Program: Measuring exercise with steps vs duration

Shelby Traynor: We have physical activity guidelines in Australia, which is great. Sometimes I do think they just exist to guilt-trip me because I'm not meeting them. What are the guidelines for someone like me? What are the guidelines for adults? 

Norman Swan: Well, the guidelines for someone like you, even though you weren't born when…

Shelby Traynor: Pedometers existed? I definitely was.

Norman Swan: They are 150 minutes a week of moderately intense exercise. Another way of looking at this is 45 minutes of moderate exercise on most days of the week. It's got to be a pattern.

Shelby Traynor: And something that I hadn't thought about until I started looking into this was that those guidelines are in durations. Lots of people measure their workouts by distance, especially if you're a runner, laps if you're a swimmer, and step count if you're a walker. But those aren't in the guidelines.

Norman Swan: No. They are in public health messaging in some countries and to some extent in Australia, but they're not part of the official one, so you do have a disconnect there.

Shelby Traynor: Yeah, and that's because there's evidence to back up exercising for this amount of time means this health outcome. 

Norman Swan: And you want simplicity, because there is evidence, for example, that high intensity interval training, you can shorten that 150 minutes, but you've got to do it properly otherwise you're not getting the benefit. So the simplest thing is to state what it is, moderate exercise. And moderate exercise is moderate for you, so that instantly tailors it. So if you've never exercised and you get up off the couch, just going for a walk along the flat, it's going to be hard to have a conversation, you're going to be breathless, but after two weeks of doing that, you're not going to be so breathless, so you've got to push yourself. And so you find after six months you're actually doing much more than you were doing when you first got off the couch.

Shelby Traynor: Well, researchers in the US have been trying to see if we can include step counts in these guidelines. So they're trying to find evidence that a certain amount of steps will equal benefits in terms of your health.

Norman Swan: And the problem there, of course, is the whole intensity equation. 

Shelby Traynor: Yes, you could be on a leisurely walk, you could be on a brisk walk…

Norman Swan: You could be walking uphill and up stairs.

Shelby Traynor: It could be really, really hot, and you could be sweating. So there's a lot of…to preface this, there's a lot of external circumstances, but it helps that this is data from a really big study. So this was a study based on data from the Women's Health Study which followed more than 14,000 people.

Norman Swan: Yeah, we've spoken about this many times, and actually quite recently on the Health Report, this was about assessing low-dose aspirin, vitamin E and hormone replacement therapy in a large group of women, and they've been extracting subsets of data from this as well.

Shelby Traynor: And they decided, well, we've already recruited all of these people into this study, let's just ask them to do another thing. And so they monitored them with an accelerometer to measure their physical activity, and that was between 2011 and 2015 and then they kept track of their health outcomes up until 2022.

Norman Swan: And what did they find? 

Shelby Traynor: So they found, at least for older women, this was women aged 62 and up, the health benefits of a high step count were pretty much on par with the benefits of moderate to vigorous exercise, and the health benefits they were measuring were all-cause mortality and cardiovascular disease. I spoke to one of the authors of the study, Dr Rikuta Hamaya.

Rikuta Hamaya: The higher physical activity in time or steps was associated with reduced risk of mortality and CVD, and the magnitude was similar. Our evidence suggests that setting a step as a goal can be another good metric, as good as a time-based goal. So that's a major take-home message.

Norman Swan: So was this evenly spread, or was it the highest group when they tracked the number of steps? And what about the 10,000 measurement?

Shelby Traynor: For the people in the highest percentile, so basically the people getting the highest amount of moderate to vigorous activity, the people that we all…

Norman Swan: Aspire to be.

Shelby Traynor: Yeah, aspire to be and hate…

Norman Swan: Or you feel guilty about.

Shelby Traynor: Yes. They were getting about two-and-a-half hours of exercise per week, and their all-cause mortality was 4.8% at follow up. So 4.8% of people in that group died within those nine years. And for people in the highest percentile of step counts, it was 4%.

Norman Swan: So they did a bit better. Was that statistically significant? 

Shelby Traynor: I'm not sure, I'm not sure. But their step count was about 7,000 so they didn't even do the 10,000 steps, the people in the highest percentile.

Norman Swan: Yeah, I think 10,000 can be a bit arbitrary, and this is not the first study to say, well, maybe 7,000 is about right there.

Shelby Traynor: Yeah. And it is about the population. These are women over the age of 62 and the median was about 71. But yeah, it speaks to how difficult exercise adherence is. It's a difficulty in everybody's everyday life. It's a difficulty in these studies as well. But one of the hopes would be that if you can put step count as a guideline, people can choose, hey, is it easier for me to meet a step count? Am I more motivated by that? Or am I more motivated to have 150 minutes of exercise each week? 

Rikuta Hamaya: Physical activity adherence is low over all the population, and the adherence is currently measured using only time. But our study suggests that step-based goals can be another goal. Older adults are more likely to engage in walking. Having that concrete goal and very visible goals can be a good motivation.

Shelby Traynor: Dr Rikuta Hamaya, who works in preventative medicine at Brigham and Women's Hospital, which is a teaching hospital of Harvard Medical School.

Norman Swan: Well, that's the Health Report for this week. I'm away for three weeks or so, and Tegan will be back, don't worry, and Shelby is going to be the rock of consistency across the show. So, keep on sending your emails in to…

Shelby Traynor: Healthreport@abc.net.au. And we also have another show where we specifically answer your questions, no matter how gross. It's called, What's That Rash?, and this week we're talking about the gluten free diet. Please send us your favourite gluten free bread recipes, and I'll forward them straight to Norman.

Norman Swan: And I'd love to hear whether or not you've got a gluten free tiramisu recipe, which will really complicate things. They will see you next week. I'll see you soon.