The standard rule of thumb is that your VO2max, a measure of aerobic fitness, declines by about one percent per year after your mid-30s, and perhaps more when you reach your 70s.
Of course, you can certainly beat the averages, and running is one good way to do that. But is training still as effective when you get older, or does your body also start to lose its ability to respond and adapt? That’s a question researchers have been debating for quite a while, and a new study offers some interesting insights.
The study is from researchers in Norway, and is published in Medicine & Science in Sports & Exercise. It involved 94 people between the ages of 20 and 83, whose physical activity levels were all “typical” for their ages—meaning not a whole lot, generally less than two hours of low to moderate activity per week.
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The subjects did an eight-week high-intensity interval program, which involved running or cycling for 4 x 4:00 hard (90 to 95 percent of max heart rate) with 3:00 recovery (70 percent of max heart rate) three times a week. Their fitness was assessed before and after the training program.
The average increase in VO2max was between 9 and 13 percent, and the researchers hypothesized that this increase would decline with increasing age. But that didn’t happen; here’s what the results looked like when broken down by decade:
There's no clear trend with age—in fact, the 60-69 age group has the biggest relative improvement of any group. There's certainly no evidence of a steady decline in improvements in the older age groups.
Instead, the best predictor of VO2max increase was baseline fitness: not surprisingly, the fittest subjects (relative to their age) increased the least. Here’s that data, where “training status” indicates VO2max relative to the average VO2max for that person’s age. For example, if the average 45-year-old has a VO2max of 40 ml/kg/min, then a 45-year-old with a VO2max of 60 would have a training status of 150 percent.
In this case, the volunteers who were more than 50 percent fitter than average for their age (i.e., training status of 150 percent) saw virtually no improvement, on average, from this eight-week training cycle. In contrast, those with a training status of 75 percent saw an average VO2max boost of about 20 percent.
It’s worth noting again that all the subjects in this study were relatively untrained. Whether age blunts training response in athletes who are already well-trained is another question. (It certainly feels that way some mornings!)
But the more important message to share with your friends and hassle your elders with is that it’s never too late. Whether you’re 35 or 75, your body will respond in a similar way if you start training vigorously, even just three times a week. And the less fit you are, the more you have to gain.