Yes water is a special medium.

Aquatic therapy makes use of the many special properties of water to provide rehabilitation for a multitude of conditions, many of which would be difficult or impossible to rehabilitate on dry land.

One of the fundamental benefits of aquatic therapy involves making use of the buoyancy principle to decrease one’s body weight in the water and provide weight bearing exercises with much reduced stress on injured or diseased joints. Water supports limbs during exercise that would otherwise be too difficult or painful to support or move without the buoyancy effect. Aquatic therapy is also used to unload the spine and provide rest to muscles that normally work to support the body in the upright position while on land.

Due to the fact that buoyancy decreases the stability of the body in water, the need to stabilize the whole body is increased when performing aquatic therapy. In addition to the primary muscles being exercised, this principle causes engagement of muscle groups that provide the body with stability and balance. At the same time, due to the buoyancy of water, the amount of force required to accomplish this balancing is reduced making the initial phases of exercise intervention easy to initiate. This leads to both strength and stability being addressed simultaneously, increasing efficiency of aquatic therapy and water rehabilitation techniques over land based exercises.

Another important principle of water is its higher viscosity or resistance properties compared to air. This creates increased resistance when limbs move through the water compared to air. The resistance is dependent on speed of movement allowing the exerciser to continually adjust the resistance to their maximal ability.  This is a very special form of exercise called isokinetic exercise which maximizes ones efforts throughout a full range of motion while minimizing overuse of the affected limbs/joints.

Water also provides increased surface pressure to the body reducing swelling in injured or inflamed areas while providing a continual gentle massage during aqua-therapy.

Water can either cool or warm the body. Aquatic therapy can keep the body cool while exercising allowing one to have an intense aerobic workout and come out refreshed.  Due to the decreased heat load, many individuals with exercise restrictions due to cardiac, respiratory or other physiologic limitations may be able to perform aquatic therapy with fewer limitations compared to land based rehabilitation.  Warm water aquatic therapy can be used to help relieve stiffness in arthritic joints and tension in sore or overused muscles. 

In summary, water is an essential part of life which provides added exercise benefits through its special properties of buoyancy, resistance, hydrostatic pressure and temperature.  This property makes aquatic therapy completely versatile allowing the weakest and the strongest to maximize their rehabilitation and recovery efforts.