498

The Effect of Exercise at Various Temperatures on Salivary Levels of Immunoglobulin A T I Housh, G. 0. Johnson, D. J. Housh, S. L. Evans, G. D. Thaip Center for Youth Fitness and Sports Research, University of Nebraska-Lincoln

T. J. Housh, G. 0. Johnson, D. J. Housh, S. L. Evans and G. D. Tharp, The Effect of Exercise at Various Temperatures on Salivary Levels of Immunoglobulin A. mt JSportsMed, Vol 12,No5,pp498—500, 1991.

Accepted: December 22, 1990

The purpose of this investigation was to determine the effect of ambient temperature on the salivary immunoglobulin A (s-IgA) response to submaximal exercise. Nine adult males ( age SD = 22 2 yrs) volunteered to perform an incremental treadmill test to exhaustion for the determination of VO2max and three 30-minute treadmill runs at 80% VO2max in an environmental chamber at temperatures of approximately 6, 19 and 34 °C. Saliva samples were collected prior to each submaximal workbout as well as immediately and 1 hr post-exercise. A 2 within subjects factors (temperature, sample time) repeated

measures ANOVA indicated no significant interaction or main effects for sampling time or temperature. The results of this study indicated that 30minutes of non-competitive exercise at temperatures rangig from 6 to 34 °C had no effect on s-IgA. These findings suggest that moderate intensity exercises at a wide range of ambient temperatures does not increase the susceptibility to upper respiratory infection by decreasing s-lgA. Key words

Exercise, temperature, salivary immunoglobulin A

Introduction

Several studies (2, 10, 12) have reported that athletes involved in high-intensity training as well as those who

participate in competitive endurance events such as the marathon have an increased risk of developing upper respiratory infection (URI). It has been proposed that this increased susceptibility may be related to low resting levels and/or an exercise-induced depression of salivary immunoglobulin A (sIgA), which acts at the muscosal surface of the upper respiraInt.J.SportsMed. 12(1991)498—500 GeorgThieme Verlag Stuttgart•NewYork

tory tract to provide a first line of defense against potentially pathogenic viruses (8, 15, 16, 17). It should be recognized, however, that s-IgA is effective against recent exposure to micro-organisms, and other defense mechanisms also play an important role against newly acquired infectious agents.

Recent investigations by Tomasi et al. (16), MacKinnon et al. (8) and Tharp and Barnes (14) have reported reductions in s-IgA of up to 65% following strenuous physical activity. Tomasi et al. (16) postulated that the decrease in s-IgA following a competitive cross-country ski race may have been due, in part, to "a large inflow of cold air which would likely

lower the temperature of the mucous membranes". Furthermore, Toniasi et al. (16) suggested that studies are needed to "determine the separate influences of ambient temperature versus exercise" on muscosal antibodies. Thus, it is possible that there is an interaction between exercise and environmental stressors that may influence immunological parameters such as s-IgA. The purpose of this investigation was to determine the effect of ambient temperatures on the s-IgA response to submaximal exercise.

Material and Methods

Nine adult males (

age

SD 22± 2 yrs)

volunteered as subjects for this investigation. Informed consent was obtained from each subject prior to testing.

On the first laboratory visit the subjects performed a continuous incremental treadmill test to exhaustion for the determination of maximal oxygen consumption rate

(VO2max). The test began at 6.4 kmhr 0% grade and in-

creased 1.6 kmhr'every three minutes to 14.5 kmhr After this the grade of the treadmill was increased by 2% (with the speed remaining constant at 14.5 km• hr 5 every three minutes until voluntary exhaustion. The test was considered maximal if there was a plateau of V02 values with an increase in workload and/or an R value > 1.15 (9). During the maximal test the subjects breathed through a Hans Rudolph valve, with gas volumes and concentrations measured by a cal-

ibrated Sensor Medics Horizon Metabolic Measurement Cart. The subjects' heart rates were monitored continuously using a UNIQ CIC heartwatch system (7).

On three additional occasions, separated by at least 48 hours, the subjects ran on a treadmill for 30 minutes at

a heart rate which corresponded to approximately 80% of VO2max. The treadmill velocity was adjusted every three minutes during the runs to maintian the appropriate heart rate. All of the submaximal runs were perfomed at the same time of

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Abstract

mt. .J. Sports Med. 12(1991) 499

The Effect of Exercise at Various Temperatures

Table 1 Salivary immunoglobulin A (jigmi) responses to the low-, moderate- and high-temperature submaximal runs

2 3 4 5 6

201

217 194 149 134

216 249 246

180 225 132 128 143 202 216 295

202

191

45

53

128 165

7 8

9 SD

post

203

214 215 244 147

1

1 hour

Moderate Temperature 1 hour PostPreexercise exercise post 217 219 206 137 109

228 196 161

137 126 125

131 221

236

227 202

227 202

195

185

182

43

46

45

155

210 269 226

day. The three randomly ordered runs were conducted in an

environmental chamber at mean (± SD) temperatures of 5.95 1.72 °, 19.07 1.93 0 and 33.75 1.66 °C. In addition, the temperature fluctuated by no more than 1.60 °C during any of the individual 30-minute runs. The mean (± SD) relative humidity values during the low-, moderateand high-temperature runs were 84.6 2.7 (range 80 to 89), 44.4 8.5 (32 to 58) and 52.7 6.7 (45 to 61) percent, respectively.

Saliva Collection and Assay After rinsing the mouth thoroughly with water (13, 14), unstimulated saliva samples were collected prior to (5 —10 minutes before exercise) as well as immediately (5 —10

minutes after exercise) and one hour after the submaximal treadmill runs. The saliva was collected in 12 ml plastic urine collection tubes, immediately frozen and stored at —20 degrees Celsius for analysis.

Salivary IgA concentrations were determined by an enzyme-linked immunosorbent assay (ELISA) using Sigma reagents (3). Polyvinyl chloride (PVC) plates were incubated for 12 hours with rabbit anti-human IgA antibodies diluted in a phosphate-buffered saline (PBS) solution. The fol-

lowing day the saliva samples were thawed, centrifuged at 2,000 rpms for 10 minutes, diluted with PBS, and 50 tl of each were incubated with the plated rabbit anti-IgA antibodies.

Using Sigma's human IgA (human colostrum IgA, Sigma #1—1010), known concentrations of IgA were also plated to establish standard values. Goat anti-IgA conjugated to alkaline phosphatase was added to the plates and allowed to in-

cubate overnight. Phosphatase substrate (PNP) was then added, and the color intensity produced after 25 minutes was measured by a photospectrometer at 405 nm. All the samples were assayed in duplicate and an average of the absorbance values was used as the representative value. Regression analysis using the relationship of standard IgA concentrations and absorbance (nm) was used to interpolate the concentration of IgA in the samples. Previous investigations have shown the ELISA assay for IgA to be highly reliable and sensitive (3, 5).

Results

The mean (± SD)VO2maX and maximal heart ml/kg-min

rate values for the subject were 51.3

223 214 195 143 113

144 207 284 225 194 53

High Temperature PrePostexercise exercise

1 hour

post

194 207 190 140 129 158 202 253 219

258 219 202 134 133

204 234 160 124

144

164 229 256 218

188

202

40

56

196 278 256

141

192 46

(range =' 42.4—57.3) and 196

bpm (range 185—208), respectively. The mean (± SD) V02 values (estimated using linear regression for V02 versus heart rate relationship from the VO2max test) during the low-, moderate- and high-tem(78% VO2max), 40.0±4.3 perature runs were 40.1 (78% VO2max) and 41.0 4.1(80% VO2max) mi/kg - min respectively. One-way repeated measures ANOVA indicated that there was no significant difference (p > 0.05) between the mean V02 values for the three submaximal runs. Table 1 includes the s-IgA values for each subject prior to as well as immediately and one-hour after the lowmoderate- and high-temperature submaximal runs. A 2 within

subjects factors (temperature, sample time) repeated mea-

sures ANOVA indicated that there was no significant (p > 0.05) interaction or main effects for sample time or tem-

perature. As a result of the low-temperature exercise, the s-IgA

levels for one subject (subject 9) increased immediately following the run, decreased for seven subjects (subjects 1, 2, 3, 4, 6, 7 and 8) and remained stable for one subject (subject 5). For the moderate-temperature run, three subjects (sujects 1, 5 and

7) exhibited an increase in s-IgA immediately post-exercise while three (subjects 4, 8 and 9) showed no change and three (subjects 2, 3 and 6) decreased. The high temperature run resulted in an increase in s-IgA immediately after the workbout for six of the subjects (subjects 1, 2, 3, 5, 8 and 9) while three (subjects 4, 6 and 7) exhibited a decrease. Only one of the subjects (subject 6) responded in the same way (decreasein s-IgA) to each of the three submaximal runs.

Discussion

The results of this study indicated that 30 minutes of non-competitive exercise at temperatures ranging from approximately 6 to 34 °C had no effect on s-IgA. Thus, it is not likely that moderate intensity activity at a wide range of ambient temperatures increases the susceptibility to URI by decreasing salivary levels of IgA. These findings are of practical importance for individuals who exercise regularly in geo-

graphic locations where temperatures can vary by many degrees. Furthermore, the exercise parameters (intensity and duration) utilized in this investigation were consistent with the

recommendations of the American College of Sports Medicine (1) and therefore reflect the exercise habits of many nonathletic individuals who are concerned with health-related fitness.

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Subject

Low Temperature PostPreexercise exercise

T. J. Housh, G. 0. Johnson, D. J. Housh, S. L. Evans, G. D. Tharp

References

Although the mean values for the total sample indicated no significant s-IgA response to the exercise bouts,

individual subjects exhibited increases of up to 33% and decreases of up to 22% at the various temperatures. Interestingly, only one subject (subject 6; Table 1) responded consistently (decreased in s-IgA) to all three submaximal runs. There appears to be great intra- as well as inter-individual variability in s-IgA responses to exercise at various temperatures. The factors that mediate the s-IgA response to exercise are presently unknown, but it is likely that both the neural and endocrine systems are influential (4, 6, 18). For example, high coritsol levels have been shown to decrease antibody production (6) and salivary cortisol has been shown to increase in response to strenuous exercise (11). Thus, it is possible that in-

dividual differences in endocrine responses to exercise at various temperatures may influence muscosal antibody levels. Further studies are needed to define the relationship between

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Recent studies have reported significant decreases in s-IgA following strenuous physical acitvity in athletes from a variety of sports (8, 14, 16). Mackinnon et al. (8) reported a 65% decline in s-IgA in competitive bicyclists following two hours of cycle ergometry at approximately 70 to

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high-intensity exercise becomes a negative stressor and may adversely affect many systems of the body, including the immune system.

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