ACTN3 and hyperinsulinemic hypoglycemia, familial, 4: As highlighted in our visual summary, rather than simply focusing in the effect of α-actinin-3 deficiency due to the ACTN3 XX genotype on “overall” sports performance, future research should seek to determine the effect of this genotype on trainability (for both strength and endurance-based training), on injury incidence and epidemiology, and on exercise-induced muscle damage.