Motivated by the goal to remain fit and stay in shape, or by the desire to get into the right shape and weight, these fitness enthusiasts regularly attend the aerobics classes at the gyms or fitness centers where they are members of. The sessions last from one hour to one and a half hours. The intensity of the training may be low, moderate, or high impact. For the purpose of coming up with this database, physical fitness trainors are asked to identify who among their club members frequently join aerobic classes. This database is frequently used by publishers of magazines on health, fitness and sports; by sponsors or organizers of sports events; by social clubs and associations seeking to expand their membership base; and by tour organizers that specialize in ecotourism. Source: selected chains of fitness clubs.