It’s a chilly Saturday morning on Cramond promenade in Edinburgh where dozens of brightly clad joggers are gathered for the weekly parkrun.
The smell of Deep Heat hangs heavy in the air as runners of all ages get in a few final stretches before setting off on a loop along the Firth of Forth.
Their number includes serious types kitted out in expensive running shoes and windcheaters, but there are also older people, families and those who admit they were never particularly drawn to exercise in the past, much less getting out of bed on a weekend for a 5km run.
Since launching in London’s Bushy Park nearly 15 years ago, parkrun has become a global phenomenon.
From humble beginnings, the free initiative in which runners are issued with their own barcode to help record their finishing time has grown to include more than 500 events across the UK and hundreds more worldwide.
To take part, all competitors have to do is register online, print out their barcode and then turn up.
In Scotland, there are 38 parkruns and 13 junior parkruns from Dumfries in the south to Bressay in Shetland in the north, with around 120,000 people known to have joined in at some point.
A study published last week by Glasgow Caledonian University merely confirmed what thousands of parkrunners already knew: taking part is good for both your physical and mental health.
Researchers polled more than 8,000 people who take part and found nearly 90 per cent believe regular running has made them happier and had a positive impact on their mental health and body image.
The runners surveyed scored 4.4 on the Oxford Happiness Questionnaire, a well-established method used by scientists to measure wellbeing, where the average score for the general population is 4.
Cath Murray, 38, from Musselburgh in East Lothian, says she first got into parkrun when her sister (a “parkrun addict”) dragged her along to an event in Portobello, Edinburgh.
“It’s so inclusive – there are adults running with kids; there’s much older people; there are people running with dogs on leads; everyone is at various levels,” she says.
“It’s free but it’s all timed, so you feel as if you’re taking part in a proper race, except you’re running against yourself rather than other people. It’s totally different from just going out for a run on your own; there’s an extra level of motivation.”
Murray, a beginner runner when she began parkrun, is now in training for her first half marathon, which takes place next month.
“I think parkrun has been important. I was never overly into exercise in the past, although I did the odd class and played netball. After having my son, parkrun got me back into keeping fit, running while pushing the buggy. What other sport can you take part in where you can run while pushing a baby in a buggy?”
Parkrun is full of stories of people who came to running relatively late in life and found the experience transformative.
Vikki Brown, 39, admits to being one of those who struggled with motivating herself to go out jogging on her own. After being diagnosed with cystic fibrosis two years ago following a chest infection, she began the Couch to 5k programme, but found it hard to stick with.
“One of the things that’s good for cystic fibrosis and keeping your lungs clear is exercise,” she says.
“I had been doing the Couch to 5k programme for ages, but I was struggling to maintain the motivation to keep pushing myself. So when I did parkrun I managed to do a 5k for the first time ever, albeit very slowly.
“I had never done a particular sport in a dedicated way before. I had always been active, cycling and walking, but I was definitely not a runner or any kind of athlete.
“I went to my first parkrun with a couple of friends and it just meant you had to keep going to the end, rather than giving up and walking.”
Since getting involved in parkrun, Brown has become a keen runner, even taking part in her first 10k at the Great Scottish Run in Glasgow last year.
“I’m not the most motivated morning person in the world, so it’s great to get your weekend started with the feeling of achievement that comes from doing a 5k.
“I would feel a bit pretentious describing myself as a ‘runner’ in any proper running circles, but I’m definitely more of a runner than I ever have been. I go running every week now.”
Parkrun’s extraordinary popularity has even reached behind bars, with a number of prisons now carrying out their own 5ks.
The first such event took place last year at HMP Haverigg, a prison in Cumbria that’s home to 286 inmates. The event, which takes place within the confines of the prison perimeter each Saturday morning, sees both prisoners and staff involved as walkers, runners and volunteer organisers.
The growth of parkrun, and the growing popularity of running more generally, has come at a time of increasing focus on the importance of exercise in tackling obesity, sedentary lifestyles and even mental ill health.
Moderate levels of exercise help release endorphins, hormones which act like a natural antidepressant, bathing the brain in what is sometimes called a “runner’s high”.
The recent research carried out by Glasgow Caledonian University went a step further, setting out to assess the benefits which came from running in a group.
The work was commissioned by Strava, a social network used by runners and cyclists to compare times.
“What seems to be happening is that people who would otherwise not run are drawn to running thanks to initiatives like parkrun and can use Strava as a way of motivating themselves,” says Dr Emmanuelle Tulle, a reader in sociology at the university.
“Whether it’s in a loose association with other runners or a more tight-knit group, it’s up to them. The point is that there is flexibility there in parkrun that enables people who otherwise wouldn’t run, to get going.
“Another thing that came out in the comments was that many people run with their families and that has a strong effect on them; they’re using parkrun as a family event.”
Tulle says the secret to encouraging people to stick with their exercise programme is for them to find an activity they can keep doing over a number of years.
“There is an increasing realisation among clinicians that physical activity is good for people irrespective of age,” she says.
“The trick is to try to get people to pick up an activity and keep it going over a long period of time so that the health benefits, whether physical or psychological, are maintained over time.
“Something like parkrun is a really good example. You can go to try and get a PB [personal best] or just to go around the course the best you can. When you see how well parkruns are attended, you see people are picking up the message about the benefits of exercise.
“The recommendation now is that physical activity should be part of the treatment. Medication on its own is not enough. If people can come off their meds because of running or other activities, then that’s wonderful. Increasingly, physical activity is recommended as at least part of the support that people can use to overcome their mental health difficulties.”
Similar research carried out last year by England Athletics found that running in a group makes 90 per cent of people happier.
In the first major poll of its kind, questioning 13,200 people over 12 months between September 2016 and August 2017, three-quarters of runners said they felt running was good for their overall mental wellbeing.
The poll showed that group runners were more likely to be regular runners (62 per cent) compared with solo runners (51 per cent).
There’s also evidence that those taking part in parkrun are becoming physically fitter – the average time for completing a 5k fell by 28 seconds in 2017 compared with the previous year.
Increasingly, there’s a realisation that less can be more when it comes to exercise. Not everyone is cut out for high-intensity training or running marathons. All the medical evidence shows that for most people, low-intensity exercise such as walking, running or cycling can be enough if done on a regular basis.
In the fad-obsessed world of exercise, the latest buzzword is “Liss”, short for Low intensity steady state, where the heart works at 60 to 80 per cent of its maximum rate.
A recent study published in the medical journal, Aging Cell, showed that not only does exercise help keep us fit as we grow older, but it can also prevent the immune system from declining and protect against infections.
The researchers followed 125 long-distance cyclists, some now in their 80s, and found they had the immune systems of 20-year-olds.
A separate study found people into late middle age can reverse or reduce the risk of heart failure caused by decades of sedentary living by exercising four or five times a week.
The report’s author said exercise needed to be incorporated into people’s daily routines in the same way as brushing their teeth.
Dr Andrew Murray, a consultant in sports medicine at Edinburgh University, has completed challenges including a 4,300km run from Scotland to the Sahara desert, as well as seven ultra-marathons on seven continents in under a week. But he’s a firm believer that most people only need to do moderate levels of exercise to see the health benefits.
“Regular exercise, for example walking, running and cycling, is one of the best things you can do for your health,” he says.
“Getting 20-30 minutes a day will help you live seven years longer and be healthier and happier than if you were a couch potato.
“Regular exercise is also the best present we can give our children, helping improve marks at school and helping with health and happiness.”