Sprint workouts not best choice for fitness newcomers: study
A trend that promotes a few extreme, 30-second sprints each day as a path to fitness might be doing more damage than good to people who aren’t seasoned athletes, says research out of B.C. and Sweden.
Robert Boushel, director of the University of British Columbia’s School of Kinesiology and the study’s senior author, says there has been growing interest in fitness training that uses all-out sprint cycling or running intervals for only three minutes a day. It takes high-intensity interval training (HIIT) — which can be effective for a wide variety of people — past its point of usefulness.
“It’s the newcomer to sprints, the explosive bouts for 30 seconds, that we’re cautioning,” Boushel said Wednesday. “Our study raises questions about what the right dose and intensity of exercise for the average person really is.”
The research, published recently by the Federation of American Societies for Experimental Biology, tested 12 healthy Swedish men who described themselves as moderately active. They repeated 30-second all-out sprints followed by rest periods on both regular stationary bicycles and arm-cranked stationary bicycles over two weeks. Researchers took muscle biopsies from their arms and thighs to find out how their bodies reacted at the cellular level.
They found that mitochondria within cells — the biological structure in which metabolism takes place and energy is produced — processed less oxygen after the workouts leading to “oxidative stress.”
That means a reduced ability to combat destructive free radicals within the body, high levels of which are linked to premature aging, organ damage and other ailments. Athletes are able to use sprints to increase their performances because their cells have adapted to increased oxidative stress over years of training.
“We’ve found the molecular mechanism that inhibits your cells,” Boushel says. “You can generate too much stress at the cellular level.” But workouts that take a more measured approach are likely less damaging.
Tara King, founder of HIIT Fitness in downtown Vancouver, runs classes that put participants through a series of 50-second rounds of full-body moves, followed by 15 seconds of rest. Although her classes are short — only 30 minutes long with 20 minutes at a go-hard pace — she says the idea of working for a fraction of that time stretches the imagination.
“Everyone wants to get fit in the shortest amount of time and smallest amount of effort, but that’s not realistic.”