THE runner’s high: Every athlete has heard of it, most seem to believe in it and many say they have experienced it. But for years scientists have reserved judgment because no rigorous test confirmed its existence.

Yes, some people reported that they felt so good when they exercised that it was as if they had taken mood-altering drugs. But was that feeling real or just a delusion? And even if it was real, what was the feeling supposed to be, and what caused it?

Some who said they had experienced a runner’s high said it was uncommon. They might feel relaxed or at peace after exercising, but only occasionally did they feel euphoric. Was the calmness itself a runner’s high?

Often, those who said they experienced an intense euphoria reported that it came after an endurance event.

My friend Marian Westley said her runner’s high came at the end of a marathon, and it was paired with such volatile emotions that the sight of a puppy had the power to make her weep.

Others said they experienced a high when pushing themselves almost to the point of collapse in a short, intense effort, such as running a five-kilometer race.

But then there are those like my friend Annie Hiniker, who says that when she finishes a 5-k race, the last thing she feels is euphoric. “I feel like I want to throw up,” she said.

The runner’s-high hypothesis proposed that there were real biochemical effects of exercise on the brain. Chemicals were released that could change an athlete’s mood, and those chemicals were endorphins, the brain’s naturally occurring opiates. Running was not the only way to get the feeling; it could also occur with most intense or endurance exercise.

The problem with the hypothesis was that it was not feasible to do a spinal tap before and after someone exercised to look for a flood of endorphins in the brain. Researchers could detect endorphins in people’s blood after a run, but those endorphins were part of the body’s stress response and could not travel from the blood to the brain. They were not responsible for elevating one’s mood. So for more than 30 years, the runner’s high remained an unproved hypothesis.

But now medical technology has caught up with exercise lore. Researchers in Germany, using advances in neuroscience, report in the current issue of the journal Cerebral Cortex that the folk belief is true: Running does elicit a flood of endorphins in the brain. The endorphins are associated with mood changes, and the more endorphins a runner’s body pumps out, the greater the effect.

Leading endorphin researchers not associated with the study said they accepted its findings.

“Impressive,” said Dr. Solomon Snyder, a neuroscience professor at Johns Hopkins and a discoverer of endorphins in the 1970’s.

“I like it,” said Huda Akil, a professor of neurosciences at the University of Michigan. “This is the first time someone took this head on. It wasn’t that the idea was not the right idea. It was that the evidence was not there.”

For athletes, the study offers a sort of vindication that runner’s high is not just a New Agey excuse for their claims of feeling good after a hard workout.

For athletes and nonathletes alike, the results are opening a new chapter in exercise science. They show that it is possible to define and measure the runner’s high and that it should be possible to figure out what brings it on. They even offer hope for those who do not enjoy exercise but do it anyway. These exercisers might learn techniques to elicit a feeling that makes working out positively addictive.

The lead researcher for the new study, Dr. Henning Boecker of the University of Bonn, said he got the idea of testing the endorphin hypothesis when he realized that methods he and others were using to study pain were directly applicable.

The idea was to use PET scans combined with recently available chemicals that reveal endorphins in the brain, to compare runners’ brains before and after a long run. If the scans showed that endorphins were being produced and were attaching themselves to areas of the brain involved with mood, that would be direct evidence for the endorphin hypothesis. And if the runners, who were not told what the study was looking for, also reported mood changes whose intensity correlated with the amount of endorphins produced, that would be another clincher for the argument.

Dr. Boecker and colleagues recruited 10 distance runners and told them they were studying opioid receptors in the brain. But the runners did not realize that the investigators were studying the release of endorphins and the runner’s high. The athletes had a PET scan before and after a two-hour run. They also took a standard psychological test that indicated their mood before and after running.

The data showed that, indeed, endorphins were produced during running and were attaching themselves to areas of the brain associated with emotions, in particular the limbic and prefrontal areas.

The limbic and prefrontal areas, Dr. Boecker said, are activated when people are involved in romantic love affairs or, he said, “when you hear music that gives you a chill of euphoria, like Rachmaninoff’s Piano Concerto No. 3.” The greater the euphoria the runners reported, the more endorphins in their brain.

“Some people have these really extreme experiences with very long or intensive training,” said Dr. Boecker, a casual runner and cyclist, who said he feels completely relaxed and his head is clearer after a run.

That was also what happened to the study subjects, he said: “You could really see the difference after two hours of running. You could see it in their faces.”

In a follow-up study, Dr. Boecker is investigating if running affects pain perception. “There are studies that showed enhanced pain tolerance in runners,” he said. “You have to give higher pain stimuli before they say, ‘O.K., this hurts.’ ”

And, he said, there are stories of runners who had stress fractures, even heart attacks, and kept on running.

Dr. Boecker and his colleagues have recruited 20 marathon runners and a similar number of nonathletes and are studying the perception of pain after a run, and whether there are related changes in brain scans. He is also having the subjects walk to see whether the effects, if any, are because of the intensity of the exercise.

The nonathletes can help investigators assess whether untrained people experience the same effects. Maybe one reason some people love intense exercise and others do not is that some respond with a runner’s high or changed pain perception.

Annie might question that. She loves to run, but wonders why. But her husband tells her that the look on her face when she is running is just blissful. So maybe even she gets a runner’s high.

跑步的人很興奮，每位運動員都聽到過這種說法，多數人看來相信這種說法，許多人說他們有過類似的經歷。但是多年以來科學家們保留對此的態度，因為沒有嚴格的實驗證明它的存在。

沒錯，一些人說他們在運動時感覺那么好，仿佛是服用了改變情緒的藥物一般。但是這究竟是一種真實的感覺還只是一種幻覺？即使這種感覺是真實的，它應該是種什么感覺，又是什么引起的這種感覺呢？

一些表示經歷過跑步者興奮的人說，這種感覺是不尋常的。鍛煉后人可能覺得放松或平靜，而只在偶然的情況下，他們才會感覺精神陶醉。難道平靜本身就是跑步者的興奮嗎？

那些說過自己經歷過強烈陶醉感的人經常說，這種感覺出現在長時間的活動后。

我的朋友瑪麗安·威斯利說，她那次跑步者的興奮是在一次馬拉松后。那種感覺下她是如此多愁善感，看見一只小狗，也能讓她感傷落淚。

其他人說，當他們在短時間內劇烈地運動，比如跑5公里賽跑，累得自己幾乎崩潰時，經歷了興奮。

可是還有其他人一些人，像我的朋友安妮·海內克，她說，跑完5公里后，她最不可能有的感覺就是陶醉。她說，”我感覺都要吐了。“

這種跑步者興奮假說提出，鍛煉有真實存在的對大腦的生化影響。人體釋放出能夠改變運動員情緒的化學物質，這些化學物質就是內啡肽－－大腦的天然鴉片。跑步不是獲得這種感覺的唯一方法，多數緊張或持續的運動都能產生這種感覺。

這種假說的問題是，要在人運動前和運動后都抽取精髓液來尋找大腦中內啡肽大量增加的證據是不可行的。研究人員能夠檢測到人在跑步后血液中的內啡肽，但是那些內啡肽是人體緊張反應的一部分，不能從血液中運輸到大腦，他們不是提高人情緒的原因。所以30多年來，跑步者興奮一直作為一項未經證明的假說。

但是現在醫學技術已經趕上了運動學說。最新一期的大腦皮質期刊上報道說，德國的研究人員使用神經科學的尖端技術，證明民間的說法是正確的：跑步確實導致大腦中釋放大量的內啡肽。這種內啡肽與情緒變化有聯系，跑步者身體中產生的內啡肽越多，效果越明顯。

這項新研究的首席研究員，波恩大學的海寧·勃克博士說，當他意識到可以直接使用他和同事們用來研究痛感的方法時，他想出了檢測內啡肽假說的方法。

這種方法是使用PET（正電子發射斷層掃描）掃描與最近出現的可以顯示大腦中內啡肽的化學物質結合，來比較跑步者在長跑前后的大腦。如果掃描顯示內啡肽產生并依附在大腦中與情緒有關的區域，這將是內啡肽假說的直接證據。而且，如果發現跑步者，他們事先不知道研究的目的，也出現與產生的內啡肽的量相關的情緒變化，那將是這種假說的另一個決定性證據。

勃克博士及其同事們招募了10名長跑選手，告訴他們說正在進行大腦中鴉片感受器的研究，但是這些長跑選手不知道研究人員正左研究內啡肽的釋放和跑步者興奮的關系。運動員們先做了一次PET掃描，在2個小時的跑步后又進行了一次掃描。他們還接受了一次標準的心理測試，以標明他們在跑步前后的情緒變化。

數據表明，確實在跑步中產生了內啡肽，并且依附在大腦與感情有關的區域，尤其是在邊緣和額葉前部。

勃克博士說，當人們發生浪漫的愛情時大腦的邊緣和額葉前部就活躍；或者是，他說，“當你聽到一首讓你陶醉得戰栗的樂曲時，比如，拉赫馬尼諾夫的第三鋼琴協奏曲。”運動員所感到的陶醉感越強，他們大腦中的內啡肽就越多。

勃克博士說“一些人在經過很長時間或強烈的訓練后，獲得這樣的極端經歷“。他本身就是一位自行車愛好者，偶爾跑跑步。他說，他在跑步過后覺得徹底放松、頭腦清醒。

研究項目也是這樣的，他說，“你真該看看兩個小時的跑步造成的不同，你能從他們臉上看出來。”

在一項后續研究中，勃克博士正在調查跑步是否影響痛感。他說，“有些研究表明跑步者的疼痛耐受力增強了，你必須給予他們更大的痛刺激，他們才會說‘對了，這很疼’。“

而且，他說，有些跑步者的故事說他們遇到了應力性骨折、甚至是心臟病，卻還繼續跑。

勃克博士及其同事們已經招募了20名跑馬拉松選手和同等數目的不跑馬拉松的人，正在研究跑步后的痛感差異，和大腦是否有相關的掃描變化。他還讓研究對象進行走路，看看那些影響是否同運動的強度有關系，有多少關系。

那些非運動員能夠幫助研究人員評估未經訓練的的人們是否經受同樣的影響。也許有些人喜歡強烈訓練而另一些人不喜歡的原因是有些人對跑步者的興奮或痛感變化有響應而另一些人沒有。

安妮也許懷疑這一點。她喜歡跑步，卻不知道為什么。她丈夫告訴她，當她跑步時她臉上的表情幸福無比。或許，她也得到了跑步者的興奮