout the repetition as the body moves through the full range of motion. As the body descends toward the floor, the percentage of body weight supported by the hands increases. At the bottom of the movement, when the elbows are bent to 90 degrees, the load reaches its maximum, often increasing to about 70% to 75% of the total body weight. This difference highlights that the push-up provides variable resistance.
Biomechanical Factors Influencing Load
The reason a push-up does not require lifting 100% of the body’s mass is due to the principles of leverage. The body acts as a rigid lever, with the feet serving as the fixed pivot point, or fulcrum, in a standard position. The hands apply force to move the body, which is positioned horizontally between the fulcrum and the center of gravity (CG).
The actual resistance is determined by the horizontal distance between the hands and the body’s CG. The longer this distance, known as the moment arm, the greater the resistance the hands must overcome. Since a portion of the body—specifically the feet and lower legs—rests on the floor past the fulcrum, their mass is not being lifted by the hands. This distribution explains why the hands support only a percentage of the total weight.
Individual body composition and limb proportions can slightly alter the standard percentages. For example, a person with a longer torso relative to their leg length may have a slightly different center of gravity. This could marginally increase or decrease the percentage of supported mass compared to the average, but it does not change the fundamental physics of the lever system.
Practical Modifications for Adjusting Resistance
Understanding the lever principle allows for the modification of the push-up’s difficulty by changing the body’s angle and the position of the center of gravity. To decrease the load and make the exercise easier, one can shorten the moment arm. Performing the push-up with the hands elevated on a surface, such as a box or bench, shifts the body into an incline position. Elevating the hands 61 centimeters (about 24 inches) above the floor can reduce the load to approximately 41% of body weight.
Another common modification is the knee push-up, which changes the fulcrum from the feet to the knees. Moving the pivot point closer to the center of gravity shortens the moment arm, reducing the supported load to roughly 49% of body weight. This adjustment provides an accessible starting point for building strength.
To increase the resistance, the opposite adjustment is made by lengthening the moment arm. Elevating the feet on a stable surface, known as a decline push-up, shifts the center of gravity further forward relative to the hands. When the feet are elevated on a 30.5-centimeter (12-inch) box, the supported load increases to around 70% of body weight. Elevating the feet to 61 centimeters can increase the resistance further, pushing the supported weight to approximately 74% of the total body mass.