Swimming is often hailed as a whole-body workout.
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Swimming works your body from top to bottom to tone, strengthen and keep your muscles flexible. As you swim, you use your arms and shoulders, back and chest, legs and feet. Your core, upper and lower body are put through an excellent workout. And all that effort in the pool causes your heart and lungs to work extra hard, keeping them in top shape, too.
Heart and Lungs for Endurance
As a cardiovascular exercise, swimming increases your heart rate and it causes the lungs to work harder to transfer more oxygen to the bloodstream. The faster the heart pumps, the more blood circulates, delivering a higher content of nutrients and oxygen to muscles, organs and tissues. Heart and lungs together increase your endurance in the pool. The accelerated heartbeat during swimming also results in a lower resting heart rate, which is associated with decreased risk of coronary disease.
Arms for Propulsion
On the back of the upper arms are the triceps and on the front the biceps. When you swim, you work these muscle groups, as they help to propel your body. The triceps and biceps let you flex the elbows, and using the muscles regularly in the water strengthens and tones them. And while you engage the rotator cuff muscles to control arm movement, the deltoid muscles over the shoulder joint also get a work out -- they twist your arms for your hands to enter and leave the water at the correct angle.
Back and Chest Muscles for Stability
When you swim, the shoulder bone -- scapula -- has to remain stable. The upper back muscles, such as the trapezius and rhomboids, make stability possible by elevating, depressing and retracting the scapula at the right times for effective swim strokes. Likewise, the chest muscles help to control shoulder movement as it guides the arms in the water. The pectoralis muscles, for example, help the arms to push and pull underwater. In the process of swimming, your back and chest muscles get an effective workout.
Strong Core for Flexibility
Swimming also engages your core muscles. In addition to the back, they include the pelvic, side and buttock muscles. The core connects your upper and lower body, and it must be flexible and strong to allow for controlled movement to flow from one end of the body to the other in the water. You need strong abdominal and oblique muscles, for example, to keep your hips from sinking in the water.
Legs for Kicks
In your legs, the hamstrings and glutes get a good workout when you swim. These muscles allow you to kick and they also keep your body in the right position in the water. The glutes control hip rotation and extension while the hamstrings also help you to extend the hips. The hamstrings play another important role by making it possible for you to rotate and flex your knees. On the back of the lower leg, the gastrocnemius and soleus muscles extend to the ankle joint. They facilitate foot flexion in swimming. Also in the lower leg, the tibialis muscles allow foot inversion, the twisting of the foot's outer side to turn the sole inward. The fibularis muscles, running from the outside of the lower leg to the outer ankle, work to evert the foot in the water. The opposite of inversion, eversion is the turning of the foot to face the sole outward.