In an article for Sports Illustrated in December 1960, president-elect John F. Kennedy lamented the state of the nation's fitness. As president, he urged people to try 50-mile hikes.
As we can see, that message did not resonate with most Americans or indeed for many in the fatter, more sedentary West. And these days, most get no planned exercise.
So at a recent meeting of the American College of Sports Medicine in Indianapolis, one of the hottest topics was not how much exercise people should do, but how little.
Dozens of presentations examining a variety of activities concluded, essentially, that a few minutes of any strenuous exercise is sufficient to improve health and fitness.
But experts say there are still questions about the long-term effects and efficacy of the wildly shrinking doses of exercise being studied and promoted by scientists.
Guidelines from the US Health and Human Services Department in 2008 recommended 150 minutes of moderate exercise per week - the equivalent of five 30-minute walks. They said 75 minutes of vigorous exercise a week, such as jogging, could be substituted.
The guidelines were based on a large body of science showing 150 minutes of moderate exercise was associated with a longer life span and a reduced risk of heart disease, diabetes and other illnesses.
But in practical terms, the guidelines have not been a success. At least 80 per cent of Americans don't meet the recommendations. That has led to the quest to find a smaller amount of exercise that will produce health and fitness benefits.
In 2006 Martin Gibala, a physiologist at McMaster University in Ontario, published a study showing a three-minute sequence on an electronic stationary bicycle - 30 seconds of punishing pedalling followed by a brief rest, repeated five or six times - led to the same muscle-cell adaptations as 90 minutes to 120 minutes of prolonged cycling.
The study, in The Journal of Physiology, soared to the top of its ''most emailed'' list.
Since then scientists have been studying the effects of brief bouts of intense exercise.
Recent research suggests a few minutes per week of strenuous exercise can improve aerobic fitness, generally more quickly than moderate activity. Norwegian scientists found three four-minute runs a week - at a pace equal to 90 per cent of a person's maximal heart rate, an intensity that will feel, frankly, unpleasant - improved volunteers' endurance capacity by about 10 per cent after 10 weeks. Other studies show 16 minutes to 30 minutes a week of intense exercise improves blood pressure and blood sugar levels.
But all the studies have been small.
Dr Paul Thompson, a cardiologist at Hartford Hospital in Connecticut, says
it is known from ''some very good'' epidemiological studies ''that 150 minutes of moderate exercise each week is clearly associated with improved health'' including longevity and reduced risk of disease. What we don't know, he says, is whether that will be the case if people rely solely on a few minutes of intense exercise a week. It's unclear whether short, hard workouts can help with weight maintenance, which requires burning more calories than consumed.
''These short sessions do not result in much energy expenditure,'' Thompson says. Nor do they aid much in building muscle. But the advantage of this approach is brevity. In a 2011 study, eight male recreational runners in Britain reported preferring a workout of six three-minute intervals to an easy 50-minute jog, because the interval session was soon over.
For now, Gibala says, if you'd like to try a high-intensity session, visit a doctor for clearance, then push yourself very hard during your next workout.
He says in his experience, 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 would indicate you'll be in pretty good shape''.
New York Times