It can help you stay at a healthy weight, improve your cardiovascular health, and even ward off depression.

運動可以幫助我們保持健康的體重，改善心血管健康，甚至可以預防憂鬱症。

But, like most things, it's possible to overdo it.

但跟大部分的事情一樣，運動有可能會做過頭。

And getting too much exercise can have serious consequences on your body and brain.

過度運動會對人體和大腦造成嚴重後果。

So, what exactly is too much exercising?

到底什麼是過度運動呢？

Well, it depends on factors like your age, health, and choice of workouts.

這取決於年齡、健康狀況和所選擇的鍛鍊等因素。

But, in general, adults should get about five hours a week of moderate exercise, or two and half hours or more of intense activity, or some combination of the two.

但一般來說，成年人每週應該進行大約五個小時的適度運動，或者兩個半小時或更長時間的劇烈運動，或是兩種結合。

That's according to the CDC.

這是根據 CDC 的說法。（CDC 為美國疾病管制與預防中心）

But research shows that going way above and beyond doesn't necessarily increase your health benefits.

但研究表明，運動遠超過建議的時間並不一定對健康更有益。

One unsurprising study found that light to moderate runners had a lower risk of death than people who didn't exercise.

一項不令人吃驚的研究發現，輕度至中度跑者的死亡風險低於不鍛煉的人。

But in a surprising turn, some people who ran at a faster pace for more than three times a week had a similar risk of dying as non-runners.

但令人驚訝的是，一些每週以更快的速度跑步超過三次的人與都不跑步的人的死亡風險相似。

So, running too much and too intensely seems to undo some of the health benefits gained from regular running.

所以跑太多和強度太大似乎會抵消定期跑步帶來的一些健康益處。

Extreme endurance exercises, like ultramarathons, may also lead to heart damage, heart rhythm disorders, and enlarged arteries in some people.

極端的耐力運動，如超級馬拉松，也可能導致某些人的心臟損傷、心律紊亂和動脈擴張。

Experts believe that extreme endurance puts extreme demands on the cardiovascular system.

專家認為，極端的耐力運動對心血管系統產生了極端的需求。

One study found that repeated extreme exercises can remodel the heart, thickening the muscles' walls and scarring tissue.

一項研究發現，反復進行極端運動會重塑心臟，使肌肉壁增厚並讓組織結疤。

Another study showed that women were less likely to have a heart attack or stroke if they were physically active at least once a week.

另一項研究表明，如果女性每周至少進行一次身體鍛煉，罹患心臟病或中風的可能性就會降低。

But that risk of heart attacks and strokes shot up for women who exercise strenuously every day.

但是對於每天進行劇烈運動的女性來說，心臟病發作和中風的風險會急劇上升。

So, excessive exercise doesn't provide more benefits than moderate exercise, and it could be more risky.

所以過度運動並不會比適度運動帶來更多好處，而且可能更具風險。

Women are at a particular risk for what's known as Female Athlete Triad.

女性尤其容易罹患所謂的女性運動員三聯症。

That includes loss of menstruation, osteoporosis, or bone mineral loss, and eating disorders.

這包括無月經症、骨質疏鬆症或骨礦物質流失以及飲食失調。

These symptoms usually arrive from a combination of over-exercise and calorie restriction.

這些症狀通常來自過度運動加上卡路里限制。

For men, intense exercise has been shown to decrease libido, possibly due to physical fatigue, and lower testosterone levels.

對於男性來說，劇烈運動已被證明會降低性慾（可能是由於身體疲勞）和降低睾丸激素的水平。

For both men and women, over-exercise raises the risk of over-use injuries, like tendonitis and stress fractures.

對於男性和女性來說，過度運動會增加過度使用而造成傷害的風險，例如肌腱炎和疲勞性骨折。

These injuries result from repetitive trauma.

這些傷害是由重複性創傷引起的。

Your immune system can likewise suffer.

免疫系統同樣會受到影響。

While moderate exercise can improve your immune system, excessive exercise can actually suppress it.

雖然適度運動可以提高免疫系統，但過度運動其實會抑制它。

There's up to a 72-hour open window of impaired immunity after intense exercise.

劇烈運動後，免疫力受損的窗口期長達 72 小時。

This basically means that viruses and bacteria have an easier time invading and infecting the body.

這基本上表示這段時間病毒和細菌更容易侵入和感染人體。

And athletes who over-exercised also experienced more upper-respiratory tract infections.

過度運動的運動員也會經歷更多的上呼吸道感染。

So we know excessive exercise can wreak havoc on your body, particularly your heart, tendons, ligaments, and immune system.

所以我們知道過度運動會對身體造成嚴重損害，尤其是心臟、肌腱、韌帶和免疫系統。

And for around one million people in the US, exercise addiction is wreaking havoc on their brains.

對於大約 100 萬美國人來說，運動成癮正在嚴重破壞他們的大腦。

Symptoms of exercise addiction include withdrawal.

運動成癮的症狀包括戒斷症狀。

That's when you feel anxious or exhausted when you miss a workout.

當錯過鍛鍊時會感到焦慮或疲憊。

Or feeling a lack of control and unable to cut down on exercise, even when you know it's hurting you.

或者感到難以控制，無法減少鍛鍊，明知知道過度運動會傷害自已的身體。

Now, it's important to understand that you shouldn't just give up on exercising.

重要的是，並不代表要就此放棄運動。

The key is to get the right amount.

重點是要適當。

So, feel free, go forth and run!

放心的向前跑吧！

Just not all the time.

只是不要一直跑。