Forget the much-touted seven-minute high-intensity interval workout. Researchers now say that overweight, inactive men can get fitter and healthier with just four minutes of vigorous high-intensity training three times per week.
The study from the Norwegian University of Science and Technology finds that only four minutes of sweat-inducing exercise can improve maximal oxygen uptake (VO2max), a well-established measure of physical fitness. Three short high-intensity sessions per week can make a substantial difference in the fitness of inactive men, the researchers said.
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Head researcher Arnt Erik Tjønna and his team measured changes in VO2max and traditional cardiovascular risk factors in 24 inactive, overweight men after they completed a 10-week training session that involved three weekly high-intensity interval sessions.
One group of 13 followed a protocol that has previously shown to be effective, known as 4x4 training, consisting of four intervals of four minutes of high intensity exercise at 90 percent of maximal heart rate interspersed with three minutes of active recovery at 70 percent maximal heart rate.
The other group followed a protocol that consisted of one four-minute interval at 90 percent of maximal heart rate. After training, VO2max increased by 10 percent in the group that had just one high-intensity session three times a week. The group that followed the 4x4 regime increased its VO2max by 13 percent. Both groups saw decreases in their blood pressure, but the group that followed the one four-minute interval high-intensity session showed greater decreases in blood pressurethan their 4x4 training counterparts for both systolic and diastolic readings.
"It has to be noted that the subjects were previously inactive, and the same effect on physical fitness cannot be expected in active individuals," Tjønna said. "Nevertheless, since we know that more and more people are inactive and overweight, the kind of improvement in physical fitness that we saw in this study may provide a real boost for inactive people who are struggling to find the motivation to exercise."