The Within-Subject Correlation Between Salivary IgA and Measures of Training Load in Elite Football Players

Figueiredo, P., Nassis, G.P., Brito, J.

Purpose: To quantify the association between salivary secretory immunoglobulin A (sIgA) and training load in elite football players.
Methods: Data were obtained over four consecutive days during the preparation camp for the Rio 2016 Olympic Games. Saliva samples of 18 elite male football players were collected prior to breakfast. The session rating of perceived exertion (s-RPE) and external training load metrics from GPS were recorded. Within-subject correlation coefficients between training load and sIgA concentration, and magnitude of relationships were calculated.
Results: sIgA presented moderate to large negative correlations with s-RPE (r=-0.39), total distance covered (r=-0.55), accelerations (r=-0.52), and decelerations (r=-0.48). Trivial to small associations were detected between sIgA and distance covered per minute (r=0.01), high-speed distance (r=-0.23), and number of sprints (r=-0.18). sIgA displayed a likely moderate decrease from day 1 to day 2 (d=-0.7) but increased on day 3 (d=0.6). The training load variables had moderate to very large rises from day 1 to day 2 (d=0.7 to 3.2), but lowered from day 2 to day 3 (d=-5.0 to -0.4), except for distance per minute (d=0.8) and sprints (unclear). On day 3, all training load variables had small to large increments compared with day 1 (d=0.4 to 1.5), with exception of accelerations (d=-0.8) and decelerations (unclear).
Conclusions: In elite football, sIgA might be more responsive to training volume rather than intensity. External load such as GPS-derived variables presented stronger association with sIgA compared with s-RPE. Salivary IgA can be used as an additional objective tool in monitoring football players.