The amazing news, buried in this New York Times piece on the growing popularity of interval training, reports that a 2005 study published in the Journal of Applied Physiology found that
after just two weeks of interval training, six of the eight college-age
men and women doubled their endurance, or the amount of time they could
ride a bicycle at moderate intensity before exhaustion. The Times reports that doing bursts of hard exercise not only improves cardiovascular fitness,
but also the body’s ability to burn fat, even during low- or
moderate-intensity workouts. It one set of experiments eight women in their early 20s cycled for 10 sets of four minutes
of hard riding, followed by two minutes of rest. Over two weeks, they
completed seven interval workouts. Researchers found that after interval training, the
amount of fat burned in an hour of continuous moderate cycling
increased by 36 percent.
Cardiovascular fitness  the ability of the heart and lungs to supply
oxygen to working muscles  improved by 13 percent.
Health, fitness and lifestyle tips for people over 50 who still like to play hard
Saturday, May 31, 2025
Fit people seldom need to burn an additional 36% of their body fat while doing a like amount of work. What’s more, their body’s use of oxygen becomes more efficient as they become fitter, so that the 13% “improvement” must mean that they are either a) working harder or b) able to work longer … neither is a sign of “low- or moderate-intensity workouts”.
The interval training might better be described as “allowing you to do more, longer, with a similar amount of apparent exertion”. Which is excellent news for those of us for whom fitness is our limiting factor.
DLMeyer – the Voice of G.L.Horton’s Stage Page Pod Cast
the 36% extra fat referred to is not a percentage of bodyfat, it is opposed to the carbs they would have otherwise metabolised to power their exercise, and the fitter a person is, the greater their ability to metabolise fat as energy during exercise.
at moderate or low intensity exercise the 13% improvement would have shown as a reduction in the HR, VO flow etc required to maintain the exercise rate.
I understand both of your ‘objections’, and they are each a) correct statements and b) may not be correct regarding what I said.
Being able to burn an additional 36% (rate) of burning your body fat – calories, not carbs – does not happen at low or moderate exercise levels.
Being able to operate with a 13% reduction in ventilation … OK, I could have said that better and will have to give you that one.
The point of the article – that interval training offers significant fitness benefits beyond what is seen with non-interval training – is certainly correct and it was not my intention to argue that point.
DLMeyer