Can one-minute of intense exercise do the job?

A new study from the University of McMaster finds that 10 minutes of sprint interval training (SIT), involving a total of just one minute of intense exercise, produces the same fitness results as a moderate intensity workout 50 minutes in length.

The study involved 25 men all classified as sedentary by an international physical activity questionnaire who engaged in a 12 week program of 3 exercise sessions per week on stationary bicycles. Nine of the participants followed an SIT program involving three intervals of 20-second bursts of “all-out” cycling interspersed with two minutes intervals of low intensity cycling plus a three minute cool-down. Ten other participants followed a moderate intensity continuous training (MICT) program of 45 minutes of continuous cycling bookended by a two minute warm-up and three minute cool down. A third group of six participants served as the control group and did no training.

After 12 weeks, the SIT group showed marked improvements in three key markers for physical fitness: a 19 per cent increase in peak oxygen uptake (a key marker for cardiorespiratory fitness) and significant increases in both insulin sensitivity and skeletal muscle mitochondrial content.

Remarkably, the results on all three markers for the moderate training MICT group turned out to be similar to those of the SIT group.

“This investigation represents the longest comparison of SIT and MICT to date and demonstrates the efficacy of brief, intense exercise to improve indices of cardiometabolic health,” say the study’s authors.

For decades, SIT (also known as high intensity interval training or HIIT) has been used by athletes to get into peak shape, but for us mere mortals possessing either moderate or even low physical fitness, the belief has long been that such training would prove too stressful on the body and potentially dangerous to the heart. Recent work has shown, however, that done correctly, SIT exercising can be adapted to people of almost any level of fitness. Add to this the fact that people consistently report a lack of time as a prime reason why they do not engage in physical activity and SIT becomes very appealing.

“Our study shows that an interval-based approach can be more efficient -you can get health and fitness benefits comparable to the traditional approach, in less time,” says Martin Gibala, professor of kinesiology at McMaster and lead author of the study.

Another recent study showed that HIIT exercise combined with electro-stimulation produces up to 30 per cent higher consumption of calories than conventional aerobic exercise and also increases the metabolism rate for several days following a workout (during which the body continues to burn calories) – a result not obtained via conventional aerobic exercise.

Often used as a rehabilitation tool or for pain management, electrical muscle stimulation or EMS involves the use of electrodes attached to the skin to produce muscle contractions similar to those created by the body’s own nervous system. Researchers found that the HIIT workout combined with EMS produced higher levels of lactate concentration in the blood than from aerobic exercise and that basal oxygen consumption – an indicator of metabolism rate – over the three days following the HIIT workout were notably higher than those recorded after aerobic exercise.

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