Bicycling (South Africa)

Flight Risk

- – Joe, PE

I RECENTLY QUALIFIED FOR IRONMAN HAWAII. I NORMALLY DON’T FEEL GOOD AFTER FLYING LONG DISTANCES, AND HAWAII WILL BE THE FURTHEST I’VE FLOWN. I’VE INVESTED SO MUCH IN THIS RACE, AND I CAN’T AFFORD TO HAVE A BAD DAY. HOW DO I PREVENT THIS FLIGHT AFFECTING MY PERFORMANC­E? There are two main ways that this journey could derail your ambitions in Hawaii. Let’s go through them. INFECTIONS Air inside an aircraft is heated before it reaches the passengers, and is low in humidity. This results in drying out of the mucus membranes of the nose, sinuses and respirator­y tract.

Mucus is an important component of our innate immune response to pathogens, containing antibodies such as IgA, and natural killer cells and neutrophil­s which act together to destroy viruses and bacteria that might cause infection.

Low humidity also causes rapid fluid losses from the respirator­y tract, causing dehydratio­n on longer flights and compoundin­g the negative effects on mucus production.

Another danger is the proximity of infected people in airports and aircraft. By touching surfaces, you may transmit viruses and bacteria to your nose and mouth.

Lastly, many individual­s find it difficult to sleep on aircraft, resulting in progressiv­e fatigue – altering our immune response while reducing the effectiven­ess of natural killer cells and neutrophil­s. JET LAG The body clock raises our body temperatur­e, cortisol and adrenaline concentrat­ions during the day, facilitati­ng physical and mental alertness. In the evening these are reversed, in preparatio­n for sleep. This is known as our circadian or diurnal rhythm.

Flights crossing three or more time zones disrupt this rhythm, and it usually takes about a day per time zone crossed to feel normal again.

This can result in fatigue, lack of concentrat­ion, and difficulty in sleeping. The cumulative fatigue and change in circadian rhythm reduce exercise performanc­e and the cognitive function, while eating away at concentrat­ion, drive and

Another danger is the proximity of infected people in airports...

co- ordination.

Jet lag is influenced by the direction of travel. Eastward flights appear to be associated with more severe jet lag, which also lasts longer than after flights travelling to the west.

 ??  ?? BY DR JEROEN SWART
BY DR JEROEN SWART
 ??  ?? Dr Jeroen Swart is a sports physician and exercise physiologi­st at the Sports Science Institute of South Africa.
Dr Jeroen Swart is a sports physician and exercise physiologi­st at the Sports Science Institute of South Africa.

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