Does exercising harder help you live longer?
Regular exercise helps you live longer, right? And vigorous exercise is particularly good for you, isn't it?
Well, probably. But everything we think we know about exercise and longevity actually comes from observational studies — the kind that tracks people over a long period of time, but where you can't prove cause and effect.
Now a group of researchers is trying to rectify this, with a large, long-term randomised trial studying the effects of exercise intensity on the risk of death, and the results have recently been published in the BMJ.
The Norwegian study followed 1,567 people in their 70s for five years, with people assigned into one of three groups.
The first two groups were instructed to either do high intensity interval training (HIIT) twice a week or moderate intensity continuous training twice a week.
The third group were just told to follow the national physical activity guidelines — this was the control group, meant to show what would happen without intervention.
But the researchers hit a surprising pothole: the control group followed instructions and ended up working out harder than the "moderate" exercise group.
"Usually if you tell people to follow the [physical activity] guidelines, in Australia, for example, they don't and you can depend on them being a control group," says Maria Fiatarone Singh from the University of Sydney, who was one of the authors on the study.
"But this [study was done in] Norway, these are Vikings. When they were told to do it, not only did they do it, but at the end of the five years, 70 per cent of the controls were actually meeting those guidelines, and another 20 per cent were also doing HIIT."
This wasn't bad for the study participants, because they got the benefits of exercise. But it did make the cause-and-effect difficult for the researchers to tease out.
However, the upshot was there did seem to be an advantage to regular HIIT over the other two approaches to exercise.
"The HIIT group came out the best in terms of mortality," Professor Fiatarone Singh says.
"It increased aerobic fitness more than the other two groups. So that was significant, and it increased quality of life, both mental and physical."
This paper is an early milestone in a long-term project, says lead author Dorthe Stensvold of the Norwegian University of Science and Technology.
"We will follow the participants for five more years, and hopefully these data will give us a clear answer if exercise intensity is important for longevity."
The power of consistency
Overactive control groups aside, the research fits with previous studies showing exercise is as much about improving life when you're alive, as it is about staving off death, says Wendy Brown of the University of Queensland, who was not involved in the study.
While all age groups can benefit from regular workouts, keeping it up in old age is particularly important, Professor Brown says.
"What was amazing was in these hundreds and hundreds of people, they went for five years," she says.
"They went through knee replacements. They went through hip replacements. They went through all kinds of other health things that happen with ageing. And then they went back and joined the group afterwards.
"The minute you stop doing it [exercise] as you age, the wheels start to fall off.
"I don't think it matters as long as you keep doing it."
Professor Stensvold agrees.
"Adding life to years, not only years to life, is an important aspect of healthy ageing," she says.
"The larger health benefits in HIIT, reflected by higher fitness and health-related quality of life, compared to [the moderate training group] and controls is an important finding."
High intensity doesn't have to mean high impact
So any exercise is better than none, and HIIT seems to give an additional advantage.
But if you're put off by the idea of high intensity training, perhaps you can be reassured by the fact it's not necessarily about pounding the pavement.
In this study, a HIIT session involved a 10-minute warm-up, followed by four lots of four-minute intervals where participants' heart rates reached about 90 per cent of their peak rate.
"You don't have to run to be at high intensity," Professor Fiatarone Singh says.
"You can climb stairs or walk briskly uphill and you'll be at 90 per cent of peak heart rate, if you're an older adult.
"The idea that you have to run, which is off-putting for many people because of arthritis, is not the case, and there are lots of low-impact ways to do it."
Article from ABC Health & Wellbeing