Kinesiology of Exercise


Most sports and occupations require working with the arms in front of the body. In time, this causes round shoulders and in some cases the appearance of a sunken chest. To counteract this tendency and to improve posture at the same time, the lateral prone raise with strict form, also known as the reverse fly, should be done. It uses the same muscles and actions as in the pronated grip seated row and bent over row. 

Major Muscles and Actions Involved

In the reverse fly the muscles of the shoulder joint that are involved are the middle and posterior deltoid, the infraspinatus, and the teres minor. They are involved in horizontal extension (abduction) in which your arms are brought from a position in front of your body (hanging down vertically with the trunk horizontal) up and to your sides until they are in line with your shoulders and above (beyond) the level of your back. In the shoulder girdle the rhomboid and the middle fibers of the trapezius are involved in scapula adduction. In this action the scapulae move from the sides of the chest to a position close to the spine.

Sports Uses

Shoulder joint horizontal abduction and scapula adduction always take place when your arm is pulled to the rear in a horizontal plane (in relation to the body). This is the plane that is perpendicular to the long axis of the body. The muscles and actions are used in the sports of rowing (sculls), gymnastics (iron cross on the rings), tennis, racquetball, and badminton (shoulder high backhand), baseball batting in the left shoulder of a right-handed batter, and archery (the pull back). At times, wrestlers use this action when trying to keep their shoulders off the mat when they are pinned down. Note that many of these uses also apply to the seated row.

Exercise Analysis

  • In the shoulder girdle, the lateral prone raise exercise fully involves the middle fibers of the trapezius (as does the seated row, T-bar row or bent-over row with the pronated grip, that is, elbows up and out to the sides). The reason for this is that scapula adduction is the only function of this portion of the trapezius muscle in all of these exercises.
  • The trapezius and rhomboid muscles are very important in making a full range of motion possible for the arms. By pulling the scapulae back toward the spine, the shoulder joint sockets are turned slightly backward. This allows your upper arms to be raised level with and behind your back.
  • Lateral prone raises become much more difficult when your arms are kept extended. In this position the weight is farther away from your body, which in turn, creates a longer resistance arm. Because of this, there is no need to use heavy weights that would place more stress on the shoulder and change the technique of execution.
  • The key element in the reverse fly is how high your elbows (arms) get. The higher they are, the greater is the shortening contraction of the muscles involved. When you use heavy weights, however, you will have to bend your elbows, which changes the joint actions and the muscles involved. Flexing your elbows slightly is permissible, especially if you feel discomfort in the elbows. When you flex your elbows to a great extent, they drop below shoulder level so that the movement is done on a diagonal pathway, not perpendicular to the trunk.
  • This exercise is most effective when executed on a high, narrow bench so that the dumbbells clear the floor in the starting position. This allows you to start with your arms straight and thus prevent excessive elbow joint flexion, which may occur when you use a low exercise bench and start with the weights on the floor.
  • In addition, the high bench allows for a greater ROM. In the starting position your shoulders will be protracted and your scapulae will be pulled away from the spine (abducted). This forces the muscles to work through a greater range under resistance to bring your shoulders back (middle trapezius and rhomboid) in order to raise the weights higher than your back.
  • This exercise is safer and more effective for isolation of the muscles involved than the seated row, bent-over row, or the T-bar row. It is very difficult to hold your spine in an arched position when doing the bent-over row, and, in addition, there is a strong tendency to use your trunk when pulling. Because of this, you cannot get full isolated strengthening of the posterior deltoid, teres minor, and infraspinatus as is possible in the lateral prone raise.

Lateral Prone Raise vs Lateral Dumbbell Arm Raise

Comparison the reverse fly and lateral arm raise exercises:

Muscles Targeted:

Reverse Fly: Primary focus on the posterior deltoids (rear shoulder muscles).
Also engages the trapezius, rhomboids, and upper back muscles.
Lateral Arm Raise (or Lateral Raise): Primarily targets the lateral deltoids (side shoulder muscles).
Engages the trapezius and other stabilizing muscles to a lesser extent.

Exercise Type:

Reverse Fly: Isolation exercise for the posterior deltoids and upper back.
Lateral Arm Raise: Isolation exercise for the lateral deltoids.


Reverse Fly: Involves horizontally abducting the arms (moving them away from the body) against resistance.
Lateral Arm Raise: Involves lifting the arms laterally (sideways) from the sides of the body.


Reverse Fly: Typically performed using dumbbells, cables, or machines.
Lateral Arm Raise: Commonly done with dumbbells, cables, or resistance bands.

Body Position:

Reverse Fly: Often performed bent over, either standing or on an incline bench, to isolate the rear delts.
Lateral Arm Raise: Usually done standing or sitting, lifting the arms laterally.

Range of Motion:

Reverse Fly: Emphasizes the horizontal movement of the arms away from the body.
Lateral Arm Raise: Emphasizes the lateral movement of the arms away from the body.


Reverse Fly: Commonly included in back and shoulder workouts to target the rear delts and upper back.
Lateral Arm Raise: Often part of shoulder workouts to enhance shoulder width and target the lateral deltoids.

In summary, while both exercises contribute to shoulder development, the reverse fly specifically targets the rear deltoids and upper back, while the lateral arm raise focuses on the lateral deltoids. Including both exercises in your workout routine can provide comprehensive shoulder development.

Want to Learn More?

Try our premium ebooks in the kinesiology of exercise. Satisfaction guaranteed.