A 20-year study of male doctors found that compared to men who were overweight and obese, men who stayed lean and fit had the lowest risk of heart failure, and that vigorous exercise reduced the risk, even if they exercised just enough to "break sweat" three times a month.

The study was the work of epidemiologist Dr Satish Kenchaiah, when he was at Brigham and Women's Hospital in Boston, US, and colleagues, and is published in the 22 December issue of the journal Circulation. Kenchaiah is now at the US National Heart, Lung, and Blood Institute.

Just under 70 per cent of Americans carry excess body weight, and only about 30 per cent of them exercise regularly. And every year about 660,000 Americans find out they have heart failure, Kenchaiah said in a press statement.

"Once heart failure develops, the quality of life deteriorates, and about 80 percent of the men and 70 percent of the women under 65 years with heart failure die within eight years," he added.

In terms of public health burden, the US has about 1 million hospital admissions and 3 million outpatient and emergency visits every year due to heart failure, at an annual cost of 35 billion dollars, based on estimates for 2008, said Kenchaiah.

In this study, Kenchaiah and colleagues found that excess weight and inactivity increased the risk of heart failure in men. The greatest risk being among overweight and obese men.

For 20 years they followed 21,094 male doctors aged between 40 and 84 years who were taking part in the Physicians' Health Study from 1982 to 2007. The participants filled in questionnaires twice in the first year and then every year after that. They answered questions about themselves, their lifestyles and medical history. Men who said they exercised one to three times a month or more were considered active.

The results showed that:
  • About 40 per cent of the participants were overweight (BMI 25 to 29.9), and about 5 per cent were obese (BMI of 30 and over) at the start of the study.

  • A greater percentage of the obese men exercised less.

  • Participants who rarely or never exercised tended to be older, with higher BMI, smoked more and had higher blood pressure and diabetes.

  • Over the 20 years of the study, 1,109 of the participants developed heart failure.

  • Men who were lean (BMI under 25) and active had the lowest risk of heart failure, while those who were obese and inactive had the highest risk.

  • After taking into account other known risk factors such as high blood pressure, diabetes and high cholesterol, the risk went up by 49 per cent among overweight men and 180 per cent among obese men, compared to men who were lean.

  • Any vigorous activity that led to sweating, from a low level of one to three times a month to a high level of five to seven times a week was linked to an 18 per cent lowering of heart failure risk, again once other risk factors were taken into account.

  • The men who exercised the most vigorously, five to seven times a week, had a 36 per cent reduction in heart failure risk compared to men who never or rarely exercised vigorously.

  • Among lean men, those who were inactive had a 19 per cent higher risk of heart failure compared to the active ones.

  • Overweight and active men had a 49 per cent higher risk of heart failure compared to lean and active men, while those who were overweight but inactive had a 78 per cent higher risk.

  • Obese and active men had a 168 per cent higher risk of heart failure compared to lean and active men, while those who were obese and inactive had a 293 per cent higher risk.
BMI stands for Body Mass Index and is equal to a person's weight in kilos divided by the square of their height in metres.

Other studies have already shown that obese men are more likely to develop heart failure, but this study shows that even overweight or pre-obese men are at higher risk.

"On average, in men who are 5 feet 10 inches [1.78 m] tall, for every 7 pounds [3.2 kg] of excess body weight, the risk of heart failure will go up by 11 percent over the next 20 years," said Kenchaiah.

Kenchaiah also said that another interesting finding was that BMI and vigorous physical activity did not influence each other in their impact on heart failure risk, as he explained:

"Higher BMI increased the risk of heart failure in inactive as well as active individuals. By the same token, the beneficial effect of vigorous physical activity in reducing the risk of heart failure was observed in lean, overweight, and also obese men."

"Adopting a healthy lifestyle, keeping a normal weight, and exercising regularly will go a long way toward reducing one's risk of heart failure and, in turn, the population burden of heart failure," said Kenchaiah.

"Both staying lean and being fit go hand in hand," he added, suggesting that future studies should concentrate on types of physical activity, total energy used, and the types of obesity that affect heart failure risk.

"Body Mass Index and Vigorous Physical Activity and the Risk of Heart Failure Among Men."
Satish Kenchaiah, Howard D. Sesso, and J. Michael Gaziano.
Circulation, published December 22, 2008.
DOI:10.1161/CIRCULATIONAHA.108.807289

Click here for Abstract.

Sources: American Heart Association.

Written by: Catharine Paddock, PhD