Warren McDonald

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.

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= 0.02). 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.

Epstein-barr virus reactivation and upper-respiratory illness in elite swimmers

PURPOSE The aim of this study was to investigate the relationships between latent viral shedding of Epstein-Barr virus (EBV) in saliva, upper-respiratory illness, and mucosal immune suppression in a cohort of highly trained swimmers undertaking intensive training. METHODS Saliva was collected before selected training sessions from 14 elite male swimmers during a 30-d period of intensive training. Prior infection with EBV was determined by EBV antibody serology. Salivary IgA concentrations were measured by enzyme linked immunosorbent assay (ELISA), and EBV viral shedding (EBV-DNA) was detected by polymerase chain reaction (PCR). Symptoms of upper-respiratory illness were recorded daily. RESULTS Eleven swimmers (79%) were seropositive for prior EBV infection. Seven EBV seropositive swimmers (64%) had EBV-DNA detected during the study period. Upper-respiratory symptoms (URS) were reported in six of seven swimmers in whom EBV-DNA was detected and in three of four swimmers with no EBV-DNA detection. No URS were reported in the EBV seronegative swimmers. There was a statistically significant relationship between EBV serology status and URS (P = 0.027). EBV-DNA was detected in saliva before the appearance of URS. Salivary IgA levels were significantly lower immediately before the URS (P = 0.01) compared with subsequent peak IgA levels and declined to pre-URS levels on average 11 d after the first appearance of URS. CONCLUSIONS The time course of appearance of EBV-DNA in relation to URS suggests latent viral EBV shedding may be a contributing factor in the URS. The low levels of salivary IgA detected before the URS indicated transient mucosal immune suppression in the study cohort. The viral shedding may alternatively be a reflection of the altered immune control mechanisms that occur in response to intensive exercise and unrelated to the URS.

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.

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.

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

ObjectiveTo analyze injuries retrospectively among female basketball players at the Australian Institute of Sport (AIS) from 1990 to 1995 inclusive. DesignThe medical records of all the female basketball players on AIS (residential) scholarships were examined, and all injuries were recorded. SettingThe Sports Medicine Department at the Australian Institute of Sport in Canberra, Australia. ParticipantsThe 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 measuresInjury presentation according to region involved, nature of injury, and most common specific injuries (diagnoses). ResultsA 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%). ConclusionsThere 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

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.

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.

Exercise, Stress and Mucosal Immunity in Elite Swimmers

Elite athletes have been reported to be susceptible to upper respiratory tract infections (URTI), particularly during the period immediately prior to major competitions.1 Studies of the effects of exercise on immune parameters have shown that alterations in systemic immunity and cytokine levels are related to the intensity of the exercise and fitness of the athlete.2 In elite athletes decreases in salivary IgA levels have been observed following intense endurance exercise3,4 but it is not clear whether the changes are associated with an increased incidence of URTI.5 Psychological stress has also been shown to decrease salivary IgA levels,6 but the relevance of this observation to the immune fitness following fatiguing exercise is unclear. This prospective study assessed the impact of long term exercise (physical stress) and psychological stress on systemic and mucosal immunity and the relationship to URTI in a cohort of elite swimmers.

Impact of Altitude on Power Output during Cycling Stage Racing.

Purpose The purpose of this study was to quantify the effects of moderate-high altitude on power output, cadence, speed and heart rate during a multi-day cycling tour. Methods Power output, heart rate, speed and cadence were collected from elite male road cyclists during maximal efforts of 5, 15, 30, 60, 240 and 600 s. The efforts were completed in a laboratory power-profile assessment, and spontaneously during a cycling race simulation near sea-level and an international cycling race at moderate-high altitude. Matched data from the laboratory power-profile and the highest maximal mean power output (MMP) and corresponding speed and heart rate recorded during the cycling race simulation and cycling race at moderate-high altitude were compared using paired t-tests. Additionally, all MMP and corresponding speeds and heart rates were binned per 1000m (<1000m, 1000–2000, 2000–3000 and >3000m) according to the average altitude of each ride. Mixed linear modelling was used to compare cycling performance data from each altitude bin. Results Power output was similar between the laboratory power-profile and the race simulation, however MMPs for 5–600 s and 15, 60, 240 and 600 s were lower (p ≤ 0.005) during the race at altitude compared with the laboratory power-profile and race simulation, respectively. Furthermore, peak power output and all MMPs were lower (≥ 11.7%, p ≤ 0.001) while racing >3000 m compared with rides completed near sea-level. However, speed associated with MMP 60 and 240 s was greater (p < 0.001) during racing at moderate-high altitude compared with the race simulation near sea-level. Conclusion A reduction in oxygen availability as altitude increases leads to attenuation of cycling power output during competition. Decrement in cycling power output at altitude does not seem to affect speed which tended to be greater at higher altitudes.