Mucosal immunity and illness incidence in elite rugby union players across a season.
OBJECTIVE
To examine the relationship between upper respiratory illness (URI) incidence with changes in mucosal immunity (saliva immunoglobulin A (s-IgA) and saliva lysozyme (s-Lys)) and training load (TL) in a squad of elite rugby union players.


METHODS
Timed resting morning saliva samples were taken from players (n = 31) at preselected time points for 11 months. Weekly illness rates and TL were assessed using a Web-based diary and from medical/coaching staff reports.


RESULTS
No significant correlation was found between absolute s-IgA or s-Lys concentrations and URI incidence. Peaks in URI (December and March) were preceded by periods of increased training intensity and reduced game activity. In 23% of all URI episodes, players reported that presence of an illness either reduced activity (14.4%) or felt the need to go to bed (8.6%). When s-IgA concentration was expressed relative to that when in a URI-free state, a 15% reduction (P = 0.08) was observed in individuals who had present URI symptoms. Decreases in absolute s-IgA (December) and s-Lys (November and February) concentrations were associated with a corresponding increase in saliva cortisol (P < 0.05). Lower s-IgA (P < 0.05) and s-Lys concentrations were consistently observed in backs than forwards, whereas URI incidence also differed for player position (3.4 forwards vs 4.3 backs).


CONCLUSIONS
Regular monitoring of s-IgA and s-Lys may be useful in the assessment of exercise stress and URI risk status in elite team sport athletes. A combination of alterations in training intensity and seasonal influence is a likely contributor to observed peaks in URI incidence. It is probable that stress-induced increases in cortisol release contribute to reductions in mucosal immunity, which, when lowered, predispose rugby players to increased risk of illness.
Cunniffe
Brian
B
Department of Health, Exercise, Sport and Science, University of Glamorgan, Wales, United Kingdom. briancunniffe@hotmail.com
Griffiths
Hywel
H
Proctor
Wayne
W
Davies
Bruce
B
Baker
Julien S
JS
Jones
Ken P
KP
D000328:Adult; D056352:Athletes / Q000706:statistics & numerical data; D005538:Football; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D006854:Hydrocortisone / Q000276:immunology; D018928:Immunity, Mucosal; D007071:Immunoglobulin A, Secretory / Q000276:immunology; D015994:Incidence; D008297:Male; D009113:Muramidase / Q000276:immunology; D010101:Oxygen Consumption / Q000502:physiology; D012141:Respiratory Tract Infections / Q000453:epidemiology*; D012463:Saliva / Q000276:immunology; D055815:Young Adult
D007071:Immunoglobulin A, Secretory; D009113:Muramidase; D006854:Hydrocortisone