Monday July 28 2014
Exercise can help mitigate the effects of ageing
"Two minute of exercise … is enough to boost pensioners' health," the Daily Mirror reports. A pilot study into high intensity training suggests it may be an effective method of combating the effects of ageing.
However, the UK media are guilty of hyping the implications of a small study, involving just 12 people, which lasted only six weeks.
The 12 participants were randomised into two groups – a control group (no information was given on what the control protocol involved) and a high intensity training (HIT) group.
The HIT group were asked to complete a 6-second "all-out" cycling sprint, two times a week, over the course of six weeks. The number of sprints in each session was progressively increased throughout the intervention, ranging from six 6-second sprints to 10 6-second sprints.
They found there was improvement in blood pressure, aerobic fitness and mobility in the HIT group compared with the control.
Since the results were based on findings from just 12 people, they will not accurately reflect the diverse and varying situations and experiences of older people in England as a whole. The results of HIT in larger groups of elderly people may be different from those seen in this small sample.
There was also no reported assessment of risks. This is an important issue as there have been anecdotal reports that intense activity can trigger health conditions such as a stroke, as was the case with broadcaster Andrew Marr.
The bottom line is this study has shown some promising findings for HIT in the elderly, but has not yet got to the stage of providing reliable evidence that it works or is safe.
Where did the story come from?
The study was carried out by researchers from the University of Dundee and was published as a letter to the editor in the peer-reviewed Journal of the American Geriatrics Society. No funding source was specified in the publication.
While generally the media reported the story accurately, there were no adequate discussions on the limitations of a small preliminary study of this type.
This could lead readers to think this exercise approach is proven to work, with lots of evidence behind it. However, based on this small study alone, this is not the case.
Claims such as the Daily Express' "Two minutes exercise a week can beat ageing" are unsupported.
What kind of research was this?
This was a study looking at whether high intensity exercise training (HIT) might improve the physical fitness and mobility of older people.
The study authors remind us that the UK Chief Medical Officer's physical activity guidelines for elderly adults recommend moderate to vigorous-intensity physical activity several days each week.
A large proportion of the elderly population do not participate in the recommended amounts, with time being reported as the most common barrier to participation, much the same as for adults of other ages.
Short bursts of high intensity training have therefore been discussed as a possible solution to the time problem, and as a way of enabling the elderly to reap the many benefits of regular exercise.
However, the authors reported nobody has investigated whether HIT actually yields physical improvements in older populations, so they designed a small study to find out.
What did the research involve?
Participants were randomly allocated to a control (n = 6; five female, one male; aged 64±2 years) or HIT (n = 6; four female, two male; aged 65±4) group before baseline measurements of mobility and physical fitness were made.
The same measures were repeated after the six-week high intensity or control intervention so see if there were any improvements, and whether the improvements in the HIT group were significantly better than the control.
Each HIT session consisted of 6-second "all-out" cycling efforts occurring two times per week over six weeks. Male participants sprinted against 7% body weight and female participants against 6.5% body weight. The number of sprints in each session was progressively increased throughout the intervention, ranging from six 6-second sprints to 10 6-second sprints.
A minimum of one minute of recovery was given between sprints, with subsequent sprints not starting until heart rate was below 120 beats per minute.
The publication did not describe what the control group were asked to do, so we do not know what the HIT group were being compared to.
Physical function was measured using a number of outcomes, including:
- a "get up and go" test – the time a person takes to rise from a chair, walk three metres, turn around, walk back to the chair, and sit down
- a "sit to stand" test – the ability of the person to repeatedly stand up from a chair and sit back down again
- a 50m "loaded walk" test – walking 50m while carrying some weight
Other measures included:
- a 12-minute single-stage walking test to determine maximum oxygen uptake (VO2 max) – a measure of the body's ability to use oxygen and a measure of aerobic fitness
- blood pressure – measured using an automated blood pressure monitor
What were the basic results?
Statistically significant improvements in the HIT group compared with the control group included:
- a 9% reduction in blood pressure
- 8% greater VO2 max – a measure of aerobic fitness
- 11% improvement in the "get up and go" test
There were also improvements in other measures of mobility and fitness within the HIT group, but these were matched by similar improvements in the control group, meaning the differences were not significantly different between the two groups. These included improvements in the "sit to stand" test, 50m loaded walk, positive engagement in physical activity, revitalisation, and physical functioning.
How did the researchers interpret the results?
The authors concluded their results "strongly suggest that performing two minutes of exercise per week for six weeks may be an effective strategy for counteracting age-related functional decline, reducing cardiovascular disease risk and promoting further engagement in physical activity within the elderly population."
This small preliminary study indicated high intensity training (two sessions per week for six weeks) improved blood pressure, aerobic fitness and mobility in and out of a chair, compared with a control group of 12 people over the age of 60.
While this research is promising, there are a number of limitations to be aware of.
We don't know anything about what the control group were asked to do. For example, control groups are often given lifestyle advice as part of an incentive to take part in studies and are otherwise free to continue whatever lifestyle habits they had before, but we don't know if this was the case in the current study.
Curiously, the control group also improved significantly on many measures, so it would be interesting to know what they were doing that also led to these improvements. It is somewhat of a strange oversight that no information was given on the control protocol – possibly a more in-depth description of the study is in the pipeline.
There was also no discussion of the potential risks of high intensity exercise in the elderly, a concern that has been raised in the past, particularly in the frail, and could include exercise-related injuries or a raised risk of heart attack.
As the publication was so brief, we do not know the basic fitness level of either group, as the results of the medical outcomes study were not presented, nor do we know if they had any medical conditions. Based on this study alone, we do not know if the potential benefits of HIT outweigh the potential risks.
The characteristics of the 12 participants were not described in any detail, so we don't know if they are typical of the over-60s. This means it's difficult to tell how relevant and generalisable the results are to the wider over-60s population in the UK.
Furthermore, the study was short at just six weeks long. This means there wasn't enough time to see if any beneficial effects were temporary or more long term, or whether this exercise approach could reduce the risk of certain diseases or increase a healthy lifespan.
The results are based on just 12 people, so they may be prone to sampling biases and chance findings.
This type of study is designed to provide a proof of concept that something may work using a small group. The intention is then to conduct larger studies to provide more reliable evidence to confirm or refute the initial findings.
This study has shown some promise for HIT in the elderly, but has not provided reliable evidence. Until that happens, current advice on physical activity and lifestyle in the elderly is unlikely to change.
Recommended activities for the over-60s include walking, swimming and cycling. Yoga and tai chi may also help improve mobility and prevent falls, which are a common cause of injury in older people.
Analysis by Bazian. Edited by NHS Choices. Follow Behind the Headlines on Twitter. Join the Healthy Evidence forum.