Exercise caution? The complexities of keeping fit

A rower takes a rest from his work-out. Picture: Getty
A rower takes a rest from his work-out. Picture: Getty
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High-intensity training has taken a bit of a pounding since TV presenter Andrew Marr blamed his stroke, in part, on an overvigorous work-out. While grist to the mill of ‘exercise deniers’, the truth – including a host of related factors – is more complex.

When it comes to keeping fit, most people would rather avoid long hours pounding the streets or the tedium of being stuck in the gym in order to stay healthy and maintain the body beautiful. Recent research outlining the benefits of just a few seconds of high-intensity exercise – giving it all you’ve got before taking a rest and repeating it again – have been enthusiastically welcomed.

A work-out could now be completed in a matter of minutes, leaving time for more enjoyable exploits such as eating, drinking and sitting on the sofa watching TV.

So when Andrew Marr returned to his Sunday morning programme to declare the stroke that almost claimed his life was the result of intensive bursts of exercise, a few shocked faces will have popped up from behind their breakfast bowls. But was it really his exercise regime to blame, or were the Scottish presenter’s stressful job and history of smoking the real culprits in this health drama?

Opinion is still divided on whether high-intensity training (HIT), also known as high-intensity interval training (HIIT), is a better alternative to the current recommendation of at least 30 minutes of moderate activity a day. Certainly, with modern life limiting time for longer work-outs, the attractions are obvious, alongside benefits highlighted in the research, such as burning fat, reducing the risk of diabetes and improving mobility in older people. But Marr’s comments – that he had torn his carotid artery during an intense session on the rowing machine – have now raised questions among some about whether these techniques are safe, particularly among older people.

Gillian Mead, professor of stroke and elderly care medicine at the University of Edinburgh, said a tear in that artery is a recognised cause of stroke and there is evidence of it being linked to sporting activity. “It is probably the rapid extension and flexion of the neck that contributes to it. Obviously most people who do sport don’t have carotid artery dissection, but there probably is an association.”

Mead said this very small risk has to be put into context. “People who are physically active are at a much lower risk of stroke overall and other diseases such as heart disease and cancer. It would be a shame if this story was used as an excuse for people saying ‘well, exercise brings on a stroke’ because that is clearly not the case at all.”

Mead said government recommendations are that people should do at least 30 minutes of moderate exercise most days of the week. Two-thirds of people currently do not meet this level of activity, meaning finding ways of making exercise easier, and less time consuming, have become a major focus for researchers.

While the “no pain no gain” mantra has long been a clarion call of some exercise proponents, many experts have warned that people need to be mindful of their own limits.

Andy Dalziell, a researcher in the Physical Activity for Health Research Centre at the University of Edinburgh, said people should “listen to their own bodies” to help them realise when they might be doing too much – or not enough. He said many studies are starting to highlight the benefits of HIT regimes for people’s health. “But those with any history, or any family history, of heart difficulties should really refrain from that level of intensity in their exercise and should be going for more aeorobic-based exercise of 30 or 40-minute duration at least two or three times a week,” Dalziell said.

“People don’t now have the same time available than before so if they can get a ten or 20-minute high-intensity regime in there they see that as being beneficial. But in some ways they should really be consulting their doctor or fitness health expert to see if they are under threat, depending on their individual history.”

Researchers investigating HIT now believe their studies – and the benefits to the health of the nation which could follow – are at risk due to the comments which followed Marr’s revelations.

Professor James Timmons, who is leading a £5 million global study into the effectiveness of the method, said most medics are not trained in exercise science and there is a lot of ignorance about HIT. He said it is “irresponsible” for people to comment on the issue without having all the facts, adding that the risk factors leading up to a stroke are long standing and people had to look at their own lives before blaming one particular issue. “Everyone has to reflect on their lifestyle. Andrew was, by his own accord, a chain-smoking individual for a number of years,” he said. “I don’t know why people believe that they can live a poor lifestyle and then think it all goes away because they change their lifestyle.”

Timmons, from Loughborough University, also points to “voluminous data” which shows that, even in people with a risk of cardiovascular disease, high-intensity exercise did not cause any problems. One study, carried out in Norway, involved 4,500 people with cardiovascular risk factors who either went through high or low-intensity training. “There was one fatality in that study and it happened to be in the lower-intensity group,” Timmons said. “That tells you that what you’re looking at is a random chance association because if you followed 5,000 high-risk people for a year someone’s going to have a stroke.

“We are dealing with a few misunderstandings here in terms of the medical science and the statistics. If you’re at high risk, it can happen when you’re sitting drinking your coffee.”

Timmons also disputes assertions that high-intensity training should be limited to younger people. In their studies, he said participants were given the standard advice on how to exercise safely. This included telling them if they had any concerns or a history of cardiovascular disease they should speak to their GP.

He said one concern is now, given the publicity over Marr’s comments, that people will be deterred from taking part in such trials. “We are running an expensive, public money-funded clinical trial and we have to recruit subjects into our trials. Andrew Marr could well have impaired our ability to complete this trial,” Timmons said.

Dr John Babraj from Abertay University’s school of social and health science in Dundee, echoed these concerns and said he is “disappointed” by the way the issue had been discussed. “There’s absolutely no evidence in the literature for blood-vessel rupture with high-intensity training, both in animal and human studies. It is not something that we have seen,” he said.

Babraj’s work has involved older people, who he said could also carry out this type of exercise safely. “They have all enjoyed it and found it really beneficial,” he said. “For the older population some really big benefits have come out of it. One of the biggest is improvement in their own functional ability, such as doing day-to-day tasks like housework.” Babraj said improving the health of this older group is vital as the country deals with an ageing population.

Philip McWilliams, a personal trainer at Pure Gym in Edinburgh, said HIT is becoming more popular, particularly as it is quicker than traditional work-outs. “You have got people with really busy lives and they want to train really hard and get a good work-out. High-intensity interval training allows you do to that,” he said.

He does not believe this kind of training will contribute to a stroke. He said he would recommend HIT using a rowing machine as a good way of working all the muscles in the body. But McWilliams said he would give advice to people about how to do it safely. “If you had high blood pressure, I maybe wouldn’t advise this type of exercise,” he said. “If you are prone to asthma attacks I wouldn’t say don’t do it, but be careful and have your inhaler with you.”

Annalisa Buchanan, director of the Penicuik-based Fitness Education Academy, which trains personal trainers, agreed that HIT is becoming more popular for people with a limited time for training.

She said the advice given to those wanting to try this approach would depend on their own level of fitness. “They could still do this training method, but the instructor would need to monitor the intensity of the individual,” Buchanan said.

The debate about how best to get the nation fit will continue as research delves more deeply into what makes the perfect work-out. But one thing scientists, medics and exercise experts all agree on is that standing still is not an option.


Researchers around the world are busy investigating the benefits of high-intensity training. Some of the recent studies include:

• Abertay University in September reported that 60 seconds of high-intensity exercise three times a week could improve fitness. Dr John Babraj’s team found fitness levels of participants improved by more than ten per cent after two weeks of doing sequences of six-second cycling sprints.

• A training regime developed at Heriot-Watt University, involving 30-second bursts of intense activity, was last year reported to be better at warding off heart disease and related conditions than hours in the gym. The team, led by Professor James Timmons, believed the method is more effective at burning fat than long daily work-outs and dulls rather than sharpens appetite.

• In 2009, Professor Martin Gibala and his team at McMaster University in Canada used 60 seconds of intense exercise followed by 75 seconds of rest, repeated for 8–12 cycles. Volunteers obtained gains similar to what would be expected from subjects who did traditional training five times per week.