Taken together, the results of the present study suggest that a Nordic walking program in patients who suffered mild COVID-19, significantly decreases lactic acid concentrations during submaximal aerobic exercise in individuals with genotypes CT and TT in ACTN3 c.1729C>T, CC and CT in AMPD1 c.34C>T and AA in CKM c.*800A>G polymorphisms. Here, ACTN3 is linked to COVID-19.