Biomechanics & Engineering

The push up operates as a Class 2 Lever system (typically), where the fulcrum is at the toes, the load is the body's center of mass, and the effort is applied through the hands. Unlike the bench press, the push up is a Closed Kinetic Chain (CKC) movement. This means the distal segment (hands) is fixed, forcing the proximal segments to move.

Kinetic Transfer

Force transfers from the palms through the triceps brachii and pectoralis major, crossing the glenohumeral joint. The anterior deltoids assist in flexion, while the serratus anterior is critical for stabilizing the scapula, specifically during the top-range protraction.

Pivots & Levers

The primary fulcrum sits at the metatarsophalangeal joints (toes) with a secondary pivot at the radiocarpal joints (wrists). This setup requires sufficient dorsiflexion and wrist extension to maintain a rigid lever arm throughout the repetition.

Stabilization Demands

The movement imposes a high demand for anti-extension core stability. The rectus abdominis and obliques must work isometrically to prevent lumbar lordosis. Simultaneously, gluteal contraction is required to posteriorly tilt the pelvis, preventing the "sagging hip" fault and locking the spine into a safe, neutral position.

Execution Protocol

The Setup (High Plank)

Place hands slightly wider than shoulder-width. Screw your palms into the floor (creating external rotation torque) to stabilize the shoulders. Feet should be together or hip-width.

Create Tension

Squeeze your glutes and brace your abs as if expecting a punch. This locks the hips to the ribcage. Your body should form a straight line from heels to crown.

The Descent

Lower your body under control. Elbows should track back at approximately a 45-degree angle (arrow shape), not flared out to the sides (T shape). Descend until the chest is just above the floor.

The Ascent & Protraction

Drive through the palms to return to the start. At the very top, push the floor away extra hard to protract the scapula (spreading shoulder blades apart), fully activating the serratus anterior.

Common Pathologies

Fault	Biomechanical Consequence	Correction
Lumbar Extension (Sagging)	Loss of core intra-abdominal pressure; shear force on lumbar spine.	Posterior Pelvic Tilt (tuck tailbone), squeeze glutes.
Chicken Winging (Elbow Flare)	Internal rotation of humerus; increases impingement risk at acromion.	Tuck elbows to 45°, "break the bar" cue.
Forward Head Posture	Cervical spine strain; false perception of full ROM.	Pack the neck, make a "double chin", look slightly forward.

Muscle Anatomy

Prime Movers (Agonists)

Pectoralis Major Horizontal Adduction
Triceps Brachii Elbow Extension
Anterior Deltoid Shoulder Flexion

Stabilizers (Isometric)

Serratus Anterior Scapular Protraction/Stability
Rectus Abdominis Anti-Extension
Gluteus Maximus Pelvic Alignment

Coach's Tip

Think of the push up as a moving plank. The moment your hips sag, you've broken the kinetic chain and lost the core benefit. If you can't maintain the plank, elevate your hands to a bench or bar rather than dropping to your knees—this preserves the core leverage mechanics.