Runners pass the first kilometre mark of the National Capital Marathon in Ottawa. (Jonathan Hayward/Canadian Press)

It is safe to run, right?

The death of a runner during a half-marathon in Toronto in September 2006 was the third in as many years in the city. It made headline news in an event that usually highlights personal achievement and physical fitness. "Runner dies in marathon," read one headline after a 41-year-old man died at the latter end of a 21.1-kilometre race that more than 4,400 people completed.

We are told that we should get fit, that about a quarter of our population is considered obese and that — along with eating better — physical activity should be incorporated into our daily lives.

As a form of exercise, running has become popular among adults in their 30s and beyond. Running shoes are relatively cheap, the empty roads and trails are plentiful and the race calendar is full of events in every major city. Toronto, Ottawa, Vancouver, Calgary, Montreal and other centres host marathons, which are 42.2 kilometres in length. Most races also offer half-marathon distances.

Thousands of Canadians are heeding the call to fitness and heading to gym treadmills or outside with their running shoes, but the question arises — can exercise and running be dangerous? How can you do it safely?

It is safe to run

John Stanton, founder of the Running Room retail stores, is an ambassador for the sport and holds clinics at his stores. "The tragedy is when a [death] like this occurs at a race, often people ask 'Why should I run?' when in fact in most cases if you talk to a physician they are saying, 'No, running will prevent such incidences in the long run.' "

The University of Toronto's Jack Goodman, who has studied deaths among marathoners, says people face a greater risk dying of inactivity while watching television than while exercising. "I should also say that deaths during marathons are very rare," he said. "They occur at about one per 100,000. On balance, people who are physically active have less of a risk of chronic disease."

Watch for the signs

Alan Brookes, the race director of the Scotiabank Toronto Waterfront Marathon, where the participant died, said race officials ensure that medical assistance is always quickly at hand. "Everything that could be done was done," he said.

"We make every effort to take every precaution, but I think individual fitness really remains the responsibility of individual participants."

Goodman notes that runners should look for early warning signs, such as shortness of breath, nausea, chest pain and fatigue. But he says there is a danger that people may simply attribute those symptoms as the result of training for long distances. So the best defence is to get medical advice.

See a physician

"The big thing when you're starting off is to make sure you assess your physical readiness," Stanton said. A marathon takes time to run. In the United States last year, the average finishing time for the race was four hours and 45 minutes.

When was your last physical? Before starting an exercise program, you should find out whether your family has a history of heart disease. A physician can put you through an exercise stress test to see if there will be any adverse effects from putting your body through strenuous exercise.

Goodman said any men who are over the age of 45 and women older than 55 should get medical clearance to exercise if they have not been active.

"If you look at the average age of the entrants, they are older than they are younger," Goodman said. "They are going to be in a more risky category." In the United States, the median age of a marathoner was 38.7 in 2005.

"But running itself is not a risk factor for having a coronary event," he said, adding that vigorous exercise such as racing can act as a "trigger" for someone with undetected coronary disease. And the first symptom can often be sudden death.

Stanton recommends people take a simple physical activity readiness questionnaire, available here. One negative answer and you should visit your doctor.

Train smartly

Experts recommend that runners follow a training program. Typical training programs are at least four months long for people who are already running. Those who are new to running should work up to a regular running routine before even starting training.

Stanton advises beginners to adopt a run-and-walk system, typically starting with 10 minutes of running followed by one minute of walking. This puts less stress on your body and allows your body to recover from vigorous exercise.

"I say be gentle," Stanton said. Many running programs that ease people into running long distances add no more than 10 per cent of the total distance per week. So, if you run 10 kilometres one week, you should add up to one kilometre the next week.

Most people who run in road races are recreational athletes, Goodman said. And they typically have trained for long runs, though not as high in intensity as on race day. "They are not stepping in on race day and racing substantially faster."

Here are some other tips:

Get rest

You can't go all out all the time, Stanton says. His run-and-walk program takes into consideration that other athletes always have rest periods to recover and get stronger. He notes that other sports, like weightlifting or sprinting, incorporate periods of rest between hard effort. Running, he said, should use the same principle.

Watch your diet

Stanton recommends drinking enough water (between eight and 10 glasses of water), eating wholesome foods and avoiding fatty foods. He says healthy runners will naturally gravitate toward eating healthier meals.

Listen to your body

The heart is a muscle, and when you are doing aerobic exercises, your heart is typically beating at between 65 per cent and 85 per cent of your maximum heart rate. The common method to find your maximum heart rate is to subtract your age from the number 220. Stanton recommends runners keep their heart at between 50 and 70 per cent and race at 80 per cent. Many runners train with heart rate monitors that can track such use. Many runners race too fast, Stanton warns, and can feel the effects later in the race. Another trick many runners use is the talk test — if you're too out of breath to hold a conversation, you're overexerting yourself.

Continue running

"Sometimes the death of a runner at any venue is sort of shocking, yet the death of someone watching TV never garners the same attention," said Stanton. "We should never be afraid to exercise. I still encourage people to get active and listen to their bodies."