Jun 27, 2013

    Short, intense workout sessions have their perks

    AT THE recent annual meeting of the American College of Sports Medicine, one of the hottest topics was not how much exercise one should be doing, but how little.

    Dozens of presentations and seminars examining a variety of activities concluded, essentially, that a few minutes of any strenuous exercise is sufficient to improve various measures of health and fitness.

    "People have forever been trying to figure out what the right amount of exercise is," said Dr Paul Thompson, a cardiologist at Hartford Hospital in Connecticut, who has long studied exercise.

    In the past, formal recommendations have called for a substantial amount of regular exercise. For example, published guidelines from the Health and Human Services Department in 2008 suggested 150 minutes of moderate exercise per week - the equivalent of five 30-minute walks. The guidelines added that 75 minutes of vigorous exercise a week, like jogging, were an alternative.

    But in practical terms, the guidelines have not been a success. That, in turn, has resulted in the rise of interest in very brief, high-intensity interval training.

    This approach to exercise started to take off in 2006, when physiologist Martin Gibala, of McMaster University in Ontario, and his colleagues published a study showing that a three-minute sequence on an electronic stationary bicycle - 30 seconds of punishing, all-out pedalling, followed by a brief rest, repeated five or six times - led to the same muscle-cell adaptations as 90-120 minutes of prolonged bike riding.

    Other studies have shown that 16-30 minutes per week of highly intense exercise improves certain markers of health, with volunteers developing improved blood pressure and blood-sugar levels after several weeks of these truncated workouts.

    Dr Thompson said "150 minutes of moderate exercise each week is clearly associated with improved health outcomes", including longevity and reduced risk of many diseases. What we don't know, he added, is whether that will be the case if people rely solely on a few minutes of intense exercise a week.

    In particular, it is unclear whether short, hard workouts can help people maintain their weight. Weight maintenance means burning more calories than one consumes, Dr Thompson said, and "these short sessions do not result in much energy expenditure".

    They also do not help much in building muscle, and short, intense exercise "does not seem to stimulate the hypertrophic physiological pathways" that result in larger, stronger muscles, he added.

    What the new, abbreviated approach to exercise has going for it is brevity. In a 2011 study, eight male recreational runners in Britain reported preferring a workout of six three-minute intervals to one involving an easy 50-minute jog, because the interval session was over sooner.

    For now, if you'd like to try a high-intensity session, visit a doctor for clearance first, then simply push yourself very hard during your next workout, be it running, cycling or Zumba, said Dr Gibala.

    He said that a minute of hard effort, followed by a minute of gentle recovery, is effective.

    Complete 10 such intervals three times a week, for a total of 30 minutes of strenuous effort, and "our data indicates you'd be in pretty good shape", he added.