Sports have always been a popular way to stay in shape.In more recent decades,the increased popularity of aerobic exercise routines has resulted in millions of gyms equipped with devices such as rowing machines,elliptical trainers,stationary bicycles,treadmills,and“StairMasters”being built all over the world,and even more millions of aerobic workout DVDs being sold to people who believe that,in order to be healthy,they need to move around a lot.
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