Scientists studied more than 1,000 healthy joggers and non-joggers over a 12-year period.

科學家們對1000多名身體健康的慢跑者和不跑步的人進行研究，追蹤時間超過12年。

Those who jogged at a steady pace for less than two and a half hours a week were least likely to die in this time。

慢跑速度較為穩(wěn)健，且每周慢跑時間不超過兩個半小時的人猝死的可能性最小。

But those who ran more than four hours a week or did no exercise had the highest death rates。

而一周跑4個小時以上或者從不鍛煉的人則有著最高的死亡率。

'Upper limit'

“上限”

Analysing questionnaires filled out by all the people in the Danish study, scientists concluded the ideal pace was about 5mph (8km/h) and that it was best to jog no more than three times a week or for 2.5 hours in total。

在丹麥進行的研究中，科學家通過分析所有參與者的問卷得出結論：理想的運動速度大約是每小時5英里(約8公里/小時);每周的運動次數(shù)不超過3次或者時長累計為2.5小時。

People who jogged more intensively - particularly those who jogged more than three times a week or at a pace of more than 7mph - were as likely to die as those who did no exercise。

進行更為密集的慢跑，尤其是那些一周跑3次以上或者速度超過每小時7英里的人，其死亡幾率和那些不運動的人相差無幾。

Researcher Jacob Louis Marott, from the Frederiksberg Hospital in Copenhagen, said: "You don't actually have to do that much to have a good impact on your health。

來自哥本哈根腓特烈斯貝醫(yī)院的研究人員雅各布·路易斯·馬羅塔(Jacob Louis Marott)說：“其實你不必強求，為自己的健康做太多。”

"And perhaps you shouldn't actually do too much。

“或許事實上你不應該做太多。”

"No exercise recommendations across the globe mention an upper limit for safe exercise, but perhaps there is one."

“目前，全球尚無有關安全鍛煉的上限建議，但或許應該有一個。”

Scientists are not yet sure what is behind this trend - but they say changes to the heart during extreme exercise could contribute。

科學家還不能確定潛在的趨勢——但他們說極端運動改善心臟狀況可能有所幫助。

'Brisk walking'

“快走”

In their report, they suggest: "Long-term strenuous endurance exercise may induce pathological structural remodelling of the heart and arteries."

在調查報告中，他們提出：“長期從事劇烈的耐力運動可能會改變心臟和動脈的病理結構。”

Maureen Talbot, senior cardiac nurse at the British Heart Foundation, said: "This study shows that you don't have to run marathons to keep your heart healthy。

英國心臟基金會高級心臟護士莫林·托爾伯特(Maureen Talbot)說：“這項研究表明，你不必為保持心臟健康去跑馬拉松。

"Light and moderate jogging was found to be more beneficial than being inactive or undertaking strenuous jogging, possibly adding years to your life。

“少量、適度的慢跑被認為比不運動或進行高強度慢跑更有益，或可延長你的壽命。”

"National guidelines recommend we do 150 minutes of moderate-intensity activity a week。

“國家指南推薦我們每周進行150分鐘的中等強度的活動。”

"It may sound like a lot, but even brisk walking is good exercise. And if you're bit of a couch potato, this is a good place to start."

“這聽起來可能很多，但即使快走也是很好的鍛煉。如果你有點宅，這對你來說是一個很好的開始。”