There is an old joke about hard work that goes like this: "He loves hard work.

He can watch it for hours." Does the same apply to sport? Apparently so. There is little cheer in yesterday's health statistics. Fewer than 40% of Scottish adults exercise enough to stay fit and, though the figure for girls has improved slightly, there has been little change for boys.

Meanwhile 64% of adults are overweight, including 28% categorised as obese. Though that figure has barely budged since 2008, Scottish children continue to get fatter. As a nation, we are losing the battle of the bulge.

Even those who criticise body mass index as a misleading yardstick can hardly argue with Glasgow University research revealing that average waistlines have increased alarmingly since 1998. In the case of women, the increase is two-and-a-half inches in 10 years, which must be the fastest increase ever in peacetime. This suggests the change is predominantly in body fat rather than muscle.

As Professor Mike Lean of Glasgow University medical school puts it: "It seems reasonable to hypothesise that adverse changes in dietary habits and reduced physical activity are the primary causes of the observed trends."

We cannot carry on like this. Quite apart from the personal legacy of unhealthy lifestyles, it is hard to see how the NHS can afford to treat ever larger numbers of patients with the resulting conditions, such as diabetes. We face the alarming prospect of the frail elderly having to compete for scarce NHS resources with those developing life-threatening conditions in middle age.

The Scottish Government's response to these figures is to point to Scotland's sports hubs offering opportunities for young people to get active. However, a very different picture emerged yesterday from two of Scotland's outstanding sportswomen with an intimate knowledge of conditions on the (sports) ground.

There has never been a better opportunity to change attitudes towards health and sport. Witness the speed with which tickets for the Track Cycling World Cup were snapped up. The challenge is to translate enthusiasm for watching sport to a passion about participation. In the period between the huge success of Team GB at London 2012 and the start of the Glasgow 2014 Commonwealth Games, there is a unique opportunity to capitalise on a raised interest in sport.

That will not happen spontaneously. Success at the elite level can even dampen the desire to join in without good quality all-weather facilities at an affordable price and coaches capable of inspiring us.

Olympic silver medallist Liz McColgan told the Holyrood Health and Sport Committee that there would be no Olympic legacy in poor areas so long as local authorities charged £3 to use sports facilities.

Meanwhile Andy Murray's mother Judy, who has a mission to increase participation and develop promising juniors, claims her sport needs hundreds of "pied pipers" to get into schools and communicate the joy of tennis. Local authorities trying to do ever more with less money cannot be expected to pick up the tab. Scotland cannot afford to waste this extraordinary opportunity.