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Wednesday, April 16, 2014

Bench Press Analysis



Chest Press or Bench Press (Barbell)

Description

The client lies on the bench in the supine position. The client secures an evenly spaced grip on the barbell and presses the barbell upward to full extension of the arms and shoulders.

The client then lowers the barbell to the starting position which is normally at the chest or slightly above the chest.

The client then presses the barbell upward through the full range of motion of the arms and shoulders.

The client repeats this sequence for the desired number of repetitions and then returns the barbell to the rack of the bench when complete.

The barbell chest press or bench press is an open kinetic chain exercise because of the following: the distal ends of the arms are free and not fixed. The muscles used in this exercise are isolated and the movement occurs in a single plane of motion. The chest press is considered nonfunctional as it does not rely on multi-joint compound movements. The proximal segments of the joints are stable as the trunk lies on a fixed bench.

Joint Analysis

The chest press or bench press (barbell) is divided into the lifting phase and lowering phase for analysis.

The wrist is in flexion (with slight extension depending on the grip on the bar) through the lifting phase and the lowering phase of the exercise.

The elbow is in extension during the lifting phase and flexion during the lowering phase of the exercise.

The shoulder is in flexion and horizontal adduction during the lifting phase and in extension and horizontal abduction during the lowering phase of the exercise.

The shoulder girdle is in abduction during the lifting phase and adduction during the lowering phase of the exercise.

Agonist muscles used during concentric contraction or lifting phase of the exercise:



Wrist: (mainly in an isometric contraction) flexor pollicus longus, flexor digitorum superficialis, flexor digitorum profundus, palmaris longus, flexor carpi ulnaris, flexor carpi radialis.

Elbow: triceps brachii and anconeus.

Shoulder: Pectoralis major, anterior deltoid, coracobrachialis and biceps brachii.

Shoulder girdle: serratus anterior and pectoralis minor.

Agonist muscles used during the eccentric contraction or lowering phase of the exercise:
Wrist: (again mainly in an isometric contraction) flexor pollicus longus, flexor digitorum superficialis, flexor digitorum profundus, palmaris longus, flexor carpi ulnaris, flexor carpi radialis.

Elbow: triceps brachii and anconeus.

Shoulder: Pectoralis major, anterior deltoid, coracobrachialis and biceps brachii.

Shoulder girdle: serratus anterior and pectoralis minor.

References:

Floyd, R.T., 2012. Manual of Structural Kinesiology. Ch 8.

Eric Dempsey
Master Sergeant, U.S. Army Retired
NASM Certified Personal Trainer & Weight Loss Specialist

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