Extreme Exercise Could Lead to Blood Poisoning
Extreme endurance events like ultra-marathons and Ironman triathlons seem to be growing in popularity, but new research suggests this type of exertion could potentially have some serious health consequences for participants.
Extreme exercise can cause intestinal bacteria to leak into the bloodstream and lead to blood poisoning, according to a new study.
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“Prolonged running with and without heat stress resulted in endotoxemia and cytokinemia in healthy trained ultra-endurance athletes,” according to lead investigator Ricardo Costa, PhD, RD, a lecturer and researcher in the Department of Nutrition and Dietetics at Monash University, in Notting Hill, Australia.
“We can only speculate on what would happen if untrained and unfit individuals were to push their bodies beyond their capacity,” he says.
Costa and his colleagues looked at the circulatory endotoxin concentration, cytokine profile, and gastrointestinal symptoms of 17 ultra-endurance runners in response to a 24-hour continuous ultra-marathon competition. The total distance ranged from 122–208 km, and the event was conducted in temperate ambient conditions in mountainous terrain.
The researchers also took venous blood samples before and immediately after the events and compared them with a control group. An analysis of these samples showed endurance exercise caused changes to the gut wall, allowing endotoxins (naturally present bacteria in the gut) to leak into the bloodstream.
Essentially, “blood flow moves into the working muscles and away from the gut, creating damage and increasing intestinal permeability,” Costa explains.
The endotoxins trigger a systemic inflammatory response from the body’s immune cells. In extreme cases, this could lead to sepsis-induced systemic inflammatory response syndrome, which can be fatal without prompt diagnosis and treatment.
However, individuals who were fitter and trained over a longer period of time prior to the ultra-marathon had higher levels of an anti-inflammatory agent known as interleukin 10, which enabled their bodies to counteract this process and reduce the negative health impact.
“The body adapts by enhancing endotoxin antibody neutralizing factors and anti-inflammatory cytokine responses,” Costa says.
He recommends that individuals who want to participate in extreme endurance events prepare by first consulting a medical professional and then developing a suitable training and nutrition program.
“Start your preparation well in advance of the competition and build—don’t attempt an ultra-marathon at first go,” he says. “Consult a qualified and registered sports dietitian for nutritional advice, and get a health and fitness check throughout your training cycle leading up to the ultra competition.”
Costa and his colleagues plan to conduct further research in this area to gain a better understanding of the degree to which exercise—with and without heat—impacts gut integrity and function. The team also hopes to develop strategies to prevent and manage gut damage and symptoms caused by exercise and heat stress.
“My research team and collaborators are currently researching prevention and management strategies, which I can’t highlight at this time, but our preliminary data is very promising,” Costa says.
—Colleen Mullarkey
Reference
Gill SK, Hankey J, Wright A, Marczak S, Hemming K, Allerton DM, et al. The impact of a 24-h ultra-marathon on circulatory endotoxin and cytokine profile. Int J Sports Med. 5 May 2015. [Epub ahead of print]. doi: 10.1055/s-0034-1398535.