The efficacy of salivary testosterone and cortisol as a biomarker of training and competition in elite rugby union athletes

Abstract

In populations of elite athletes, the short-term and long-term effects of endogenous testosterone and cortisol play an important role in both training and competition. In a season-long competition format, understanding the effects and demands of competition and training plays a pivotal role in player management. This research sought to improve the understanding of salivary testosterone and cortisol responses of elite rugby union players in response to competitive match play and training. The first study examined the association of pregame testosterone and cortisol concentrations with competitive game play and outcome. Grouped pregame testosterone concentrations were significantly higher before games won than before games lost (p<.001) and were also positively correlated with a game ranked performance score (r = .81, p<.05). Analysis by playing position further demonstrated that, for the players in the ‘backs’ position, both pregame testosterone concentrations (p<.001) and the testosterone to cortisol ratio (T/C) (p<.05) were significantly higher before a win than before a loss and were positively correlated to game-ranked performance (r = .81–.91, p<.05). Key performance indicators are routinely collected throughout training and gameplay to assess the performance of individuals and their relative capacity or ability. An overall score to summarise a player’s performance during games has merit in terms of an objective measure of performance throughout a season-long competition format. The results of the second study demonstrated that an aggressive-based performance indicator (AggPI) score could significantly discriminate between game outcomes over a season-long competition format. For a subset of six games, AggPI was significantly correlated with pregame testosterone concentrations (r = .86, p<.05), pregame T/C ratio (r = .86, p<.05) and the change from pre to post (peri) testosterone concentrations (r = −.87, p<.05). Whilst the first two studies established the relationship between acute salivary hormones concentration and performance outcomes, the purpose of the third study was to investigate the association of mid-week hormone concentrations with subsequent match performance and outcomes. The mid-week pre-training T/C ratio was significantly lower (p<.01) before a win than a loss and the increase in pre to post concentrations for both testosterone (p<.01) and T/C ratio (p<.001) was also significant. Significant relationships were also observed between pregame testosterone concentration and the relative change in pre to post mid-week concentrations for both cortisol (r = –.90, p= .01) and the T/C ratio (r = .90, p= .01). The fourth study evaluated the acute salivary testosterone and cortisol concentrations in response to four exercise protocols. The first two protocols were resistance training based. These consisted of 5 sets of 15 repetitions at 55% of 1 repetition maximum (1RM), (5 × 15–55%), and 3 sets of 5 repetitions at 85% 1RM, (3 × 5–85%) respectively. The third protocol was a strongman (STRNG) session consisting of three stations of exercises within a circuit, which was completed four times. The fourth protocol was combative (COMB) and consisted of exercises inspired by boxing and wrestling. In groups of two, the athletes worked through six different stations and were completed twice. There was no difference in the average testosterone concentration in response to each exercise stimulus between any intervention. However, when pooled according to the protocol that demonstrated the greatest absolute increase in testosterone concentration, significant (p<.01) increases in testosterone concentrations were observed for three (5 × 15–55%, STRNG and COMB) of the four intervention protocols. This study highlighted the importance of a protocol-dependent approach based on each individual athletes response to the training stimulus also the potential usefulness of employing strongman and combative training protocols as an alternative stimulus to resistance training. The use of salivary hormones appears to be a suitable biomarker for evaluating training response and assessing competition readiness in rugby union players. The routine use of salivary hormones could be utilised to better understand not only the acute effects of a training stimulus but also the interactive factors associated between training and competition.