NUTRITION IN SPORT

increased loss of water from the respiratory tract
and through skin. Drinking fluids before, during
and after travel is essential. Carrying bottled
water can provide fluid, while sport drinks, juice
packs and soft drinks provide both carbohydrate
and fluid. On transcontinental flights, most air-
lines are aware of the risks of dehydration and
frequently offer water, juice or soft drinks. If this
service is not sufficient, ring the flight attendant
call button and request fluids on a routine (e.g.
hourly) basis. Ask for a whole bottle or can, or
even two, rather than a small glass. When a large
team is travelling together, the airline might
be warned in advance that demand for fluids
is likely to be high and an extra provision
requested. In any case, it is unwise to rely on

an adequate amount being available and each

athlete should be self-sufficient for the duration

of the flight. Particularly when travelling to hot

climates, sufficient fluid should be taken to allow

for delays at immigration and customs upon

arrival.

Jet lag

Jet lag is a common problem for athletes who

travel through different time zones (Reilly et al.

1997a). It results from a disruption of the body’s

rhythms and sleep–wake cycle. Fatigue, distur-

bances of sleeping patterns, poor concentration,

digestive problems and irritability are usual

symptoms of jet lag. Studies have shown that the

‘competitive edge’ can be lost after crossing as

few as one or two time zones (US Olympic Com-

mittee 1988). Symptoms of jet lag are generally

more severe when travelling from west to east

rather than in the opposite direction (Reilly et al.

1997b). Although athletes generally suffer less

than sedentary individuals, in terms of general

symptoms (Reilly et al. 1997a), the implications

for performance are perhaps more serious for

the athlete who may have to recover quickly

and compete soon after arrival. A rough rule of

thumb is that one day is required at the new

destination for each time zone crossed, but it is

clear that there is a large variability between

individuals in the speed of adjustment.

Both the type of food consumed and timing of

meals are important considerations in helping

the body adapt to time zone shifts. Although the

light–dark cycle is perhaps the most important

signal involved in setting the body’s internal

clock, the timing of meals and of exercise are also

important signals. The composition of meals and

the amount of food eaten may also have some

impact. High-protein foods (meats, cheese, fish,

poultry and tofu) are reported to stimulate the

adrenaline pathway and increase alertness.

High-carbohydrate foods (pasta, rice, bread,

fruit) increase insulin secretion, which facilitates

the uptake of tryptophan, an essential amino

acid which is then converted to serotonin, and

ingestion of meals with a high carbohydrate

the travelling athlete 487

Fig. 36.1In many sports, elite performers travel long
distances on a regular basis. This adds many problems
when there is little time for recovery between
competitions. Photo © Allsport / A. Bello.