News Review From Harvard Medical School -- Study: Fitter People Less Sick as they Age
People who are fit at midlife not only live longer, but live better, with less illness, a new study suggests. The research included more than 18,600 men and women. They were all part of another long-term health study. When the study began, their median age was 49. Fitness levels were measured using a type of treadmill test. Researchers kept track of people for about 26 years. Once people reached age 65, researchers tracked their health with Medicare claims information. People who were most fit at midlife not only lived longer, but spent less time being sick. The fittest group had slightly over half the rate of chronic (long-lasting) diseases as people who were least fit. Diseases included coronary artery disease, Alzheimer's, heart failure, diabetes and others. About 2,400 people died during the study. In their last 5 years of life, the people who had been most fit at midlife spent about 50% less time with 4 or more chronic diseases than the least fit group. They spent 34% more time with no more than 1 chronic disease. The journal Archives of Internal Medicine published the study. HealthDay News wrote about it August 27.
By Howard LeWine, M.D.
Harvard Medical School
What Is the Doctor's Reaction?
There are many benefits to staying physically active and exercising daily. Exercise decreases your risk of diabetes and heart disease. It also helps to preserve memory and prolong life.
Exercise improves quality and length of life by:
- Strengthening the heart
- Making blood vessels more flexible and responsive, which allows blood to flow easily throughout the body
- Helping with control of blood pressure and cholesterol
- Improving muscles' use of sugar
- Reducing stress
But the most important result of exercise is something that doesn't get enough attention: fitness.
Fitness is a measure of how well your heart, blood vessels, blood and lungs work to supply muscles with oxygen during sustained exercise. It also reflects how efficiently the muscles use the oxygen.
The most precise way to determine fitness is by measuring maximum oxygen consumption (VO2max) during exercise. The higher your VO2max, the greater the ability to deliver oxygen to muscles. It also means your muscles are better able to use oxygen and create energy. Therefore, you can exercise harder.
Direct measurement of VO2max is complicated and costly. It requires breathing through a mask that captures the air you breathe in and out while walking, running or cycling. A machine takes readings from the inhaled and exhaled air to calculate oxygen use.
An easier way to gauge fitness is with the kind of treadmill test that cardiologists commonly use. But instead of looking at an EKG, the test measures maximum exercise effort. The speed of the treadmill remains constant. But the grade of the incline is increased over time according to a specific plan.
The amount of time a person can stay on the treadmill is used to calculate the VO2max. It's almost as accurate as the mask and air analyzer. This is what the researchers used for this study.
Exercise capacity is usually measured in metabolic equivalents (METs). One MET is the amount of oxygen used when sitting still or sleeping. Nonathletic, healthy, middle-aged men and women have peak exercise capacities in the range of 8 to 10 METs. Marathon runners can have values as high as 18 to 24.
What Changes Can I Make Now?
We already knew that staying physically active can help you live longer. Improving your fitness level can help you live better. That's the main message from this study.
Living better from improved fitness means more years of quality living. This means developing fewer chronic (long-lasting) conditions, such as coronary artery disease, heart failure, diabetes and Alzheimer's disease.
So how do you improve your fitness? Increase the amount and the intensity of exercise over time.
This study looked at fitness levels in middle-aged people. But you are never too young or too old to get more fit.
To determine your current fitness level, you don't need an expensive exercise stress test. Many fitness centers have exercise machines that show METs. Some home treadmills and elliptical trainers also show METs.
If you don't have access to a new treadmill, or don't like exercising on a machine, you can measure your current fitness with a simple walking test. All it takes is a one-mile track or level terrain that you know is one mile long. You'll also need a stopwatch or watch with a second hand, paper and a pen or pencil.
Once you are warmed up, record the starting time and start walking as fast as you can. Push yourself, but don't overdo it. When you cross the one-mile mark, record the time it took from start to finish.
For a 50-year-old man, time in minutes to walk a mile:
- Excellent -- under 13:24
- Good -- between 13:24 and 14:24
- Average -- between 14:25 and15:12
- Fair -- between 15:13 and 16:30
- Poor -- over 16:30
For a 50-year-old woman, time to walk a mile:
- Excellent -- under 14:42
- Good -- between 14:42 and 15:36
- Average -- between 15:37 and 17:00
- Fair -- between 17:01 and 18:06
- Poor -- over 18:06
Don't be concerned about how low your METs are now or how slow you walked. You can boost your fitness level with regular exercise that challenges your body. That means working hard enough to speed up your heartbeat and breathing.
The goal is to increase your METs or decrease the number of minutes it takes you walk the mile. Don't rush it. Improving fitness starts within weeks but will continue for months.
What Can I Expect Looking to the Future?
The current advice -- exercising for at least 150 minutes per week -- should be your minimum goal.
What is the ideal amount of exercise time? And how high you should push the intensity of exercise? The best way to exert yourself to improve health will be different for each person. The aim is to improve your fitness without causing injury.