Neuroimmunological and physiological responses of professional Australian Rules Football athletes to competition.

  • Sam Coad

Student thesis: Doctoral Thesis


The present thesis aimed to enhance the current understanding of neuroimmunological responses of Australian Rules Football athletes to competition. Lateral flow salivary analysis technology was utilized to examine bio-markers, sIgA and sAA, as markers of neuroimmunological function in AFL athletes. Additionally, the present thesis aimed to quantify the acute and chronic trends in neuroimmunological markers following AFL match-play in order to develop a more in-depth understanding of AFL athlete recovery. In order to achieve pragmatic outcomes for coaches and physical performance staff, research investigating neuroimmunological responses was conducted in a field-based environment of an AFL club, and highlighted realistic methods, techniques and benefits for AFL athletes. Outcomes included providing novel information regarding neuroimmunological profiles which may be used to improve recovery and training strategies in AFL athletes. Chapter 3 (Experimental Study 1) The aim of the present study was to examine the validity and reliability of a novel immunoassay, developed to assess salivary Immunoglobulin A (sIgA). Validity and reliability of the Individual Profiling Lateral Flow Device (IPRO LFD) for sIgA concentrations ([sIgA]) was assessed in males (n = 12) and females (n =13) who were involved in recreational activities. Reliability of the IPRO LFD method was assessed by comparing [sIgA] of two saliva samples collected concurrently, while validity was assessed comparing to an enzyme-linked immunosorbent assay (ELISA) method. The IPRO LFD had a strong positive correlation (r = 0.93, p < 0.001), with no significant difference in [sIgA] compared to the ELISA. The IPRO LFD was considered reliable (ICC r = 0.89, p < 0.001 and CV = 9.40 %) for measures of [sIgA]. We concluded that the IPRO LFD method can be used as a substitute to the ELISA method for measurements of [sIgA]. Chapter 4 (Experimental Study 2) Purpose: To (1) examine the pre- and post-match salivary Immunoglobulin A concentration ([sIgA]) response to AFL match-play, and (2) investigate the acute and cumulative influence of player workload and post-match [sIgA] following repeated participation in AFL match-play. Methods: Eleven elite AFL athletes (21.8 ± 2.4 years, 186.9 ± 7.9 cm, 87.4 ± 7.5 kg) were monitored throughout three matches during the pre-season, which were separated by seven days. Saliva samples were collected across each AFL match at 24 hours (h) and 1 h pre-match, and 1 h, 12 h, 36 h, and 60 h post-match, to determine [sIgA]. Global Positioning Systems (GPS) with integrated tri-axial accelerometers (IA) were used to determine total player workload during match-play. Null-hypothesis testing was conducted for time dependant changes in [sIgA] and PlayerLoad using a repeated measures ANOVA. Results: PlayerLoad during match three (1266 ± 124.6 AU) was significantly (p < 0.01) greater than match one (1096 ± 115.1 AU) and match two (1082 ± 90.4 AU). Across match three; [sIgA] was significantly (p < 0.01) suppressed at two post-match measures (12 h and 36 h) compared to pre-match measures (24 h and 1 h) which coincided with significantly (p < 0.01) elevated PlayerLoad. Conclusion: Our findings indicate that an increase in PlayerLoad during AFL pre-season match-play may result in compromised post-match mucosal immunological function. Longitudinal assessment of AFL match PlayerLoad, and mucosal immunological function across the first 60 h of recovery can augment monitoring and preparedness strategies for athletes. Chapter 5 (Experimental Study 3) Purpose: To assess match-to-match variations in salivary immunoglobulin A concentration ([sIgA]) measured at 36 h post-match throughout an Australian Football League (AFL) premiership season and to assess the trends between 36-h-postmatch [sIgA] and match-play exercise workloads throughout the same season. Methods: Eighteen elite male AFL athletes (24 ± 4.2 y, 187.0 ± 7.1 cm, 87.0 ± 7.6 kg) were monitored on a weekly basis to determine total match-play exercise workloads and 36-h-postmatch [sIgA] throughout 16 consecutive matches in an AFL premiership season. Global positioning systems (GPS) with integrated triaxial accelerometers were used to measure exercise workloads (PlayerLoad) during each AFL match. A linear mixed-model analyses was conducted for time-dependent changes in [sIgA] and PlayerLoad. Results: A significant decrease was found for longitudinal post-match [sIgA] data (F16, 240 = 3.78, P < .01) and increase for PlayerLoad data (F 16, 66 = 1.98, P = .03). For all matches after and including match 7, a substantial suppression in [sIgA] after round 7 of on average -24.47 % for 36-h postmatch values compared with a pre-season baseline. Conclusion. The current study provides novel data regarding longitudinal trends in 36-h-postmatch [sIgA] for AFL athletes. Results demonstrate that weekly in-season AFL match-play exercise workloads may result in delayed mucosal immunological recovery up-to and beyond 36 h post-match. The inclusion of individual athlete-monitoring strategies of [sIgA] can be advantageous in the detection of compromised post-match mucosal immunological function for AFL athletes. Chapter 6 (Experimental Study 4) Salivary Alpha Amylase (sAA) has been considered a surrogate bio-marker of autonomic nervous system activity, and may be considered useful to highlight periods of physiological fatigue in athlete’s. Novel lateral flow technology has allowed for rapid salivary assessment and offers an alternative practical method for monitoring salivary markers such as Alpha Amylase in AFL athletes throughout the in-season. Therefore, the present study aimed to (1) examine week-to-week and month-to-month variations in AFL athletes’ sAA concentrations ([sAA]) throughout a 16 match period of the AFL in-season, and (2) examine the acute relationship between post-match measure of [sAA] and match-play exercise workloads. Twenty elite male Australian Rules Footballers (24.3 ± 4.2 years, 186.7 ± 7.3 cm, 87.6 ± 8.0 kg) were monitored throughout 16 in-season AFL matches for sAA taken 36-hours post-match and exercise workloads (PlayerLoad) using GPS IA. The present study utilized linear mixed model analyses for time dependent changes in (sAA) and PlayerLoad. A significant main effect was found for week-to- week analysis of 36-hour post-match [sAA] (F (15, 36) = 5.12, p < 0.001) and for match-play PlayerLoad (F (15, 61) = 2.33, p = 0.011). Further a significant main effect (F (3 19) = 11.88, p < 0.001) was found for month-to-month increases in 36-hour post-match [sAA]. Finally, high inter- (103 %) and intra-subject (110 %) variation of [sAA] were found. The present study presents novel data of trends in 36-hour post-match [sAA] for AFL athletes. A significant increase in month-to-month 36-hour post-match [sAA] peaking in the final month of the study was found. Month-to-month analysis of [sAA] indicates evidence of increased SNS activity throughout the AFL in-season, however results on a week-to-week basis need to be analysed with caution given the high levels of intra- and inter-subject variation.
Date of Award12 Feb 2020
Original languageEnglish
SupervisorChristopher McLellan (Supervisor) & Bon Gray (Supervisor)

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