While the pronated foot is implicated as a risk factor for sports injury in some studies, others suggest that a supinated foot posture increases the risk of overuse lower limb injuries. Athletes in a given sports discipline may tend to have a similar foot morphology, which varies from that observed elsewhere. Further, the foot morphology that is beneficial for performance in a sport may be detrimental with regard to injury. Intra- and inter-rater reliability of the Foot Posture Index (FPI-6) as a measure of foot morphology was determined (ICC (2,1) 0.88 and 0.69 respectively). Thereafter, in a prospective cohort study using the FPI-6, 76 adolescent male indoor football (Futsal) players were measured and followed monthly over one competition season. Coach-rated ability and reports of any overuse injuries at the ankle and/or foot over this period were obtained. A significant negative linear relationship was found between the mean FPI-6 scores and coach-rated ability (p=0.008), with supinated and under-pronated postures related to higher ability level. Overall, 33% of injuries at the ankle and/or foot were classified as overuse. Foot Posture Index scores of less than 2, indicating the supinated and under-pronated feet, were found to be associated with a significant increase in the risk of overuse injury (p=0.008). The greater rigidity of these foot types may assist adolescent, male, indoor football players to perform at a higher level in their sport. Unfortunately, these players are also more likely to sustain ankle and/or foot overuse injuries.