Search PubMed⌕ Search

Biomedical subjects

D B Pyne

Publications and source records attributed to D B Pyne.

At least 19 recordsLinked to original sources

Positional differences in fitness and anthropometric characteristics in Australian football.

To evaluate the utility of fitness assessment and trends in drafting of players in the Australian Football League, we analysed height, mass, skinfolds, 20-m sprint, vertical jump, agility run and endurance assessed in the 495 players attending the annual national draft camps between 1999 and 2004. Effects of player position and assessment year were expressed as standardised mean differences (Cohen effect sizes) and interpreted qualitatively. Effect of birth month on chance of being drafted, which may be important in team sports, was also analysed. Compared with midfield players, ruckmen, tall forwards and tall defenders were decisively taller (effect-size range 1.33-1.95, large) and heavier (1.30-1.63, large), but had poorer sprint speed (0.23-0.57, small), aerobic ability (0.66-1.18, moderate) and agility (0.64-1.11, moderate). The only substantial changes in fitness scores over the 5-year period were an increase in height (0.76, moderate) and an increase in 20-m sprint time (0.39, small). A majority (65%) of players attending the camps were born in the first half of a given year, but their chance of being drafted (70%) was similar to that of players born in the second half (64%). We conclude that fitness assessment is useful for differentiating between player positions and identifying some annual trends in recruitment in Australian football, and that players with a second half birth month have been disadvantaged with lower representation at the national draft camp.

Adolescent↗

Anthropometry profiles of elite rugby players: quantifying changes in lean mass.

OBJECTIVE: To demonstrate the utility of a practical measure of lean mass for monitoring changes in the body composition of athletes. METHODS: Between 1999 and 2003 body mass and sum of seven skinfolds were recorded for 40 forwards and 32 backs from one Super 12 rugby union franchise. Players were assessed on 13 (7) occasions (mean (SD)) over 1.9 (1.3) years. Mixed modelling of log transformed variables provided a lean mass index (LMI) of the form mass/skinfolds(x), for monitoring changes in mass controlled for changes in skinfold thickness. Mean effects of phase of season and time in programme were modelled as percentage changes. Effects were standardised for interpretation of magnitudes. RESULTS: The exponent x was 0.13 for forwards and 0.14 for backs (90% confidence limits +/-0.03). The forwards had a small decrease in skinfolds (5.3%, 90% confidence limits +/-2.2%) between preseason and competition phases, and a small increase (7.8%, 90% confidence limits +/-3.1%) during the club season. A small decrease in LMI (approximately 1.5%) occurred after one year in the programme for forwards and backs, whereas increases in skinfolds for forwards became substantial (4.3%, 90% confidence limits +/-2.2%) after three years. Individual variation in body composition was small within a season (within subject SD: body mass, 1.6%; skinfolds, 6.8%; LMI, 1.1%) and somewhat greater for body mass (2.1%) and LMI (1.7%) between seasons. CONCLUSIONS: Despite a lack of substantial mean changes, there was substantial individual variation in lean mass within and between seasons. An index of lean mass based on body mass and skinfolds is a potentially useful tool for assessing body composition of athletes.

Adult↗

Validation of a skinfold based index for tracking proportional changes in lean mass.

BACKGROUND: The lean mass index (LMI) is a new empirical measure that tracks within-subject proportional changes in body mass adjusted for changes in skinfold thickness. OBJECTIVE: To compare the ability of the LMI and other skinfold derived measures of lean mass to monitor changes in lean mass. METHODS: 20 elite rugby union players undertook full anthropometric profiles on two occasions 10 weeks apart to calculate the LMI and five skinfold based measures of lean mass. Hydrodensitometry, deuterium dilution, and dual energy x ray absorptiometry provided a criterion choice, four compartment (4C) measure of lean mass for validation purposes. Regression based measures of validity, derived for within-subject proportional changes through log transformation, included correlation coefficients and standard errors of the estimate. RESULTS: The correlation between change scores for the LMI and 4C lean mass was moderate (0.37, 90% confidence interval -0.01 to 0.66) and similar to the correlations for the other practical measures of lean mass (range 0.26 to 0.42). Standard errors of the estimate for the practical measures were in the range of 2.8-2.9%. The LMI correctly identified the direction of change in 4C lean mass for 14 of the 20 athletes, compared with 11 to 13 for the other practical measures of lean mass. CONCLUSIONS: The LMI is probably as good as other skinfold based measures for tracking lean mass and is theoretically more appropriate. Given the impracticality of the 4C criterion measure for routine field use, the LMI may offer a convenient alternative for monitoring physique changes, provided its utility is established under various conditions.

Absorptiometry, Photon↗

Fitness testing and career progression in AFL football.

Relationships between fitness testing and career progression in the Australian Football League (AFL) are under-explored. This study investigated relationships between anthropometric and fitness tests conducted at the annual AFL National Draft Camp and subsequent career progression of players. A total of 283 players was tested over three consecutive camps (1999-2001). The anthropometric and fitness measures were: height, mass, sum of skinfolds, 20-m sprint test, vertical jump (standing and bilateral running), agility run and a multi-stage incremental shuttle run. The five outcome variables were: drafted (yes/no), AFL debut (yes/no), number of AFL games played to the end of 2003, and subjective ratings of career potential and career value (5-point scale). Of 205 players (72%) subsequently drafted, 166 (59%) eventually made their AFL debut. Players drafted to AFL clubs were faster over 5 m, 10 m and 20 m, ran further in the shuttle run and ran marginally faster in the agility test than players not drafted. Multi-regression analysis showed small to moderate correlations (r = 0.27-0.31) between the designated outcome variables and selected fitness tests: 20-m sprint time (faster), agility run test (faster), and running vertical jump (higher absolute height and smaller difference between left and ride sides). Regression analysis for the standing vertical jump relative to standing reach height showed a counterintuitive negative correlation with positive outcomes, possibly reflecting non-compliance with testing procedures by the less successful athletes. We conclude that the 20-m sprint, jump, agility and shuttle run tests have a small but important association with career progression of AFL footballers.

Adolescent↗

Characterising the individual performance responses to mild illness in international swimmers.

OBJECTIVES: To determine individual differences in the impact of illness on the change in performance of swimmers in international competitions. METHODS: Subjects were members of the Australian swimming team (33 male and 39 female, aged 15-27 years). Swimmers provided a weekly seven day recall of symptoms of illness during final six weeks of preparations for international competition over a three year period. Swimmers were categorised as either ill (one or more episodes of illness) or healthy. The measure of performances was the international point score. Mean changes in points score were calculated for healthy and ill swimmers between a national championship and an international competition ( approximately 16 weeks later). Likelihoods of substantial effects of illness on an individual's true change in performance (beneficial/trivial/harmful) were estimated from means and standard deviations, assuming a smallest substantial change of 6 points. RESULTS: Illness was reported before international performances by 38% of female and 35% of male swimmers. For female swimmers the change in performance was -3.7 (21.5) points (mean (SD)) with illness and -2.6 (19.0) points when healthy; for male swimmers the changes were -1.4 (17.5) points with illness and 5.6 (13.2) points when healthy. The likelihoods that illness had a substantial beneficial/trivial/harmful effect on performance of an individual swimmer were 32%/31%/37% for female and 17%/31%/52% for male participants (90% confidence limits approximately +/-10% to 20%). CONCLUSIONS: Although mild illness had only a trivial mean effect on female swimmers and a small harmful mean effect on male swimmers, there were substantial chances of benefit and harm for individuals.

Adolescent↗

CD94 expression and natural killer cell activity after acute exercise.

This study examined the effects of acute exercise on natural killer (NK) cell numbers, their expression of CD94 and cytotoxic capacity in triathletes over a 10-week training period. Nine highly trained male triathletes (age 25.9+/-4.1 yrs, VO2max 5.14+/-0.33 L.min(-1)) attended the laboratory on weeks 0, 2, 5 and 10 for incremental submaximal and maximal cycle ergometry. Peripheral blood was analysed for white blood cell counts, lymphocyte phenotype and cytolytic activity (51Cr release from K562 cells). Maximum oxygen consumption increased from week 2 (5.14+/-0.33 L.min(-1)) to week 10 (5.28+/-0.32 L.min(-1)). Resting NK cell numbers and their expression of CD94 were not altered over the 10-week study period. Natural killer cells expressing CD94+ were not differentially recruited into the circulation and cytolytic activity of exercise-recruited NKs did not differ from those present at rest. There was longitudinal stability (over the 10 weeks of the study) in CD94 expression on NK cells, exercise recruitment of CD94+ NK cells and cytolytic capacity of NK cells. The distribution and functional activity of NK cells are not markedly influenced by 10 weeks of training in competitive triathletes. Natural killer cytotoxic activity after exercise reflects numbers of NK cells and not a changed activation state of these cells per se.

Adaptation, Physiological↗

In-vivo cell mediated immunity in elite swimmers in response to training.

This study investigated in-vivo cell-mediated immune (CMI) responses in elite swimmers over a 5-month training season, to assess the impact of intense training on changes in T-lymphocyte function. The CMI Multitest was performed early in the season after a period of rest, during peak high-intensity training, and late in the season during the precompetition taper period. The CMI tests were performed at rest prior to a morning training session. There were no significant differences between the swimmers and a control group for any of the seven CMI antigen responses at any of the test points during the season. In the swimmers, there were no significant differences in the number of positive responses to the CMI antigens between the three test points (Friedman's test = 9.6364, p = 0.47) and no significant differences for the CMI cumulative scores (Friedman's test = 11.98, p = 0.29) at each test point. There was no consistent pattern for changes in CMI cumulative scores for individual swimmers over the training season. The findings of this study indicate that, despite reported transient T-lymphocyte immunosuppression immediately after intense exercise, probably associated with acute redistribution and temporary pooling of blood T cell subsets in extremities, the T-lymphocyte function involved in CMI responses is not compromised by extended periods of training at an elite level.

Adult↗

Improved running economy in elite runners after 20 days of simulated moderate-altitude exposure.

To investigate the effect of altitude exposure on running economy (RE), 22 elite distance runners [maximal O(2) consumption (Vo(2)) 72.8 +/- 4.4 ml x kg(-1) x min(-1); training volume 128 +/- 27 km/wk], who were homogenous for maximal Vo(2) and training, were assigned to one of three groups: live high (simulated altitude of 2,000-3,100 m)-train low (LHTL; natural altitude of 600 m), live moderate-train moderate (LMTM; natural altitude of 1,500-2,000 m), or live low-train low (LLTL; natural altitude of 600 m) for a period of 20 days. RE was assessed during three submaximal treadmill runs at 14, 16, and 18 km/h before and at the completion of each intervention. Vo(2), minute ventilation (Ve), respiratory exchange ratio, heart rate, and blood lactate concentration were determined during the final 60 s of each run, whereas hemoglobin mass (Hb(mass)) was measured on a separate occasion. All testing was performed under normoxic conditions at approximately 600 m. Vo(2) (l/min) averaged across the three submaximal running speeds was 3.3% lower (P = 0.005) after LHTL compared with either LMTM or LLTL. Ve, respiratory exchange ratio, heart rate, and Hb(mass) were not significantly different after the three interventions. There was no evidence of an increase in lactate concentration after the LHTL intervention, suggesting that the lower aerobic cost of running was not attributable to an increased anaerobic energy contribution. Furthermore, the improved RE could not be explained by a decrease in Ve or by preferential use of carbohydrate as a metabolic substrate, nor was it related to any change in Hb(mass). We conclude that 20 days of LHTL at simulated altitude improved the RE of elite distance runners.

Acclimatization↗

Expression of CD94 and 56(bright) on natural killer lymphocytes - the influence of exercise.

This study was undertaken to determine the effects of acute intense exercise on the cell membrane-bound glycoprotein designated cluster of differentiation (CD) 94. This marker on natural killer (NK) lymphocytes contributes to control of cell function. CD94 was measured on natural killer lymphocytes from 11 adult (average 25 yrs), well-trained male subjects, (Vdot;O 2 peak mean, 5.01 L x min -1) before and immediately after a final, 4 min all-out, cycle ergometry test. Using flow cytometry, lymphocyte populations were distinguished as either having (CD94 +) or lacking (CD94 -) the cell marker. The absolute number of CD94 + and CD94 - natural killer cells increased with exercise but the mean fluorescence intensity (MFI) for CD94 decreased from pre 131, to post 117 (p = 0.01). The percentage of NK cells that were CD94 + did not change, but exercise did mobilise natural killer cells of greater MFI for the surface markers designated CD16/CD56 (pre 750 to post 1 050, p < 0.001). The latter suggests that some exercise-mobilised natural killer cells may have originated from the liver as CD56 +bright cells.

Adult↗

Monitoring the lactate threshold in world-ranked swimmers.

PURPOSE: To determine whether lactate profiling could detect changes in discrete aspects of endurance fitness in world-ranked swimmers during a season. METHODS: Eight male and four female Australian National Team swimmers aged 20--27 yr undertook a 7 x 200-m incremental swimming step test on four occasions over an 8-month period before the 1998 Commonwealth Games (CG): January (10 d before the World Championships), May (early-season camp), July (midseason), and August (16 d before the CG). The lactate threshold (LT) was determined by a mathematical formula that calculated the threshold as a function of the slope and y-intercept of the lactate-velocity curve. RESULTS: Maximal 200-m test time declined initially from 127.7 +/- 4.2 s (January 1998) to 130.2 +/- 4.5 s (May 1998) and 129.1 +/- 4.3 s (July 1998) before improving to 126.8 +/- 4.2 s (August 1998) (P < 0.005). The swimming velocity at LT (s.100 m(-)1) also declined midseason before improving before the CG (P < 0.02) (January 1998: 70.5 +/- 2.1; May 1998: 72.0 +/- 2.2; July 1998: 72.2 +/- 2.2; and August 1998: 70.8 +/- 2.1). The blood lactate concentration at the LT decreased (P < 0.02) from 3.6 +/- 0.2 mM to 3.2 +/- 0.1 mM and 2.9 +/- 0.2 mM before returning to 3.4 +/- 0.2 mM for January, May, July, and August, respectively. The lactate tolerance rating (LT(5--10)), defined as the differential velocity between lactate concentrations of 5.0 and 10.0 mM, declined midway through the season (P < 0.015): 6.6 +/- 0.5 s.100 m(-1), 7.7 +/- 0.5 s.100 m(-1), 8.5 +/- 0.5 s.100 m(-1), and 6.9 +/- 0.4 s.100 m(-1), for January, May, July, and August, respectively. Despite these improvements in indicators of fitness, there was no significant improvement in competition performance across the season. CONCLUSIONS: Maximal effort 200-m time, lactate tolerance rating, and swimming velocity at LT (s.100 m(-1)) all improved in world-ranked swimmers with training, but these changes were not directly associated with competition performance.

Adult↗

Mucosal immunity, respiratory illness, and competitive performance in elite swimmers.

PURPOSE: Exercise and training are known to elicit changes in mucosal humoral immunity, but whether these alterations have any impact on competitive performance remains unclear. This investigation examined relationships between salivary immunoglobulin (Ig) concentration, the incidence of respiratory tract illness (RTI), and competitive performance in elite swimmers. METHODS: Forty-one members of the Australian Swimming Team (21 males and 20 females) aged 15-27 yr were monitored during preparations for the 1998 Commonwealth Games. Twenty-five coaches and staff (19 males and 6 females) aged 32-65 yr, serving as "environmental controls," were also monitored. Salivary IgA, IgM, and IgG and albumin concentration (mg.L-1) were measured in both groups in May 1998 and again in August 1998, 17 d before competition. Subjects were categorized as "ill" (at least one RTI) or "healthy". RESULTS: There were no significant changes in salivary IgA, IgM, or IgG concentration in the swimmers between May and August, nor were there any differences between healthy (N = 23) and ill (N = 18) swimmers. There was a significant positive relationship between IgM and performance in the male swimmers (r = 0.85, P < 0.001) but not for any other parameter. There was no significant difference in performance between ill and healthy swimmers (P = 0.11). Gold medal winners (N = 9) had higher IgM levels than other swimmers (N = 32) in May (P = 0.02) and higher IgG in August (P = 0.02). CONCLUSION: These data indicate that a season of training by elite swimmers did not alter salivary immunoglobulin concentrations, and the presence of RTI had no significant impact on competitive performance.

Adolescent↗

Evaluation of the Lactate Pro blood lactate analyser.

An evaluation of the hand-held portable Lactate Pro Analyser (KDK) was undertaken to assess its accuracy, reliability and versatility. Capillary blood samples were drawn from elite athletes in both laboratory and field settings and analysed in parallel. Accuracy was determined in relation to three other lactate analysers: (1) the ABL 700 Series Acid-Base analyser (n = 172 cases), (2) the Accusport Lactate Meter (n = 118 cases), and (3) the YSI 2300 Stat lactate analyser (n = 22 cases). The level of agreement was determined over the range of 1-18 mM. The repeatability of results between two different Lactate Pro analysers was also determined over the same range. Versatility was assessed in the field, where the Lactate Pro was used with elite athletes under a range of outdoor and indoor testing conditions. The correlations between the Lactate Pro and the ABL 700 Series Acid-Base analyser, YSI 2300 and Accusport were r = 0.98, r = 0.99, r = 0.97. The correlation between the two Lactate Pro analysers on the same sample (n = 96 cases) was r = 0.99. The level of agreement between the Lactate Pro and other analysers was generally less than +/- 2.0 mM over the physiological range of 1.0-18.0 mM (range of mean difference: -0.06 mM to 0.52 mM). The Lactate Pro was easy to operate and successfully completed the sample analysis in 100% of the tests performed. In summary, the Lactate Pro is accurate, reliable and exhibits a high degree of agreement with other lactate analysers.

Adolescent↗

Neutrophil oxidative activity is differentially affected by exercise intensity and type.

The differential effects of exercise intensity and type on neutrophil activation were assessed in eight well-trained male runners. Each subject undertook, on different days, three separate 40 min interval (8 x 5 min) treadmill bouts: an intense uphill run (90% VO2 max), a moderate-intensity near-level run and an eccentrically-biased downhill run (both at 52% VO2 max). Blood granulocyte count increased (p< 0.05) after all three treadmill bouts (range 25-108%). Chemiluminescence activity of isolated neutrophils decreased (p< 0.05) immediately after (-58%) and 1-h after (-72%) uphill running, but became significantly elevated (p< 0.05) at 6-h after the near-level (+71%) and downhill (+84%) runs. The ability of neutrophils to release the superoxide anion radical was reduced (p< 0.05) immediately after near-level (-29%) and uphill (-21%) running in cells stimulated with opsonized zymosan. Epinephrine concentration increased by 430% (p=0.01) after uphill but not with near-level or downhill running. The plasma concentration of elastase increased (p< 0.05) immediately after uphill and near-level running, and one hour after uphill running. These results suggest that a population of neutrophils mobilised into the circulation became directly activated in response to exercise, and that neutrophil oxidative activity is affected differentially by both the intensity and type of exercise undertaken.

Adult↗

Training strategies to maintain immunocompetence in athletes.

Clinical experience and empirical evidence have led to the modeling of exercise and training as a form of stress on the immune system. Coaches, athletes, and medical personnel are seeking guidelines on ways to reduce the risk of illness that compromises training or competitive performance. The immune system is influenced by a wide range of physical, environmental, psychological, and behavioural factors which, combined with clinical assessment, collectively form the basis of the following intervention strategies: 1) training: careful management of training volume and intensity, variety to overcome training monotony and strain, a periodised approach to increasing loads, and provision of adequate rest and recovery periods; 2) environmental: limiting initial exposure when training or competing in adverse environmental conditions (heat, humidity, altitude, air pollution) and acclimatising where appropriate; 3) psychological: teaching athletes self-management and coping skills and monitoring of athletes' responses to the psychological and psychosocial stresses of high-level training and competition; 4) behavioural: adopting a well-balanced diet with adequate intake of macro- and micro-nutrients, limiting transmission of contagious illnesses by reducing exposure to common infections, airborne pathogens, and physical contact with infected individuals; and 5) clinical considerations: medical screening, pathology testing, immunization and prophylaxis, and routine management of illness-prone athletes. Future experimental studies are required to develop and enhance the effectiveness of these strategies in reducing illness in athletes.

Australia↗

Immune status and respiratory illness for elite swimmers during a 12-week training cycle.

The impact of a 12-week training program by elite swimmers on systemic and mucosal immunity was studied prospectively to examine the relationship between changes in immune parameters and the incidence of respiratory illness. Saliva was collected before and after selected training sessions at 2 weekly intervals. There were significant decreases in salivary IgA (p=0.05) and salivary IgM (p < 0.0001) concentrations after individual training sessions, but no significant changes in salivary IgG or albumin concentrations. Over the 12-week training program there were small but statistically significant increases in pre-exercise concentrations of salivary IgA (p<0.001), IgM (p=0.015) and IgG (p=0.003) and post-exercise salivary IgA (p <0.001). There were no significant trends over the 12 weeks for any class of serum immunoglobulins but a significant fall in NK-cell numbers (p<0.001). There were no associations between serum or salivary immunoglobulin levels or NK-cell numbers and upper respiratory tract illness (URTI) during the 12-week program. The data indicated that despite changes in some immune parameters during this final training program prior to competition there were no associations detected with URTI for this cohort of elite swimmers.

Adolescent↗

Reticulocyte parameters as potential discriminators of recombinant human erythropoietin abuse in elite athletes.

This study investigated using reticulocyte (retic) parameters as indirect markers of human recombinant erythropoietin (r-HuEPO) abuse in elite athletes. Absolute reticulocyte count (# retic), the per cell haemoglobin content of reticulocytes (CHr), reticulocyte haemoglobin mass per litre of blood (RetHb) and red blood cell:reticulocyte haemoglobin (RBCHb:RetHb) ratio were assessed using flow cytometry. Venous blood was drawn from 155 elite athletes from six sports during regular training to establish reference ranges (95% confidence interval) for these parameters. The reference ranges were compared with those of a non-athletic population (n = 23), four groups of athletes (n = 24) before and after exposure to simulated altitudes (2,500-3,000 m for 11-23 nights), two groups of elite cyclists (n = 13) before and after four weeks of training at natural altitude (1,780 and 2,690 m), and with those of non-athletic subjects from a separate study (n =24) before and 1-2 days after they were injected with 1,200 U x kg(-1) r-HuEPO over a 9-10 day period. Generally the changes induced by r-HuEPO injection exceeded by approximately 100% the magnitude of the changes associated with natural altitude exposure. Simulated altitude exposure did not significantly alter the reticulocyte parameters. From the sample of 155 non-users and 24 r-HuEPO users, the population mean and variance, as well as the 95% confidence limits for the population mean and population variance, were estimated. Relative to arbitrarily chosen cut-off levels, the confidence limits for the rate of true positives and rate of true negatives were also calculated. Based on the lowest rate of false positives and highest rate of true positives, the best discriminator between r-HuEPO users and non-users was # retic, marginally superior to RBCHb: RetHb ratio and RetHb. At a cut-off for # retic of 221 x 10(9)x L(-1) we could be 95% sure that we would find no more than 7 false positives in every 100,000 tests. We would expect to pick up 51.8% of users, and could be 95% sure of picking up at least 38% of current or recent users. This result highlights the potential power of retic parameters for detecting r-HuEPO abuse among athletes. However, the efficacy of these cut-offs for detecting r-HuEPO abuse is unknown if an athlete is a chronic user or stops using r-HuEPO several weeks before being tested.

Bicycling↗

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.

Exercise↗

Salivary IgA levels and infection risk in elite swimmers.

UNLABELLED: The effects of exercise on the immune system has been shown to be dependent on the level of fitness of the subjects, the degree of intensity, and the duration of the exercise. A reduction in salivary IgA levels occurs after individual sessions of exercise. PURPOSE: The purpose of this study was to assess the relationship between changes in salivary IgA and training volume, psychological stress, and infection rates in a cohort of 26 elite swimmers over a 7-month training period and to compare the changes with a group of 12 moderately exercising controls. METHODS: Salivary IgA concentrations were measured by an electroimmunodiffusion. Exercise gradings were assessed by a standardized aerobic-anaerobic rating system. Psychological stress/anxiety was evaluated by the Spielberger State-Trait Anxiety Inventory. Infections were physician-verified. RESULTS: Salivary IgA levels showed an inverse correlation with the number of infections in both elite swimmers and moderately exercising control subjects. The pretraining salivary IgA levels in swimmers were 4.1% lower for each additional month of training and 5.8% lower for each additional infection. The posttraining salivary IgA levels in swimmers were not significantly correlated with infection rates but were 8.5% lower for each additional 1 km swum in a training session and 7.0% lower for each additional month of training. The number of infections observed in the elite swimmers was predicted from regression models by the preseason (P = 0.05) and the mean pretraining salivary IgA levels (P = 0.006). The trends in pretraining salivary IgA levels over the 7-month season, calculated as individual slopes of pretraining IgA levels over time, were also predictive of the number of infections (P = 0.03) in the swimmers. CONCLUSIONS: These results indicate that measurement of salivary IgA levels over a training season may be predictive for athletes at risk of infection.

Adolescent↗