A well-rounded fitness program should include cardiovascular and flexibility components, a sound nutritional diet and a strength training program. Most people looking to do resistance training programs will undoubtedly head toward the wide array of exercise equipment and machinery located in most gyms. If your gym has a pool you should consider the benefits of water resistance; including cardiovascular and range of motion benefits. But the pool has so much more to offer. In reality, it is a multidimensional, variable resistance machine.
Water Resistance
As a variable resistance machine, the water allows for three-dimensional movement with a built-in overload factor. You are surrounded by resistance in any direction of movement: horizontal, vertical and diagonal. To increase fitness and function of your musculoskeletal system, the overload principle must be implemented, and the most common overload in strength training is resistance training. Resistance training increases the probability of achieving your weight loss and body image goals, along with an overall fitness benefit.
The physics governing the laws of motion in water include the terms of buoyancy, drag, turbulence and inertia. Water supports the body through buoyancy, and buoyancy counteracts the effect of gravity on the body. At chest height, a body will weigh approximately 35% of body weight, and at shoulder height, this will decrease to 10%. Because of the effect of buoyancy, the compression of joints is decreased, resulting in less joint stress and greater range of motion. The diminished effects of gravity allow for gains in muscle balance and stability.
Although buoyancy and the feeling of weightlessness is most likely the first effect you will notice upon entering the pool, you will work more against drag, which is the primary force opposing movement in the water. Water is 12 times more viscous than air. As a muscle exerts force to move a body part, it presents a surface area in direction of movement to the surrounding water. This is called frontal resistance. As the body part moves against the opposing drag, turbulence is created in the irregular movement of the water and the formation of eddies. As the body part moves through the water, inertia is created. This motion causes the water to move and travel in the direction of movement. When a change in direction is made, the body part will be moving against inertia, thus increasing the resistance encountered.
According to Newton's law, to every action there is an equal and opposite reaction; therefore, the more force you exert against the water, the more resistance you will encounter. In swimming, the goal is to streamline the body and create less turbulence. In water fitness, the properties of water are utilized to create more turbulence and increase the resistance. This creates the variable resistance of the water.