Salivary IgA is not a reliable indicator of upper respiratory infection in collegiate female soccer athletes

Saliva as a diagnostic tool in soccer: a scoping review

Background

A high-performance sport like soccer requires training strategies that aim to reach peak performance at the right time for the desired competitions. Thus, the investigation of biochemical markers in saliva is a tool that is beginning to be used in athletes within the physical training process. There is still no evidence on universal saliva collection and analysis protocols in soccer. This review aims to map the use of saliva as a tool for analyzing athletic performance in soccer, from the biomarkers used to the validated protocols for these analyses.

Methods

A broad systematic literature search was carried out in the electronic databases Web of Science, Livivo, Scopus, PubMed, LILACS and gray literature (Google Scholar and ProQuest). Two reviewers selected the studies and extracted data on the type of salivary collection used, the salivary biomarker evaluated and monitored.

Results

Ninety-three articles were included. The most frequently analyzed salivary biomarkers were cortisol (n = 53), testosterone (n = 35), secretory immunoglobulin A (SIgA) (n = 33), salivary alpha amylase (n = 7), genetic polymorphisms (n = 4) and miRNAs (n = 2). The results of the studies indicated beneficial effects in monitoring salivary biomarkers in the assessment of sports performance, although most studies did not include a control group capable of comparison. Salivary collection and analysis protocols were varied and commonly not reported.

Conclusions

This scoping review provides a comprehensive overview of the current landscape of salivary biomarker research in soccer. The findings underscore the importance of these biomarkers in assessing athletes' physiological responses and overall well-being. Future research should focus on refining methodologies, exploring additional biomarkers, and investigating the practical implications of salivary biomarker monitoring in soccer and other sports.

Relationship between Training Load Management and Immunoglobulin A to Avoid Immunosuppression after Soccer Training and Competition: A Theoretical Framework Based on COVID-19 for Athletes' Healthcare

Immunoglobulin A (IgA), which is the main effector against upper respiratory tract viruses such as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has been related to training load management. The aim of this systematic review was to establish the relationship between training load and salivary IgA based on current evidence in order to avoid immunosuppression after exercise and players´ vulnerability to virus contagion. A systematic review of relevant articles was carried out using two electronic databases (PubMed and Web of Science) until 19 May 2021. From a total of 127 studies initially found, 23 were included in the qualitative synthesis. These studies were clustered depending on stress level. The salivary IgA was analysed considering soccer-specific treadmill exercise and repeated sprint drills (n = 5), matches (n = 7), and during certain periods during the season or pre-season (n = 11). Repeated sprint ability tests and treadmill exercises are suitable exercises for the first steps on return to play periods yet still maintain social distance. A rest or moderate training sessions (technical/tactical) are suggested after official matches to ensure 16-18 h to recover IgA levels, while periods with multiple matches per week with limited recovery time should be avoided. Weekly training load should assume a small increment (<10%) to ensure IgA immune responses, especially, during the post coronavirus disease 2019 (COVID-19) season.

Neuromuscular, Endocrine, and Perceptual Recovery After a Youth American Football Game

ABSTRACT

Davis, JK, Wolfe, AS, Basham, SA, Freese, EC, and De Chavez, PJD. Neuromuscular, endocrine, and perceptual recovery after a youth American football game. J Strength Cond Res 35(5): 1317-1325, 2021-American football is a high-intensity intermittent sport consisting of various movements and repeated collisions which highlights the importance of adequate recovery from a game to prepare for the next competition. Therefore, the purpose of this study was to determine the time course of recovery markers after a youth American football game. Thirteen male American football youth players were monitored for 7 days after a single football game. Baseline measures were taken 28 hours pregame for lower-body neuromuscular function by countermovement jumps (CMJs) to determine peak power (PP), jump height (JH), flight time (FT), and takeoff velocity (TOV). Saliva was analyzed for cortisol, testosterone, and C-reactive protein (CRP). Perceptual recovery was assessed by the modified profile of mood states (POMS), perceived recovery status (PRS), and a daily wellness questionnaire. These measures were repeated immediately postgame (30 minutes) and at 20, 44, 68, 92, 116, and 140 hours postgame. Compared with baseline values, there was a significant decrease (p < 0.05) in CMJ PP, JH, and TOV up to 68 hours postgame and FT 44 hours postgame. No significant difference existed among time points for salivary testosterone and CRP. Cortisol levels significantly increased postgame compared with baseline (p < 0.05). Total mood disturbance, assessed by POMS, and daily wellness markers for energy were significantly decreased (p < 0.05), whereas daily wellness markers for soreness were significantly increased (p < 0.05) immediately after the game. Players exhibited a significant decrease in PRS up to 44 hours postgame (p < 0.05), similar to the decrease in neuromuscular function. Neuromuscular function and PRS are impaired for up to 44-68 h postgame.

Salivary IgA as a Potential Biomarker in the Evaluation of Respiratory Tract Infection Risk in Athletes

In recent years, there has been attention focused on the value of salivary IgA (sIgA) as a potential biomarker for the identification of athletes who may be at increased risk of developing respiratory tract infection (RTI). The utility of sIgA, in this context, is based on biological plausibility and several observational studies revealing an apparent association between sIgA and RTI susceptibility. The overall published evidence evaluating the value of sIgA in this context is however conflicting, and there is currently a lack of clear guidance as to whether this marker has a place in the health surveillance and care of athletes. In this review, we critically appraise the literature assessing the potential for sIgA to be used in this context, evaluating it against 4 key biomarker characteristics, including its (1) practicality, (2) reproducibility, (3) specificity/sensitivity, and (4) potential clinical impact and relevance. This process reveals that although there is an apparent association between respiratory illness and sIgA in many studies, with some promising results, overall there remains a paucity of evidence supporting its overall value in this context. Key deficiencies in the metrics employed to endorse a valid biomarker are apparent, including a lack of reproducibility and low specificity and sensitivity in the detection of RTI susceptibility. The review outlines these issues and makes future recommendations.

No Association between Vitamin D and Acute Respiratory Tract Infections Amongst Elite New Zealand Rugby Players and Rowers

Upper respiratory tract infections are the most common infections reported by elite athletes. Low vitamin D status has been associated with an increased risk of upper respiratory tract infections. The aim of this study was to investigate associations between serum 25-hydroxyvitamin D (25(OH)D), salivary immunoglobulin A (S-IgA) concentrations, and acute respiratory tract infections (colds/flu) (ARI) in elite rowers and rugby players. A total of 53 (23 rugby players, 30 rowers) elite New Zealand athletes volunteered to participate in an interview, and to provide a blood and a saliva sample. Testing occurred twice, 6 months apart. Athletes' serum 25(OH)D concentrations and s-IgA levels were both significantly higher in summer, 108.9 (CI 102.8, 115.4) nmol/L, than in winter, 86.8 (CI 81.8, 92.1) nmol/L (p < 0.01, p = 0.028). The occurrence of an acute respiratory tract infection did not differ significantly between the time points (p = 0.322). However, ARI duration was significantly longer in winter than in summer (6.9 ± 4.3 days vs 4.8 ± 3.0 days; p = 0.044). There were no significant correlations between athletes' 25(OH)D levels and their s-IgA levels (p > 0.05) nor with acute respiratory tract infection occurrence (p > 0.05) nor duration (p > 0.05) in summer or winter. These findings suggest there may not be any associations between serum 25(OH)D concentrations and acute respiratory tract infections in this population. However, this null finding may be attributed to the high vitamin D concentrations seen in these athletes.

Respiratory Infections

Respiratory infections are the most frequent cause of athletes’ visits in medical practices. Simultaneously, contradictory beliefs are generally held regarding influence of repeated exercise on immunity reflected in susceptibility to infections. Many tend to claim that exercise weakens the immunity and renders regular exercisers more prone to develop airway infections. On the other hand, voices are heard in favor of the possible beneficial influence of regular exercise on immune system efficiency. This chapter focuses on the associations of various kinds of exercise with respiratory infection susceptibility. Influence of exercise, in particular associated with competitive performance, on selected innate and acquired immune response mechanisms is also addressed.

Realising the Potential of Urine and Saliva as Diagnostic Tools in Sport and Exercise Medicine

Accurate monitoring of homeostatic perturbations following various psychophysiological stressors is essential in sports and exercise medicine. Various biomarkers are routinely used as monitoring tools in both clinical and elite sport settings. Blood collection and muscle biopsies, both invasive in nature, are considered the gold standard for the analysis of these biomarkers in exercise science. Exploring non-invasive methods of collecting and analysing biomarkers that are capable of providing accurate information regarding exercise-induced physiological and psychological stress is of obvious practical importance. This review describes the potential benefits, and the limitations, of using saliva and urine to ascertain biomarkers capable of identifying important stressors that are routinely encountered before, during, or after intense or unaccustomed exercise, competition, over-training, and inappropriate recovery. In particular, we focus on urinary and saliva biomarkers that have previously been used to monitor muscle damage, inflammation, cardiovascular stress, oxidative stress, hydration status, and brain distress. Evidence is provided from a range of empirical studies suggesting that urine and saliva are both capable of identifying various stressors. Although additional research regarding the efficacy of using urine and/or saliva to indicate the severity of exercise-induced psychophysiological stress is required, it is likely that these non-invasive biomarkers will represent "the future" in sports and exercise medicine.