In tennis, mental toughness is often considered highly important in achieving the elite level. The current study is the first to examine behavioural expressions of mental toughness on the court and their relationships with self-reported measures. Based on the input of five experienced tennis coaches of junior tennis players and behaviours used in previous studies, we developed a taxonomy consisting of six positive behaviours and ten negative ones. To investigate the relationship between these on-court behaviours of mental toughness and how the players rated their own mental toughness, emotional control in particular, six talented tennis players (aged 10-13) were recorded during tennis matches and filled out the self-reported measure of mental toughness (MTQ48). The intra- and inter-rater reliability of the taxonomy was high. With regard to the relationships between on-court behaviours and self-reported mental toughness (total score and subscale emotional control), results revealed no significant correlations between the ratios of positive and negative behaviours (range r = -0.49 - 0.11, p > 0.05) or between the variability of negative behaviours (r = 0.54 & r = 0.10, p > 0.05) and the self-reported measure. However, interestingly, we found negative correlations between the variability of positive behaviours and self-reported mental toughness (r = -0.93 & r = -0.84, ρ < 0.05). These results indicate that variability in on-court behaviours provides interesting information about tennis players' mental toughness, more specifically on the (in)stability of their psychological state during a match.
Keywords: behavioural expressions; emotional control; performance; variability; youth sports.