Monash University’s Ricardo Costa studies the link between extreme exercise and blood poisoning. Photo: Eddie Jim
Extreme endurance exercise such as ultra-marathons can lead to blood poisoning, according to Australian research.
The Monash University studies, the first in the world to look at the physiological demands of endurance exercise, compared a five-day Spanish ultra-marathon competition in extreme heat with a Scottish 24-hour ultra-marathon in more temperate conditions.
Research leader and former professional athlete Ricardo Costa said blood samples taken before and after exercise indicated that as the races progressed, blood poisoning worsened and the body’s defensive response gradually increased.
This was caused by changes to the gut wall allowing bacteria in the gut to leak into the bloodstream.
“Normally when somebody stops exercising, everything comes back to baseline and recovers within the next 24 hours,” Dr Costa said. “But in this situation we saw that athletes were just getting worse and worse.”
Dr Costa said current literature focused only on the dangers of exercise and heat.
“It’s not just heat. Just the exercise itself if you do it for long enough – it will create the same gut disturbance and will cause the bacterial leaking into the blood,” he said.
Blood poisoning can be fatal if not quickly diagnosed and treated with intravenous antibiotics.
But Dr Costa said ultra-marathon runners rarely died as a result of competing in such races because being fit and following a gradual training program enabled them to develop stronger immune systems.
However, the number of fatalities could increase as endurance events become more popular with recreational athletes, he said.
“If a race organiser just wants to get numbers into the race and has an open entry, you get people that want to challenge themselves without appropriate training,” Dr Costa said. “It’s then very likely that we are going to have some health issues and fatal outcomes.”
He said there was an increased risk of developing longer-term chronic diseases, while deaths were seen in situations where people with more sedentary lifestyles overexerted themselves. He cited mining, the military and farming as examples.
According to The Australian Sepsis Network, each year more than 3000 people die from blood poisoning in Australia. There are 15,700 new cases a year, with an estimated cost of $39,300 per episode.
Dr Costa’s advice to would-be ultra-marathon runners is to slowly build to endurance events and train properly.
“Start training a year in advance and increase duration and intensity in your training as you get closer to the race,” he said.
“If you’re not trained to do these distances, you’re looking for trouble.”
The Monash University studies are published in journals The International Journal of Sports Medicine and Exercise Immunology Review.