Providing a wide range of group exercise classes could radically improve a club's retention levels.

A member satisfaction survey - conducted in partnership by IHRSA, training company Les Mills and consultancy Health Club Development Company (HCD) - found that that 60 per cent of club members rate group fitness as a club's most important offering, higher than any other service or amenity.

The survey questioned more than 2,200 health club members in the United States and Canada during February and March 2009.

Phillip Mills, founder of Les Mills International, said: "The power of group exercise starts with its ability to motivate individuals and create a fun and motivating social atmosphere.

"This survey shows how the positive impact on members translates into growth and financial strength for health clubs.

"Top-quality group fitness is a very cost-effective way to meet the fitness needs of large numbers of members. Those members repay the investment with unmatched loyalty, renewal rates and word-of-mouth advertising."