A lack of free time is no longer a viable excuse for avoiding exercise, according to a new study in The Journal of Physiology.

Researchers studying interval training have found that it not only takes less time than what is typically recommended, but the regimen does not have to be overly intense to be effective in helping reduce the risk of such diseases at Type 2 diabetes.

The study adds to a growing body of research that has zeroed in on this particular style of exercise in which a person trains hard but for less time.

"What we've been able to show is that interval training does not have to be 'all out' in order to be effective and time-efficient," says Martin Gibala, professor and chair of the Department of Kinesiology at McMaster University. "While still a very demanding form of training, the exercise might be more achievable by the general public—not just elite athletes—and it certainly doesn't require the use of specialized laboratory equipment."

The new study involved eight to 12 one-minute bouts of exercise on a standard stationary bicycle at a relatively lower intensity with rest intervals of 75 seconds, for a total of 20-25 minutes per session. The workload was still above most people's comfort zone —about 95% of maximal heart rate — but only about half of what can be achieved when people sprint at an all-out pace.

"That is the trade-off for the relatively lower intensity," says Gibala. "There is no free lunch; duration must increase as intensity decreases."

Subjects used in the study performed six training sessions over 14 days. After the two week training period, the subjects showed the same benefits that Gibala's team has previously observed after traditional, long-duration endurance training: improved exercise performance and
muscular adaptations that are linked to reduced risk of diseases such as Type 2 diabetes.

et al., 'A practical model of low-volume high-intensity interval training induces mitochondrial
biogenesis in human skeletal muscle: potential mechanisms, Journal of Physiology, March 2010; doi: 10.1113/jphysiol.2009.181743