Stepping out

Leon Mabire,  a  University of Otago  School of  Physiotherapy PhD  student, puts another  walker to work on a  treadmill. Photo by Gerard O'Brien
Leon Mabire, a University of Otago School of Physiotherapy PhD student, puts another walker to work on a treadmill. Photo by Gerard O'Brien

The most popular recreational pursuit in New Zealand, walking offers many benefits. Shane Gilchrist puts one foot in front of the other. 

Within the labyrinth that is the University of Otago School of Physical Education, there are corridors that offer various metabolic metaphors: some are light and bright, full of vigour; others are gloomy, as constricted as an artery clad in cholesterol.

Having strolled various passages, I am now walking with more purpose. Specifically, I am on a treadmill, being studied like a rat on a wheel.

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The rhythm of my heart. The air that I breathe. No longer themes for songs, they are instead indicators of exertion, University of Otago researcher Leon Mabire explains after attaching oxygen mask and pulse monitor, both of which send my vital signs to an adjacent computer.

That walking is good for one's health is without question. The research is conclusive and includes a 2015 report by German academics claiming a brisk 20-minute daily walk could add seven years to a person's life; another report last year in the British Journal of Sports Medicine showed regular walkers enjoyed decreases in blood pressure, resting heart rate, weight, body fat and cholesterol.

Stretching the legs also helps our higher faculties. A recent University of Otago study suggests regular engagement in aerobic exercise, such as brisk walking, improves cerebrovascular and cognitive functioning even in healthy young adults.

According to the researchers (more on this later), such findings challenge old ideas that young people do not have to worry about exercising since they are in their prime developmentally.

Mabire is another academic attempting to reframe our conversations about walking.

The University of Otago School of Physiotherapy PhD student is particularly interested in undoing an oft-aired mantra, cited by many governmental health departments, including New Zealand's: which is the recommendation of 150 minutes each week of moderate intensity exercise for adults between 18 and 65 years of age.

Mabire describes this guideline as too simplistic, a "one-size-fits-all'' dose. He says there is increasing evidence to suggest this approach does not fit all. Significantly, too much exercise could be harmful to some.

"These guidelines are over 20 years old, but are still in use all over the world,'' Mabire points out.

He says the origins of the guidelines go back even further, to the 1950s when heart disease was the leading cause of death for men.

Researchers found that male British civil servants (on average, 1.73m tall and weighing 75kg) who walked for a total of 30 minutes, five days each week as part of their daily commute had a lower risk of heart disease than their sedentary colleagues.

Using data from the 1920s, the researchers knew that the average man would burn about 6.5 calories each minute. And men who burned 1000 calories each week by walking reduced their risk of heart disease by 20%-30%. So it would take him 150 minutes each week to burn 1000 calories. Voila - the recipe, still promulgated.

Mabire is in the final stages of completing a research project titled, "Walking towards health: Does size matter?'', the aim of which has been to challenge the current physical activity guidelines, and demonstrate that it is possible to give each individual their own dose of walking to keep fit or lose weight.

"We chose walking as surveys have shown that it is the most popular physical activity for everyone. For men and women, young and old, underweight or overweight, walking is by far the most popular activity.''

Certainly, a recent Nielsen report backs that up. A survey of more than 14,000 New Zealanders showed walking is our most popular recreational activity, enjoying a 29% rise in popularity since 2010.

Likewise, Sports New Zealand's 2013-2014 Sports and Active Recreation report (involving 6500 adults) had walking participation at a sliver under 60%; the next closest was swimming, at 30.4%.

Here are some more statistics: the 2014-2015 New Zealand Health Survey found almost one in three adults (aged 15 years and over) were obese (31%) and a further 35% of adults were overweight but not obese.

[Obesity and overweight definitions are based on the body mass index (BMI), a commonly used measure calculated by dividing weight in kilograms by height in metres squared (kg/m2). A BMI greater than or equal to 25 is overweight; a BMI greater than or equal to 30 is obese. However, BMI does not distinguish between weight associated with muscle and weight associated with fat, so it provides only a crude measure.]

Extra weight increases the risk of "exercise overdose'', Mabire says, adding the adverse effects are apparent: overweight and obese adults who follow the recommendation of 150 minutes per week have an 80% risk of injury, according to his research.

"Just one in 400 obese adults will achieve and maintain a weight loss, and some obese adults will even gain weight.''

Instead of focusing on time, Mabire's study looks at calorific expenditure, specifically using 1000 calories a week, a goal associated with a reduction in heart disease.

Each of the 62 people involved in the study were put on a treadmill, hooked up to an oxygen mask and set the task of walking at 4.8kmh on a flat gradient for 15 minutes. 

"We have used the easiest moderate intensity to make it nice and safe for everybody. Even so, for our largest participants, those who had body mass indexes of 55-65 and over, this exercise was actually too hard for them and we had to stop the test,'' Mabire explains.

"The smallest people we tested, these tiny athletes who weighed around 55kg, would need to walk for more than 200 minutes each week to get the same benefits as, say, someone like me [75kg], for whom the benefits of 150 minutes per week would apply.

"In contrast, someone who was morbidly obese, at around 150kg, would do less than 100 minutes. There is a huge spread in the amount of walking people need to do in order to realise those health benefits.''

Regular walkers (from left) Marilyn Yates (66), Jo Springett (76) and Kathleen  West (70)  dress for the conditions at St Clair Esplanade, Dunedin, earlier this  week. ‘‘We usually walk for an hour, sometimes longer,’’ Mrs Springett says.  ‘‘W
Regular walkers (from left) Marilyn Yates (66), Jo Springett (76) and Kathleen West (70) dress for the conditions at St Clair Esplanade, Dunedin, earlier this week. ‘‘We usually walk for an hour, sometimes longer,’’ Mrs Springett says. ‘‘We talk a lot. In fact, we often don’t notice where we are walking because we enjoy one another’s company so much.’’

On a midweek morning, five women cluster under umbrellas at the St Clair Esplanade. They are about to commence their regular hour-long walk. However, the rain has gone from steady to intense. So, thinking on their feet, they suggest the coffee and chat that often caps off their endeavours might just have to be brought forward.

Among the group are some who are members of the Multi-Peak Fitness Walkers. Comprising a core of friends who meet once a week, every week, they've been doing this for more than two decades.

"The number of people I see out walking, from husbands and wives to friends ... it's huge,'' says Marelda Gallaher who, despite no longer walking regularly with the Multi-Peak group, still gets out with friends.

"When I was involved with the walking group, we'd go everywhere: around town, the beach, Ross Creek, the Pineapple Track ... We'd walk for an hour, but we were never that fast and it was more about being social than the fitness.

"I remember being at a formal dinner a while back and here we all were, five or six women in ball dresses and we all were wearing our Fitbits or similar devices. None of us had taken them off, which was weird.

"I'm in my mid-50s and it is something I can still do.''

And all that walking could well be exercising the grey matter, according to a recent study by University of Otago researchers.

Liana Machado, of the University of Otago Brain Health Research Centre and Department of Psychology, points to her findings published in Psychophysiology last year suggesting moderate physical activity (including brisk walking) at least five days a week for at least 30 minutes may be sufficient to gain benefits with respect to brain function.

"The lowest intensity exercise considered in our study was brisk walking, so our study does not inform us about whether `a stroll around the block' would do the trick, but I would guess that elevating heart rate would be important,'' Dr Machado says.

Dr Liana Machado,  of the University of Otago’s Brain Health  Research Centre and Department of Psychology, says regular  moderate physical activity, including brisk walking, offers  benefits for the brain. Photo by Gerard O'Brien
Dr Liana Machado, of the University of Otago’s Brain Health Research Centre and Department of Psychology, says regular moderate physical activity, including brisk walking, offers benefits for the brain. Photo by Gerard O'Brien

"We found evidence suggesting that higher oxygen availability in the brain is one of the cerebrovascular factors that helps support better cognitive performance in people who exercise more regularly, thus providing important insight towards understanding why cognitive performance improves with regular exercise.''

Dr Machado and her research team have found similar links between higher oxygen availability in the brain and better cognitive performance in both studies of older adults and healthy young adults.

"As we age, it is well known that the brain deteriorates in terms of structure and function, and thus it is not particularly surprising that the brains of older adults would benefit from regular engagement in physical activity.''

However, given the development of the brain peaks in young adulthood, Dr Machado says it is "quite surprising'' that there would be room for improvement in brain function in healthy young adults.

Putting aside any issues of cognitive improvements, physiological benefits, or the implications of prescribing exercise more accurately, walking offers other gains, too: a chance to talk, to reflect, both with or without others.

And as one of those women, wrapped up in a raincoat and pondering a sky so leaden it threatened to join the sea, had put it: "Walking is part of life. Everyone can do it''.

"People used to ring me and ask how fit our group was. I'd ask them if they had a pair of shoes. As long as they could put one foot in front of the other ...''

Keeping track

University of Otago researcher Leon Mabire has developed an algorithm he claims is far more accurate at counting calories than some popular fitness devices.

Based on data collected during Mabire's doctoral thesis, his ‘‘Calorie Cost Calculator'' uses age, sex, height and weight to arrive at a personalised prescription for brisk walking.

The calculator uses an equation that can predict how many calories an adult uses during a brisk walk with an accuracy of 94%.

‘‘This means we can calculate the length of time an individual will need to walk to burn 1000 calories, as intended by Ministry of Health guidelines,'' Mabire says.

‘‘We compared my equation with two different devices and found the accuracy of those devices was between 60%-70%.''

That means someone trying to lose weight, relying on such a device, might be expending fewer calories than they think.

‘‘The accuracy of step counts and kilometres travelled etc are fine. The biggest margins of error in such devices is in their calorie counts, and that is key for weight and health.''

The university's intellectual property unit, Otago Innovation Ltd, is looking at potential uses for the algorithm, Mabire says.

It could be licensed to a device manufacturer or, if registered as a low-risk medical device, someone could get a tracker from a GP as a green prescription.

If a wristband device is developed, rather than monitoring activity, it would prescribe it, then count calories until a goal was reached.


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