To best understand the connection between body parts in sports and activities, we must look at the kinetic chain. This is a series of links and segments of body parts that work as a unit. Together, they make a force and send it through the body.

For example in swimming, the legs are moving the swimmer through the water. At the same time, the muscles of the hip, abdomen, and low back (lumbopelvic region) are the base of support for the trunk and arms. This is where abdominal muscle strength and coordination are part of the swimmer’s kinetic chain.

Likewise, the larger muscles of the trunk hold the body steady while the arm is raised out of the water. The abdominal muscles work together with the trunk muscles. This happens as the swimmer starts the pull phase of the freestyle stroke. Without this coordination of movement, the swimmer would lose speed and start to sink down in the water.