High-intensity interval training

"The concept of “high-intensity interval training, ” or HIIT , is relatively new and quite different from the old-school approach to intervals that most of us remember from high school track. With HIT , you don’t intersperse interval sessions on one day with longer workouts on others.You only do intervals, day after day , finishing the hard work in a matter of minutes. “There was a time when the scientific literature suggested that the only way to achieve endurance was through endurance-type activities, ” such as long, relatively easy runs or bike rides or , perhaps,six-hour swims, says Martin Gibala, Ph.D., a professor at McMaster University in Canada, who’s been at the fore front of HIIT science.
But ongoing research from Dr . Gibala’s lab proves otherwise. In one study (which was the most e-mailed document on the website of the Journal of Applied Physiology for almost two years), Dr . Gibala and his colleagues had a group of healthy college students ride a stationary bike at a sustainable pace for between 90 and 120 minutes. Another set of students grunted through a series of short, strenuous intervals: 20 to 30 seconds of cycling at the highest intensity the riders could stand. “We describe it as an ‘all -out’ effort, ” Dr . Gibala says, which requires straying “well out of your comfort zone. ” After resting for 4 minutes, the students pedaled hard again for another 20 to 30 seconds, repeating the cycle 4 to 6 times (depending on how much each person could stand), “for a total of two to three minutes of very intense exercise per training session,” Dr. Gibala says.
Each of the two groups exercised three times a week. After two weeks, both groups showed almost identical increases in their endurance (as measured in a stationary bicycle time trial ), even though the one group had exercised for six to nine minutes per week, and the other for about five hours each week. Both groups, in biopsies, showed dramatic molecular changes deep within their muscle cells indicating increased physical fitness. In particular , they had far more mitochondria now, the microscopic organelles that allow muscles to use oxygen to create energy . Six minutes or so a week of hard exercise (plus the time spent warming up, cooling down, and resting between the bouts of intense work) had proven to be as good as about 300 minutes of less strenuous exercise for achieving basic fitness.
Sadly, those six minutes had to hurt."