Association Between Hematological Parameters and Iron Metabolism Response After Marathon Race and ACTN3 Genotype

Abstract

α-Actinin-3 ( ACTN3 R577X, rs.1815739) polymorphism is a genetic variation that shows the most consistent influence on metabolic pathway and muscle phenotype. XX genotype is associated with higher metabolic efficiency of skeletal muscle; however, the role of ACTN3 polymorphism in oxygen transport and utilization system has not yet been investigated. Therefore, the aim of this study was to determine the influence of ACTN3 polymorphisms on hematological and iron metabolism response induced by marathon race. Eighty-one Brazilian amateur male endurance runners participated in the study. Blood samples and urine were collected before; immediately after; and 1, 3, and 15 days after the marathon race. Urine, hematological parameters, iron metabolism, and ACTN3 genotyping analyses were performed. The marathon race induced a decrease in erythrocytes, Hb, and Ht, and an increase in hematuria, creatinine, myoglobin, red cell distribution width, mean corpuscular hemoglobin concentration, mean corpuscular hemoglobin, direct and indirect bilirubin and erythropoietin. Moreover, an elevation immediately or 1 day after the marathon race follows a reduction 3 or 15 days after the marathon race were observed on transferrin saturation and iron and transferrin levels. Hematological parameters and iron metabolism changes induced by marathon race were not observed in XX genotypes. Hematuria and decreased erythrocytes, Hb, Ht, and iron and transferrin levels were observed only in RR and/or RX genotypes but not in XX genotypes. The percentage of runners with hematuria, leukocyturia, iron deficiency, creatinine, myoglobin, and bilirubin imbalance was higher in RR compared to XX genotypes. ACTN3 polymorphism is associated with iron metabolism and hematological responses after endurance exercise. Despite these results being based on a small sample, they highlight a protective role of the XX genotype on hematological and renal changes induced by long-distance exercise. Therefore, these findings should be further replicated.

Anemia in Sports: A Narrative Review

“…Iron loss during exercise occurs in several ways: sweating, hematuria, gastrointestinal bleeding, inflammation, and intravascular and extravascular hemolysis [ 34 , 35 ]. Sweating is involved in thermoregulation and is important in physical exercise [ 36 ].…”

“…It is a sarcomeric scaffold protein that forms a contractile apparatus at the muscle Z line, where it anchors actin filaments together with α-actinin-2 [ 63 ]. A polymorphism of ACTN 3 (R577X, rs1815739) will influence metabolic pathways and muscle phenotype: the XX phenotype is associated with higher metabolic efficiency of the skeletal muscle, but also of the iron metabolism [ 34 ]. A marathon race induced in most runners a decrease in RBC, Hb, and Hct, with an increase in hematuria, myoglobin, red cell distribution width, mean corpuscular hemoglobin concentration, mean corpuscular hemoglobin, bilirubin, erythropoietin, and creatinine [ 34 ].…”

“…A polymorphism of ACTN 3 (R577X, rs1815739) will influence metabolic pathways and muscle phenotype: the XX phenotype is associated with higher metabolic efficiency of the skeletal muscle, but also of the iron metabolism [ 34 ]. A marathon race induced in most runners a decrease in RBC, Hb, and Hct, with an increase in hematuria, myoglobin, red cell distribution width, mean corpuscular hemoglobin concentration, mean corpuscular hemoglobin, bilirubin, erythropoietin, and creatinine [ 34 ]. Similarly, iron and transferrin levels and transferrin saturation increased immediately after the race and decreased up to 15 days thereafter [ 34 ].…”

“…A marathon race induced in most runners a decrease in RBC, Hb, and Hct, with an increase in hematuria, myoglobin, red cell distribution width, mean corpuscular hemoglobin concentration, mean corpuscular hemoglobin, bilirubin, erythropoietin, and creatinine [ 34 ]. Similarly, iron and transferrin levels and transferrin saturation increased immediately after the race and decreased up to 15 days thereafter [ 34 ]. A decrease in hematological parameters after an endurance exercise was noted only in RR and RX genotypes of ACTN3 but not in the XX genotypes [ 34 ].…”

“…Similarly, iron and transferrin levels and transferrin saturation increased immediately after the race and decreased up to 15 days thereafter [ 34 ]. A decrease in hematological parameters after an endurance exercise was noted only in RR and RX genotypes of ACTN3 but not in the XX genotypes [ 34 ]. Homozygotes for the 577X alleles form about 20% of the world population and are completely deficient in α-actinin-3 [ 63 ].…”