If it isn't taxes, it is OPEC but oil prices are likely to go up - people are still going to drive. It's necessary.

So is physical fitness but a new economics analysis finds that if prices to swim go up, people are inclined to drop it rather than pay more - but a gym membership stays. That's reason enough for economists behind a new paper to advocated a new government subsidy.

The work by Brunel University London's Health Economics Research Group consisted of interviews with 1,683 people, 83% of whom took part in physical activity in some form. It found that people facing 10% higher entry fees to swimming pools were 29% less active, once other variations such as their age and differences in income were taken into account. 

A similar 10% higher price of a gym workout would hardly dent enthusiasm, with participation dropping by just 3%. In the case of brisk walking, the expected drop would be even less at 2%.

Prof Julia Fox-Rushby, Professor of Health Economics at Brunel's HERG, said, "Among those surveyed there was a very clear understanding that physical activity is a means of getting healthy, losing weight and having fun. 

"But, we have shown for the first time in England, that engaging in physical activity costs you real money and people make a trade-off between whether to go to a leisure centre and how much it would cost them."

They conclude that subsidizing the price of swimming would lead to an increase in the quantity of physical activity people participate in, whereas most practical people assume it will just make it cheaper for the people already doing it - voting is free but many people don't do it. And it also leads to discussion about why one unpopular activity should be subsidized for a tiny subset of the population while larger programs are not.