How 1-Minute Intervals Can Improve Your Health

While many of us wonder just how much exercise we really need in order to gain health and fitness, a group of scientists in Canada are turning that issue on its head and asking, how little exercise do we need?
The emerging and engaging answer appears to be, a lot less than most of us think — provided we’re willing to work a bit.
In proof of that idea, researchers at McMaster University in Hamilton, Ontario, recently gathered several groups of volunteers. One consisted of sedentary but generally healthy middle-aged men and women. Another was composed of middle-aged and older patients who’d been diagnosed with cardiovascular disease.
The researchers tested each volunteer’s maximum heart rate and peak power output on a stationary bicycle. In both groups, the peaks were not, frankly, very high; all of the volunteers were out of shape and, in the case of the cardiac patients, unwell. But they gamely agreed to undertake a newly devised program of cycling intervals.
Most of us have heard of intervals, or repeated, short, sharp bursts of strenuous activity, interspersed with rest periods. Almost all competitive athletes strategically employ a session or two of interval training every week to improve their speed and endurance.
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The results, published in a recent review of HIIT-related research, were especially remarkable in the cardiac patients. They showed “significant improvements” in the functioning of their blood vessels and heart, said Maureen MacDonald, an associate professor of kinesiology at McMaster who is leading the ongoing experiment.
It might seem counterintuitive that strenuous exercise would be productive or even wise for cardiac patients. But so far none have experienced heart problems related to the workouts, Dr. MacDonald said. “It appears that the heart is insulated from the intensity” of the intervals, she said, “because the effort is so brief.”
Almost as surprising, the cardiac patients have embraced the routine. Although their ratings of perceived exertion, or sense of the discomfort of each individual interval, are high and probably accurate, averaging a 7 or higher on a 10-point scale, they report enjoying the entire sessions more than longer, continuous moderate exercise, Dr. MacDonald said.
“The hard work is short,” she points out, “so it’s tolerable.” Members of a separate, exercise control group at the rehab center, assigned to complete standard 30-minute moderate-intensity workout sessions, have been watching wistfully as the interval trainers leave the lab before them. “They want to switch groups,” she said.
The scientists have noted other benefits in earlier studies. In unfit but otherwise healthy middle-aged adults, two weeks of modified HIIT training prompted the creation of far more cellular proteins involved in energy production and oxygen. The training also improved the volunteers’ insulin sensitivity and blood sugar regulation, lowering their risk of developing Type 2 diabetes, according to a study published last fall in Medicine & Science in Sports & Exercise.

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