In the various swimming styles, each with its own specific movement, swimming mainly develops the arms, shoulders and trunk, and only to a lesser extent the legs.

For each style there are muscles that are affected more and consequently develop more, and others that are stimulated to a lesser extent.

The arms, which in swimming are the connection between the muscles that develop strength, are mostly dorsal and pectoral, while to float and swim fast you also need a lot of coordination between the movement of the arms and that of the legs, and this passes through strength of things from the muscles of the trunk, especially the abdominals.

The legs, important in competitive swimming for starts and turns and in general for balancing movement in the water ensuring a linear and stable line.

 In the Crawl and Dolphin from a biomechanical point of view the muscles mainly engaged are::

  • pectoralis major, latissimus dorsi, arm muscles (biceps, brachialis, triceps), shoulders (deltoid, rotator cuff).

These muscles listed above do most of the propulsive work. 

The muscles used as stabilizers are:

  1. scapula stabilizers,piccolo pettorale, romboide, elevatore della scapola, trapezio, dentato anteriore
  2. abdominal stabilizers, transversus, rectus abdominis, internal oblique, internal oblique, spinal erectors

The legs have a simultaneously propulsive and stabilizing function and engage in the following order:

  • ilio-psoas, rectus femoris, quadriceps, vastus lateralis, vastus intermedius, vastus medialis, gluteus maximus and medius, hamstring muscles (biceps femoris, semitendinosus and semomembranosus), gastrocnemius and soleus).
In backstroke swimming, the muscular effort is substantially identical, the greatest contribution is given by the latissimus dorsi in the initial phase of the stroke..
 
The breaststroke swim is characterized by more powerful muscle contractions and different biomechanics. Breaststroke is characterized by more powerful muscle contractions and different biomechanics.
 
The muscles that come into play in the breaststroke are:
  • pectoralis major, latissimus dorsi, paraspinal muscles, shoulders (anterior deltoid), arms (biceps and triceps brachii).
  • The role of the stabilizing muscles of the scapulae and the lumbar and abdominal region is fundamental.
  • The frog leg muscles come into operation in a different order and with even greater intensity: glutes, hamstring muscles, rectus femoris, quadriceps, adductors, calf muscles, rectus femoris, ilio-psoas..