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staying ahead of the curve
By Markian Hawryluk / The Bulletin
Published: November 12. 2009 4:00AM PSTYou're approaching age 45. You have a healthy body mass index. But are you more likely to sit on the couch and watch TV ..... ..... or are you going for a run, riding your bike and generally staying active? The answer may make a difference in the future.
When it comes to fitness and athletics, even the most hardened enthusiasts realize at some point they're over the hill. Who knew the hill begins to crest by age 45?
A new study published last month in the Archives of Internal Medicine found that cardiovascular fitness in both men and women begins to decline sometime in the fifth decade of life and that the drop speeds up as you get older.
Experts disagree on whether that means the rate of decline is inevitable or whether a commitment to physical fitness can flatten out the curve. But there is widespread agreement that what you do now will have a profound effect on your fitness and your health in the latter decades of life.
Many researchers believed that the decline in fitness levels pretty much followed a straight line, that individuals lost a standard amount of cardiovascular fitness every year. But Dr. Andrew Jackson, an exercise physiology professor at the University of Houston, said that notion came mainly from cross-sectional studies. Those types of studies tested athletes at different ages at one point in time, then compared fitness levels.
“If you use longitudinal data, people who have been measured several times, then what you're getting is a better measure of change within the individual,” Jackson said.
Jackson and his colleagues examined data from the Aerobics Center Longitudinal Study that tested the fitness levels of more than 20,000 men and women between two and 23 times over the course of 32 years.
They calculated results from the treadmill tests in metabolic equivalents, or METs, a measure of how much oxygen the body is using or how much energy the body is expending. One MET represents the amount of energy used when a person is at rest.
At age 40, the men in the test averaged just over 12.6 METs. (METs convert to VO2 Max, another common measure of aerobic capacity, by multiplying by 3.5. So 12.6 METs is equivalent to a VO2 Max of 44.)
Between the ages of 40 and 50 the average MET for men dropped by a half point; between ages 50 and 60 it dropped by a full point; and between 60 and 70 it dropped by two points. Women had a less steep decline but started at a lower level, about 10.6 METs.
“Essentially after about age 40 to 45, you start to lose your aerobic capacity, and that accelerates over time,” Jackson said.
Lifestyle matters
When researchers took into account other factors, including smoking, weight and physical activity levels, they found those lifestyle factors were closely correlated to physical fitness. People who were overweight, smoked and were inactive started at a lower level of fitness at age 45. As a result, they reached lower levels of fitness at an earlier age than normal weight, nonsmokers who exercised regularly.
“If they are, like a lot of people in Oregon, active lean people, their aerobic capacity at 45 is going to be considerably higher than somebody who isn't, and if they continue that lifestyle, they're going to in the same sense go down, but they'll maintain that difference,” Jackson said. “This is one reason why you can have 70- or 80-year-old men running marathons. They've been doing it all their lives, and they've got the aerobic capacity of maybe somebody that's 50.”
In other words, the higher your fitness level, the more you have to lose and the longer you can stave off the consequences of a low level of fitness.
Previous research has established that once men fall below a fitness level of 8 METs and women below 7 METs, their risk of health problems — including hypertension, diabetes, heart disease, cancer and death — increase. And it's less likely they'll be able to live independently.
The Social Security Administration, for example, uses a VO2 Max of 18, or just over 5 METs, as the standard for disability.
“We're talking about the ability to carry on an active life,” Jackson said. “They would have trouble with daily life, climbing up stairs, walking and so on.”
Peak performance
Although the study group involved a higher percentage of active people than the general population, it did include many sedentary people. Other research has shown that active individuals may be able to maintain a high level of fitness longer.
“There are these small measurable declines that happen. There are real physiologic changes that happen with aging,” said Dr. Vonda Wright, a professor of orthopedics at the University of Pittsburgh. “They don't always translate into athletic performance.”
Wright studied results from the 2001 National Senior Olympic Games, comparing the winning times for different age groups. She found that the senior athletes showed an average 3.4 percent decline per year from age 50 to 85. Men showed the same decline in both sprint and endurance events, while women showed a greater decline in sprint than in endurance events. Results dropped slowly from age 50 to 75, then there was a marked drop-off in performance after age 75.
“So what that means is the 50-year-old runs his mile in 4:34 and the 70-year-old runs his mile in 7 minutes. That's faster than many couch potato 30-year-olds,” Wright said.
Eventually, the cumulative effect of wear and tear on the body takes its toll, she said. Cardiovascular capacity drops off, muscles tighten and lose flexibility, affecting stride length, and other effects of aging take over.
The drop-off in fitness levels even among elite athletes is evident locally with the record times for the Pilot Butte Challenge. The race held annually in September times runners up the 1.2-mile route to the top of the 490-foot butte in Bend.
The record time for men, 7:10, was set by Lars Flora at age 31. Results for each age group after 45 get progressively slower. For women, results are more varied in the younger age groups but show the same progressive decline in times past age 45.
But the record times, which are posted at the start of the Pilot Butte trail, show that new records for various age groups are set each year. Of the 17 age groups, the record time was set in the past three years for eight of the men's groups and 10 of the women's groups. There is even a record time for the 90 and older age group for men, set by Bill Lauderback at 18:17. While historical results aren't posted, it's likely that some of the current age group record times are faster than previous records for younger age groups.
It's a trend that's evident throughout the world.
“The older athlete is redefining what normal aging is and what's possible for people who are middle age or older,” said Dr. Michael Joyner, an anesthesiologist with the Mayo Clinic in Rochester, Minn.
Joyner said athletes of all ages continue to improve record times because of better training methods, equipment and medical care.
“Your VO2 Max typically starts to decline in your 30s, but a highly trained athlete can delay that decline until they are in their later 30s or even early 40s,” Joyner said. “An average sedentary person loses about 10 percent per decade starting at about age 30, but for someone who is able to continue to train very hard into their 40s or 50s, they only lose about half that much, primarily due to the fact they continue to train hard.”
Wright, who authored the book “Fitness After 40,” said older adults can keep fitness levels high, but they have to change the way they exercise.
“People continue to try to train like they're 20 years old,” she said. “The runners just go out and run. They don't do anything else. But that's not good for a 40-year-old body.”
She recommends that men and women after age 40 adopt a program that includes stretching, aerobics, resistance training and balance work.
• Stretching: “Aging muscles and tendons get tighter and tighter every day you don't stretch,” she said. “What that does is decreases your stride length, it decreases your range of motion, it causes back pain, and it throws your biomechanics off.”
She suggests a slow, 30-second stretch of every major muscle group in the body. While that sounds ominous, she said, it can be done fairly quickly.
• Aerobics: Most older athletes focus on aerobic work, but Wright said sometimes they overdo it.
“It makes no sense to be intense every single day because you don't give your body time to recover, and our recovery capacity is slower as we age,” she said.
• Resistance training: Wright doesn't talk about weight lifting as much because she believes functional resistance training has more real-life benefit.
“When we're running and doing athletics, we don't sit on a chair, and haul weight around,” she said. “I like weight lifting to be done through a functional range of motion, using a variety of different resistance methods: bands, kettlebells, medicine balls. And there is room for iron weight, but not how we've always envisioned these things.”
• Balance: At age 20, our balance starts to decline, Wright said. Any sort of balance training can help you maintain function longer. “Balance and equilibrium are totally retrainable,” she said. “You just have to do it every day.”
Markian Hawryluk can be reached at 541-617-7814 or mhawryluk@bendbulletin.com.
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