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Respiratory tract symptoms in endurance athletes - A review of causes and consequences

52 Current Allergy & Clinical Immunology, June 2010 Vol 23, No. 2
re s p i r a t o r y t r a C t s y m p t o m s i n
e n d u r a n C e a t h l e t e s a r e v i e w o f
C a u s e s a n d C o n s e q u e n C e s
It is well established that medical conditions can be
associated with endurance physical activities and
that respiratory tract symptoms (RTS) is one of the
more common medical conditions that is encoun-
tered in these athletes. RTS are particularly during
intense training and immediately after competition.
There are many studies documenting that alterations
in immune parameters occur in athletes undergoing
intense training and competition. It is a common as-
sumption that RTS in endurance athletes are as a
result of infections during periods where there are
known alterations in immune parameters. However,
there are no studies directly linking alterations in
immune parameters in response to training and
documented evidence of infections in athletes. Al-
lergic conditions, in particular allergic rhinitis, are also
common in endurance athletes, and there is some
overlap in the symptomatology of upper respiratory
tract infection (URTI) and allergic rhinitis. Chronic
allergic rhinitis may also predispose to the develop-
ment of URTI. The infective hypothesis, the allergic
hypothesis and alternate hypotheses to explain the
high prevalence of RTS in endurance athletes require
further investigation. Current clinical guidelines for
the management of RTS in athletes are mainly based
on the assumption that RTS in athletes are only as a
result of an infective cause. If other causes for RTS
in athletes are documented, these guidelines may
require modification.
Correspondence to: Prof Martin Schwellnus, e-mail
MP Schwellnus, MB BCh, MSc (Med) Sports
Science, MD (Sports and Exercise Medicine), FACSM,
M Lichaba, MB ChB, MPhil (Sports Medicine)
EW Derman, MB ChB, PhD (Sports and Exercise
Medicine), FACSM, FFIMS
UCT/MRC Research Unit for Exercise Science and
Sports Medicine, Department of Human Biology,
University of Cape Town, International Olympic Com-
mittee Research Centre, Cape Town, South Africa
It is well established that regular exercise training is
beneficial in the primary and secondary prevention of
chronic diseases of lifestyle.1-3 There is therefore a
perception that athletes are generally healthy individu-
als, and that exercise training also protects against
the risk of acquiring acute medical illnesses, includ-
ing infections.4,5 However, epidemiological evidence
shows that increased exercise training (volume and
intensity), particularly in endurance athletes, can be as-
sociated with an increased risk of developing respira-
tory tract symptoms (RTS) that may be associated with
This review paper focuses on the medical conditions
that affect the respiratory system in endurance athletes,
and more specifically the possible mechanisms that
may lead to the development of RTS. These symptoms
can occur at various stages of training and competition:
the pre-competition period (during the preparation train-
ing period), during the competition (intra-competition),
or the post-competition recovery period (from immedi-
ately after the finish up to 2-6 weeks later).
Terminology and definitions
Endurance athletes can present with RTS ranging
from ‘blocked nose’, ‘runny nose’, sore throat, swollen
glands, cough, wheeze to chest pain. These symptoms
may be accompanied by additional systemic symptoms
such as fever, headache, muscle aches, joint pains and
general fatigue. In some instances the term ‘flu-like’ ill-
ness has been used for RTS which are accompanied
by systemic symptoms. In most studies where these
RTS, or more specifically upper respiratory tract symp-
toms (URTS), have been documented, these were
self-reported by athletes, without any evidence of ac-
tual infection.15 We are aware of only a few studies in
which attempts have been made to obtain actual evi-
dence of an infective agent in athletes presenting with
RTS.14,16-18 Therefore, the general use of the term up-
per respiratory tract infections (URTI), as has been used
in many reports, without documenting actual evidence
that these symptoms are due to an infection, may well
be incorrect.
At present, it is well recognised that an athlete present-
ing with RTS that are localised to the upper airways
(nose and orophraynx) is given different medical ad-
vice about exercise and training, when compared with
an athlete presenting with RTS below the orophraynx
(cough, wheeze, chest pain), or athletes presenting
with accompanying systemic symptoms such as fever,
myalgia, arthralgia and general fatigue.7 This clinical
test has also been referred to as the ‘neck check’.19-21
The use of the terms upper respiratory tract symptoms
(URTS) (‘blocked nose’, ‘runny nose’, sore throat, swol-
len glands), lower respiratory tract symptoms (LRTS)
(cough, wheeze, chest pain) and systemic symptoms
(SS) (fever, myalgia, arthralgia, general fatigue) to de-
scribe these clinical presentations is therefore more ap-
For the purposes of this paper, the following terminol-
ogy is used:
• Upper respiratory tract symptoms (URTS) refer
to the presence of respiratory symptoms that are
localised to the nose and pharynx (‘blocked nose’,
‘runny nose’, sore throat)
• Lower respiratory tract symptoms (LRTS) refer
to the presence of respiratory symptoms below the
level of the phraynx (cough, wheeze, chest pain)
• Systemic symptoms (SS) of infection refer to
symptoms such as fever, myalgia, arthralgia and
general fatigue that may accompany infections.
It should be pointed out that we are fully aware of the
fact that RTS in athletes could also be due to many
other cardiorespiratory conditions. In particular, we rec-
ognise that asthma is a very common respiratory condi-
Current Allergy & Clinical Immunology, June 2010 Vol 23, No. 2 53
tion in athletes that could give rise to RTS. However, in
this paper we wish to confine the discussions to RTS
that have been related to infections, and the main focus
is on URTS. We also acknowledge that the SS listed
above can also occur as a result of many other infec-
tions (not only those affecting the respiratory tract) and
other systemic conditions.
Respiratory tract infections (RTI), in particular URTI, are
very common in the general population,22 and are more
likely to affect individuals in the extremes of age and
the immune-compromised individual.23 It has been re-
ported that 75-80% of all acute morbidities in the popu-
lation of the USA are due to respiratory disease, 80% of
which are due to viral infections of the respiratory tract,
with an average of 3-6 respiratory tract illnesses per
person per year.22,24 URTI are the most common types
of infection, and are mainly caused by viruses.22
In athletes, it has also been reported that URTI (com-
monly caused by viruses) are by far the leading cause of
infectious diseases in the training room.22 A number of
studies have documented URTS in endurance athletes,
including runners,25-29 cyclists,14 cross-country skiers,30
swimmers,12,31,32 rowers,33 and in participants of other
sports such as tennis players,34, gymnasts,35 wheel-
chair athletes,36 and even in those undergoing military
training.37 It is very important to note that in all these
studies, there is no verification that the symptoms are
due to an infection. Hence, in all these studies it is cor-
rect to describe these as symptoms of URTI rather than
actually documented URTI. The term URTS is therefore
used consistently in this paper, when referring to these
The risk of developing URTS in athletes has been
reviewed.6,13,38 In one of the first studies to document
the relationship between URTS and endurance ex-
ercise, Peters and Bateman25 in 1983 found that the
incidence of URTS was twice as high in ultradistance
runners in the first 10-14 days following an endurance
race, when compared with suitable sedentary controls
followed up in the same time period. These researchers
also reported that the incidence of URTS was higher
among the faster runners.
Following that first report, there have been a number of
retrospective,11,39,40 and prospective14,17,18,26,27,36,41-43
studies documenting URTS in different groups of ath-
letes. An in-depth discussion of the findings of all these
studies is beyond the scope of this review. However, a
summary of the main findings from these studies is as
• Following endurance events (mainly ultramarathon
running) athletes experience an increased incidence
of URTS compared with sedentary controls.25,27,39
• Prospectivestudiesandretrospectivesurveysinen-
durance athletes over months show that increased
training is associated with an increased risk of
• Some studies report other factors that increase an
athlete’s risk of developing URTS including female
gender,11,26 decreased vitamin C intake,27 perceived
stress,11 sleep deprivation,11 and lack of awareness
about nutrition.11
• Intwoprospectivestudies,moderateintensitytrain-
ing resulted in increased natural-killer-cell function,
increased T-cell function and reduced incidence of
Over the past decade, the results of studies in athletes
and other populations have led to the commonly accept-
ed hypothesis that the relationship between exercise
training and risk of URTS is a ‘J’-shaped curve.11,19,44,45
It appears that physical inactivity is associated with an
increased risk of URTS,46 while moderate intensity and
duration of physical activity has been shown to be pro-
tective in some10,47-50 but not in all studies.51,52 How-
ever, high-intensity, prolonged exercise, such as during
endurance training and competition, may increase the
risk of developing URTS.11,26,41,53
Until recently, it was generally assumed that RTS in
athletes were due to an infective cause, and that this
increased risk of infection was because prolonged, in-
tense training or competition has been associated with
a ‘suppression’ of a variety of parameters in the immune
system. The ‘suppression’ of immune parameters in
the 3-72 hours following intense and prolonged training
has been termed the ‘open window’ period. During this
period, it is hypothesised that infective agents entering
the URT would cause URTI. Additional factors that may
increase the risk of infection are the large volumes of air
entering the respiratory tract particularly when mouth
breathing is used by athletes during high-intensity exer-
cise54 and nutritional deficiencies, in particular carbohy-
drate55 and vitamin C deficiency.28,29,56-58
However, it is also well established that RTS are not
always due to an infection and that there may be
other causes for these symptoms such as allergies
or inflammation caused by other physical or chemical
irritants.12,17,18,59 It is only more recently that other
possible causes of URTS in athletes during training or
competition have been proposed. The possible hypoth-
eses for the cause of RTS in endurance athletes are
discussed under the following headings: infective hy-
pothesis, allergic hypothesis, and other causes. Scien-
tific evidence for each of these is briefly reviewed.
Infective hypothesis for RTS in athletes
Since 1990, the relationship between an acute exer-
cise bout and immune parameters, as well as the re-
lationship between exercise training and changes in
the immune parameters, has received more and more
attention. Over the past 10-15 years, the number of
publications in this field have increased by more than
10-fold.60 There is now an extensive body of knowl-
edge documenting the relationship between exercise
and the immune system and this has been reviewed in
a number of publications.5,8,15,60-65 The main focus of
this review is not on exercise immunology, and hence
an in-depth review of the interaction between exercise
and the immune system is beyond the scope of this
review. However, the main current findings relating to
changes in the immune system as a result of exercise,
and how these may relate to RTS in athletes are briefly
It is well established that an acute bout of exercise as
well as exercise training can alter a variety of immune
parameters. Changes in systemic immunity,5 mucosal
immunity, and cytokines62 in response to exercise have
been reviewed.66 To date, there have been numerous
studies that were conducted to relate these changes in
immune parameters to URTS in athletes. However, in
most of these studies, no direct relationship between
changes in immune parameters and the presence of
URTS could be documented. This lack of association
between measures of immune function and URTS was
first pointed out by Shephard in 2000,15 and again more
recently.60,63 The evidence for a direct link between ob-
served changes in immune parameters, and the devel-
opment of URTS can be summarised as follows:
54 Current Allergy & Clinical Immunology, June 2010 Vol 23, No. 2
training can alter systemic 8,33,42,43,67-72 and mucosal
immunity34,35,37,47,73-81 by enhancing some param-
eters and suppressing others.
•Thebiological signicanceofthesealterationsinthe
immune system is not well established, and requires
further investigation.
eters and the development of RTS in athletes has
been examined,31,34,35,37,70,74,75,79,82 but to date, no
consistent cause-effect relationship has been docu-
• Nutritional interventions to change immune system
parameters and decrease the risk of URTS in athletes
have been reviewed.83,84
• Althoughtheeffectof nutritionalsupplementssuch
as carbohydrates,55 glutamine,85 and vitamin C28,29,56-58
on immune parameters have been studied,86-89 with
the exception of vitamin C supplementation,27 none
of the other supplements has been shown to de-
crease URTS in athletes.55,87
• There is early experimental evidence from one
study90 to suggest that the use of probiotics may be
of value in reducing the duration and severity of RTS
in endurance athletes, perhaps by modulating the im-
mune response to exercise training.91
It is therefore clear that the relationship between exer-
cise-induced changes in immune parameters and the
development of RTS in athletes is not well established.
Furthermore, there are no studies confirming the diag-
nosis of an infection in athletes presenting with URTS
where either serological criteria have been used, or
where actual pathogens have been cultured. In conclu-
sion, scientific evidence supporting the infective hy-
pothesis as the cause of URTS in athletes undergoing
training or competition is lacking. Alternative hypothe-
ses, perhaps linking changes in the immune system pa-
rameters during intense exercise, and the development
of RTS have to be considered. It has been suggested
that allergic disorders, which are also mediated through
the immune system, may account for the development
of at least some RTS in athletes. This hypothesis will
now be explored.
Allergic hypothesis for RTS in athletes
It is well established that allergies are very common
worldwide and that the prevalence of allergies has in-
creased over the last few decades.92,93 The prevalence
of allergic diseases in the population of industrialised
countries has been estimated at 10-25%. As men-
tioned, allergies have increased significantly over the
last 50 years in developed countries, probably as a re-
sult of air pollution.94 There is a very wide spectrum
of clinical presentations of allergic conditions, ranging
from a benign rash to exercise-induced anaphylaxis.95
Allergic conditions of the respiratory tract in athletes
can vary from allergic sinusitis, allergic rhinitis, allergic
rhinoconjunctivitis to allergic asthma, and these condi-
tions have been reviewed in other papers in this issue
of the journal.93,96-99 In summary, there is evidence that
allergies are common in elite athletes with the preva-
lence of any allergy varying between 16% and 32%.
For the purposes of this review paper, it is important
to note that the clinical presentation of allergic condi-
tions that affect the respiratory tract may mimic those
of URTI. Common URTS that could be due to either
infections or allergies are ‘blocked nose’ and ‘runny
nose’, while more systemic symptoms, such as head-
ache, malaise and fatigue, can also occur as a result of
allergies.93 Associated symptoms, such as itchy nose,
sneezing and itchy runny eyes, are more likely due to
allergic than infective causes.54,98,100 However, chronic
allergies can, similarly to infections, also result in im-
paired sports performance; the mechanisms underlying
this effect have been described in this edition of the
journal.93,101 It can be therefore be hypothesised that
URTS in endurance athletes may be related to allergies
rather than being infective in nature, or there may be
an interaction between these two mechanisms. There
may well be a continuum of URT disease with an over-
lap between respiratory tract allergies and infections,
which has to date not been explored.
Other hypotheses for RTS in athletes
(physical factors)
Any discussion of the possible causes of RTS in ath-
letes will not be complete unless it is mentioned that
many other irritants can also cause an inflammatory
response in the respiratory tract. A non-allergic, non-
infective rhinitis can be caused by physical factors.
Physical factors that may cause RTS in athletes include
high ventilatory rate, cold, dry air, increased air turbu-
lence, mouth-breathing, and inhaled irritants (physical,
chemical and allergens).12,17 When the ventilatory rate
exceeds 30 l/min there is a tendency towards both
mouth breathing and nasal breathing and this causes
deposition of airborne allergens and irritants in the up-
per and lower respiratory tracts.54 Pollutant irritants are
classified as primary or secondary. Primary pollutants
are directly from the source such as inorganic gases.
Secondary pollutants result from chemical reactions
of emitted and natural precursors. Pollutants of major
concern to respiratory health are sulphur dioxide (SO2),
photochemical smog (ozone and nitrogen dioxide, NO2)
and airborne particulates.94 Recently, it has been docu-
mented that there is an increase in airway inflamma-
tory cells, possibly related to increased ventilation of
cold and dry air.102,103 The precise relationship between
these observed inflammatory cells and respiratory tract
pathology in athletes requires further investigation.102 It
is important to point out that other hypotheses relating
physical and chemical factors to RTS in athletes may
require further study.
Summary: Hypotheses for the aetiology of
RTS in athletes
In summary, the precise aetiology and pathogenesis of
RTS in athletes during training, and immediately after
intense competition is not clear. Until recently, the pre-
vailing hypothesis for the high incidence of mainly URTS
in endurance athletes following competition was that
alterations in the immune system postexercise cause
infections. However, actual infection has never been
documented either clinically, by serological means, or
through culture of organisms. Furthermore, despite nu-
merous attempts, no clear relationship between altered
immune parameters and URTS has been documented.
Therefore, the infective hypothesis for RTS in athletes
requires further study, or alternative hypotheses have
to be considered.
Concomitantly, it has been documented that respira-
tory tract allergies, in particular allergic rhinitis, are com-
mon in athletes, especially in endurance athletes. The
symptoms of allergic conditions of the URT and the
symptoms of URTI overlap, and the possibility that RTS
in endurance athletes is related to allergies has to be
considered. Finally, other physical factors causing RTS
in athletes must not be disregarded.
Current Allergy & Clinical Immunology, June 2010 Vol 23, No. 2 55
The effect of RTS on training and performance has not
been well investigated. This is probably because the
aetiology of RTS in athletes is not established. The ef-
fects of both RTI and allergic conditions of the respira-
tory tract on training and athletic performance will now
be discussed.
There are only a few studies where the effects of
RTI on training and performance have been exam-
ined. The main reason for this is that although very
rare, some infective agents can cause an associated
myocarditis.22,104-106 Viral myocarditis has been the
cause of sudden death in athletes.105,106 Therefore, the
current guideline for athletes with documented RTS is
to avoid training if there are any symptoms of possible
concomitant myocarditis, such as chest pain, short-
ness of breath at rest, resting tachycardia, or systemic
symptoms, such as fever, myalgia or joint pain. If any of
these symptoms are present, athletes are advised not
to train at all based on clinical evidence.22 For obvious
ethical reasons the validity of this advice has not been
studied systematically.7 If symptoms are localised to
the URT, athletes frequently do not seek medical assis-
tance and, according to anecdotal evidence, many con-
tinue training. However, the effects of these localised
URTS on training and performance have not been well
The effects of febrile illness on muscle function in hu-
mans have been investigated in a few studies. In one
study where a fever was induced in seven volunteers
by inoculation with the sandfly fever virus, it was doc-
umented that there is a transient decrease in muscle
function which correlated with myalgia, rather than the
presence of fever.107 In this study, it was not possible
to distinguish between inactivity (bed rest) or the febrile
illness as the main cause of loss of muscle strength.
In another study by the same investigators, isometric
muscle strength and isometric muscle endurance were
recorded serially (during fever, after fever, at 1 and 4
months after the infection) at the time of an acute infec-
tious disease of viral or mycoplasmal aetiology in over
30 young men. In this study, the febrile illness resulted
in a 5-15% decrease in isometric muscle strength and
a 13-18% decrease in isometric muscle endurance as
compared with control subjects undergoing bed rest for
the same time period as the infected subjects.108,109 It
is important to point out that in these studies the infec-
tion was clearly documented, and that it was associ-
ated with SS (fever). The effects of a localised URTI on
exercise performance and training have to our knowl-
edge not been studied, other than in a report where
URTI was the main medical reason for absence from
training in elite skiers.30
The clinical advice that is currently given to athletes pre-
senting with RTS is largely based on whether the RTS
are confined to the upper airways (above the neck), or
whether there are LRTS or SS (below the neck). This
clinical test has been termed the ‘neck check’.19-22 The
main reasons for adopting this clinical approach are
twofold. Firstly, LRTS or SS may indicate a generalised
(systemic) infection, and systemic viral or bacterial in-
fections may be associated with myocarditis, and this
is a potential cause of sudden death in an exercising
athlete.22,104,105 Secondly, as has been discussed, there
are indications that exercise performance is impaired
significantly when LRTS or SS are present.
Therefore the current clinical approach when athletes
present with RTS is to document localised (‘runny
nose’, ‘blocked nose’, sore throat) or additional LRTS
(cough, chest pain, wheeze) or SS (muscle aches, joint
pain, fever, fatigue). If only localised symptoms are
present, moderate intensity exercise is allowed for a
short duration, and depending on how the athlete feels,
this can be continued. In the presence of any LRTS or
SS exercise is not allowed and follow-up clinical assess-
ment is advocated.19-22
However, in this current clinical approach, the pres-
ence or absence of allergic symptoms and their man-
agement, which is different to that of URTI,93,98,100 are
largely ignored. If a closer association between RTS
in athletes undergoing intense training and allergies is
documented, this current clinical approach may have to
be reconsidered.
• Medicalconditionsassociatedwithendurancephysi-
cal activities are common.
• RTSisoneofthemorecommonmedicalconditions
that is encountered in endurance athletes, particu-
larly during intense training and immediately after
• There are many studies documenting alterations in
immune parameters in athletes undergoing intense
training and competition.
• It is a common assumption that RTS in endurance
athletes are as a result of infections during periods
where there are known alterations in immune param-
• Therearenostudiesdirectlylinkingalterationsinim-
mune parameters in response to training and docu-
mented evidence of infections in athletes.
• Allergic conditions, in particular allergic rhinitis, are
common in endurance athletes.
• There is some overlap in the symptomatology of
URTI and allergic rhinitis.
• Chronicallergicrhinitismaypredisposetothedevel-
opment of URT infections.
• Theinfectivehypothesis,theallergichypothesisand
alternative hypotheses to explain the high prevalence
of RTS in endurance athletes require further investi-
• Current clinical guidelines for the management of
RTS in athletes are mainly based on the assumption
that RTS in athletes are only as a result of an infective
• Ifother causesforRTSinathletesaredocumented,
these guidelines may require modification.
Declaration of conflict of interest
The authors declare no conflict of interest.
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... Higher incidence (>four times annually) of URI in athletes is not a fact but it is observed in a lot of studies [13–16]. It is more prevalent in athletes with heavy exercise comparing with those with moderate to low activity [12, 16]. Different families of viruses cause URI including rhinoviruses, coronaviruses, respiratory syncytial, Para influenza and Influenza. ...
... Healthy adult get URI up to six times annually. Higher incidence (>four times annually) of URI in athletes is not a fact but it is observed in a lot of studies [13–16]. It is more prevalent in athletes with heavy exercise comparing with those with moderate to low activity [12, 16]. ...
Full-text available
There is a relationship between exercise and changes in immunity. So athletes are prone to different medical problems such as injuries and infections. Infection is an important medical problem which could be a reason for athletes' absence from training. The relationship between physical activity and immune system, characteristics of different types of infections in athletes with emphasis on special clinical presentations or complications, time to return to physical activity and training and strategies to prevent development and transmission of infections in athletes or physically active people are the main topics of this review.
... Regardless of whether URS are due to infectious causes or other inflammatory stimuli (allergies, airway irritation) mimicking infection, the potential for a negative impact (e.g. impaired performance) on the individual athlete may be the same[8,9]. Despite being an active and rapidly growing area of research, there remains a lack of effective countermeasures to risk of URS during exercise training[10]. ...
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Background Bovine colostrum is proposed as a nutritional countermeasure to the risk of upper respiratory symptoms (URS) during exercise training. The aim of this systematic review and meta-analysis was to estimate the size of the effect of bovine colostrum supplementation on URS. Methods Databases (CDSR, CENTRAL, Cinahl,, Current Controlled Trials, DARE, EMBASE, Medline, PROSPERO and Web of Science) of published, unpublished and ongoing studies were searched for randomised controlled trials of healthy adults (≥18 years), evaluating the effect of oral bovine colostrum supplementation compared to a concurrent control group on URS. Results Five trials (152 participants) met the inclusion criteria, all of which involved individuals involved in regular exercise training. Over an 8–12 week follow-up period, bovine colostrum supplementation when compared to placebo significantly reduced the incidence rate of URS days (rate ratio 0.56, 95 % confidence intervals 0.43 to 0.72, P value < 0.001) and URS episodes (0.62, 0.40 to 0.99, P value = 0.04) by 44 and 38 % respectively. There were limited data and considerable variation in results of included studies for duration of URS episodes hence a meta-analysis of this outcome was deemed inappropriate. The risk of bias assessment in this review was hindered by poor reporting practices of included studies. Due to incomplete reporting of study methods, four of the five studies were judged to have a moderate or high risk of overall bias. Our findings must be interpreted in relation to quantity and quality of the available evidence. Conclusions The present systematic review and meta-analysis provides evidence that bovine colostrum supplementation may be effective in preventing the incidence of URS days and episodes in adults engaged in exercise training. The fact that the majority of included studies did not report significant effects on URS outcomes mitigates concerns about publication bias. The point estimates of the random-effects meta-analyses are greater than the smallest clinically important difference, but the low precision of the individual study estimates means the evidence presented in this review needs to be followed up with an appropriately designed and adequately powered, randomised control trial. Trial registration Protocol was registered (CRD42015014925) on the International Prospective Register of Systematic Reviews (
Objective To review risk factors associated with acute respiratory illness (ARill) in athletes, including non-infectious ARill and suspected or confirmed acute respiratory infections (ARinf). Design Systematic review. Data sources Electronic databases: PubMed-Medline, EbscoHost and Web of Science. Eligibility criteria Original research articles published between January 1990 and July 2020 in English were searched for prospective and retrospective full text studies that reported quantitative data on risk factors associated with ARill/ARinf in athletes, at any level of performance (elite/non-elite), aged 15–65 years. Results 48 studies (n=19 390 athletes) were included in the study. Risk factors associated with ARill/ARinf were: increased training monotony, endurance training programmes, lack of tapering, training during winter or at altitude, international travel and vitamin D deficits. Low tear-(SIgA) and salivary-(IgA) were immune biomarkers associated with ARill/ARinf. Conclusions Modifiable training and environmental risk factors could be considered by sports coaches and athletes to reduce the risk of ARill/ARinf. Clinicians working with athletes can consider assessing and treating specific nutritional deficiencies such as vitamin D. More research regarding the role and clinical application of measuring immune biomarkers in athletes at high risk of ARill/ARinf is warranted. PROSPERO registration number CRD42020160928.
In this review there are modern data concerning the prevalence of allergic diseases among athletes of the highest achievements, their influence on health and level of athletic achievements.
Background: Cough is a common symptom experienced by athletes, particularly after exercise. We performed a systematic review to assess in this population: 1) the main etiologies of acute and recurrent cough, either exercise-induced or not; 2) how it is assessed; and 3) how cough is treated in this population. From the systematic review, suggestions for management were developed. Method: ology: This review was done according to the CHEST methodological guidelines and GRADE framework up to April 2015. To be included, studies had to meet the following criteria: participants had to be athletes, adults and adolescents aged ≥ 12 years, and complaining of cough, regardless of its duration or relation with exercise. The Expert Cough Panel based their suggestions on the data extracted from the review and final grading by consensus according to a Delphi process. Results: Only 60 reports fulfilled the inclusion criteria and the results of our analysis revealed only low quality evidence on cough etiology and to support how to assess and treat cough specifically in athletes. Although there was no formal evaluation of causes of cough in the athlete population, the most common etiologies reported were asthma, exercise-induced bronchoconstriction, respiratory tract infections, upper airway cough syndrome (mostly from rhinitis) and environmental exposures. Cough was also reported to be related to exercise-induced vocal cord dysfunction among a variety of less common etiologies. Although gastroesophageal reflux disease (GERD) is frequent in athletes, we found no publication on cough and GERD in this population. Assessment of cough etiologies was mainly done with bronchoprovocation tests and suspected disease-specific investigations. The evidence to guide treatment of cough in the athlete was weak or non-existent, depending on the etiology. As data on cough in athletes were hidden in a set of other data (respiratory symptoms), evidence tables were difficult to produce, and were done only for cough treatment in athletes. Conclusions: Etiology of cough in the athlete appears to differ slightly from the general population. It is often related to environmental exposures related to the sport training environment and occurs predominantly following intense exercise. Clinical history and specific investigations should allow identification of the etiology of cough and targeting the treatment. Until management studies have been performed in the athlete, current guidelines that exist for the general population should be applied for the evaluation and treatment of cough in the athlete taking into account specific training context and anti-doping regulations.
Full-text available
The modern-day athlete participating in elite sports is exposed to high training loads and increasingly saturated competition calendar. Emerging evidence indicates that inappropriate load management is a significant risk factor for acute illness and the overtraining syndrome. The IOC convened an expert group to review the scientific evidence for the relationship of load—including rapid changes in training and competition load, competition calendar congestion, psychological load and travel—and health outcomes in sport. This paper summarises the results linking load to risk of illness and overtraining in athletes, and provides athletes, coaches and support staff with practical guidelines for appropriate load management to reduce the risk of illness and overtraining in sport. These include guidelines for prescription of training and competition load, as well as for monitoring of training, competition and psychological load, athlete well-being and illness. In the process, urgent research priorities were identified.
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Aim: The aim of this study was to investigate the influence of IL-10 gene polymorphisms on URTI incidence. Methods: To this end, one hundred healthy elite male athletes participating in the study were classified as either healthy or prone to frequent URTI. Blood samples and DNA isolation, multiplex PCR, and Taqman real-time PCR were carried out. Genomic DNA was extracted from peripheral leukocytes of whole blood samples using the QIAmp DNA Blood Mini Kit (Qiagen, Hilden, Germany). For comparison of the distribution of genotypes between two groups and for estimating odds ratios (OR) for URTI susceptibility in relation to the IL-10 polymorphism, Pearson's chi-square and Logistic regression method were used respectively. Results: The IL-10-1082 genotype distribution differed between athletes with URTI and healthy athletes (χ2=8. 14, P=0.017). The IL-10 high-expression genotype (GG), relative to the other two genotypes combined (AG + AA), was associated with a tendency for an increased likelihood of frequent URTI (OR: 4. 63, 95% CI: 1. 58-21. 53; P=0. 033). Conclusion: In conclusion, findings from this study have identified a potential role of genetic variation in influencing the risk for URTI in athletic populations and SNPs in the IL-10 genes were associated with an altered risk profile. These measures may have a predictive value in the identification of individuals who are more likely to experience recurrent infections when exposed to high physical stress in the areas of athletic endeavor.
Full-text available
Heavily exercising endurance athletes experience extreme physiologic stress, which is associated with temporary immunodepression and higher risk of infection, particularly upper respiratory tract infections (URTI). The aim of this review is to provide a critical up-to-date review of existing evidence on the immunomodulatory potential of selected macronutrients and to evaluate their efficacy. The results of 66 placebo-controlled and/or crossover trials were compared and analysed. Among macronutrients, the most effective approach to maintain immune function in athletes is to consume ≥6% carbohydrate during prolonged exercise. Because inadequate nutrition affects almost all aspects of the immune system, a well-balanced diet is also important. Evidence of beneficial effects from other macronutrients is scarce and results are often inconsistent. Using a single nutrient may not be as effective as a mixture of several nutritional supplements. Due to limited research evidence, with the exception of carbohydrate, no explicit recommendations to reduce post-exercise URTI symptoms with single macronutrients can be derived.
Background: Unaccustomed intense endurance exercise is associated with short-term suppression of natural immunity. However, it is not established whether intensified endurance training alters resting immune status or increases the risk of upper respiratory infection (URI). Purpose: This study examined the effect of intensified endurance training for performance enhancement on resting immune status in nine healthy, male competitive cyclists. Design: Data were collected during 4 weeks of usual training (baseline), followed by prescribed cycle training that consisted of volume-building at customary training intensity (V phase, 6 weeks), unaccustomed very high intensity interval training at 100% maximal heart rate (1 phase, 18 days), and an unloading taper (U phase, 10 days). Methods: The main performance criterion was a simulated 20 km time-trial. Aerobic capacity measures included power output at ventilatory threshold (POTvent) and maximal oxygen uptake (VO2max). Markers of immune status (lymphocyte subset counts, serum cytokine levels, and new URI cases) and physiological indicators of training stress (cycling economy, 24-hour urinary cortisol excretion, and serum testosterone concentration) were evaluated in the rested state, 36 to 44 hours postexercise, during baseline, and after each training phase. Results: Time-trial performance, POTvent, VO2max, and cycling economy improved significantly (p < 0.001) after the V phase, and remained higher than baseline (p < 0.001) after the I and U phases. As compared with the V phase, performance time was faster after the U phase (p < 0.01). In contrast, lymphocyte counts, cytokine levels, incidence of URI, cortisol excretion, and serum testosterone concentration were not significantly different from baseline in any phase. Conclusions: Cycling efficiency and performance improved while resting immune status was maintained throughout the 10-week training program. This study provides encouraging data in support of immunological robustness during intensified endurance training.
[Two of the authors respond:] We agree with Herbert Nehrlich that there are many situations in which physicians would benefit from the assistance of health and fitness professionals. It is essential that such advice be sought from professionals who have received formal training and attained national accreditation. In North America1 these would be professionals certified by the Canadian Society for Exercise Physiology or the American College of Sports Medicine. Together, physicians and health and fitness professionals will be able to provide information that is based on sound physiological principles and a clear knowledge of the absolute and relative contraindications to exercise for a variety of populations. Giuseppe Lippi and associates correctly point out that vigorous exercise may lead to supplemental health gains in sedentary community-dwelling individuals. There is growing evidence to suggest that certain groups may benefit greatly from high-intensity exercise training. We1 have advocated high-intensity exercise training for sedentary individuals2 and patients with cardiovascular disease3 and chronic heart failure.4 However, we are careful to acknowledge that adherence to this form of exercise may be poor and the risk of musculoskeletal injury higher. Therefore, we must weigh carefully the potential advantages and disadvantages of vigorous exercise for each individual client. As pointed out by Ediriweera Desapriya and colleagues, discussion of the barriers to exercise and innovative means to deliver inclusive and culturally appropriate physical activity interventions is of great importance. Furthermore, more effective lifestyle interventions are required to address the global crisis of physical inactivity. We have worked diligently to address the barriers to physical activity and have taken a transdisciplinary approach to the creation of novel exercise interventions. More work is required to “develop and deliver” inclusive interventions for all, but we believe that our work1,5 is a step in the right direction. As Rajesh Chauhan and associates point out, the determinants of health are multifactorial and physical activity is not the sole factor influencing health status. However, physical inactivity is an independent predictor of the risk for many chronic diseases and premature mortality. In fact, the risk for chronic disease and premature mortality in North America appears to be about 20% to 50% greater among those with a physically inactive lifestyle.5 Furthermore, physical activity appears to be protective in the presence of other known risk factors for chronic disease. Therefore, there is compelling evidence to support the independent health benefits of physical activity.
Presents current information on exercise, immunity, and infection in athletes and active people, focusing on well-established immunologic changes and practical clinical aspects of common infections. The article also guides physicians on what to advise active and athletic patients. (SM)
FUSAFUNGINE REDUCES SYMPTOMS OF UPPER RESPIRATORY TRACT INFECTIONS (URTI) IN RUNNERS AFTER A 56KM RACE Schwellnus, M FACSM; Kiessig, M; Derman, W FACSM; Noakes, T FACSM Author Information University of Cape Town, South Africa (Sponsor: M Schwellnus, FACSM) Supported by Servier Laboratories SA (Pty) Ltd The effect of Fusifungine, a topical anti-inflammatory/anti-bacterial nasal/oral spray, on the incidence of symptoms of upper respiratory tract infections (URTI) in the 9 days following a 56km running event was studied. Male runners (n=96) with a 42km time of <3hrs. with no history of allergy, and with daily intakes of i) < 1000mg Vitamin C, ii) < 18mg Beta carotene, and iii) < 400 IU Vitamin E were recruited. Prior to the race, subjects were instructed on the proper use of the medication (4 sprays into each nostril and the throat 4 times daily) and then randomly allocated to either a group receiving Fusafungine (F: n=48) or a placebo (P: n=48) in a double blind manner. Subjects completed a daily logbook detailing symptoms [runny nose (RN), blocked nose (BN), all nasal symptoms (N=RN+BN), sore throat(ST), and all URT symptoms (URTS=RN+BN+ST), in the 2 days before the race, the first 3 days after, and the 4-9 days after the race. All the symptomatic subjects underwent medical evaluation. Throat swabs and viral gargles for culture were taken. No athlete with symptoms had a positive bacterial or viral culture. The incidence of symptoms (%) in the F and P group was as follows (Table not included): There was a decreased incidence (%) in URTS in the F group (F=17%; P=40%: *: p<0.05) in the period Day 0-3 after the race, with a tendency for the nasal symptoms to be lower (F=9%; P=23%: +:p=0.08) in the same period. In summary, post-race URTS are not of infective origin (viral or bacterial) and their incidence can be reduced by a topical anti-inflammatory agent. Hence post-race URTS are likely the result of an inflammatory and not an infective process.
Overtraining is a process of excessive exercise training in high-performance athletes that may lead to overtraining syndrome. Overtraining syndrome is a neuroendocrine disorder characterized by poor performance in competition, inability to maintain training loads, persistent fatigue, reduced catecholamine excretion, frequent illness, disturbed sleep and alterations in mood state. Although high-performance athletes are generally not clinically immune deficient, there is evidence that several immune parameters are suppressed during prolonged periods of intense exercise training. These include decreases in neutrophil function, serum and salivary immunoglobulin concentrations and natural killer cell number and possibly cytotoxic activity in peripheral blood. Moreover, the incidence of symptoms of upper respiratory tract infection increases during periods of endurance training. However, all of these changes appear to result from prolonged periods of intense exercise training, rather than from the effects of overtraining syndrome itself. At present, there is no single objective marker to identify overtraining syndrome. It is best identified by a combination of markers, such as decreases in urinary norepinephrine output, maximal heart rate and blood lactate levels, impaired sport performance and work output at 110% of individual anaerobic threshold, and daily self-analysis by the athlete (e.g. high fatigue and stress ratings). The mechanisms underlying overtraining syndrome have not been clearly identified, but are likely to involve autonomic dysfunction and possibly increased cytokine production resulting from the physical stress of intense daily training with inadequate recovery.
Upper respiratory tract infections and allergic diseases are particularly common in children. It seems that atopy may predispose to more severe symptoms during infections and may facilitate together with other genetic factors and with adverse environmental conditions the occurrence of chronic rhinosinusitis (CRS) and chronic otitis media with effusion (OME). The initial event in CRS is the obstruction of the osteomeatal complex, while obstruction and dysfunction of the Eustachian tube may be the preliminary event for the development of OME.
Exercise-related allergies vary from the benign rash of cholinergic urticaria to life-threatening exercise-induced anaphylaxis. Rapid diagnosis is essential, but it can be difficult to tell the two conditions apart. The size of the wheals and the patient history provide the best clues. Giving epinephrine and taking steps to protect the patient's airway, breathing, and circulation are standard treatment for exercise-induced anaphylaxis. Effective management for less severe cases involves exercising with a partner, keeping self-injectable epinephrine on hand, and avoiding exercise before and after meals. Prophylactic antihistamines are more effective for cholinergic urticaria than for exercise-induced anaphylaxis.