“We found that two to three days, unfortunately, did almost nothing for you,” said Levine, who also is a professor of cardiology at the University of Texas Southwestern. “But four to five days a week got you most of the way there.”
In another study, Levine and colleagues compared the impact of 30 years of aging with the effects of three weeks of bed rest. He looked at five men who were put on three weeks of strict bed rest in 1966, at the age of 20, to study how that lack of activity affected healthy individuals. Thirty years later, he tested their ability to use oxygen (VO2 max), their cardiac output and their body fat composition.
The results of this study, which were published in 2001, clearly showed that the bed rest was far more damaging to their aerobic fitness than three decades of aging, reinforcing the notion that what we consider a normal decline in physical fitness is actually the result of too little activity.
“Much of the age-associated decline may be avoidable or reversible with regular exercise,” the researchers wrote.
Gaining speed, or slowing its decline, depends, of course, on how fast you are when you start. Someone who is doing no exercise will certainly improve his speed and fitness as he begins any form of cardiovascular training.
But such people aside, most exercisers can expect their fitness profiles to follow a rough bell curve over time, said Lisa Reichmann, a running coach and co-founder of Run Farther and Faster,
a running program in Rockville.
Training makes a difference
Less naturally talented athletes and others who aren’t training efficiently can be boosted toward their proper spot on that curve, she said. “If you haven’t worked out in a while or you haven’t been properly trained, you’re going to be below” the curve, she said. “And if you get proper training, you can improve.”
As I have grown older and heavier, and concentrated on running longer distances, I have noticed how sharply my speed has fallen off. Ten-minute miles several years ago have become 10:45 or even 11:00 today at age 55, which makes a 10-mile run a nearly two-hour endeavor.
In preparing to do this story, I decided to see what Reichmann and program co-founder Julie Sapper could do for me in two months of training. I had only one request: “Make me faster.”
After I filled out a detailed questionnaire, they designed a six-day-per-week training schedule that included one day of speedwork, two days of core-strengthening exercises and three days of roadwork, including a weekly long run (seven to 10 miles) and a weekly medium-long run (five to seven miles). They also sent me recommendations on eating more healthfully, which I utterly failed to adopt.