Competitive swimmers work their entire body when swimming any of the four swimming strokes – the butterfly, freestyle, backstroke and breaststroke. The energy demands on the body are great, as evidenced by Olympic swimmer Michael Phelps' rigorous training regimen that requires a 10,000-calorie diet to provide the necessary fuel for his muscles. In competitive and non-competitive swimming, the body’s muscle and skeletal systems must work together to keep each body part moving correctly and efficiently as the swimming stroke is performed.

Shoulder and Chest Muscles

According to “Swimming Anatomy,” the arm movement in each of the swimming strokes relies on the shoulder and chest muscles. These muscles permit the arm to propel the body forward. The chest muscle, the pectoralis major, and the lower chest and back muscle, the latissimus dorsi, generate the beginning of the arm stroke; the pectoralis major generates most of the force in the butterfly, freestyle and breaststroke. The shoulder’s deltoid and rotator cuff muscles are also used during the arm's propulsion and recovery stages and provide support to the shoulder joint. Muscles near the shoulder blades stabilize and support the shoulder blade during the arm stroke.

Arm Muscles

The arm muscles, such as the biceps, triceps and brachialis, allow the elbow to extend and flex as the arm stroke is performed. Muscles near the wrist maintain the hands in the proper position for each stroke.

Core Muscles

The core, which includes the abdomen and back muscles, stabilizes and balances the body as the arms and legs move during all swimming strokes. These core muscles, which include the paraspinal muscles found along the spine, also make possible the body’s undulating motion during the butterfly, the breaststroke frog kick and the freestyle and backstroke flutter kicks.

Hip and Gluteal Muscles

The hip and glute muscles provide the force needed to perform a stroke’s leg kick. The propulsion of the body by the leg kicks begins in the hips and continues with a contraction of two of the gluteal muscles, the gluteus maximus and gluteus medius. The glutes tend to be most active during a stroke’s recovery phase.

Leg Muscles

The leg muscles include the quadriceps, hamstrings and calves. The thighs and calves are involved in the execution of the freestyle and backstroke flutter kick, the butterfly dolphin kick and the breaststroke frog kick. The hamstrings and quadriceps help to flex and extend the knee during the leg kick. The calf muscles assist in the flexing of the feet and ankles during the leg stroke.


  • Swimming Anatomy; Ian A. McLeod
  • Human Anatomy Laboratory Guide and Dissection Manual; Michael J. Timmons and Ralph T. Hutchings

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Eileen Rojas holds a bachelor's and master's degree in accounting from Florida International University. She has more than 10 years of combined experience in auditing, accounting, financial analysis and business writing.

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