June 27 (UPI) -- Performing strenuous exercise, like taking part in a 24-hour ultramarathon, won't permanently hurt a person's heart, new research shows.
High-intensity running puts more strain on the heart and drives up biomarkers that would otherwise indicate cardiac risk, according to a study published in June in Heliyon. However, those elevated biomarkers don't cause permanent damage.
"Experienced runners performed with greater intensity and speed which placed strains on their hearts," Rodrigo Hohl, a researcher at Federal University of Juiz de Fora and study co-lead investigator, said in a news release. "Novice runners ran with less intensity, which resulted in lower cardiac biomarker levels."
The study included 25 people who took blood tests before and after they ran in a 24-hour ultramarathon. Through a five-year period, 11 experienced runners ran roughly 62 miles a week. The remaining runners had participated in at least one marathon but never ran an ultramarathon.
In a 24UM, a competitor sees how far they can run within a 24-hour period.
No one in the group smoked cigarettes, used steroids, or had a history of cardiovascular, metabolic disease or musculoskeletal injury.
The researchers looked at the increase of cardiac biomarkers in experienced and inexperienced runners. Those biomarkers include cortisol, total creatine kinase, C-reactive protein, and leukocyte levels, all of which measure damage inflammation and injury heart tissue, inflammation and blood restriction to the heart.
The findings showed an increase in cortisol in the experienced runners. However, that didn't mean intense running posed a threat to those runners -- although the researchers were cautious not to rule out the danger.
"Our study provides evidence for caution and self-monitoring, especially for experienced runners. After participating in an ultramarathon, runners should recover for at least two days before running any significant distance. This time is needed to normalize cardiac markers and allow the heart time to recover after such a challenge," Hohl said.