AILSA CHANG, HOST:
So when is the last time you did some form of high-intensity exercise? I'm talking about short bursts of effort that leave you breathless, like sprinting. Well, new research suggests that there may be something special about this kind of exercise. NPR health correspondent Will Stone reports.
WILL STONE, BYLINE: We all know a sprint feels different than a longer, take-it-slow kind of workout. Your heart is pounding. You gasp for air. Maybe your muscles burn. But it turns out even your blood behaves differently, as Dr. Paul Cohen saw when he drenched human fat cells with blood in a petri dish in his lab at Rockefeller University.
PAUL COHEN: And we saw far greater changes in the fat cells that had been exposed to sprint interval training.
STONE: For example, these included many genes involved in fat and whole-body metabolism. Now, this was just one experiment in a larger study published in the journal Cell Reports Medicine. Cohen and his partners analyze blood samples for thousands of proteins and molecules from two groups of people. The sprinters did a 30-second maximum push on the bike a total of six times, each spaced with a four-minute rest. The others spent 90 minutes on the bike at a moderate pace. It was striking, he says. The sprinters had a much more robust response in their blood.
COHEN: What we can conclude from that is that sprint interval training has a greater effect on remodeling the molecules in the blood.
STONE: Exactly what those changes mean is the subject for a future study. But they do have some clues because they compared their results to a database of 50,000 people. The proteins that were altered in the sprinters were associated with improved cardiovascular and metabolic health. Cohen emphasizes this does not prove that sprinting is better, though the hope one day is to give targeted advice for each person.
COHEN: This is just the first step towards providing those kinds of recommendations.
STONE: This work reflects a broader effort to unpack all the ways molecules in muscles, the liver and other organs respond to exercise, including different intensities. Scott Trappe directs the Human Performance Lab at Ball State University.
SCOTT TRAPPE: All these organs are communicating. It's like a superhighway, and the circulation is that highway.
STONE: He says this new research is impressive and underscores the value of high-intensity interval training, or HIIT.
HUMAN PERFORMANCE LAB DIRECTOR, BALL STATE UNIVERSITY: These data are clearly showing that there are some potential benefits you're leaving on the table if you don't do the high-intensity.
STONE: Now, there are caveats with the study. The biggest is that it was done with a small number of healthy and fit young adults, mostly men. Todd Astorino is an exercise physiologist at California State University, San Marcos.
TODD ASTORINO: They did six 30-second sprints. That takes approximately 30 minutes. That is an extremely exhaustive protocol.
STONE: Meaning it may not be realistic for the average person. Astorino has studied high-intensity interval training for almost two decades. He says, overall, the data from human studies suggest it's largely comparable to moderate steady-state training when you look at measures of fitness. The upside is you can get a lot of return for your effort in a short amount of time.
ASTORINO: Sometimes people maybe worry too, too much about time, their frequency. And they don't understand, yeah, you probably don't, like, have to worry about those things as much. What you should be focusing on is intensity.
STONE: His advice is, first, do the exercise you like so you actually do it. And if you're up for a challenge, push yourself to do a few rounds of high-intensity work.
Will Stone, NPR News.
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