高強度運動中怎麼防感冒 Causes and cures for runny nose of endurance sport

It has long been known that regular, moderate exercise is one of the best things you can do for your health, with studies showing that trained athletes have increased levels of natural killer cells that fight infection. But as anyone who practises endurance sports probably knows, hard training for an event like a cycle race or a marathon run can leave you with a dandy head cold or other upper respiratory tract infection (URTI).

人們很早以前就知道，定期而適度的鍛鍊是對健康最有益的事情之一。研究表明，受過訓練的運動員體內抗感染的“自然殺傷細胞”水平升高。不過，練習耐力運動的人也許都知道，爲參加自行車比賽或馬拉松長跑這樣的賽事而開展的艱苦訓練，可能會讓你患上頭傷風或其他上呼吸道感染(URTI)。

At the moment I’m trying to fight off a suspicious soreness in my throat, a warning sign that a URTI may be on the way. I wondered: what is it about working out and sweating heavily that makes you more vulnerable to illnesses?

眼下，我正在對付自己喉嚨中的可疑疼痛感，這是個警告信號，顯示我可能已得了上呼吸道感染。我奇怪的是：鍛鍊和大量出汗怎麼會令人更容易得病呢？

David Nieman, a researcher, tracked 2,311 participants in the 1987 Los Angeles marathon and came up with some startling results: during the week following the race, 12.9 per cent of runners reported being sick, compared with 2.2 per cent of control runners who did not take part in the race that year.

研究人員戴維尼曼(David Nieman)通過追蹤1987年洛杉磯馬拉松的2311名參賽者，得出了一些令人吃驚的結果：在比賽結束後的那周裏，12.9%參賽者曾報告身體不適；相比之下，沒有參加比賽的對照組跑步者感到不適的比例只有2.2%。

One of Dr Nieman’s findings was that prolonged intense exercise caused the athletes’ immune systems to respond as if they were fighting infections, with a sharp increase in stress hormones and inflammation-fighting cells called neutrophils and monocytes after the run.

尼曼的一個發現是，長時間的高強度鍛鍊，會使運動員的免疫系統做出彷彿在對抗炎症的反應。在跑完馬拉松之後，選手們的應激激素、以及被稱爲中性粒細胞及單核白血球的抗炎細胞因子急劇升高。

In addition, other research has found that mucosal systems — the moist bits in the mouth, nose and eyes — produce a substance called secretory immunoglobulin A (SIgA), which is the body’s first line of defence against pathogens such as colds and the flu.

此外，其他一些研究發現，人的粘膜系統（口腔、鼻腔和眼睛中的溼潤部位）會產生一種叫做“分泌型免疫球蛋白A”(SIgA)的物質，這是軀體抵禦感冒和流感等病原體的第一道防線。

But SIgA has been shown to decline after a heavy stretch of training. “Consensus exists that reduced levels of saliva SIgA are associated with increased risk of URTI during heavy training,” said one study.

然而，在經過持續大量鍛練之後，研究顯示SIgA的水平會下降。研究報告表示：“存在這樣一個共識，高強度鍛練期間，唾液中SIgA水平的下降與患上呼吸道感染的風險增大存在聯繫。”

Everyone’s mother has a favourite treatment for a cold, but here are a few with scientific support.

每一位媽媽都有各自偏愛的治療感冒的方法，這裏卻要列舉幾個有科學依據的療法。

One of the most widely studied is the mineral zinc, which has been shown to inhibit replication of the rhinovirus, which is the cause of about 40 per cent of colds. The Journal of the American Medical Association reported in 2014 that “oral zinc is associated with a shorter duration of the common cold in healthy people”, but other studies have found mixed results.

被研究得最多的治感冒藥物之一是礦物鋅，它被證明能抑制鼻病毒的複製，後者是約40%感冒的罪魁禍首。《美國醫學會雜誌》(Journal of the American Medical Association)曾在2014年稱，“口服鋅與健康人羣普通感冒持續時間縮短有關”。不過，其他研究則顯示了相互矛盾的結果。

The primary reason, according to George Eby, the US researcher who discovered zinc’s effect on colds, is that only positively charged ionic zinc is effective against infections, so athletes should look for lozenges containing zinc acetate or zinc gluconate, not commonly available zinc citrate.

發現鋅對感冒有用的美國研究人員喬治伊比(George Eby)認爲，主要的原因在於，只有帶正電荷的鋅離子具有抗感染功效。因此，運動員應該服用含有乙酸鋅或葡萄糖酸鋅的藥片，而不是常見的檸檬酸鋅。

One Cochrane Review of data in 2013 found that the much touted Vitamin C generally failed to protect against colds, although it may offer some benefit to heavy exercisers.

2013年《考科藍回顧》(Cochrane Review)的一項數據顯示，倍受吹捧的維生素C通常不能預防感冒——儘管它可能對高強度鍛鍊者有某些益處。

Another nutritional supplement recently studied is a green alga known as chlorella. One relatively small study found that athletes who took chlorella during heavy training did not suffer the same reduction in SIgA that other athletes did.

另一種最近被研究的營養補充劑是一種被稱爲小球藻的綠藻。一項規模相對較小的研究發現，在高強度訓練期間服用小球藻的運動員並未出現與其他運動員一樣的SIgA減少現象。

Finally, a simple but effective protection and cure that is common in Japan, but less so in North America or Europe: gargling. A randomised controlled trial in Japan showed that the occurrence of respiratory tract infections was significantly reduced in people who gargled several times a day. The most effective gargle was tap water, not the various medicinal gargles available, most probably because chlorine added to drinking water inhibits viruses.

最後，一個很簡單而又有效的防治方法是漱口，這種方法在日本十分常見，在北美或歐洲卻不那麼普遍。在日本開展的一項隨機對照試驗顯示，在一天多次漱口的人羣中，呼吸道感染的發生率顯著降低。最有效的漱口水是自來水，而不是市面上可以見到的各種藥用漱口水，最有可能的原因是飲用水中添加的氯能夠抑制病毒。