This study investigated the effect of long-term training on the development of mental toughness (MT). Thirty recreationally active participants (age: 33.53±6.83years; height: 177.41±7.11cm; weight: 78.40±11.94kg; maximal oxygen uptake (VO2max): 47.00±6.48 ml.kg-1.min-1) undertook 6-months of training prior to completing an iron-distance triathlon. Mental toughness questionnaires (MTQ48) were completed at 0,2,4,6 months of training and 1-month post-race. Repeated measures ANOVAs were performed for each MTQ48 variable with consideration to faster v slower finishers. No significant differences (p>0.05) were found between fast and slow finishers on any of the MT criteria. There was an effect for time with overall mental toughness (OMT) improving from baseline-post race (cohens d = 0.52; p<0.01) and month 2-post race (d = 0.39; p<0.01), commitment improving from baseline-post race (d = 0.60; p<0.05) and confidence increasing from month 2 post-race (d = 0.39; p<0.05). MT was not associated with race time. The findings indicate that longitudinal training culminating with competitive experience may favourably impact MT
