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“2 minutes exercise will stop you ageing”

by on 2014/07/31

Headlines reporting medical breakthroughs or general health-related stories are often particularly attention grabbing. A justification could be that by their nature, such stories are about things that might potentially save or shorten your life. When those headlines are combined with being splashed across the front page of a major newspaper, it’s certainly worth taking note. This week, The Daily Express led with “2 minutes exercise will stop you ageing” (or “Two minutes exercise a week can beat ageing” for the online version). Just two minutes of exercise per week? That’s something even I could probably manage!

What about the actual research?

The research, led by Dr John Babraj from Abertay University, Dundee, was published as a Letter to the Editor in the Journal of the American Geriatrics Society. The article is titled: “Extremely short-duration high-intensity training substantially improves the physical function and self-reported health status of elderly adults”. Describing the results as “substantial” sets up the expectation that they are likely to be compelling and based on a very sound methodological basis. It’s rare, though not completely unheard of, to see such terminology used in a scientific title; journals often have strict rules about what you can and cannot say, to stop the findings being misrepresented before the reader has a chance to decide for themselves (a bit like the way headlines in the media are often accused of not matching what they actually report, but by the time you’ve found that out, the paper has already got the sale or a click to their website. Have a look at our How to “Research the Headlines”).

Anyway, on with the research. The study examined whether high-intensity training (HIT) affected physical function and self-reported health in a group of older adults. HIT is essentially very short bursts of exercise performed at a person’s maximum capacity. That is, pushing yourself to your limit, but only for short periods of time, and only on a few occasions per session. While HIT has been examined before, the researchers note theirs was the first study to consider it in older adults.

In total, 12 older adults were enrolled in the study: 6 underwent HIT for 6 weeks, and 6 were controls who did not participate in any training. Those in the HIT group attended the clinic twice a week over the trial. On each occasion, they performed “all-out cycling efforts” for 6 seconds at a time. They started with sessions of 6 cycle sprints, which increased to up to 10 over the trial. The participants were carefully monitored and had a short break between each “all-out” sprint. The break between sprints was at least a minute, and their heart rate had to return to a specific level before they completed the next one.

Both HIT and control groups reported their health status at the start and end of the 6 week period, and had a number of physical measures taken such as how quickly they could get up from a seated position, and their blood pressure. With only 12 participants, it is very difficult to state much, though the authors report that the HIT group showed significant improvements in blood pressure (systolic), oxygen uptake, time to stand up, walk time and “physical functioning”. All of those changes were within the trained group such that their performance was better at the end of the 6 week trial when compared with their initial performance. However, the nature of having a control group who were not trained is so that their performance can be seen as the benchmark – the trained group have to improve more than the untrained group, not just get better compared to themselves. Interestingly, none of the analyses showed any differences between the control group and the HIT group. In summary, the group that underwent the HIT training did not show any changes with respect to those who did not undergo any training.

That is important, so I’ll repeat it: none of the analyses showed any difference between the control group and the HIT group. The intervention which is being reported as a potential way to “beat ageing” showed no effect. And while the authors noted that in the results, their main focus was on the changes seen within the HIT group. The open-minded critic would say that’s a misunderstanding of the basic stats, the cynic might suggest it is intentionally misleading.

To take that further, even if there was a demonstrable difference between the trained and untrained groups, it would not be possible with the current design to say that it was HIT that produced the effect. It might be the changes within the HIT group were because those participants got a lot of contact over 6 weeks from the research team, and had to make two visits a week to the lab, or because they knew they were receiving training which was expected to produce an effect. That is often described under the “Hawthorne Effect”, where an observed effect is in the direction you might expect from your intervention, but is not actually caused by that manipulation, rather some other cause or causes such as knowing you’re in a test group (a nice summary to get you started on that can be found here). To be more certain of what might underlie any trained versus untrained differences, studies should employ an active control group. That would be a group who don’t do the main intervention (HIT in this case), but still come to the lab and have as much contact with the researchers. They might also follow a ‘normal’ exercise regime so that it would be possible to distinguish any benefits of HIT over and above an increase in physical activity more generally.

The summary above is a very basic description, and there have been more detailed critiques of the statistical analyses on social media. What much of that has focussed on is that the size of the differences reported in the study seem to be very large, improbably so (for example, have a look at Professor Keith Law’s twitter feed for details).

What did the media say?

The media, of which The Daily Express coverage is only one part, do a fair job of summarising the study as it is, basing this on the press release from Abertay University. Unfortunately, the press release does nothing to account for the lack of differences between trained and untrained groups, and so the media have taken the “large effects” in the study and given them the coverage they would deserve if true. The Daily Express coverage also failed to note how the study was based on only 12 individuals which would mislead many, by omission, into thinking it was adequately powered: to be really informative, and front-page worthy, a study would need many, many more participants, and follow them for longer. On the latter aspect, the language is misleading across the media coverage of this study. For example, the headlines are all about ageing: “A burst of two minutes exercise a week is the easy way to beat ageing, new research shows”. The study isn’t long enough to examine ageing per se. Rather it looks at how physical function and self-reported health are affected over a short period of follow-up, although to be fair to the researchers, there is no mention of “ageing” as an outcome in their paper.

The bottom line.

As a researcher who examines the lifestyle factors that influence health and wellbeing, particularly in midlife and old age, I am always interested in new methods that might help people become more active. One of those ways is of course trying to get people to exercise in the most effective (and efficient) ways possible. However, while HIT might produce interesting results in the future, it seems that the current media coverage is at best premature, and very possibly misguided. By focussing on this small study, it will likely add to confusion about how best to get active, and at worst, lead to distrust of public health messages.

Adamson, S. B., Lorimer, R., Cobley, J. N., & Babraj, J. A. (2014). Extremely short-duration high-intensity training substantially improves the physical function and self-reported health status of elderly adults. Journal of the American Geriatrics Society, 62, 1380-1381. DOI: 10.1111/jgs.12916

Note. Thanks to Dr Stuart Ritchie for comments on an earlier draft of this post.

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