Relationships between salivary free testosterone and the expression of force and power in elite athletes

Aim. This study examined the predictive relationships between the salivary free testosterone (T) concentrations of elite athletes and the expression of force and power. Methods. A group of elite male rugby players (N.-64) were assessed for peak force (PF), peak rate of force development (PRFD), force at 100 milliseconds (F100 ms) and 250 milliseconds (F250 ms) during an isometric mid-thigh pull (IMTP), and/or peak power (PP) and height during a countermovement jump (CMJ). Saliva samples were collected before testing and assayed for free T. Relationships between individual T concentrations and performance were assessed as a pooled group and 4 sub-groups of equal size. Results. As pooled data sets, none of the IMTP and CMJ performance variables were significantly correlated with free T in either the PF or PP groups (r0.01-0.23). The PF and PP abilities of the 4 sub-groups were significantly different, so that PF1>PF2>PF3>PF4 (P<0.001) and PP1>PP2>PP3>PP4 (P<0.01). When the 4 sub-groups were analysed, the T concentrations of the PF4 group were significantly (P<0.05-0.01) correlated to PRFD (r0.69) and F100 ms (r0.55) during the IMTP, as was F100 ms in the PFl group (r0.66). In the PP1 group, free T also correlated to CMJ height (r0.62). Conclusions: The key conclusion is that the expression of force and power in an elite athletic group may be dependent, to some extent, on individual variation in salivary free T concentrations and existing strength or power levels. The current results also confirm that the grouping of elite athletes of mixed strength or power ability may bias predictive results in a manner not reflective of sub-groups within this population.