Islamabad - Brisk walking may be more effective than jogging in controlling blood sugar levels in people with pre-diabetes, a new study suggests.

People with pre-diabetes have higher-than-normal blood sugar levels but not so high that it’s full-blown diabetes. The “gold standard” approach to diabetes prevention involves weight loss, diet and exercise.

“We know the benefits of lifestyle changes ... but it is difficult to get patients to do even one behaviour, not to mention three,” said study author Dr. William Kraus. So he and his colleagues wanted to know if exercise alone could achieve similar benefits.

“When faced with the decision of trying to do weight loss, diet and exercise versus exercise alone, the study indicates you can achieve nearly 80 percent of the effect of doing all three with just a high amount of moderate-intensity exercise,” said Kraus, a professor of medicine at Duke University in Durham, N.C.

The study included 150 people with prediabetes who were divided into four groups. One group followed a gold-standard program that included a low-fat, low-calorie diet and moderate-intensity exercise equivalent to 7.5 miles of brisk walking a week.

The other participants were assigned to one of three exercise groups: low amount at moderate intensity equivalent to walking briskly for 7.5 miles a week; high amount at moderate intensity equal to walking briskly for 11.5 miles weekly; and high amount at vigorous intensity equivalent to jogging for 11.5 miles a week. After six months, patients using the three-pronged approach had an average 9 percent improvement in oral glucose tolerance — a measure of how readily the body processes sugar and an indicator used to predict progression to diabetes.

Among those who did exercise only, there was a 7 percent improvement in the moderate-intensity 11.5-mile group; a 5 percent improvement in the moderate-intensity, 7.5-mile group; and a 2 percent improvement in the vigorous-intensity 11.5-mile group. “Another way to say it is that a high amount of moderate-intensity exercise alone provided nearly the same benefit on glucose tolerance that we see in the gold standard of fat and calorie restriction along with exercise,” said study co-author Cris Slentz, an assistant professor of medicine at Duke. High-intensity exercise tends to burn glucose more than fat, while moderate-intensity exercise tends to burn fat more than glucose, Kraus explained.

“We believe that one benefit of moderate-intensity exercise is that it burns off fat in the muscles,” he said. “That’s important because muscle is the major place to store glucose after a meal.”

How sweat works, why we owe it

Seeing someone wiping their brow is a fairly common sight in summer, but it reveals a simple and fascinating truth about our species. Without sweat, we would not still be here - nor would we have climbed our way to the top of evolutionary pile. Many animals perspire, but no others use it as such an efficient and refined cooling technology.  Vybarr Cregan-Reid, a reader from the University of Kent, explains how sweat works and why we owe it so much. 

Vybarr Cregan-Reid, a reader, from the University of Kent says without sweat humans would not have climbed their way to the top of evolutionary pile

It is obvious we are able to process more intellectual stimuli than other mammals, but any PC owner knows that computational power is completely useless if the cooling system fails.

And this is what really sets us apart. It is our ability to maintain an effective working temperature, not just so that we can keep moving, but so that we can keep thinking while in motion, efficiently chasing down the quarry.

As a species, over short distances, we are hopeless runners. We might be able to go a long way but what use is that if we can’t catch anything? 

The truth is that we never could if it weren’t for several factors that make us identifiably human.  And it is our ability to perspire which renders them all effective.  So we may have perfect bodies for distance running, but those features that enable us to move so effectively are useless without correct temperature control.

There are distinct thermoregulatory advantages to being a two-legged human. 

Being merely upright, for example, means that less of the sun hits you when it’s at its hottest.  The bipedal human exposes only about 7 per cent of their surface area to sunlight; it is triple this for a quadruped. 

This fact alone means that being on two legs enables you to move with greater heat efficiency. Also, by being upright, we can take advantage of the fact that our brains are further away from the harsher micro-climate at ground level. 

Half a million calories of heat can be lost if a litre of sweat is able to evaporate off the surface off of skin

It is hotter there because it is heated by the sun and because there is less air movement. And with air movement comes evaporation, which is the real miracle technology.  Evaporation is such an effective way to lose heat that if a litre of sweat is able to evaporate on the surface of your skin, you can lose about half a million calories of heat in the process.

While most quadrupeds sweat, they do so to maintain skin health and create scent (we do this, too), and even to create ear wax (which, amazingly, is a sort of sweat). 

But for thermoregulation, most animals use interior air movement (panting) to cool down – where their bodies have to actively work to lose heat. 

So that means, on a hot day, we could chase down a quadruped, and when it stopped to shed some heat, we humans could keep going and close the gap a little. 

Eventually, the distance between predator and prey would close as their technology failed, and ours kept functioning. Sweat meant that we were much better hunters than we appeared.