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.

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.

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.

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.

Inhibition of interferon, cytokine, and lymphocyte proliferative responses in elite swimmers with altitude exposure.

To determine the immunologic consequences of athletic training at altitude, blood samples were taken at rest from 10 swimmers and 8 control nontraining but altitude-exposed members of the 1996 Australian Olympic Swimming Team, near the start and completion of a 21-day training camp at 2102 m. Blood leukocyte numbers dropped in both groups (p < 0.05), with the decrease greater in the swimmers (-38% swimmers, -3% controls). Concanavalin A (ConA)-induced blastogenesis decreased in both groups (p < 0.01), but the drop was greater in the control group (-32% swimmers, -56% controls, p < 0.05). Lipopolysaccharide (LPS)-induced blastogenesis more than doubled in both groups (281% swimmers, 249% controls, p < 0.01). Increases in mitogen-induced interleukin-1beta (IL-1beta), IL-4, and interferon-gamma (IFN-gamma) production and a decrease in IL-2 levels were observed in both groups after altitude exposure (all p < 0.05). The percentage of cells expressing HLA-DR fell (-33% swimmers, -20% controls, p < 0.01), whereas those expressing CD-4 expression increased (16% swimmers only, p < 0.01). Although training at medium-level altitude alters some immunologic parameters, the training-induced changes may be secondary to those induced by altitude alone.

Salivary IgA subclasses and infection risk in elite swimmers.

The concentrations of total IgA, IgA1 and IgA2 were measured in saliva collected from 25 elite swimmers in the early and late phases of a 7 month training season and compared with the number of respiratory infections during the season. The IgA1 concentrations in the early phase of the training season were significantly associated (P = 0.01) with the number of respiratory infection episodes during the training season. The lower the concentration of IgA1, the greater the number of infection episodes. Swimmers with four or more infections during the training season had significantly lower salivary IgA1 concentrations than those with less than four infection episodes (P = 0.01). The proportion of IgA1 in the saliva of the elite swimmers (80%) was higher than for normal non-exercising adults (60%). A small proportion of athletes had salivary IgA2 concentrations below the detection limit of the assay and the mean concentration of IgA2 was significantly lower than the concentrations for a normal adult population (P = 0.01). This study suggests that measurement of IgA subclasses, in particular IgA1, at the commencement of a training season may predict infection risk in elite swimmers.

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.

Injuries of young elite female basketball players over a six-year period.

OBJECTIVE: To analyze injuries retrospectively among female basketball players at the Australian Institute of Sport (AIS) from 1990 to 1995 inclusive. DESIGN: The medical records of all the female basketball players on AIS (residential) scholarships were examined, and all injuries were recorded. SETTING: The Sports Medicine Department at the Australian Institute of Sport in Canberra, Australia. PARTICIPANTS: The participants were 49 elite female basketball players, holding full scholarships at the AIS, with an average age of 17.6 years at the time of injury presentation. MAIN OUTCOME MEASURES: Injury presentation according to region involved, nature of injury, and most common specific injuries (diagnoses). RESULTS: A total of 223 injuries were recorded: 139 were acute and 84 were chronic. The regions most frequently injured were the knee (18.8%), ankle (16.6%), lumbar spine (11.7%), and lower legs (10.8%). The most frequent diagnoses were ankle lateral ligament sprain (12.1%), patellar tendinitis (6.7%), lower limb stress fractures (5.4%), finger sprains (4.9%), and mechanical low back pain (4.5%). CONCLUSIONS: There was a high incidence of knee and ankle injury in this group of young elite female basketball players, and stress fractures were not uncommon. The incidence of injury in female basketball players may be increasing. Further research in this area may help reduce the risk of stress fractures and serious ankle and knee injuries.

Injuries to elite rowers over a 10-yr period.

The purpose of this study was to analyze retrospectively all injuries occurring in a population of elite rowers over a 10-yr period to determine their pattern of injury. The medical records of all rowers at the Australian Institute of Sport from 1985 to 1994 inclusive were reviewed and all injuries included. Injuries were categorized according to time, location, cause, and whether acute or chronic. The study found a significant incidence of chest injuries, rib stress fractures, and low back injuries, and a high number of injuries occurring outside specific training. Elite rowers have little risk of major injury, but mild and moderate injuries are common.

Pneumococcal antibody responses in elite swimmers.

The ability of elite swimmers to mount an antibody response to the pneumococcal vaccine, Pneumovax 23, was assessed at the end of an intensive 12-week training programme. Antibody titres to six pneumococcal polysaccharide types were measured in 20 elite swimmers (10 male, 10 female) aged 17-23 years and 19 sedentary age- and sex-matched students (eight male, 11 female) aged 18-23 years. Blood samples were tested 14 days apart to assess the magnitude of the antibody response and changes in serum immunoglobulin isotypes and IgG subclasses. There were no significant differences in any of the pneumococcal antibody responses to the Pneumovax between swimmers and controls, and no gender effect, either before or after vaccination. The clinically adequate response to the vaccine was greatest for the pneumococcal serotype 4, which was 97% for the total study population. There were no significant correlations between the magnitude of any of the pneumococcal antibody responses and (i) changes in the scores for the swimmers' international performance; (ii) infection rates in either swimmers or controls; (iii) any psychological variables, assessed by the Profile of Mood States (POMS) questionnaire for either swimmers or controls. Swimmers had significantly lower concentrations of serum IgG2 (P = 0.04) and IgG3 (P = 0.002) before pneumococcal vaccination. The swimmers had an increase in all immunoglobulin isotypes and IgG subclasses post-vaccination, suggesting a polyclonal response to the vaccine that was not observed in control subjects. The magnitude of the subclass responses after vaccination was significantly greater in swimmers compared with controls for IgG1 (P = 0.04), IgG3 (P = 0.04) and IgG4 (P = 0.01). The data indicated that elite swimmers undertaking an intensive training programme were capable of mounting an antibody response to pneumococcal antigens equivalent to that of age- and sex-matched sedentary control subjects, despite the swimmers having lower prevaccination levels of serum immunoglobulins.

The effect on immunity of long-term intensive training in elite swimmers.

The impact of long-term training on systemic and mucosal immunity was assessed prospectively in a cohort of elite swimmers over a 7-month training season in preparation for national championships. The results indicated significant suppression (P < 0.05) of serum IgA, IgG and IgM and salivary IgA concentration in athletes associated with long-term training at an intensive level. There was also a trend towards lower IgG2 subclass levels in serum in athletes compared with controls (P = 0.07). There were no significant changes in numbers or percentages of B or T cell subsets, but there was a significant fall in natural killer (NK) cell numbers and percentages in athletes over the training season (P < 0.05). After individual training sessions there was a significant decrease in salivary IgA levels for athletes compared with controls (P = 0.002). In athletes there was a downward trend in salivary IgA levels over the 7-month training period in both the pre-exercise (P = 0.06) and post-exercise samples (P = 0.04). There were no significant trends in salivary IgG levels over the study period in either athletes or controls. The only significant change in salivary IgM levels was an increase in detection rate in the pre-competition phase in athletes (P = 0.03). The study suggests that training of elite athletes at an intensive level over both short- and long-time frames suppresses both systemic and mucosal immunity. Protracted immune suppression linked with prolonged training may determine susceptibility to infection, particularly at times of major competitions.

Effects of an intensive 12-wk training program by elite swimmers on neutrophil oxidative activity.

The effects of an intensive 12-wk training program by 12 national-level swimmers on neutrophil oxidative activity were studied. Eleven sedentary (untrained) subjects (6 males and 5 females) served as environmental controls. Blood samples (10 ml) were taken at rest from an antecubital vein and neutrophils isolated by standard separation techniques. The oxidative burst activity of isolated neutrophils was assessed with an in vitro flow cytometric assay that used the fluorescent probe dihydrorhodamine 123. Two-way ANOVA (repeated measures) showed that oxidative activity was lower (P < 0.05) in the elite swimmers compared with the sedentary control group across the 12-wk period. Analysis of cells from swimmers in training was made: repeated measures ANOVA provided evidence of a significant decline (P < 0.05) in the number of cells responding positively ito in vitro challenge. Despite this decline, there was no significant difference in self-reported upper respiratory tract infection rate between the swimmers and sedentary individuals. These data show that: (i) elite swimmers undertaking intensive training have a significantly lower neutrophil oxidative activity at rest than do age- and sex-matched sedentary individuals; (ii) aspects of oxidative activity in swimmers are further suppressed during periods of strenuous training, and (iii) the extent of the suppression does not appear to be of clinical significance.

A case of chronic depression.

The authors describe a case of chronic depression in a designated Naval Aviator with a concomitant history of hypothyroidism. The differential diagnosis of dysthymia is discussed and the associated therapeutic alternatives are reviewed. The case demonstrates the importance of comprehensive physical and psychiatric evaluation of those patients with complex or atypical presentations. Issues pertaining to the aeromedical disposition of such patients are discussed, with emphasis on the role of the flight surgeon.

Efficacy of Levamisol on milk production of dairy cows: a field study.

Twelve hundred ninety-six cows on 88 farms were alternately injected at calving with Levamisol or saline. Each farm was visited every 2nd wk from May to October to administer treatments to cows that would calve prior to our next visit and to collect fecal grab samples from cows for worm egg counts. Production records were collected for each cow for their first 6 mo of lactation. Fecal worm egg counts were reduced in cows treated with Levamisol for the first 2 mo postcalving. Daily milk produced was higher in cows treated with Levamisol by 1.24 kg. Milk fat and protein percentages were not different between treatment groups; however, milk fat production was higher in cows treated with Levamisol for the first 2 mo post-calving. Cows treated with Levamisol produced 235 kg more milk than control cows during their first 6 mo of lactation and were projected to produce 339 kg more milk for a 305-d lactation. Month of calving improved milk production by cows treated with Levamisol. Cows treated with Levamisol and calved in months May to July showed the highest improvement in milk production while cows that were treated with Levamisol and calved in months August to October showed no significant improvement in production. Injection of cows with Levamisol at calving improves milk production and reduces gastrointestinal worm burdens.

Factors affecting Staphylococcus epidermidis growth in peritoneal dialysis solutions.

Staphylococcus epidermidis is the most frequent cause of peritonitis complicating continuous ambulatory peritoneal dialysis. We studied factors that might influence the growth of S. epidermidis in commercially available peritoneal dialysis solution (PDS). Test strains were inoculated into PDS and incubated overnight at 37 degrees C. Samples were removed at appropriate intervals, bacterial counts were performed, and growth curves were constructed. We studied the effects of various osmolarities, the neutralization and acidification of fresh and spent PDS, and the effect of intraperitoneal dwell time on the ability PDS to support growth of S. epidermidis. In fresh PDS, numbers of bacteria remained constant after 24 h. No significant differences in growth were observed among PDS with 0.5, 1.5, 2.5, and 4.25% glucose. Neutralizing acidic fresh PDS had no effect on bacterial growth. However, growth did occur in spent PDS. PDS which was recovered after only 2 h in the peritoneal cavity supported growth to the same extent as did PDS recovered after 4 to 6 h. Mean log10 changes after 24 h of incubation were as follows: for fresh PDS, -1.3; after 2 h dwell time, 2.9; after 4 h dwell time, 1.9; and after 6 h dwell time, 1.3. Acidification of spent PDS to less than pH 6.35 produced less rapid growth; mean log10 increases after 24 h of incubation were 1.9 for pH 7.75, 1.6 for pH 6.35, 0.6 for pH 5.75, and 0.7 for pH 4.95. Fresh PDS of all available osmolarities neither supported the growth of S. epidermidis nor was bactericidal. Spent PDS supported bacterial growth, and this growth was partly independent of the neutralization which occurred during the dialysis.