High-intensity “sprint training” can do more harm than good if you´re not used to this form of exercise, according to a new study.
Canadian and European researchers found signs of stress in the muscle tissues of non-athlete, untrained subjects after ultra-intense leg and arm cycling exercises. Participants also had a weakened ability to fight off free radicals — molecules that can alter DNA and harm healthy cells.
The study was carried out with a dozen male volunteers in Sweden, all of whom were in good health but self-identified as untrained or only moderately active. Over a period of two weeks the men participated in high-intensity training which involved repeated 30-second all-out sprints, followed by rest periods.
After analysing tissue samples, the researchers found that the subjects´ mitochondria, the powerhouse of cells, were only firing at half-power post-training. This reduced their capacity to consume oxygen and their ability to fight off damage from free radicals, the University of British Columbia reported.
High levels of free radicals in the body have been linked to medical conditions including cancer, premature ageing and organ damage.
“Our study raises questions about what the right dose and intensity of exercise for the average person really is,” commented Robert Boushel, the study´s senior author and director of the University of British Columbia´s School of Kinesiology. “We need to be cautious about supporting sprint training in the general population.”
Athletes and those who are well trained have built up antioxidant enzymes in their bodies to protect against free radicals, Boushel explained. He recommends that beginners start slowly and gradually increase intensity over time, under the supervision of a trained professional or kinesiologist.
“If you´re new to going to the gym, participating in high-intensity ‘sprint´ classes may increase your performance but might not be healthy for you,” he said.
The potential long-term adverse effects of high-intensity sprint training are not yet known, but the researchers are continuing to study different levels of exercise, measuring these against various biomarkers for health.
The findings have been published in the FASEB Journal, the official journal of the Federation of American Societies for Experimental Biology.