Why Your Workout Should Be High-Intensity

From a New York Times article:

Many people with chronic health problems resign themselves to lives of modest activity or no activity at all, thinking vigorous exercise is unsafe or that they lack the stamina for it. But recent studies are proving just the opposite.

They are showing that high-intensity exercise may be even better than regular aerobic activities for many patients with conditions like heart disease, diabetes, stroke, pulmonary disease, arthritis and Parkinson’s disease.

The studies strongly suggest that a more demanding but more efficient and often more enjoyable form of exercise known as high-intensity interval training, or HIIT, is not only safe for most patients but more effective at preventing or reversing the deficits associated with many chronic ailments.

Although once reserved for athletes seeking a competitive advantage and for healthy people wanting to burn more body fat,HIIT is now being studied as a treatment that is sometimes as effective as medication for many people with chronic health problems.

Researchers have found that repeatedly pushing the body close to its exercise limits for very brief periods, interspersed with periods of rest, is more effective than continuous moderate activity at improving cardiovascular, respiratory, metabolic and mechanical functions.

Instead of continuous movement for 20 or more minutes, as is typical for exercise walkers, joggers and cyclists, HIIT usually involves 30 to 60 seconds of exercise near the peak of a person’s ability, followed by a comparable recovery period of easy activity, with the sequence repeated for a total of about 20 minutes three times a week.

“We know that exercise is good for people at risk of chronic disease, but people tend not to exercise,” said Jonathan P. Little, a specialist in exercise physiology at the University of British Columbia at Okanagan. Yet he and other researchers report that study participants find interval training more enjoyable than continuous aerobic exercise, making it more likely that people will continue it on their own.

Various activities can be adapted to interval training, including cycling, swimming, walking and jogging, especially on a machine like a stationary bike or treadmill. But HIIT is possible indoors and out, for example by alternating sprints with more moderate exercise.

The intensity is tailored to an individual’s starting ability. “The high-intensity component is set at 80 to 90 percent of the person’s maximum aerobic capacity,” Dr. Little said. Researchers commonly use exercise bikes and treadmills to adjust the pace mechanically.

However, high-intensity exercise, even just half a minute at a time, is not appropriate for everyone. In a recent report in the American College of Sports Medicine’s Health & Fitness Journal, Dr. Little; his wife, Mary E. Jung, also at the University of British Columbia; and Marcus W. Kilpatrick of the University of South Florida wrote that HIIT “is only appropriate for low-risk individuals, moderate-risk individuals who have been cleared for vigorous intensities by a medical professional, and high-risk individuals who are under direct medical supervision during exercise training.”

Among the physiological benefits of HIIT are the body’s increased ability to use oxygen and insulin, as well as arteries that are more elastic than continuous moderate exercise can achieve.

“We’ve seen, for example, that interval training is remarkably effective at lowering glucose levels in people with diabetes,” Dr. Little said in an interview. “Just one session improves a person’s glucose level.”

A 12-week controlled study in Denmark of high-intensity interval walking for patients with Type 2 diabetes showed it helped control blood glucose levels better than continuous moderate exercise, even though the same number of calories was expended by both groups. Interval training also was more effective at enhancing the patients’ physical fitness and reducing body fat relative to lean muscle tissue.

By making blood vessels better able to expand, HIIT can improve the cardiovascular system’s ability to respond to added exertion. Oxygen-carrying blood can flow more smoothly through arteries that are wide open, which also reduces the risk of a vessel-blocking clot.

The body’s ability to use oxygen efficiently improves markedly “after as little as two weeks of training” with HIIT, the researchers wrote. Peak oxygen uptake — the amount of oxygen an individual can use during intense exercise — is considered the best indicator of cardiovascular fitness and an independent predictor of illness and death in cardiac patients.

“Too many people think incorrectly that high-intensity exercise is only for athletes, that it’s a heart attack waiting to happen,” Dr. Little said. On the contrary, the research strongly suggests, it is more likely to reduce the risk of a heart attack.

In a 2012 report reviewing the effects of HIIT in patients with coronary artery disease and heart failure, researchers in Canada, France and Switzerland wrote that “HIIT appears safe and better tolerated by patients than moderate-intensity continuous exercise” and more effective at increasing patients’ peak oxygen uptake, blood vessel flexibility and pumping ability of the heart.

Patients with chronic obstructive pulmonary disease are often unable to exercise long enough to gain needed health benefits. But they can do HIIT for long periods with less shortness of breath and leg discomfort, researchers at the National and Kapodistrian University of Athens have reported.

Stroke patients with persistent disabilities can also benefit from HIIT. As rehabilitation specialists at the University of Cincinnati wrote this month in BioPortfolio, stroke patients with residual weakness “enter a vicious cycle of limited activity and deconditioning.” But while regular aerobic exercise can improve their function and cardiovascular health, preliminary studies, including one in Trondheim, Norway, suggest that patients do even better with HIIT. The Norwegian team reported that the improvements persisted for months after the six-week high-intensity exercise program ended.

And Polish researchers demonstrated that HIIT could alleviate the rigidity and excessive muscle tone that makes it difficult for Parkinson’s disease patients to move their arms and legs. The researchers, from the University School of Physical Education in Krakow, Poland, showed in 11 patients with mild to moderate Parkinson’s symptoms that eight weeks of HIIT, three times a week, on a stationary bike had a global benefit, improving both lower and upper body function.

Reductions in rigidity and stiffness correlated with an increase in a substance called brain-derived neurotrophic factor, which the researchers suggested could have stimulated the growth and function of nerves normally influenced by dopamine, the neurotransmitter that declines in Parkinson’s disease.

How Exercise Keeps Us Young

From a New York Times article:

Active older people resemble much younger people physiologically, according to a new study of the effects of exercise on aging. The findings suggest that many of our expectations about the inevitability of physical decline with advancing years may be incorrect and that how we age is, to a large degree, up to us.

Aging remains a surprisingly mysterious process. A wealth of past scientific research has shown that many bodily and cellular processes change in undesirable ways as we grow older. But science has not been able to establish definitively whether such changes result primarily from the passage of time — in which case they are inevitable for anyone with birthdays — or result at least in part from lifestyle, meaning that they are mutable.

This conundrum is particularly true in terms of inactivity. Older people tend to be quite sedentary nowadays, and being sedentary affects health, making it difficult to separate the effects of not moving from those of getting older.

In the new study, which was published this week in The Journal of Physiology, scientists at King’s College London and the University of Birmingham in England decided to use a different approach.

They removed inactivity as a factor in their study of aging by looking at the health of older people who move quite a bit.

“We wanted to understand what happens to the functioning of our bodies as we get older if we take the best-case scenario,” said Stephen Harridge, senior author of the study and director of the Centre of Human and Aerospace Physiological Sciences at King’s College London.

To accomplish that goal, the scientists recruited 85 men and 41 women aged between 55 and 79 who bicycle regularly. The volunteers were all serious recreational riders but not competitive athletes. The men had to be able to ride at least 62 miles in six and a half hours and the women 37 miles in five and a half hours, benchmarks typical of a high degree of fitness in older people.

The scientists then ran each volunteer through a large array of physical and cognitive tests. The scientists determined each cyclist’s endurance capacity, muscular mass and strength, pedaling power, metabolic health, balance, memory function, bone density and reflexes. They also had the volunteers complete the so-called Timed Up and Go test, during which someone stands up from a chair without using his or her arms, briskly walks about 10 feet, turns, walks back and sits down again.

The researchers compared the results of cyclists in the study against each other and also against standard benchmarks of supposedly normal aging. If a particular test’s numbers were similar among the cyclists of all ages, the researchers considered, then that measure would seem to be more dependent on activity than on age.

As it turned out, the cyclists did not show their age. On almost all measures, their physical functioning remained fairly stable across the decades and was much closer to that of young adults than of people their age. As a group, even the oldest cyclists had younger people’s levels of balance, reflexes, metabolic health and memory ability.

And their Timed Up and Go results were exemplary. Many older people require at least 7 seconds to complete the task, with those requiring 9 or 10 seconds considered to be on the cusp of frailty, Dr. Harridge said. But even the oldest cyclists in this study averaged barely 5 seconds for the walk, which is “well within the norm reported for healthy young adults,” the study authors write.

Some aspects of aging did, however, prove to be ineluctable. The oldest cyclists had less muscular power and mass than those in their 50s and early 60s and considerably lower overall aerobic capacities. Age does seem to reduce our endurance and strength to some extent, Dr. Harridge said, even if we exercise.

But even so, both of those measures were higher among the oldest cyclists than would be considered average among people aged 70 or above.

All in all, the numbers suggest that aging is simply different in the active.

“If you gave this dataset to a clinician and asked him to predict the age” of one of the cyclists based on his or her test results, Dr. Harridge said, “it would be impossible.” On paper, they all look young.

Of course, this study is based on a single snapshot of an unusual group of older adults, Dr. Harridge said. He and his colleagues plan to retest their volunteers in five and 10 years, which will provide better information about the ongoing effects of exercise on aging.

But even in advance of those results, said Dr. Harridge, himself almost 50 and an avid cyclist, this study shows that “being physically active makes your body function on the inside more like a young person’s.”