하루 4분만 관리하면 건강해질 수 있다.

The 4-Minute Workout

운동이 건강에 도움이 된다는 사실은 너무나도 널리 알려진 상식에 가깝습니다. 하지만, 얼마만큼의 운동이 건강을 유지시키는데 최소한으로 필요한 것일까요? 결론부터 말씀드리면, 현재까지는, ‘4분’ 입니다.

노르웨이에 있는 한 대학교(the Norwegian University of Science and Technology in Trondheim)의 연구팀이 지난 5월 지구력과 여러 건강 지표들을 향상시키기 위한 최소한의 운동량을 밝히는 연구결과를 발표했습니다. 연구팀은 일주일에 세 번, 최대 심박수의 90% 수준에서 4분간만 운동을 하더라도, 이미 효과가 있다고 검증된 16분의 다른 운동세트와 거의 동등한 수준으로 건강을 증진시킬 수 있다는 사실을 밝혀냈습니다.
많은 기존의 연구들은 전체적인 운동 시간이 마라톤이나 장거리 자전거 타기에 비해 비교적 짧더라도, 짧게 지속되는 강도 높은 세트를 반복적으로 한 번에 진행하면 건강과 적합도 시험에서 더 큰 향상을 보일 수 있다는 사실을 꾸준히 뒷받침해왔습니다. 이전까지 밝혀진 최소한의 운동시간은 심박수의 90% 수준에서 진행되는 4분간의 운동을, 각 간격마다 1분 간의 쉬는 시간을 두고, 4회 반복하는 16분이었습니다. 하지만, 노르웨이 대학 연구팀은 바쁘게 살아가는 현대인들에게 이 16분간의 운동시간조차도 큰 부담이 될 수 있을 것이라 생각했습니다.

따라서, 그들은 운동 시간을 줄이면서도 비슷한 효과를 낼 수 있는 최소한의 운동량을 알아보기 위해 4분 운동을 4회 연속적으로 반복 실행하는 집단과 4분 운동을 1회만 실행하는 집단을 설정하고 각각의 집단이 10주동안 일주일에 3회 지정된 양만큼의 운동을 했을 때 건강에 어떠한 변화가 일어나는지 그 결과를 비교해 보았습니다. 놀랍게도 두 집단 모두 심혈관건강상태, 지구력, 혈당조정능력, 혈압상태에서 비슷한 수준의 향상을 보였습니다.

이 연구 결과는 4분간 언덕을 급히 뛰어 올라가거나 계단을 반복적으로 뛰어오르는 행위들만으로 장시간 지속되는 자전거타기, 수영, 가벼운 조깅과 비슷한 운동효과를 낼 수 있다는 사실을 제시합니다. 하지만, 노르웨이 연구팀은 이러한 운동법이 체중을 감량하는 방법과는 거리가 멀다고 말합니다. 실험에 참여한 두 집단 모두에게서 향상되는 다른 건강지표와는 달리 체지방에는 전혀 변화가 없었기 때문입니다. (NYT)

뉴욕타임즈 원문 보러가기

Thanks to an ingratiating new study, we may finally be closer to answering that ever-popular question regarding our health and fitness: How little exercise can I get away with?

The answer, it seems, may be four minutes.

For the study, which was published last month in the journal PLoS One, researchers from the Norwegian University of Science and Technology in Trondheim, Norway, and other institutions attempted to delineate the minimum amount of exercise required to develop appreciable endurance and health gains. They began by reconsidering their own past work, which had examined the effects of a relatively large dose of high-intensity intervals on various measures of health and fitness.

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“Reduced Shakespeare Workout”
“Born to Run”
For those unfamiliar with the term, high-intensity intervals are just that: bursts of strenuous exercise lasting anywhere from 30 seconds to several minutes, interspersed with periods of rest. In recent years, a wealth of studies has established that sessions of high-intensity exercises can be as potent, physiologically, as much longer bouts of sustained endurance exercise.

In a representative study from 2010, for instance, Canadian researchers showed that 10 one-minute intervals — essentially, 10 minutes of strenuous exercise braided with one-minute rest periods between — led to the same changes within muscle cells as about 90 minutes of moderate bike riding.

Similarly, the Norwegian scientists for some years have been studying the effects of intense intervals lasting for four minutes, performed at about 90 percent of each volunteer’s maximum heart rate and repeated four times, with a three-minute rest between each interval. The total meaningful exercise time in these sessions, then, is 16 minutes.

Which, the researchers thought, might just be too much.

“One of the main reasons people give” for not exercising is that they don’t have time, says Arnt Erik Tjonna, a postdoctoral fellow at the Norwegian University of Science and Technology, who led the study.

So he and his colleagues decided to slim down the regimen and determine whether a single, strenuous four-minute workout would effectively improve health and fitness.

To do so, they gathered 26 overweight and sedentary but otherwise healthy middle-aged men, determined their baseline endurance and cardiovascular and metabolic health, and randomly assigned them to one of two groups.

Half began a supervised exercise program that reiterated the Norwegian researchers’ former routine. After briefly warming up, these volunteers ran on a treadmill at 90 percent of their maximal heart rate — a tiring pace, says Dr. Tjonna, at which “you cannot talk in full sentences, but can use single words” — for four four-minute intervals, with three minutes of slow walking between, followed by a brief cool-down. The entire session was repeated three times a week for 10 weeks.

The second group, however, completed only one four-minute strenuous run. They, too, exercised three times a week for 10 weeks.

At the end of the program, the men had increased their maximal oxygen uptake, or endurance capacity, by an average of 10 percent or more, with no significant differences in the gains between the two groups.

Metabolic and cardiovascular health likewise had improved in both groups, with almost all of the men now displaying better blood sugar control and blood pressure profiles, whether they had exercised vigorously for 16 minutes per session, or four minutes per session, and despite the fact that few of the men had lost much body fat.

“This is not a weight-loss program,” Dr. Tjonna says. It is, instead, he says, “a suggestion for how people can make a kick-start for better fitness,” or maintain fitness already gained, when other obligations press on your time.

The results, Dr. Tjonna says, persuasively suggest that “getting in shape does not demand a big effort” in terms of time.

That finding, though, inevitably raises the question of whether the bar could drop even lower. Could, for instance, a mere two minutes of strenuous training effectively improve health and fitness?

Dr. Tjonna, the killjoy, doubts it. There are other groups of scientists looking at even shorter bouts of exercise, he says, “but it seems like they don’t get the same results regarding the maximal oxygen uptake” as the four-minute sessions used in his experiment. Since improved maximal oxygen uptake can reliably indicate better overall cardiovascular health, he suspects that “we need a certain length of the interval to trigger” such health and fitness benefits.

Thankfully, for those worried that a trip to the gym is an inefficient means of completing four minutes of exercise, the workout can effectively be practiced anywhere, Dr. Tjonna says. Sprint uphill for four minutes or race up multiple flights of steps. Bicycle, swim or even walk briskly, as long as you raise your heart rate sufficiently for four minutes. (Obviously, consult your doctor first if you haven’t been active in the past.)

“Everyone, we think,” Dr. Tjonna says, “has time for this kind of exercise three times a week.”