INTRODUCTION
Exercise is one of many non-pharmacological and non-immunological
stimuli that can produce acute episode of airway obstruction in patients with
asthma.1 National Heart Lung
and Blood Institute and National Institute of Health in its consensus report on
diagnosis and management of asthma defined Exercise induced bronchospasm
(EIB) as the occurrence of airway obstruction immediately to 30-min after
moderate exercise.2 Athletes with asthma have a wide range of
disability, allowing them restricted participation in sport.3.A
history of post-exercise signs and symptoms such as dyspnea,
coughing, shortness of breath and wheezing usually manifest it. The intensity and duration of action
necessary to produce bronchospasm is 5 to 8 min of
maximum effort.4
EIB is a temporary narrowing
of the airway or bronchospasm, which is induced by
exercise5 Many highly trained athletes of various events experience
exercise induced bronchospasm (EIB).6-8 In addition to genetic predisposition,
social and environmental factors such as economic prosperity, western life
style, and housing conditions are important determinants in the expression of
asthma. Exercise induced bronchospasm is a common
feature of asthma and exercise Challenge test provides a non–invasive tool for
determining airway hyperresponsiveness in
epidemiological studies of both children and young people.1
It is believed that this is
the first study describing EIB in Pakistani athletes. Our objective was to determine frequency of Exercise-induced Bronchospasm (EIB) in athletes at Karachi, who had
represented or were aspiring to represent Pakistan at national
and international level.
MATERIAL AND METHODS
One hundred and seventy nine (179) athletes met our
criteria and were included in the study. They played in-door and/or out-door
games and performed exercise daily. This was a descriptive study on the frequency of EIB in
athletes at Karachi. An athlete was defined as one who was trained or
skilled in exercises, sports or games requiring physical strength, agility or
stamina9.
Male athletes of 18 to 40 years were
included who represented national, provincial, district, departmental or
institutional team. Athletes with asthma or taking medication for asthma,
hypertensive or taking anti-hypertensive medications with history of cold, sore
throat, runny nose, cough for the last 4 weeks smoker
and/or tobacco chewer of any frequency or duration were excluded. Athletes with
known diagnosis of cancer, diabetes mellitus, tuberculosis, ischemic heart
diseases and history of abdominal or chest surgery or any medical condition(s)
limiting their ability to participate in challenge exercise testing.
An acquaintance session was
conducted to introduce the athletes to the study. All questions were answered during the
session to increase co-operation of athletes. Peak expiratory flow meters (Pocketpeak
– Hudson Respiratory Care Inc.)10 were shown to the athletes and the
instructions related to the use of PEF meters were explained. The field
investigator showed them how to record the peak respiratory flow rate. Under
supervision each player practiced till his three consecutive readings with a
difference of not more than 5% between each reading was recorded. To minimise
the technical sources of variation athletes through out the study used same PEF
meter. To minimize the biological sources of variations of lung function, PEF
reading were recorded according to the guidelines laid down by American
Thoracic Society11.
Athletes were advised not to perform any
exercise, stretching or warm-up on field testing day prior to exercise and
following pre-exercise readings were measured:
·
Pulse
rate by pulse oximeter (Pulse oximeter
Model 305, Palco labs, Inc.)12
·
PEF
rate; three readings were recorded out of which one with maximum value was
selected
·
Blood
pressure by mercury desk type sphygmomanometer.
·
Weight
without shoes by bathroom scale after calibration.
·
Height
without shoes by placing scale against a wall.
·
Temperature
of the ground by dry and wet bulb and relative humidity of the ground by
Stevenson Screen Hydrometric Tables were measured.13
Athletes ran competitively for six minutes on track or
ground where they practised in batches of two at a time. Pulse rate was
measured by pulse oximeter at 0, 5, 15 and 30
minutes. Those athletes who achieved 70% of the target heart rate at 0-minute
post exercise were included.
Three readings of PEF rate at 5, 15, and 30 minutes
were taken and the one with maximum value was selected from each of the three
readings.An
athlete was considered EIB positive based on a post exercise decrement in PEF
rate ³ 15%. 1,14-16
The data was fed on computer package “Microsoft
Excel” and analysis was done on computer package “EPI-info” ver
6.0 software of CDC (Centre for Disease Control, Atlanta, USA). The results were given in the text as
number for qualitative variables like personal, biological and environmental
characteristics, mean and standard deviation (S.D.) for quantitative variables
like age, Peak Expiratory Flow (PEF) rate. Mean, Standard Deviation of PEF rate
pre and post exercise between groups ( EIB –ve and EIB +ve athletes) by
Student t-test (paired) were compared , and odd ratio calculated. In all
statistical analysis, only p-values <0.05 were considered significant.
RESULTS
The number of athletes who suffered from EIB in
various sports is given in table 1. The mean age of athletes was 27+ 6 years. The pre-exercise mean PEF rate was 552 + 77 L/min
at 5-min post exercise it was 547 + 79 L/min, at 15-min post exercise
543 + 79 L/min and at 30-min post exercise 541 + 79 L/min. The
pre and post exercise PEF rate in athletes with and without EIB is given in
table 2. The post-exercise PEF rate was compared with pre exercise value to
diagnose the presence of EIB. Thirteen
athletes had ³ 15% decreased in PEF rate. Five athletes developed
EIB at 5-min while one continued it till 15-min and one continued till 30-min.
Seven athletes developed EIB while three continued it till 30-min. EIB
continued from 5-min to 30-min only in one player.
Table 3 shows univariant
analysis of environmental and biological risk factors for EIB.
Table-1: Games of athletes who suffered from EIB
|
Games
|
No.
|
|
Swimming
|
1
|
|
Boxing
|
4
|
|
Foot Ball
|
1
|
|
Hockey
|
6
|
|
Basket Ball
|
1
|
|
Total Athletes:
|
13
|
Figure-1:Frequency of EIB in
athletes
DISCUSSION
Exercise testing is often used as an objective method
for the diagnosis of asthma in epidemiological studies.17-22 It is probably the first study
to determine the frequency of EIB in athletes in Pakistan.The goal of our study was to screen
athletes for EIB using a protocol that tested the athletes in the environment
of their training at an exertion level at which they are commonly trained.
These reports and our finding of a 7% incidence of EIB suggest that EIB may be
common and warrant extensive screening of athletes at risk. The frequency
reported herein is comparable to what has been found previously in young
athletes and Air Force personnel .4,14,23-27
Katten et al established that PEF rate and FEVI
were the most sensitive tests and were abnormal in 83% and 84% respectively, of
those asthmatic children who had a positive exercise test response. The use of
peak flow meter was chosen for its practical usage for a large group of
athletes in the field environment. We noted that evaluating the FEVI , is an accepted value but full spirometry evaluation was not practical and the PEF rate
can give reasonable indicator of broncho-constriction
as suggested in other studies .1,14-16,28 The importance of performing testing instead of
relying on symptoms, lack of symptoms or surveys as a method of EIB diagnosis
or exclusion has been emphasised because of a lack of correlation between
subjective symptomatic parameters and testing positive for EIB. 7,14,24,
25,29-31 In analysing the survey
results to correlate those testing positive for EIB and giving a positive
response to survey questions we found no correlation it confirms the findings
of others workers.14,24, 25,29-31 It demonstrates the lack of
specificity of reported EIB symptoms. Recent studies regarding the screening
and diagnosis of EIB have focused on testing the athletes in the environment of
competition. Performing the exercise challenge in the environment was of
specific interest in our study population of athletes. The temperature of the
ground was measured by dry and wet bulb and later on converted into relative
humidity of the ground by Stevenson Screen Hydrometric Tables .13 The result presented in this
report increase the need for assessment and therapeutic control. Pulmonary
function testing is easily carried out at training and competition sites and
under these conditions probably yield the most useful
information concerning EIB in competitive athlete. It is suggested that either the department or national
sports body should screen for EIB making it a part of their training sessions,
so that performance of athletes with EIB could be enhanced. Diagnosed cases
should then be treated as per the guidelines laid down by International Olympic
Committee Medical Commission.
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