Antidote to Guilt About Not Doing Enough Exercise Is a HIT
That may no longer have to be the case. A Canadian university study concludes that short-term, high-intensity (HIT) interval training works as well as more moderate, longer-term exercise to achieve aerobic goals. In short, say researchers at McMaster University in Hamilton, Ontario, exercisers can even achieve as much, if not more, with far less expenditure of time.
For example, thrice-weekly sessions of only 10 one-minute sprints on a stationary bicycle, with one-minute rests in between, works as well at toning and building muscle mass as 10 hours of moderate road biking over a two-week period.
The key element in HIT, as it is in all interval training, is to alternate short bursts of intense effort with short recovery periods. The intense efforts are not all out, but do push the heart and muscles to work at a high percentage of their maximum ability. The body adjusts to the effort by increasing the number of blood vessels that supply muscles and raising the number of mitochondria-the "powerhouses of the cell"-in them. In a short time, the body is able to quickly return to a lower respiration and heart beat.
Muscles built up by endurance training more efficiently metabolize glucose and are less resistant to insulin-two key factors in preventing the onset of diabetes.
In previous tests with young students, the researchers had tested the difference between standard long-term endurance training, such as regular bike rides, and "all-out" exercises on special stationary bicycles where subjects expended maximum effort.
The switch to HIT, which demanded less effort, turned out to deliver results as effective as those gained from longer-term exercise. It also turned out to be an attractive alternative for time-stressed older, unfit, slightly overweight people who are not suited to all-out exercises.
A next step in research on HIT's usefulness will be to see its effects on people who are overweight or have diabetes.
The McMaster University team published its findings in the April 1, 2010, online edition of The Journal of Physiology.
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