Health for life

But an hours walk every day makes no difference: Intensity rather than duration is what counts

The findings indicate that it is the intensity, rather than the duration, of exercise that counts in combating the impact of metabolic syndrome - a combination of factors, including midriff bulge, high blood pressure, insulin resistance, higher than normal levels of blood glucose and abnormal blood fat levels - say the authors.

Genes, diet, and lack of exercise are thought to be implicated in the development of the syndrome, which is conducive to inflammation and blood thickening.

The authors base their findings on more than 10,000 Danish adults, between the ages of 21 and 98, who were initially assessed in 1991-94 and then monitored for up to 10 years. All the participants were quizzed on the amount of physical activity they did, which was categorised according to intensity and duration.

At the initial assessment, around one in five (20.7%) women and just over one in four (27.3%) men had metabolic syndrome. Prevalence was closely linked to physical activity level.

Among the women, almost one in three of those who had a sedentary lifestyle had the syndrome whereas only one in 10 of those who were very physically active had it. Among men, the equivalent proportions were just under 37% and just under 14%

Of the remaining 6,088 participants without metabolic syndrome, just under two thirds (3,992) completed the fourth and final survey and assessment, by which point one in seven (15.4%; 585) had developed it.

Again, the prevalence was higher among those leading a sedentary lifestyle, with almost one in five (19.4%) affected compared with around one in nine (11.8%) of those who were very physically active.

It was not only the amount of exercise, but also the intensity which helped curb the likelihood of developing the syndrome.

After taking account of factors likely to influence the results, fast walking speed halved the risk, while jogging cut the risk by 40 per cent. But going for an hours walk every day made no difference.

"Our results confirm the role of physical activity in reducing [metabolic syndrome] risk and suggest that intensity rather than volume of physical activity is important," conclude the authors.

Researchers at Duke University recently reported that aerobic exercise was better than resistance training (e.g. exercising with weights) for reducing belly fat:



The Effects of Aerobic versus Resistance Training on Visceral and Liver Fat Stores, Liver Enzymes and HOMA from STRRIDE AT/RT: A Randomized Trial, American Journal of Physiology, August, 2011



Their study involved 249 subjects (155 completed). They were between 18 and 70 years old, overweight, sedentary, and with moderately high LDL (130-190 mg/dL) or moderately low HDL (≤40 mg/dL men, ≤45 mg/dL women).



Subjects were randomly assigned to one of three groups for 8 months:

1. Resistance Training (RT) - 3 days/wk, 8 exercises, 3 sets/exercise, 8-12 repetitions/set.
   
   
2. Aerobic Training (AT) - about 19.2 km/wk (12 miles/wk).
   
   
3. Full Aerobic Training plus full Resistance Training (AT/RT).

Findings:



Aerobic Training led to significant reductions in:

• Liver fat
  
  
• Visceral fat (fat between abdominal organs, called belly fat)
  
  
• Liver enzymes (ALT)
  
  
• Insulin resistance (HOMA)
  
  
• Both total and subcutaneous abdominal fat

Resistance Training led to significant reductions in:

• Subcutaneous abdominal fat

RT did not significantly improve the other variables.



When it came to using energy, aerobic training burned 67% more calories than resistance training.



Results of AT plus RT were not different from AT alone.



The authors concluded:

"For overweight and obese individuals who want to reduce measures of visceral fat and fatty liver infiltration and improve [insulin resistance] and [liver enzymes], a moderate amount of aerobic exercise is the most time efficient and effective exercise mode."

Lead author Cris Slentz, PhD, added:¹

"When it comes to increased health risks, where fat is deposited in the body is more important than how much fat you have."



"Resistance training is great for improving strength and increasing lean body mass. But if you are overweight, which two-thirds of the population is, and you want to lose belly fat, aerobic exercise is the better choice because it burns more calories."



"What really counts is how much exercise you do, how many miles you walk, and how many calories you burn. If you choose to work at a lower aerobic intensity, it will simply take longer to burn the same amount of unhealthy fat."

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¹ Want To Lose Belly Fat? Aerobic Exercise Beats Weights, Medical News Today, August 30, 2011