The other men started a typical moderate exercise program, riding their bikes through the lab five times a week at a pace they could comfortably sustain for 30 to 40 minutes.
Over the next six weeks, the HIIT group pedaled intensively for a grand total of less than an hour, while the moderate intensity group trained for at least 2.5 hours a week during the same period.
At the end of the six weeks, the two groups returned to the laboratory for a new test, after which the scientists examined their results for disparities. They found many.
Almost all men were more fit and almost the same, regardless of how they had exercised. But only those in the moderate exercise group lost a lot of body fat, improved their blood pressure, or became better able to metabolize the extra fat from the unctuous shake.
Perhaps most interestingly, everyone’s blood sugar control at home was best only on the days they exercised, that is, three times a week for HIIT runners and five for the moderate group. In the remaining days, blood sugar levels tended to increase.
Taken as a whole, the results indicate that traditional intervals and exercises alter our bodies in divergent ways, and we can consider what we hope to achieve with exercise when choosing the best way to exercise, says Jamie Burr, professor at the University of Guelph , who conducted the new study with his student Heather Petrick and other colleagues.
“All exercises are good,” says Dr. Burr. But “there are nuances”. Frequent, almost daily, moderate exercise may be preferable to improving blood pressure and continuous blood sugar control, compared to infrequent intervals, he says, while a little HIIT will likely get you as effective as hours and hours of easier cycling or similar effort.
Of course, this study was small-scale and short-term and involved only overweight and out-of-shape men, so we cannot be sure that the results apply to the rest of us. But the main lesson seems broadly applicable. “Move often,” says Dr. Burr, which means that if you HIIT today, walk tomorrow and repeat.