Analysis Of Exercise In Varied Environments

Analysis by Dr Paul Batman Ph.d

Under varying exercise conditions, muscle recruitment patterns will differ. Lets take as an example a ‘lateral raise’.

In the lateral raise performed with weighted dumbbells, the exercise is performed in a slow and controlled manner.

The supraspinatus and deltoid contract concentrically at the shoulder joint in the up phase and eccentrically in the down phase.

The serratus anterior, trapezius and the pectoralis minor contract concentrically in the up phase and eccentrically in the down phase.

The elbow joint muscles are the biceps. brachialis, brachioradialis and the pronator teres, all of whom statically contract in both the up phase and in the down phase.

It is widely accepted that the eccentric contraction of a resistance training exercise is an important stimulus for muscle hypertrophy. To meet this end, the down phase eccentric movements are often intentionally slowed to ensure the muscles recruited are placed under maximum tension for an extended time period. This is often referred to “time under tension”.

Lateral Raise Performed With a Weighted Dumbbell (Concentric Phase is the Up Phase)

* The down phase is caused by the eccentric contraction of the same muscles that caused the up phase.

Aerobics Class

Performing a lateral raise in an aerobics class without a dumbbell is very different to that of a resistance training exercise. In the aerobics class, the movements at each of the joints are much faster and of course there is no weight attached to the hands. The exercises are used in an aerobics class as a vehicle to increase the workload and consequently increase heart rate. This in turn, assists in producing a strong aerobic response.

It is very unusual for there to be a significant increase in muscle strength or hypertrophy from participation in such classes. This is partly due to the increased speed of the movements, which uses momentum to move the joints, reducing the concentration of the muscle contraction.

In the up phase of a lateral raise the muscles contracting concentrically at the shoulder joint are the suprapinatus and the deltoid. The speed of this movement is fast leading for a need to slow the joint down towards the later degrees of the range of motion. The reduction in speed in caused by eccentric bursts from the antagonist muscles located on the opposite side of the shoulder joint. These include the latissimus-dorsi, teres major and subscapularis.

The mechanics of the movement in the down phase of the lateral raise in an aerobics class is quite different from that in resistance training. Resistance training movements are performed in a slow and controlled manner, particularly the down phase. This is to ensure that the weight is always controlled. In an aerobics class, the arms are moved much faster in the down phase, often to keep up with the tempo of the music. As the speed of the down phase increases the limb begins to move faster than the fall of gravity. As this occurs the shoulder joint adductors contract concentrically. These muscles include the latissimus dorsi, teres major, subscapularis, triceps and partly the pectoralis major.

Again as the speed is greater than the fall of gravity, the limb must be slowed down. This braking effect is caused by the sporadic eccentric bursts of the deltoid and supraspinatus.

Lateral Raise Performed in an Aerobics Class

Aqua-aerobics

Exercises in aquafitness classes have been classified as double positive or double concentric. In other words, because the exercises are being performed in the water there is a constant resistance.

As the body is immersed in water during the workout, resistance is always encountered in all phases of the exercise. In the up phase of the lateral raise performed in the water with hand paddles or aqua gloves, the supraspinatus and deltoid contract concentrically to move the shoulder joint into abduction.

The shoulder girdle muscles of the trapezius, serratus anterior and pectoralis minor cause abduction and upward rotation of the scapula.

Unlike the previous lateral raises, the down phase in an aquafitness class encounters the resistance of the water. The shoulder joint is pulled down into adduction by the concentric contraction of the latissimus dorsi, teres major, pectoralis major, subscapularis and triceps. Concurrently, the shoulder girdle is pulled into adduction and downward rotation by the concentric contraction of the trapezius, rhomboids and the pectoralis minor. There is little need to brake any movements as the speed of the contraction is controlled by the resistance of the water.

Buoyant Dumbbells

In the lateral raise in an aquafitness class with buoyant dumbbells, the resistance is encountered in the down phase of the exercise. This resistance is due to the buoyancy of the dumbbell that is created by their floatation ability.

When the dumbbells are pulled below the surface of the water they attempt to refloat with considerable force. In the down phase of the exercise, the shoulder joint is adducting against the resistance of the buoyant dumbbell.

This is caused by the concentric contraction of the latissimus-dorsi, teres major, pectoralis major (latter part), triceps and subscapularis. The shoulder girdle is adducting and downwardly rotating by the concentric contraction of the trapezius, rhomboids and the pectoralis minor.

Due to the floatation ability of the dumbbells, the latissimus dorsi, teres major, pectoralis major, triceps and the subscapularis contract eccentrically to control the movement by slowing and allowing the dumbbell to come to the surface. The floatation ability of the buoyant dumbbells ensures that the muscles recruited in the up phase of this exercise is quite different from the up phase of the lateral raise with hand paddles.

Lateral Raise Performed in an Aquafitness Class With Hand Paddles

Up Phase (concentric phase)

Down Phase (concentric phase)

Lateral Raise Performed in an Aquafitness Class With Buoyant Dumbbells

Down Phase (concentric phase)

* The up phase of this lateral raise is caused by the eccentric contractions of the same muscles that caused the down phase.