不要戴着口罩做運動!

The coronavirus began to affect sporting events as early as January 30, when the Chinese Football Association announced it was delaying the start of the football season. Two months later it was revealed that the Tokyo Olympic Games would be postponed until the summer of 2021 – the first postponement in modern Olympic history.

從1月30日開始，疫情就對體育賽事造成了影響，當時中國足球協會宣佈推遲足球賽季的起始時間。兩個月後東京奧運會也宣佈推遲到2021年夏季召開，這是現代奧運史上第一次延期。

Sporting administrators are only now exploring ways to enable a return to training and competition at both professional and amateur levels. In the absence of a vaccine, though, there are several challenges. One of them is around breathing.

體育管理者現在試圖鼓勵專業和業餘運動員恢復訓練和競賽。但由於缺乏疫苗，恢復體育運動還存在一些困難，其中就包括呼吸問題。

When playing sport, breathing is faster and harder than at rest, which increases the risk of passing the disease on. As a result, premier league football is considering introducing face masks. Others may follow suit.

做運動時的呼吸比休息時更快更用力，會增加疾病傳播的風險。因此英超足球正考慮引進口罩，其他人可能也會效仿。

Yet a mask makes it harder to inhale the quantity of air needed to perform at the highest levels. We know that wearing a surgical mask can increase the resistance to airflow. Exercise invariably leads to faster and harder breaths, so wearing a mask during exercise places a further strain on airflow.

但在運動量達到最大時戴口罩會使空氣吸入量不足。我們都知道佩戴醫用口罩會增加氣流阻力。鍛鍊一定會導致呼吸更快更用力，所以運動期間佩戴口罩對氣流會造成進一步的壓力。

At low to moderate-intensity exercise, effort will feel slightly harder than normal with a mask, but you can still walk comfortably. The challenge appears to be more during heavy exercise (say, rugby or football) taking in air at rates of about 40-100 litres per minute.

進行中低強度鍛鍊時會感覺比平時戴口罩時呼吸更費力，但你走路時依舊很舒服。做劇烈運動（如橄欖球或足球）時問題就更嚴重了，每分鐘吸入空氣量約爲40-100升。

When we do heavy exercise, our muscles produce lactic acid, which causes that burning sensation. It is then converted to carbon dioxide and exhaled. But what happens if the carbon dioxide is trapped by the mask? As you move from moderate to heavy exercise, you may be re-breathing carbon dioxide, which can reduce cognitive function and increase breathing rate.

做劇烈運動時，我們的肌肉產生乳酸，會有灼熱的感覺，然後轉化爲二氧化碳呼出。但如果二氧化碳被口罩擋住了會怎樣？隨着你的運動強度從中度到劇烈，你可能會重新吸入二氧化碳，這會降低認知功能，增加呼吸頻率。

There may also be less oxygen in the recycled air, which could imitate exercising at higher altitudes. So it is important we gain a better understanding of the limitations of heavy exercise with a face mask.

循環的空氣中氧氣可能變少，這就像是在高海拔地區做運動。所以重點是我們要更明白戴口罩做劇烈運動的限制。