According to a new challenging study, the best exercise for many of us may not be the shortest, comparing the health benefits of training at short and intense intervals with those of longer and gentler training.
The study, published in Medicine and science in sports and exercise, concludes that each exercise approach has its advantages, but that the effects on blood pressure, body fat and other aspects of metabolism may be greater after standard training, half an hour and moderate, than fast interval workouts.
As we know those of us who follow fitness, high intensity training or HIIT (High Intensity Interval Training), is seductive, fashionable and a common topic of this column, as well as the science of exercise.
HIIT, a mixture of extremely short periods of intense exercise Followed by a minute or two of rest, it is fast and strong, and studies show that a few minutes – or even seconds – of interval training can improve people’s health and longevity over time.
But there are still many unanswered questions about the relative advantages of fast intervals over more traditional sustained aerobic workouts, such as full speed, running or cyclingEspecially if someone only engages in one type of exercise and not the other.
Frequent moderate exercise is linked to improved blood pressure and glucose control. Photos Shutterstock.
Recently, scientists at the University of Guelph in Ontario have begun to study how people’s bodies change whether they train exclusively with intervals or standard and moderate training, following current guidelines.
Interestingly, many previous studies comparing short HIIT routines and longer moderate workouts did not follow formal exercise recommendations because scientists wanted to match the frequency of workouts or other measures. Thus, the volunteers in these studies used to exercise three times a week, either completing a few minutes of HIIT or half an hour of walking.
But the guidelines for each type of activity differ. Medical and sports groups suggest that we do not train at intervals more than three times a week to avoid muscle overload and cardiovascular systems, which means that if we exercise only with HIIT, we will be inactive four days a week or so. Comparable guidelines for moderate exercise suggest going out and moving at least five times a week and at least 30 minutes each time.
So Guelph scientists thought: what if people do HIIT three days a week and don’t exercise the other four or train moderately five times a week?
To find out, they first recruited 23 sedentary and overweight adult men. They did not include women out of concern that menstrual cycles would affect metabolic outcomes, but hoped to include women in a larger future experiment.
They invited these men to the lab, measured their physical capacity, body composition and blood pressure, and asked them to drink shakes loaded with high amounts of fat to see how their metabolism reacted to nutrients. They also equipped them with blood sugar monitors to take home for a week to measure their daily blood sugar control, a measure of metabolic health.
Then they asked half of the men to start training three times a week on stationary bikes in the lab, pedaling as hard as possible for 30 seconds, resting for two minutes and repeating that sequence four to six times.
The other men began a typical moderate exercise program, cycling in the lab five times a week at a pace they could keep comfortable. for 30 to 40 minutes.
Over the next six weeks, the HIIT group cycled vigorously for a total of less than one hour, while the moderate intensity group exercised for at least 2.5 hours each week for the same period.
At the end of the six weeks, both groups returned to the laboratory for further testing, after which the scientists examined the results for disparities. They found a lot.
Differences
Almost all the men were fitter and more or less the same, no matter what exercise they did. But only those in the moderate exercise group had shed a lot of fat body, improved their blood pressure or were able to better metabolize the extra fat in the smoothie.
Perhaps the most interesting thing is that everyone’s blood sugar control at home was better only on the days they exercised, ie three times a week for those who did HIIT and five times a week for the moderate group. The rest of the day, blood sugar levels tended to rise.
Taken together, the results indicate that traditional intervals and exercise change our bodies in divergent ways and we may want to consider what we hope to achieve with exercise when choosing the best way to do this, says Jamie Burr , professor at the University of Guelph. , who conducted the new study with her graduate student Heather Petrick and other colleagues.
“All exercises are good”Said Burr. But “there are nuances.” Frequent exercise, almost daily, may be preferable for improving blood pressure and continuous control of blood sugar compared to rare intervals, he says, while a little HIIT will get you in shape as efficiently as hours and easier pedaling hours or similar effort.
Of course, this study was small-scale and short-term, and only overweight and overweight men participated in it, so we cannot be sure that the results apply to the rest of the population. But the main lesson seems to be widely applicable.
“Move often,” Burr said, meaning if you do HIIT today, you’ll go tomorrow.
By Gretchen Reynolds © The New York Times