The latissimus dorsi is a large triangular muscle in the lower back. It starts at the lower half of the spine and hip and travels up to attach to the top of the upper arm. The latissimus dorsi is responsible for drawing the upper arm downward and backward and rotating it inward. The ability to perform these moves well and strongly has a great impact in swimming efficiently.
The freestyle swim also is called the crawl or Australian crawl. In this stroke, you lie prone in the water and pull each arm down and back alternately as you move through the water. Your legs maintain the balance of your body using a flutter kick. Although other arm and back muscles are used in this stroke, the latissimus dorsi are the main engines for your impetus through the water.
The breaststroke also makes good use of the latissimus dorsi. In this stroke, your arms pull back at the same time in a circular movement and then push forward together from under your chest. You draw your legs up together with your feet facing outward and then kick them out and back. With this stroke, the only part of your body that leaves the water is your head. You are relying on your latissimus dorsi to lift your head out of the water and move your torso forward.
The backstroke is performed by lying on your back and propelling yourself forward by lifting each arm over your head in turn as you tilt your body slightly toward the water on that side. Your arm then swings through the water, exiting at your hip. While this method does engage the latissimus dorsi, the muscles of the shoulders and the trapezius are the main engines for this stroke.
Building the Latissimus Dorsi
The latissimus dorsi is the powerhouse of swimming strokes. Developing this muscle requires specific and targeted exercise besides swimming. The muscles of the upper body should be trained using strength exercises once or twice a week. For strengthening the latissimus dorsi and improving swim technique, these muscles should be specifically targeted using the weight-assisted dip or pullups.
Improve Swimming Technique
Improving your swimming technique will affect the how hard your muscles have to work to propel you through the water. Building strength and power in your latissimus dorsi is a great way to gain speed but an increase in efficiency will allow you to use more of that extra strength. Investing in a few swimming lessons or learning how to improve your stroke with the aid of books and videos can increase your enjoyment of the sport.