Peter A. Fricker

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.

Oral administration of the probiotic Lactobacillus fermentum VRI-003 and mucosal immunity in endurance athletes

Objective To evaluate the ability of a probiotic Lactobacillus fermentum VRI-003 (PCC) to enhance the mucosal immune system of elite athletes. Design and setting A double-blind, placebo-controlled, crossover trial was conducted over a 4-month period of winter training. Participants 20 healthy elite male distance runners. Interventions PCC was given at a daily dose of 1.26×1010 as a freeze-dried powder in gelatin capsules. Placebo capsules contained an inert excipient. Main outcome measures Treadmill performance (monthly), mucosal and systemic immunity (monthly), training (daily) and illness (daily) were assessed. Serum cytokine levels, salivary IgA levels and incidence, duration and severity of respiratory tract infections were measured. Results Subjects reported less than half the number of days of respiratory symptoms during PCC treatment (30 days) compared with placebo (72 days, p<0.001). Illness severity was also lower for episodes occurring during the PCC treatment (p = 0.06). There were no significant differences in the mean change in salivary IgA and IgA1 levels, or in interleukin (IL)4 and IL12 levels, between treatments. However, PCC treatment elicited a twofold (p = 0.07) greater change in whole-blood culture interferon gamma (IFNγ) compared with placebo. No substantial changes in running performance measures were seen over the study period. Conclusions Prophylactic administration of PCC was associated with a substantial reduction in the number of days and severity of respiratory illness in a cohort of highly trained distance runners. Maintenance of IFNγ levels may be one mechanism underpinning the positive clinical outcomes.

Injuries to elite gymnasts over 10 yr

This retrospective study of 42 male and 74 female elite (artistic) gymnasts at the Australian Institute of Sport (AIS) reviews all the injuries reported between 1982 and 1991 (inclusive). The injuries were categorized according to type of injury and their specific anatomical distribution. The study also analyzes the incidence of stress fractures in the gymnasts and the prevalence of spondylolysis. Although it is noted from the literature that gymnastics can be a hazardous sport, this study demonstrates an absence of catastrophic injuries and a low number of severe injuries.

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.

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.

Lactobacillus fermentum (PCC®) supplementation and gastrointestinal and respiratory-tract illness symptoms: a randomised control trial in athletes

BackgroundProbiotics purportedly reduce symptoms of gastrointestinal and upper respiratory-tract illness by modulating commensal microflora. Preventing and reducing symptoms of respiratory and gastrointestinal illness are the primary reason that dietary supplementation with probiotics are becoming increasingly popular with healthy active individuals. There is a paucity of data regarding the effectiveness of probiotics in this cohort. The aim of this study was to evaluate the effectiveness of a probiotic on faecal microbiology, self-reported illness symptoms and immunity in healthy well trained individuals.MethodsCompetitive cyclists (64 males and 35 females; age 35 ± 9 and 36 ± 9 y, VO2max 56 ± 6 and 52 ± 6 ml.kg-1.min-1, mean ± SD) were randomised to either probiotic (minimum 1 × 109Lactobacillus fermentum (PCC®) per day) or placebo treatment for 11 weeks in a double-blind, randomised, controlled trial. The outcome measures were faecal L. fermentum counts, self-reported symptoms of illness and serum cytokines.ResultsLactobacillus numbers increased 7.7-fold (90% confidence limits 2.1- to 28-fold) more in males on the probiotic, while there was an unclear 2.2-fold (0.2- to 18-fold) increase in females taking the probiotic. The number and duration of mild gastrointestinal symptoms were ~2-fold greater in the probiotic group. However, there was a substantial 0.7 (0.2 to 1.2) of a scale step reduction in the severity of gastrointestinal illness at the mean training load in males, which became more pronounced as training load increased. The load (duration×severity) of lower respiratory illness symptoms was less by a factor of 0.31 (99%CI; 0.07 to 0.96) in males taking the probiotic compared with placebo but increased by a factor of 2.2 (0.41 to 27) in females. Differences in use of cold and flu medication mirrored these symptoms. The observed effects on URTI had too much uncertainty for a decisive outcome. There were clear reductions in the magnitude of acute exercise-induced changes in some cytokines.ConclusionL. fermentum may be a useful nutritional adjunct for healthy exercising males. However, uncertainty in the effects of supplementation on URTI and on symptoms in females needs to be resolved.Trial registrationThe trial was registered in the Australia and New Zealand Clinical Trials Registry (ACTRN12611000006943).

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

The effect of exercise on innate mucosal immunity

Methods The authors conducted a prospective observational study comparing salivary lactoferrin and lysozyme concentration over 5 months (chronic changes) in elite rowers (n=17, mean age 24.3±4.0 years) with sedentary individuals (controls) (n=18, mean age=27.2±7.1 years) and a graded exercise test to exhaustion (acute changes) with a cohort of elite rowers (n=11, mean age 24.7±4.1). Results Magnitudes of differences and changes were interpreted as a standardised (Cohens) effect size (ES). Lactoferrin concentration in the observational study was approximately 60% lower in rowers than control subjects at baseline (7.9±1.2 µg/ml mean±SEM, 19.4±5.6 µg/ml, p=0.05, ES=0.68, ‘moderate’) and at the midpoint of the season (6.4±1.4 µg/ml mean ± SEM, 21.5±4.2 µg/ml, p=0.001, ES=0.89, ‘moderate’). The concentration of lactoferrin at the end of the study was not statistically significant (p=0.1) between the groups. There was no significant difference between rowers and control subjects in lysozyme concentration during the study. There was a 50% increase in the concentration of lactoferrin (p=0.05, ES=1.04, ‘moderate’) and a 55% increase in lysozyme (p=0.01, ES=3.0, ‘very large’) from pre-exercise to exhaustion in the graded exercise session. Conclusion Lower concentrations of these proteins may be indicative of an impairment of innate protection of the upper respiratory tract. Increased salivary lactoferrin and lysozyme concentration following exhaustive exercise may be due to a transient activation response that increases protection in the immediate postexercise period.