The effects of high-intensity intermittent exercise on saliva IgA, total protein and alpha-amylase

Developmental differences in infant salivary alpha-amylase and cortisol responses to stress

This study examined developmental differences in infants' salivary alpha-amylase (sAA) and cortisol levels and responses to the well-baby exam/inoculation stress protocol at 2, 6, 12, and 24 months of age. Mother-infant pairs (n=85; 45 girls) were assessed during well-baby visits and saliva was sampled before the well-baby exam/inoculation procedure (pre-test) and at 5, 10, and 20 min post-inoculation stress. Older infants (24 months) had higher levels of sAA than younger infants (2, 6 and 12 months). Stress-related sAA increases were evident at 6 and 12 months, but not at 2 or 24 months of age. Stress-related cortisol increases were present at 2 and 6 months, but not at older ages. Mothers had higher sAA levels than their infants, but did not show sAA or cortisol increases to their infants' inoculation. Pre-test, maternal and infant sAA levels were positively correlated (rs .47 to .65) at 6, 12, and 24 months of age, but not at 2 months. These findings suggest that the association between the sympathetic branch of the autonomic nervous system and the secretion of sAA develops between 2 and 6 months of age, when levels of sAA are responsive to exposure to a painful stressor.

Influence of concentration of fragrances on salivary alpha-amylase

The objective is to reveal the influence of the concentration of fragrances on salivary biomarkers, which reflect the human stress system, in 15 female young healthy adults. Lavandula officinalis and Citrus aurantium were used as the test samples. Salivary biomarkers such as alpha-amylase activity (AMY), cortisol (CORT) and dehydroepiandrosterone (DHEA) were measured during baseline, inhalation and post-inhalation periods. Our results indicated that (i) a significant difference was not observed for the control and the 3 wt% test samples, however, the AMY was decreased by inhalation of the 1 wt% test samples (P < 0.05); (ii) AMY levels changed more significantly than did the hormone levels; (iii) a tendency of negative correlation was not observed between DHEA and CORT. It was considered that the time-course change of AMY might be a useful index of the inhalation of fragrances, which reflects the acute psychosomatic reactivity of humans.

Salivary alpha-amylase as a non-invasive biomarker for the sympathetic nervous system: current state of research

Development of new biomarkers is a constantly evolving field of research endeavor in psychoneuroendocrinology. Salivary biomarkers have received special attention since they are readily accessible and easily obtained. Salivary alpha-amylase (sAA) has been proposed as a sensitive biomarker for stress-related changes in the body that reflect the activity of the sympathetic nervous system (SNS), and a growing body of research is accumulating to support the validity and reliability of this parameter. However, questions remain to be answered before sAA can be accepted as an index of SNS activity. This review describes sAA as an emerging biomarker for stress and provides an overview of the current literature on stress-related alterations in sAA. It critically discusses how sAA might reflect changes in the autonomic nervous system. Finally, current and future fields for the application of sAA measurement are outlined.

Determinants of salivary alpha-amylase in humans and methodological considerations

Salivary alpha-amylase (sAA) has been proposed as a marker for activity of the sympathetic nervous system (SNS). Recent studies in support of this hypothesis have led to an increased number of researchers integrating amylase measurements into their study designs. Salivary alpha-amylase is produced locally in the salivary glands, controlled by the autonomic nervous system. This entails some methodological consequences and potential pitfalls that might lead to increased error variance and thus prevent successful testing of hypotheses. The goal of this review is to summarize basic and recent findings on methodological issues and potential factors influencing sAA measurement, and to derive a set of recommendations enabling researchers to successfully using sAA in psychoneuroendocrinological experiments.

Effects of simulated firefighting on the responses of salivary cortisol, alpha-amylase and psychological variables

The aim of this study was to evaluate the effects of a simulated firefighting intervention on salivary alpha-amylase (sA-A), free cortisol (sC), anxiety (STAI), and profile of mood states (POMS) in 20 male firefighters (age 32 +/- 1 years, VO(2peak): 43 +/- 5 ml/kg per min). During the 12-min firefighting intervention (ambient temperature: 13 +/- 1 degrees C; relative humidity: 63 +/- 1%), individuals spent 63 +/- 28% of the time working at heart rate (HR) >85% of individual HR(max), [La] (peak) 9.2 +/- 2.9 mM and ratings of perceived exertion 16 +/- 2. At 30 min post-intervention significant (p < 0.001) increases in sA-A (174%) and sC (109%) were found with regard to values recorded before and after 90 min of the firefighting intervention. Since no differences emerged between pre-intervention and post intervention for STAI and POMS values, the hormonal changes were attributable to the intense physical stress of the simulated intervention. Further research is needed during real firefighting activities, where high emotional stress may also be present.

Mental and physical fatigue-related biochemical alterations

OBJECTIVE

To confirm fatigue-related biochemical alterations, we measured various parameters just before and after relaxation and fatigue-inducing mental or physical sessions.

METHODS

Fifty-four healthy volunteers were randomized to perform relaxation and fatigue-inducing mental and physical sessions for 4 h in a double-blind, three-crossover design. Before and after each session, subjects were asked to rate their subjective sensations of fatigue, and blood, saliva, and urine samples were taken.

RESULTS

After the fatigue-inducing mental and physical sessions, subjective scores of fatigue were increased. After the fatigue-inducing mental session, the vanillylmandelic acid level in urine was higher and plasma valine level was lower than after the relaxation session. In contrast, after the fatigue-inducing physical session, serum citric acid, triacylglycerol, free fatty acid, ketone bodies, total carnitine, acylcarnitine, uric acid, creatine kinase, aspartate aminotransferase, lactate dehydrogenase, cortisol, dehydroepiandrosterone, dehydroepiandrosterone sulfate, plasma branched-chain amino acids, transforming growth factor-beta1 and -beta2, white blood cell and neutrophil counts, saliva cortisol and amylase, and urine vanillylmandelic acid levels were higher and serum free carnitine and plasma total amino acids and alanine levels were lower than those after the relaxation session.

CONCLUSION

Some mental or physical fatigue-related biochemical changes were determined. Various biochemical alterations reflecting homeostatic perturbation and its responses might be shown. We believe that our results contribute to clarifying the mechanism of fatigue, developing evaluation methods, and establishing a basis for treatment.

Salivary Alpha Amylase Levels under Conditions of Extreme Examination Stress

11 healthy adult graduate students were studied on two separate occasions 2 wk. apart at the same time of day. Self-rating of perceived stress and serial measurements of salivary alpha-amylase levels were performed at T1 = 15 min. before, T2 = 1 min. before, T3= 1 min. after, and T4= 15 min. after an event. The events were a highly stressful master's degree oral examination on the first occasion and 15 min. of typing on a computer on the second occasion as a control activity. A kinetic assay was used to estimate salivary alpha-amylase activity. Students rated higher stress on the oral examination day, and their salivary alpha-amylase activity was higher during the oral examination period than on the second less stressful control day.

Clinical Performance of a Salivary Amylase Activity Monitor During Hemodialysis Treatment

The hemodialysis procedure is thought to be a physical stressor in the majority of hemodialyzed patients. Previous studies suggest that elevated salivary amylase level may correlate with increased plasma norepinephrine level under psychological and physical stress conditions. In this study, we investigated biological stress reactivity during hemodialysis treatment using salivary amylase activity as a biomarker. Seven patients (male/female = 5/2, age: 67.7+/-5.9 years) who had been receiving regular 4 h hemodialysis were recruited. Salivary amylase activity was measured using a portable analyzer every hour during the hemodialysis session. Salivary amylase activity was shown to be relatively stable and constant throughout hemodialysis, whereas there were significant changes in systolic blood pressure and pulse rate associated with blood volume reduction. Our results show that hemodialysis treatment per se dose not affect salivary amylase activity.

Comparative profiling of human saliva by intact protein LC/ESI-TOF mass spectrometry

Human saliva is finding increasing interest for proteomic and biomarker-discovery studies, due to the ease of collection and potential for simpler processing workflows compared to serum or plasma. However, it is known that salivary protein composition can vary with physiological and environmental factors. In this work, we have examined intra- and inter-person variability of saliva protein composition using an LC/MS methodology to profile low molecular weight human salivary proteins. Whole saliva was analyzed from four individuals over three consecutive days. Additional samples were used to determine baseline analytical and sample processing variation and to identify phosphoproteins. Individuals were observed to have a similar salivary protein pattern over multiple days, although the expression levels of particular proteins were variable. Significant differences in protein profiles were observed between subjects, allowing for delineation of individuals based on their protein profile. Comparison with alkaline phosphatase treated saliva revealed that several identified proteins were singly, doubly, or triply phosphorylated.

Salivary immunoglobulin A response at rest and after exercise following a 48 h period of fluid and/or energy restriction

The aim was to investigate the effects of a 48 h period of fluid, energy or combined fluid and energy restriction on salivary IgA (s-IgA) responses at rest and after exercise. Thirteen healthy males (age 21 (sem 1) years) participated in four randomised 48 h trials. In the control trial participants received their estimated energy (12 154 (sem 230) kJ/d) and water (3912 (sem 140) ml/d) requirements. On fluid restriction (FR) participants received their energy requirements and 193 (sem 19) ml water/d to drink and on energy restriction (ER) participants received their water requirements and 1214 (sem 25) kJ/d. Fluid and energy restriction (F+ER) was a combination of FR and ER. After 48 h, participants performed a 30 min treadmill time trial (TT) followed by rehydration (0–2 h) and refeeding (2–6 h). Unstimulated saliva was collected at 0, 24 and 48 h, post-TT, and 2 and 6 h post-TT. Saliva flow rate (sflw) and s-IgA (ELISA) remained unchanged in control conditions and on ER. However, 48 h on FR decreased sflw (64 %) which most probably accounted for the increase in s-IgA concentration (P < 0·01). Despite a decrease in sflw (54 %), s-IgA concentration did not increase on F+ER, resulting in a decreased s-IgA secretion rate by 24 h (0 h: 20 (sem 2); 24 h: 12 (sem 2) μg/min; P < 0·01). Post-TT s-IgA secretion rate was not lower compared with 48 h on any trial. s-IgA secretion rate returned to within 0 h values by 6 h post-TT on F+ER. In conclusion, a 24–48 h period of combined F+ER decreased s-IgA secretion rate but normalisation occurred upon refeeding.

Determinants of the diurnal course of salivary alpha-amylase

OBJECTIVE

Previous data from our group and others have shown that salivary alpha-amylase activity increases in response to stress. It has been suggested that salivary alpha-amylase may be a marker for adrenergic activity. Less is known about other determinants of salivary alpha-amylase activation. The objective of the current study was to describe the diurnal pattern of salivary amylase and its determinants.

METHODS

Saliva samples were collected immediately after waking-up, 30 and 60 min later, and each full hour between 0900 and 2000 h by 76 healthy volunteers (44 women, 32 men). Compliance was controlled by electronic monitors. In order to control factors which might influence the diurnal profile of salivary alpha-amylase (such as momentary stress, mood, food, or body activity), at each sampling time point the subjects filled out a diary examining the activities they had carried out during the previous hour.

RESULTS

Salivary alpha-amylase activity shows a distinct diurnal profile pattern with a pronounced decrease within 60 min after awakening and a steady increase of activity during the course of the day. Mixed models showed a relative independence of diurnal salivary alpha-amylase from momentary stress and other factors, but significant associations with chronic stress and mood.

CONCLUSIONS

Our results suggest that diurnal profiles of salivary alpha-amylase are relatively robust against momentary influences and therefore may prove useful in the assessment of sympathetic nervous system activity. The findings underscore the need to control for time of day in studies using salivary alpha-amylase as a dependent variable.

Evaluation of the Sedative Effect of Fragrance on Filipinas Using a Biochemical Marker

The purpose of this study is to evaluate the usefulness of salivary amylase activity as an indicator of the acute psychological sedative effects of fragrances used in household products such as clothing softeners. Twenty seven healthy Philippine female subjects in their late 30 s were enrolled (38.7+/-5.2 yr). This study was undertaken to investigate the favorite fragrance of Asian and Pacific Islander women. Our results indicated that (i) a mixed floral fragrance might be a favorite fragrance for Filipinas; (ii) fragrances contained in a softener significantly induced a sedative effect in humans, as assessed by both analysis of the biochemical marker and subjective evaluation; (iii) salivary amylase activity has the potential to be an excellent indicator for the evaluation of the acute psychological sedative effects of fragrance.

Elevated plasma interleukin-6 levels in trained male triathletes following an acute period of intense interval training

The aim of the present study was to investigate possible changes in the plasma IL-6 levels, subjective reporting of sources and symptoms of stress and the innate immune system in response to an acute period of intensified run training in highly trained endurance athletes. Eight healthy endurance trained male subjects (mean +/- SD age 23 +/- 2 years, VO(2max) 64.8 +/- 2.6 ml kg(-1) min(-1), mass 77.1 +/- 2.9 kg) completed the study which took place over a 4 week period. In weeks 2 and 3, in addition to their normal endurance training, subjects completed interval-training run sessions on three successive days. Saliva and venous blood samples were taken at the end of each week. Blood samples were analysed for leukocyte counts; neutrophil function; plasma IL-6; creatine kinase activity; and cortisol. Symptoms and sources of stress were assessed by questionnaire. Plasma IL-6 and creatine kinase activity were elevated following intensified training. Neutrophil function was reduced but total leukocyte and neutrophil counts, plasma cortisol and salivary IgA remained unchanged. There was a worsening in symptoms of stress despite there being no significant change in the sources of stress during intensified training. In conclusion, an acute period of intensified training can induce a suppression of the innate immune system and a chronic elevation in IL-6. This was associated with an increase in fatigue and generalised malaise which lends support to the recent cytokine theories of unexplained, underperformance syndrome.

Hand-held monitor of sympathetic nervous system using salivary amylase activity and its validation by driver fatigue assessment

In order to realize a hand-held monitor of the sympathetic nervous system, we fabricated a completely automated analytical system for salivary amylase activity using a dry-chemistry system. This was made possible by the fabrication of a disposable test-strip equipped with built-in collecting and reagent papers and an automatic saliva transfer device. In order to cancel out the effects of variations in environmental temperature and pH of saliva, temperature- and pH-adjusted equations were experimentally determined, and each theoretical value was input into the memory of the hand-held monitor. Within a range of salivary amylase activity between 10 and 140 kU/l, the calibration curve for the hand-held monitor showed a coefficient with R(2)=0.97. Accordingly, it was demonstrated that the hand-held monitor enabled a user to automatically measure the salivary amylase activity with high accuracy with only 30 microl sample of saliva within a minute from collection to completion of the measurement. In order to make individual variations of salivary amylase activity negligible during driver fatigue assessment, a normalized equation was proposed. The normalized salivary amylase activity correlated with the mental and physical fatigue states. Thus, this study demonstrated that an excellent hand-held monitor with an algorithm for normalization of individuals' differences in salivary amylase activity, which could be easily and quickly used for evaluating the activity of the sympathetic nervous system at any time. Furthermore, it is suggested that the salivary amylase activity might be used as a better index for psychological research.

Exercising in Environmental Extremes

Athletes, military personnel, fire fighters, mountaineers and astronauts may be required to perform in environmental extremes (e.g. heat, cold, high altitude and microgravity). Exercising in hot versus thermoneutral conditions (where core temperature is > or = 1 degrees C higher in hot conditions) augments circulating stress hormones, catecholamines and cytokines with associated increases in circulating leukocytes. Studies that have clamped the rise in core temperature during exercise (by exercising in cool water) demonstrate a large contribution of the rise in core temperature in the leukocytosis and cytokinaemia of exercise. However, with the exception of lowered stimulated lymphocyte responses after exercise in the heat, and in exertional heat illness patients (core temperature > 40 degrees C), recent laboratory studies show a limited effect of exercise in the heat on neutrophil function, monocyte function, natural killer cell activity and mucosal immunity. Therefore, most of the available evidence does not support the contention that exercising in the heat poses a greater threat to immune function (vs thermoneutral conditions). From a critical standpoint, due to ethical committee restrictions, most laboratory studies have evoked modest core temperature responses (< 39 degrees C). Given that core temperature during exercise in the field often exceeds levels associated with fever and hyperthermia (approximately 39.5 degrees C) field studies may provide an opportunity to determine the effects of severe heat stress on immunity. Field studies may also provide insight into the possible involvement of immune modulation in the aetiology of exertional heat stroke (core temperature > 40.6 degrees C) and identify the effects of acclimatisation on neuroendocrine and immune responses to exercise-heat stress. Laboratory studies can provide useful information by, for example, applying the thermal clamp model to examine the involvement of the rise in core temperature in the functional immune modifications associated with prolonged exercise. Studies investigating the effects of cold, high altitude and microgravity on immunity and infection incidence are often hindered by extraneous stressors (e.g. isolation). Nevertheless, the available evidence does not support the popular belief that short- or long-term cold exposure, with or without exercise, suppresses immunity and increases infection incidence. In fact, controlled laboratory studies indicate immuno-stimulatory effects of cold exposure. Although some evidence shows that ascent to high altitude increases infection incidence, clear conclusions are difficult to make because of some overlap with the symptoms of acute mountain sickness. Studies have reported suppressed cell-mediated immunity in mountaineers at high altitude and in astronauts after re-entering the normal gravity environment; however, the impact of this finding on resistance to infection remains unclear.

Effects of competition, exercise, and mental stress on secretory immunity

It has been suggested that the psychological stress associated with competitive sports events may help to explain the increased susceptibility to respiratory infections due to reductions in secretory immunity. In the current study, we investigated the influence of competitive exercise and psychological stress on secretory immunoglobulin A (s-IgA). Salivary s-IgA and heart rate were measured in 62 healthy young recreationally active men at rest and, in a between-subjects design, following one of four 8-min tasks: mental arithmetic, cycling at workloads of 60 to 180 W (mean = 146 W), mental arithmetic while cycling, or competitive cycling. Mental arithmetic was associated with significant increases in s-IgA concentration (mean = 49 microg.min(-1)) and s-IgA secretion rate (mean = 25 microg.ml(-1)) compared with rest, while mental arithmetic combined with exercise was associated with a significant increase in s-IgA concentration only (mean = 124 microg.min(-1)). In contrast, competitive exercise and exercise alone did not influence s-IgA concentration or secretion rate. Heart rate increased modestly to mental arithmetic (mean = 7 beats.min(-1)) and substantially, and similarly, to the three exercise tasks (mean = 56(62 beats.min(-1)). The hypothesis that the psychological stress of competitive exercise contributes to increased susceptibility to infection via reductions in s-IgA requires further investigation.

Mucosal IgA and URTI in American college football players: a year longitudinal study

PURPOSE

The purpose of this study was: (a) to evaluate secretory immunoglobulin A (s-IgA) over a 12-month time period in college football players, and (b) to assess which of the commonly used standard methods of reporting s-IgA, either alone or in combination, serves as the best predictor of incidence of upper respiratory tract infection (URTI).

METHODS

One hundred college-aged males (75 varsity college football athletes, 25 nonfootball controls) were studied at eight points over a 12-month period. Resting mucosal IgA, protein and osmolality levels were determined from saliva using established procedures. In addition, incidence of URTI over the 12-month study duration was calculated from completed standard research logs. Repeated-measures ANOVA were conducted on the dependent variables and eight separate stepwise multiple regression analyses were conducted to predict the dependent variable "number of colds" by the independent variables, s-IgA, saliva flow rate, secretion rate of s-IgA, protein, s-IgA:protein, osmolality and s-IgA:osmolality at each data collection point.

RESULTS

There was a significant main effect for group, time, and the group x time interaction for s-IgA, the secretion rate of s-IgA, and the number of colds. In the regression model, the only variable that made a significant contribution to the variance at all time points was the secretion rate of s-IgA.

CONCLUSION

These findings suggest that a season of training in American football results in a significant decrease in both s-IgA and the secretion rate of s-IgA as well as an increase in the incidence of URTI. Among the various methods commonly employed to express s- IgA levels, the secretion rate of s-IgA may be the most useful clinical biomarker to predict the incidence of URTI.

Human salivary alpha-amylase reactivity in a psychosocial stress paradigm

Biological indicators for stress reactions are valuable markers in psychophysiological research and clinical practice. Since the release of salivary enzyme alpha-amylase was reported to react to physiological and psychological stressors, we set out to investigate human salivary alpha-amylase changes employing a reliable laboratory stress protocol to investigate the reactivity of salivary alpha-amylase to a brief period of psychosocial stress. In a within-subject repeated-measures design, 24 healthy adults were exposed to the TSST and a control condition on separate days with randomized sequence. Salivary alpha-amylase, salivary cortisol and heart rate were repeatedly measured before, during and after both conditions. Significant differences between psychosocial stress and the rest condition in alpha-amylase activity [F(3.74,86.06)=4.52; P=0.003], cortisol levels [F(4.21,88.32)=12.48; P<0.001] and heart rate [F(1,22)=81.15; P<0.001] were observed, with marked increases before and after stress. The data corroborate findings from other studies that showed increased levels of alpha-amylase before and after psychological stress. We discuss the role of salivary alpha-amylase as a promising candidate for a reliable, noninvasive marker of psychosocial stress.

Relationships between physiological and psychological stress and salivary immunoglobulin A among young female gymnasts

We investigated whether psychological and physical stress induced by training or competition influence the secretory immune system among 12 highly trained young female gymnasts. Salivary levels of secretory IgA and cortisol responses to gymnastic training session or competition were assessed a total of 10 times, immediately before and after two training sessions which had different intensities and just before and after a major competition. These parameters were also measured on two non-training days. The Brunel Mood Scale was also used to assess the gymnasts's overall mood on each test day. IgA:Protein ratio was calculated. Significant decreases in this ratio were found after each exercise session, related to the physiological and psychological stress induced by exercise. Over the 5-mo. training period the presession IgA:Protein ratios were unchanged. Gymnasts registered any episodes of upper respiratory tract infection. Bouts of exercise induce transitory effects on the immune system in relation to the workload and the stress induced by the exercise without any relation to increased susceptibility to illness in children.

Effect of psychological stress on the salivary cortisol and amylase levels in healthy young adults

OBJECTIVE

Saliva sampling has the advantage that it is non-invasive, making multiple sampling easy and stress free. We examined the effects of psychological stressor and soother on the salivary cortisol and amylase levels in young adults, and compared the characteristics of these parameters.

DESIGN

The subjects completed the trait version of State-Trait Anxiety Inventory (STAI) to assess the predisposition to personal anxiety. The video of corneal transplant surgery was served as the stressor for 15 min. A scenic beauty video viewing was also used as the soother. Unstimulated whole saliva was collected every 3 min throughout the session.

RESULTS

The amylase level was significantly increased just after the beginning of the stressful video viewing, and immediately returned to the pre-stress level just after the end of the video viewing. The cortisol level was also increased, but to a lesser extent compared with that of amylase. The latency time to the peak level for cortisol was longer than that of amylase. The carry-over effect was not observed in the amylase response but was in cortisol. Although the correlation between the amylase level and the STAI score was highly significant, cortisol level did not. In addition, soothing video viewing significantly decreased the amylase level, but did not affect the cortisol level.

CONCLUSION

Salivary amylase level was more significantly increased and reacted more rapidly than cortisol by psychological stressor, suggesting that it is a better index of stress. Furthermore, it is suggested that the enzyme is a soothing or relaxation index.

Psychosocial Stress-Induced Activation of Salivary Alpha-Amylase: An Indicator of Sympathetic Activity?

Assessment of sympathoadrenal medullary system (SAM) activity is only possible to date via measurement of catecholamines in blood plasma or via electrophysiological methods. Both ways of measurement are restricted to endocrinological or psychophysiological laboratories, as both require either immediate freezing of blood samples or complex recording devices. Efforts have therefore been undertaken to find a method comparable to salivary cortisol measurements, in which noninvasive samples can be taken at any place and stored at room temperature for sufficient time before later analysis in the laboratory. Salivary alpha-amylase (sAA) is a candidate that may prove useful in this context. We show here that sAA activity is increased by acute psychosocial stress (Trier Social Stress Test) and that increases in sAA correlate with increases in norepinephrine. We further report that sAA exhibits a stable circadian pattern that mirrors that of salivary cortisol. In conclusion, the current data show that salivary alpha-amylase may serve as an easy-to-use index for SAM activity. However, some questions remain to be answered; for example, what impact does salivary flow rate exert on stress-induced sAA activity?

Salivary IgA response to prolonged exercise in a hot environment in trained cyclists

The aim of this study was to determine the effects of prolonged exercise in hot conditions on saliva IgA (s-IgA) responses in trained cyclists. On two occasions, in random order and separated by 1 week, 12 male cyclists cycled for 2 h on a stationary ergometer at 62 (3)% V(.)O(2 max) [194 (4) W; mean (SEM)], on one occasion (HOT: 30.3 degrees C, 76% RH) and on another occasion (

CONTROL

20.4 degrees C, 60% RH). Water was available ad-libitum. Venous blood samples and 2-min whole unstimulated saliva samples were collected at pre, post and 2 h post-exercise. The s-IgA concentration was determined using a sandwich-type ELISA. Exercising heart rate, rating of perceived exertion, rectal temperature, corrected body mass loss (P<0.01) and plasma cortisol (P<0.05) were greater during HOT. The decrease in plasma volume post-exercise was similar on both trials [HOT: -6.7 (1.1) and

CONTROL

-6.6 (1.3)%; P<0.01]. Saliva flow rate decreased post-exercise by 43% returning to pre-exercise levels by 2 h post-exercise (P<0.05) with no difference between trials. Saliva IgA concentration increased post-exercise (P<0.05) with no difference between trials. Saliva IgA secretion rate decreased post-exercise by 34% returning to pre-exercise levels by 2 h post-exercise (P<0.05) with no difference between trials. These data show that a prolonged bout of exercise results in a reduction in s-IgA secretion rate. Additionally, these data demonstrate that performing prolonged exercise in the heat, with ad libitum water intake, does not influence s-IgA responses to prolonged exercise.

Saliva flow rate, total protein concentration and osmolality as potential markers of whole body hydration status during progressive acute dehydration in humans

OBJECTIVE

To identify whether saliva flow rate, total protein concentration and osmolality are sensitive non-invasive markers of whole body hydration status, we compared changes in these parameters with changes in body mass during progressive acute dehydration.

DESIGN

Twelve euhydrated males reported to the laboratory following an overnight fast and cycled on a stationary ergometer at 60% maximal oxygen uptake in an environmental chamber (30 degrees C and 70% RH) until progressive body mass loss (BML) of 1.1+/-0.0, 2.0+/-0.0 and 2.9+/-0.2%. After exercise, subjects were given a volume of carbohydrate electrolyte solution equivalent to 150% BML to consume within 1h. Unstimulated whole saliva samples were collected over a 2 min period into pre-weighed tubes at pre-exercise, 1.1, 2.0 and 2.9% BML and then at 75, 135 and 195 min post-exercise.

RESULTS

Saliva total protein concentration and osmolality increased and flow rate decreased (P<0.01) during dehydration. Saliva total protein concentration and osmolality correlated strongly with % BML during dehydration (mean r=0.97 and 0.94, respectively: P<0.01). The correlation for saliva total protein concentration with % BML was greater (P<0.05) than the correlation for saliva flow rate with % BML (mean r=-0.88: P<0.01) during dehydration.

CONCLUSIONS

These data show that changes in saliva total protein concentration and osmolality, and to a lesser extent flow rate, are strongly associated with changes in body mass during progressive acute dehydration.

Mild dehydration: a risk factor for dental disease?

A review of the published international literature was undertaken to investigate whether dehydration is a risk factor for dental disease. Published evidence of associations between saliva and dental disease and between saliva and dehydration was observed, but the precise nature of these associations is unclear and no evidence of a direct link between dehydration and dental disease was found. It is concluded that no direct link between dehydration and dental disease has been proven, although there is considerable circumstantial evidence to indicate that such a link exists.

Flow-injection-type biosensor system for salivary amylase activity

The authors aim to establish a method that can quantitatively evaluate vital reactions to stress. We have been examining the correlation between stress and salivary amylase activity in order to verify its validity as a stress index. In order to quantify human stress, which changes over time, the relationship between stress and salivary amylase activity must be verified by fast and repeated analysis of salivary amylase activity. Standard biosensors are designed such that the enzyme immobilized on an electrode (enzyme electrode) and the substrate-dependent activity is measured. The reverse approach of measuring the alpha-amylase-dependent activity was adopted. We fabricated an amylase activity analytical system. Maltopentaose was selected as a substrate for alpha-amylase and a flow-injection-type device was used to supply maltopentaose continuously. alpha-Glucosidase, having relatively low enzyme activity, was immobilized on a pre-activated membrane so that it could be enclosed in a pre-column, Glucose oxidase, having higher enzyme activity, was immobilized on a working electrode so that it could function as an amperometric biosensor. A saliva-collecting device was fabricated to make saliva pretreatment unnecessary. As a result, an amylase activity analytical system was fabricated that enabled us to measure salivary amylase activity from 0 to 30 kU/l, with an R(2) value of 0.97. The time-course changes in the salivary amylase activities for 1 week were 5.1%, and the initial sensitivity remained nearly constant. Through this study, we were able to verify the possible development of the amylase activity analytical system.

Immunological responses to overreaching in cyclists

INTRODUCTION

Acute bouts of prolonged strenuous exercise are often associated with immune suppression and an increased risk of infection. However, few studies have examined immunological responses to intensified training that results in overreaching or overtraining. We investigated the effects of intensified training on plasma cytokines, glutamine, glutamate, and other related immunological variables in endurance-trained cyclists.

METHODS

Eight male subjects (age 27.0 +/- 3.0 yr, [OV0312]O(2max) 58.0 +/- 1.7 mL.kg-1.min-1, mass 73.7 +/- 2.1 kg) completed 6 wk of training: 2 wk each of normal training (N, 7 +/- 2 h.wk-1), intensified training (ITP, 14 +/- 5 h.wk-1) and recovery training (R, 3.5 +/- 2.5 h.wk-1). During the study period, subjects completed six graded cycle ergometer tests to exhaustion (MT), six simulated time trial tests (TT), and eight 2 x 10-min maximal effort bouts (IT). Subjects also completed questionnaires to assess mood state. Plasma concentrations of tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6), salivary IgA, plasma glutamine, glutamate, ammonia, urea, creatine kinase activity, and routine hematological measures were determined once per week.

RESULTS

ITP resulted in overreaching in all subjects identified by a significant decline in performance and disturbances of mood state. Significant increases during the ITP were observed in creatine kinase activity and glutamate, whereas the glutamine/glutamate ratio (Gln/Glu ratio), red blood cell numbers (RBC), hemoglobin concentration (Hb), and packed cell volume (PCV) declined after ITP. No significant changes were observed in TNF-alpha, IL-6, salivary IgA, glutamine, ammonia, urea and various routine hematological measures.

CONCLUSION

Alterations in plasma cytokines do not appear to be related to the decline in performance and increased mood state characteristic of overreaching; however, the Gln/Glu ratio may be of use as a marker of overreaching and/or overtraining.

Salivary IgA response to prolonged exercise in a cold environment in trained cyclists

PURPOSE

The purpose of the present study was to determine the effect of a prolonged bout of exercise in freezing cold conditions on saliva immunoglobulin A (s-IgA) responses in endurance-trained males.

METHODS

Using a randomized cross-over design, 15 trained male cyclists cycled for 2 h on a stationary ergometer at 70% VO(2max) in an environmental chamber on one occasion at a temperature of -6.4 +/- 0.1 degrees C (cold) and on another occasion at a temperature of 19.8 +/- 0.2 degrees C (control). Trials began at 12:30 h to avoid the fall in s-IgA concentration that occurs during the morning hours. Unstimulated whole-saliva samples were collected over a 2-min period at preexercise, postexercise, and 2-h postexercise. The s-IgA concentration was determined using a sandwich-type ELISA method.

RESULTS

Saliva flow rate decreased postexercise by 31%, returning to preexercise levels by the 2-h postexercise collection (main effect of time: < 0.01). The decrease in saliva flow rate postexercise in the control trial (39% compared with 22% on cold trial) approached significance (interaction: = 0.08) and may have accounted for the corresponding increase in s-IgA concentration postexercise in the control trial (s-IgA concentration: control preexercise; 91 +/- 12; postexercise; 110 +/- 13 mg x L(-1); < 0.05). Saliva IgA secretion rate decreased postexercise by 19.5% returning to preexercise levels by 2-h postexercise measure (main effect of time: < 0.05).

CONCLUSIONS

These data show that performing a bout of prolonged exercise results in a reduction in s-IgA secretion rate. Additionally, these data demonstrate that performing prolonged exercise in freezing cold conditions does not influence saliva flow rate or s-IgA secretion rate responses to prolonged exercise.

Carbohydrate and fluid intake affect the saliva flow rate and IgA response to cycling

PURPOSE

The purpose of this study was to examine the effect of regular CHO beverage ingestion and restricted fluid intake on various salivary parameters during prolonged cycle exercise.

METHODS

In a randomized block design, 15 recreationally active men cycled for 2 h at 60% VO2max on three occasions, separated by 1 wk. On the CHO and placebo (PLA) treatments, subjects consumed either a glucose (60 g x L(-1)) or placebo drink before (400 mL), during (150 mL every 15 min), and after (400 mL) the exercise. On the restricted fluid intake (RFI) treatment subjects were given a total of 200 mL of placebo fluid to take as desired every 15-min during the exercise. Timed, unstimulated saliva samples were collected preexercise, at 1, 1.5, and 2 h of exercise and at 1 h postexercise. Blood samples were obtained from a subset of 8 subjects preexercise, postexercise, and at 1 h postexercise.

RESULTS

Postexercise plasma glucose levels were 18% and 20% lower on the PLA and RFI treatments, respectively, compared with the CHO treatment (P < 0.01). Saliva flow rates were significantly higher on the CHO treatment compared with the RFI treatment at 1.5 h and 2 h of exercise (P < 0.01 and P < 0.05, respectively). Salivary IgA (s-IgA) concentration was significantly lower on the CHO treatment compared with the RFI treatment throughout the exercise (P < 0.05). No other differences were seen between treatments for either saliva flow rate or s-IgA concentration. Neither s-IgA secretion rate, alpha-amylase activity, nor alpha-amylase secretion rate were affected by treatment.

CONCLUSIONS

These findings suggest that CHO and fluid intake influence the s-IgA and saliva flow rate response to prolonged submaximal exercise.

Special feature for the Olympics: effects of exercise on the immune system: exercise effects on mucosal immunity

The present review examines the effects of exercise on mucosal immunity in recreational and elite athletes and the role of mucosal immunity in respiratory illness. Habitual exercise at an intense level can cause suppression of mucosal immune parameters, while moderate exercise may have positive effects. Saliva is the most commonly used secretion for measurement of secretory antibodies in the assessment of mucosal immune status. Salivary IgA and IgM concentrations decline immediately after a bout of intense exercise, but usually recover within 24 h. Training at an intense level over many years can result in a chronic suppression of salivary immunoglobulin levels. The degree of immune suppression and the recovery rates after exercise are associated with the intensity of exercise and the duration or volume of the training. Low levels of salivary IgM and IgA, particularly the IgA1 subclass, are associated with an increased risk of respiratory illness in athletes. Monitoring mucosal immune parameters during critical periods of training provides an assessment of the upper respiratory tract illness risk status of an individual athlete. The mechanisms underlying the mucosal immune suppression are unknown.