Eighteen sweaty minutes striding "uphill" on a treadmill may be better than 30 minutes of moderate-intensity walking for warding off diabetes, a new study suggests.
The experiment was small but is considered important because it builds on other evidence that indicates the international recommendation of mostly moderate exercise is not enough to turn around the West's twin epidemics of diabetes and obesity.
"A short walk around the block with a geriatric dog is not going to solve the problem," said Otago University diabetes and obesity expert Professor Jim Mann.
The Health Ministry recommends 30 minutes of moderate-intensity physical activity on most if not all days, plus some vigorous exercise.
Seven per cent of adults have been diagnosed with diabetes. It is estimated that more than a quarter of adults have a resistance to insulin, a hormone that helps the body to use glucose.
Insulin resistance is a key step on the path to diabetes.
The exercise study by Otago University researchers, published in a European diabetes journal, monitored the blood-glucose levels of nine insulin-resistant people whose average BMI was in the obese range. Two were diagnosed with diabetes as part of the study.
The participants performed each of three exercise routines on different days: short bouts of intense exercise before breakfast, lunch and dinner; a similar programme but with resistance exercises replacing some of the vigorous walks; and a more traditional routine of 30 minutes of moderate intensity walking before dinner. Averaged across the day of exercise, the two intense routines reduced three-hour-post-meal glucose levels by 12 per cent, in contrast to no improvement from moderate exercise. The reductions persisted for the following day.
Sustained, high glucose levels following meals was a feature of insulin resistance, said researcher Monique Francois.
She said that because insulin resistance was so widespread, physical activity guidelines should be changed to put more emphasis on intense exercise.