Fit Beats Thin in Extending Life, Study Says

December 6, 2011

News Review From Harvard Medical School --

Maintaining or improving fitness can help you live longer, whether you lose weight or not, a new study concludes. The research included more than 14,000 middle-aged men. They were given treadmill tests to measure fitness at the start of the study and about 6 years later. Fitness was measured in metabolic equivalents (METs). In all, researchers kept track of the men for 11 years. In that time, men who became more fit had a 40% lower death rate from heart disease and from all causes than those who became less fit. Just staying at the same fitness level reduced death rates by 30%. Every 1-MET increase in fitness was linked to a 19% decrease in death rates from heart disease and stroke. The risk of death from any cause was 15% lower for each increase in METs. But a reduction in body mass index, a measurement of weight linked to height, did not change death rates. The journal Circulation published the study online. HealthDay News wrote about it December 5.







By Howard LeWine, M.D.
Harvard Medical School


What Is the Doctor's Reaction?
Improving or at least maintaining your physical fitness helps you live longer and better. And the path to staying fit is regular exercise. Exercise and maintaining fitness have many positive effects on the body. They include:


- Strengthening the heart to pump oxygen and nutrient-rich blood more efficiently
- Making blood vessels more flexible, which eases delivery of blood to all parts of the body
- Lowering blood pressure at rest
- Decreasing insulin resistance, the main reason for type 2 diabetes
- Helping hold down inflammation, a contributor to heart and blood vessel diseases


Maintaining a healthy body weight does some of the same things as keeping fit. But fitness is more important than body weight, according to this new study and other research.
Fitness is a measure of how well your heart, blood vessels, blood and lungs supply muscles with oxygen during sustained exercise. It also takes into account how well your muscles use that oxygen.


The most precise way to determine fitness is to measure maximum oxygen consumption during exercise. This is a complicated and expensive procedure. It's usually limited to research or training elite athletes.


An easier way to gauge fitness is to use a treadmill. The test is similar to the treadmill test used by heart specialists. Instead of looking for signs of heart problems, the treadmill is used to measure peak exercise capacity.


The speed and incline of the treadmill are increased until you can't go any further. Exercise capacity is usually measured in metabolic equivalents (METs). One MET is the amount of oxygen used when sitting still or sleeping. Your number of METs at peak exercise capacity is determined by a formula based on your speed and the incline at your peak.


This is the method that the researchers in this study used to determine fitness as measured in METs. People had a treadmill test at the start of the study and later on. The researchers also measured their body mass index ( BMI) before each treadmill test. This is a measurement of weight in relationship to height. The average time between the first and last assessments was 6.3 years.


Every 1-MET improvement in fitness was linked to a 15% decrease in overall death rates and 19% decrease in the heart-related death rate. Changes in BMI were not linked with any differences in death rates.