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214
INTRODUCTION
Global travel and international compe-
tition are inevitable for the modern-day
athlete and sports team. Jet lag can cause
disarray for the individual athlete as well
as for the whole team. Jet lag is caused by
rapid transmeridian travel across different
time zones, and is generally considered as
a syndrome where the internal body clock
is out of sync with the destination time
zone. Its impact depends on the duration
and direction of flight, the flight schedule,
and individual differences. Jet lag tends to
be transient and can result in physiologic
disturbances and a complicated set of
physical symptoms1,2 .
Furthermore, in the short-term, at the
new location, the traveling athlete is exposed
to diverse allergens or strains of pathogenic
organisms, unfamiliar environmental con-
ditions (temperature, humidity, altitude,
pollution), and variation in diets that may
lead to a higher burden of illness3,4.
Knowledge regarding the preparation
and management strategies to assist
travelling athletes and teams are therefore
essential for the accompanying physician
and support staff. The aim of this article is
to firstly equip the travelling athlete and
-team with a methodical approach during
the pre-travel-, flight- and post-travel
periods in order to minimise the effects
of jet lag1,2 and to secondly give practical
advice on strategies to manage the risk of
illness during traveling – protecting athlete
health3,5,6.
A. THE MANAGEMENT OF JET LAG IN-
CLUDES PRE-TRAVEL, IN-FLIGHT JOURNEY,
AND POST-TRAVEL PERIODS
Pre-travel period:
Pre-travel strategies to mitigate jet lag
can be complicated due to the athletes’
constrained schedules and limited options
of flight selections7. Choice of flight-times
and the period of layover when travelling
will assist with effective adaptation1,8,9.
In the seven days prior to travel, modified
training routines with reduced training
volume and intensity should be adopted7,
and the adjustment of training times to the
destination time zone can be considered.
Adequate sleep (typically defined as six
to eight hours per night) is important and
COPING WITH
JET LAG AND
PROTECTING
ATHLETE HEALTH
WHEN TRAVELLING
– Written by Dina C Janse Van Rensburg, Audrey Jansen van Rensburg and Martin P Schwellnus, South Africa
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SPORTS MEDICINE AND SCIENCE IN ATHLETICS TARGETED TOPIC
several studies have highlighted that good
sleep results in better sports performance10-14.
Sleep debt should therefore be reduced to
the minimum. Evidence also exists that
shifting the sleep schedule at one hour per
day towards the destination time zone is
effective to assist with phase advance or
-delay, but may be impractical7,15.
Pre-departure pearls include:
• Get enough sleep to avoid sleep
deprivation (six to eight hours per
night).
• Reduce training volume & intensity
(seven days prior to departure).
• Consider travel schedules, to assist
sleep-wake cycle .
• Shift bed- and mealtimes one to two
hours earlier before travelling east &
one to two hours later before travelling
west to adapt to local time at the new
destination time zone (effective pre-
adaptation).
During journey:
The in-flight management period
of the journey is crucial for recovery
and adaptation, and to prepare for the
destination. A few factors need to be
considered, including travel fatigue and jet
lag, hypoxia due to reduced cabin pressure
and infection risk due to the confined
environment.
In a study by Waterhouse et al2,
individuals with a short interval between
their last full sleep before their flight and
their first one at their destination, had less
jet lag than those whose interval between
full sleeps were longer. Physicians can also
strategically use sedatives and/or melatonin
to facilitate sleep, but only if athletes have
used these substances before.
During journey pearls to mitigate travel
fatigue and jet lag include1:
• Comfortable shoes and clothing.
• Avoid large meals.
• Keep hydrated.
• Avoid alcohol and caffeine.
• Adjust watch to destination time.
• Maximum rest/sleep.
• Follow sleep/wake pattern of desti-
nation.
• Minimal distractions (e.g. electronic
devices).
• Stretch and walk when awake.
Physical performance may not only be
impacted by circadian rhythm disruption,
but also by hypoxia suffered during airline
travel. During routine commercial flights
the cabin is only pressurised to a reduced
atmospheric pressure of 2438 m altitude,
resulting in a decrease of arterial oxygen
partial pressure (PaO2) from 95 mmHg to
60mmHg, and a 3–4% decrease in systemic
oxyhaemoglobin saturation. This may lead
to mild hypoxia16. It is plausible to consider
that time spent on long-haul flights should
be seen as time spent at altitude with
similar consequences17-18. Furthermore the
cabin is a closed environment with fellow
passengers and specific areas like tray tables
posing a high risk for infection19-21.
During journey pearls to mitigate hypoxia
and an increased risk of infection20:
• Understand the impact of lower cabin
air humidity, altitude and hypoxia in
the athlete.
• Beware of seat location or contact areas
for infection risk and take prevention
(Also refer to section on protection of
athlete health, and specifically Table 5):
• sitting in an aisle seat,
• proximity to ill passengers,
• contact areas: head rest, tray tables,
arm rests, seat controls, seat belt
buckle, toilet flush button, bathroom
stall lock, drinking fountain buttons,
etc.),
• overhead air vent.
Post-travel (at destination):
The post flight period of substantial jet lag
disturbance extends from two to four days
on arrival. During this time, the athlete’s
216
Figure 1: Impairments as a consequence of circadian desynchronization.
Table 1
Table 1: Implications of circadian rhythm disruption.
Cognitive impairment
(memory, motivation, mood,
reaction time, alertness,
vigilance, interval
timing)
Jet lag
Circadian misalignment
Sleep
deprivation
Fatigue
(physical decline,
rest defects)
Risk of
injury / illness
Physical
performance
Sleep
disturbance:
• Daytime sleepiness
• Night-time sleep interruption, insomnia
• Intermittent fatigue
• Avoid long naps - it anchors the body clock to the departed time-zone
• Altered and irregular sleep-wake cycles
• Difficulty falling asleep and staying asleep travelling west
• Difficulty waking up and staying awake traveling east
• Changes in sleep-wake cycles are transient - normal sleeping patterns tend to restore before
internal body temperature returns to normal
Gastrointestinal
(GIT)
disturbance:
• Indigestion may lead to heartburn, nausea
• Diarrhoea may give rise to dehydration
• General bowel irregularities, constipation, discomfort
• Para-athletes have varying severity
Cognitive
implications:
• Changes in mood, depression, not feeling refreshed
• Decreased cognitive skills, impaired concentration and memory
• Reduced reaction time, poor eye-hand coordination
• Low motivation, morale, increased stress, anxiety
• Reduced vigilance & alertness, decreased performance
Other
implications:
• Plasma insulin fluctuation and blood glucose response to time of meals (important in diagnosed
diabetics)
• Inappropriate meal times may impact metabolic function and lead to neural and behavioural
changes as well as appetite and metabolism disruption
• Inhibited sleep may cause altered neuromuscular performance with impact on concussion and
musculoskeletal injury
• Menstrual cycle abnormalities
activities (including meals, sleep, rest, and
recovery) need to be strategically planned
by the support team to accommodate rapid
circadian adjustment. The direction of travel
is very important as, in most individuals,
the body’s circadian rhythm is naturally
longer (approximately 24.2 hours) than the
set 24-hour light–dark cycle of one day. As
a result, it is easier for individuals to adapt
to a longer day than to a shorter one22-24. The
impact of travelling eastward is therefore
more detrimental than travelling westward
for most individuals. The fastest rate of
adapting to the new destination time zone
is approximately half a day per time zone
crossed when travelling west, or 1 day per
time zone crossed when travelling east7,22,25.
The direction of travel may also have
implications for training and preparation
for matches. A hypothesis related to
circadian rhythm of performance is that
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SPORTS MEDICINE AND SCIENCE IN ATHLETICS TARGETED TOPIC
Figure 2: Phase shifts (advances or delays) of the body clock as produced by exposure
to light and exogenous melatonin ingestion, at different times of the day (Adapted from
Waterhouse et al2).
performance peaks in the evening, and the
time of competition may be a critical factor
affecting performance post-travel. Winter et
al reported that in early afternoon baseball
competitions, the teams travelling east-to-
west will have a disadvantage over time
zone adapted teams in the west, since the
game would occur closer to the travelling
team’s local bedtime26.
Furthermore, travelling between the
northern and southern hemispheres
causes disorientation due to changes in
winter-summer climate and a shift in
timing (sunrise and sunset). Travellers also
experience variation in natural lighting
and the amount of solar irradiation with
seasonal changes – predominantly during
mid-winter/mid-summer when light
variances are greatest and less in autumn/
spring2.
Due to circadian rhythm disruption,
the traveling athlete may in the short-
term be exposed to sleep disturbances, a
change in mood and fatigue levels and a
possible higher burden of illness and injury.
However, additional research is needed to
support this. The duration and severity of
symptoms experienced by the individual
athlete, depend on the number of time
zones crossed27, and the direction of travel18.
This may potentially have a negative impact
on physical performance28,29 as is explained
by Figure 1 and further discussed in Table 1.
Optimising the timing of interventions to
counteract jet lag is complicated by some
challenges:
The circadian phase is synchronised to
the local solar light–dark cycle and promotes
alertness during the day, and sleep at night.
The challenge remains to determine the
best timing of an intervention for circadian
re-entrainment after time-zone shift9. In
the clinical setting several measures are
currently used to evaluate the human
circadian system. These include wearable
wrist-watch accelerometer, melatonin and
cortisol biomarkers (hourly urine, saliva or
blood samples for 1 to 2 days) and core body
temperature measurement (rectal probe,
oesophageal probe or ingested telemetry
pill monitoring)30-34.
There are significant intra- and inter-
individual variation in the ability to
tolerate circadian phase misalignment.
An individual’s chronotype preference
(evening-types vs morning-types) may
affect their travel responses, and adaptation
rates to eastward and westward travel32,35.
Chronotype is partly influenced by our
environment, but the differences in
circadian rhythms are also linked to
individual genetic variances36-39.
Incorrect timing of interventions may
induce a phase-shift in the wrong direction
and pharmacologic interventions may
cause side effects.
Management strategies for jet lag:
A combination of scheduled light
therapy, light avoidance, and melatonin
therapy can be implemented as fatigue
countermeasures1. The phase shifts of the
body clock (advance and delay) created by
light and exogenous melatonin ingestion at
different times during the day is illustrated
in Figure 2.
Additionally, the careful use of a nap that
coincides with the circadian nadir (lowest
point in each 24-hour cycle) to reduce
cumulative sleep debt and consequent
fatigue, and caffeine according to each
individual’s need can improve the alertness
of the athlete and reduce symptoms of
fatigue.
Effective management strategies that
are described in scientific literature, can
be divided into pharmacological and non-
pharmacological interventions, and are
summarised in Table 2.
Post-travel (at destination) pearls include:
• Take a shower on arrival at destination.
• Take a brief nap, if feeling exhausted.
• Time-zone transitions < 8 hours east,
promote a phase advance of the body
clock.
• Time-zone transitions < 8 hours west,
promote a phase delay of the body clock
• For journeys > 9 time zone hours east, it
is more convenient to adjust by phase
delay.
• The direction of adjustment may
have implications for training and
preparation for matches.
• Most important determining factors are
timely light exposure, physical exercise
and melatonin administration.
Body clock time (h)
DLMO
DLMO
1200 1800 2400
Dim-light melatonin onset
Tmin: Core Body Temperature minimum range
Normal sleep time
0600 1200
Tmin
Melatonin
Light
Normal sleep time
Delay
Delay
Advance
Advance
218
• The rule is to modify behaviour rather
than use medication to facilitate
adjustment.
B. PROTECTING ATHLETE HEALTH
Protection of the health of the athlete
starts before travel commences. Essential
points to consider are listed in Table 3.
Important factors that need to be
considered at the destination are different
environmental conditions and culture, as
well as the availability of medical facilities
and services as explained in Table 4.
Athletes are exposed to an increased
risk of illness and injury during travel and
participating at events. During the 2016
Olympic Games in Rio de Janeiro it was
reported that overall, 8% of the athletes
incurred at least one injury, and 5% an
illness. This was slightly lower than in
the Olympic Summer Games of 2008 and
201243. Accumulation of evidence shows
the incidence and characteristics of sports
injuries and illnesses that occur during
sports events varies substantially between
sports, perhaps demonstrating the need to
tailor preventative measures to the specific
context of each sport3,43-52.
Furthermore para-athletes are a
unique group with a wide variety of
medical conditions, including intellectual
or sensory (e.g. visual) or physical (e.g.
amputation, spinal cord injury, cerebral
palsy) impairments. They are often disabled,
not only by their physical or intellectual
impairments, but by a society that does not
accommodate difference. Some common
medical issues will prevail in relation to the
impairment types that need to be considered
as part of medical provisions at events.
Over the course of time, epidemiological
studies to monitor injury and illness in
para-athletes have been initiated at both
Paralympic Summer and Paralympic Winter
Games45,53.
In an article by Janse van Rensburg et
al. describing epidemiology, risk markers
and preventative strategies among para-
athletes, the key points were6:
• The para-athlete has a documented risk
of contracting an illness at times of key
sporting events.
• Illness patterns are consistent for the
Summer and Winter Paralympic Games.
• Illness mainly affects respiratory,
dermatological, and digestive systems.
• Sporting code (specifically athletics)
may be an important extrinsic risk
marker for illness.
• Age and sex are not accountable as risk
markers.
Non-
pharmacological
• Light exposure early evening & first part of the night (on home, not destination time) induce
adjustment by phase delay following westward travel
• Light exposure early morning & second half of the night (home, not local time) induce
adjustment by phase advance following eastward travel
• Avoid exposure to blue light shortly before bedtime (laptops, tablets, TVs, LED, etc.)
• Optimize quantity and quality of sleep. Perform quiet activities before going to sleep (reading)
• Sleep in a quiet and comfortable room
• Disciplined approach to food & hydration (avoid exotic/spicy meals)
• Shift meal times to destination time
• Caffeinated drinks increase destination daytime alertness - avoid after midday
• Low intensity exercise session for first few days after a long flight while jet lag effects are most
severe
• Optimum exercise time, amount & type needed to effectively reset circadian clock has not been
established
• Athletes are likely to engage in physical exercise as part of normal training for competition &
can strategically plan time & intensity of training as per the strategy for light exposure
Pharmacological
• Melatonin has both hypnotic and chronobiotic properties, and is beneficial in rapid
resynchronization and for promoting sleep in intercontinental jet travellers. Concerns re. timing
and dosage, legal status in different countries, World Anti-Doping Agency rules
• Strategic use of sedatives (hypnotics) to improve sleep e.g. Zolpidem®
• Stimulants can be used, e.g. slow-release caffeine early morning at local time. Avoid stimulants
(caffeine, nicotine, , alcohol) before bedtime
Table 2
Table 2: Non-pharmacological and pharmacological Interventions9,22,40.
The prevention
of illness in
athletes involve
implementation
of behavioural,
lifestyle and
medical
strategies in
order to limit the
transmission of
infections.
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Table 3
Table 3: Essential points to assist in journey planning.
Table 4: Factors and conditions to consider at the new destination.
Table 1: Non-pharmacological and pharmacological Interventions9,22,40.
Medical screening • Past medical history (asthma, allergies, diabetes, etc.)
• Current health status (any acute illness/injury)
• Current medications and restrictions (acute or chronic)
Special needs (e.g.
para-athletes)
• Number of accessible disabled aircraft seating, transportation of guide dogs and additional
luggage/equipment & charges
• Accessibility of shower- and dressing rooms, public transport at destination, competition and
training facilities
• Special medical needs including pressure sores, acclimatisation, body temperature regulation,
stump–socket interface, urinary tract infections
Journey planning
• Documentation requirements - passport, visa, insurance
• Best flight options include time and duration of flight, arrival time, lay-over time, direction of
travel (east vs. west)
• Countermeasures related to seat selection, isolation of symptomatic athletes on the plane,
wiping high risk contact areas (travel medicine literature)
Vaccinations* • Depending on destination e.g. yellow fever
Chemo-
prophylaxis*
• Depending on destination and taking into consideration certain endemic areas e.g. malaria,
chikungunya virus, zika virus, etc.
Other
• Preventative clothing/equipment
• Insect repellent
• Destination country pharmaceutical legislation (e.g. travelling with codeine)
*Centers for Disease Control and Prevention (CDC) publish a fully revised and updatedversion of ‘Health Information for Internation-
al Travel’ (commonly called the Yellow Book) every two years as a reference for health professionals providing care to international
travellers. It contains the most current travel health guidelines, including emerging infectious disease threats, pre-travel vaccine and
antibiotic recommendations, destination-specific health advice, and easy-to-reference maps, tables, and charts41.
*World Health Organization (WHO) is a specialised agency of the United Nations concerned with international public health, working
with 194 member states, across six regions, and from more than 150 offices42.
Table 4
Exposed to
different
environmental
conditions
including
• Temperature differences, northern vs southern hemisphere (winter/summer), and individual
locations that differ (e.g. tropical vs desert)
• Altitude changes, from sea level to high altitude or vice versa
• Low vs high humidity
• Air, water, light and noise pollution
• Aeroallergen exposure e.g. pollen in springtime
• Strains of organisms at destination e.g. Zika virus
• Availability of drinking water
Culture
• Language at visiting country - may need a translator
• Food at destination e.g. spicy foods
• Social customs, dress codes and laws of the country
Local medical
facilities
• What is available? (hospital, medicine, medical disciplines, etc.)
• Proximity to your accommodation, contact detail
220
Personal hygiene:
a. Athletes are advised to minimise contact with people outside the team and support staff
b. Avoid shaking hands with people
c. Avoid crowded areas
d. Minimise contact with infected people (including children, animals and contagious objects)
e. Keep a distance from people who are coughing, sneezing or have a ‘runny nose’ (consider to
wear a disposable mask)
f. Rather cough or sneeze onto the elbow and not on the hands
g. Always wash hands and nose after sneezing or coughing
h. Wash hands regularly and efficiently with soap and water (especially before meals, and after
direct contact with potentially contagious people, animals, blood, secretions, public places and
bathrooms)
i. Limit hand to mouth/nose contact when suffering from upper respiratory symptoms or
gastrointestinal illness (use disposable paper towels, and refrain from touching eyes/nose to
avoid viral self-inoculation)
j. Keep insect repellent and alcohol-based hand wash gel at hand
k. Do not share drinking bottles, cups, cutlery, towels, etc. with other people
l. Avoid raw vegetables and undercooked meat, wash and peel fruit before eating, choose
beverages from sealed bottles
m. Wear covered clothing (covering the arms and legs) during training sessions when travelling in
tropical areas, particularly at dusk and dawn
n. Wear open footgear in public showers, swimming pools and locker rooms to avoid
dermatological diseases
o. Follow strategies to ensure good quality sleep e.g. strategic napping during the day and correct
sleep hygiene practices at night
Medical staff
responsibilities:
a. Develop, implement and monitor illness prevention guidelines
b. Screen for airway inflammation disturbances (asthma, allergy and other inflammatory airway
conditions)
c. Identify and manage high-risk athletes (allergies, upper respiratory tract infections, gastro-
intestinal tract problems, competition load)
d. Vaccinate for at home & foreign travel exposure; preferably out of season, including support
staff, be aware of possible side effects:
§Influenza vaccines (5-7 weeks to take effect)
§Hepatitis A & B
§Human Papilloma Virus
§Tetanus prophylaxis
§Dukoral for travellers’ diarrhoea
e. Implement on-going illness surveillance systems
f. Use sensitive tools for sub-clinical signs of illness e.g. non-specific symptoms and signs /
selected special investigations
g. Monitor for early symptoms & signs of overreaching / overtraining
h. Treat at onset of upper respiratory tract infections (zinc lozenges), to reduce sick days
i. Screen for serious medical conditions
i. Cardiac:
§Sudden cardiac death incidence 2.3 to 4.4/100,000 per year in USA
§Hypertrophic obstructive cardiomyopathy in men & African Americans
§Coronary artery anomalies, ruptured aortic aneurysm, myocarditis and arrhythmias
Table 5
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Medical staff
responsibilities:
ii. Other:
§Pulmonary embolism, exercise induced asthma, sickle-cell disease
j. Single room accommodation during tournaments for athletes with high competition load,
high performance priority or susceptibility to respiratory tract infections
k. Use facial masks during strenuous exercise to protect athlete’s airways from direct exposure to
cold (<0°C) and dry air
l. Consider zinc lozenges (>75 mg zinc/day; high ionic zinc content) at the onset of upper
respiratory symptoms (some evidence of reduced number of days with illness symptoms)
Nutrition:
a. Well-balanced diet with sufficient intake of nutrients
b. Individualised nutrition programs. Avoid essential micronutrient deficiencies
c. Encourage carbohydrate intake (during & after exercise); carbohydrate & protein (after
exercise)
d. Consider ingestion of probiotic e.g. Lactobacillus or yoghurt
e. Supplement vitamin C, vitamin D, cystine and theanine
f. Other: regular consumption of fruits and plants, polyphenol supplements (e.g. quercetin), non-
alcoholic beer, green tea etc. to reduce risk of illness
Manage load:
a. Detailed & individualised training & competition planning
b. Detailed post-event recovery plan (encompassing nutrition, hydration, sleep, and psychological
recovery)
c. Monitor and manage competition & training load (external and internal load)
d. Individualise for intra- and inter-individual variances (variances in the timeframe of response
and adaptation to load)
e. Small weekly increments of less than 10%
f. Stress management techniques, variation in psychological stressors
Table 5: General guidelines and advice to athletes, medical staff and athlete support teams to reduce the risk of illness in athletes while
competing or training abroad.
Table 6: Differences between travelling as an individual vs as a Team.
Table 6
Travelling Individual Travelling Team
Positives
• Individual adaptation possible
• No room mates, lower potential infection,
better sleep
• Time of exercise, meals, etc. not prescriptive
due to team schedule
• Shared responsibility, management
support
• Support and motivation from team
members
Negatives
• No support. All responsibility lies with the
athlete including travel arrangements,
accommodation, nutrition, medical support
• Continuous close contact with team
members, higher potential for infection
• Bed time may be a challenge
• Difficult to individualise management
strategies e.g. training times
222
Practical clinical guidelines to reduce the risk
of illness in athletes
Illness prevention is a key component to
protect the health of the athlete, and practi-
cal approaches to prevent illness are essential
to reduce the risk of illness that can restrain
participation in important competitions.
The prevention of illness in athletes involve
implementation of behavioural, lifestyle
and medical strategies in order to limit
the transmission of infections. Nutritional
strategies to maintain immunity in athletes,
strategies to measure, monitor and manage
training and competition load, and methods
to detect early signs and symptoms of
illness, over-reaching and overtraining are
also important. General guidelines while
competing or training abroad include
advice to athletes, and measures that can be
applied by medical staff and athlete support
teams (Table 5)3,5-6.
Although travelling abroad may be
considered to equally affect both the
individual athlete and the team-sport
athlete in a similar way, there are several
important elements of concern to consider
(Table 6).
CONCLUSION:
The travelling athlete or team may
suffer from travel fatigue and jet lag and
may be exposed to a variety of insults
e.g. allergens, pathogenic organisms and
unfamiliar environmental conditions
and cultures at the new destination. The
extent thereof depends on intra- and
inter-individual variation in the ability to
tolerate circadian phase misalignment.
Although many uncertainties exist on
methods to advance or delay the circadian
body clock, jet lag is potentially modifiable
with strategic exposure to or avoidance
of light, administration of melatonin
and correct timing of exercise and meals.
Furthermore, to ensure uncomplicated
travel, environmental conditions need to
receive attention and illness preventative
measures need to be in place. The key to
success remains in meticulous planning.
References
Available at www.aspetar.com/journal
Dina C. Janse Van Rensburg, M.B.Ch.B.,
M.Sc., M.Med., M.D., F.A.C.S.M., F.F.I.M.S.
Audrey Jansen van Rensburg, M.Sc.
Section Sports Medicine and SEMLI
Faculty of Health Sciences
University of Pretoria
Pretoria, South Africa
Martin P. Schwellnus, M.B.B.Ch., M.Sc.
(Med.), M.D., F.A.C.S.M., F.F.I.M.S.
Section Sports Medicine and SEMLI
Faculty of Health Sciences
University of Pretoria
Pretoria, South Africa
International Olympic Committee (IOC)
Research Centre
South Africa
Contact:
christa.jansevanrensburg@up.ac.za
PREVENTION IN ATHLETICS