Fitness clubs around Japan are embarking on a major campaign to attract middle-aged and elderly members by promoting exchanges and introducing discount rates.

A quarter of the 3.1 million fitness club members in Japan are more than 50 years old, and that number is expected to continue to rise as the population ages, industry officials said.

The Club Management Network, a magazine publisher for the fitness club industry, predicts the number of fitness clubs in Japan will increase by 500 to about 2,300 in 2010, and membership will top 4.7 million, nearly half of whom will be 50 or older.