The present invention concerns novel methods of selecting or matching a sport or sporting event to an individual (e.g. a sprint/power sport or an endurance sport) and predicting athletic performance, the methods involving assessing ACTN3 genotype. In alternative embodiments, training regimens may be optimally designed for athletes by assessing the ACTN3 genotypes. Certain embodiments concern combining the assessment of the ACTN3 genotype with other known fitness-related genes to better assess the athletic potential of an individual. In addition, the genotypic analysis of the ACTN3 gene may be combined with physiological tests, physical measurements and/or psychological assessments to more optimally design a training regimen for an individual athlete.