ACTN3 genotype influences exercise-induced muscle damage during a marathon competition.
OBJECTIVE
Exercise-induced muscle damage has been identified as one of the main causes of the progressive decrease in running and muscular performance in marathoners. The aim of this investigation was to determine the influence of the ACTN3 genotype on exercise-induced muscle damage produced during a marathon.


METHODS
Seventy-one experienced runners competed in a marathon race. Before and after the race, a sample of venous blood was obtained and maximal voluntary leg muscle power was measured during a countermovement jump. In the blood samples, the ACTN3 genotype (R577X) and the changes in serum creatine kinase and myoglobin concentrations were measured. Data from RX heterozygotes and XX mutant homozygotes were grouped as X allele carriers and compared to RR homozygotes.


RESULTS
At the end of the race, X allele carriers presented higher serum myoglobin (774 ± 852 vs 487 ± 367 U L-1; P = 0.02) and creatine kinase concentrations (508 ± 346 vs 359 ± 170 ng mL-1; P = 0.04) than RR homozygotes. Pre-to-post-race maximal voluntary leg muscle power reduction was more pronounced in X allele carriers than RR homozygotes (-34.4 ± 16.1 vs -27.3 ± 15.4%; P = 0.05). X allele carriers self-reported higher levels of lower limb muscle pain (7 ± 2 vs 6 ± 2 cm; P = 0.02) than RR homozygotes at the end of the race.


CONCLUSIONS
In comparison to RR homozygotes, X allele carriers for the R577X polymorphism of the ACTN3 gene presented higher values for typical markers of exercise-induced muscle damage during a competitive marathon. Thus, the absence of a functional α-actinin-3 produced by the X allele might induce higher levels of muscle breakdown during prolonged running events.
Exercise Physiology Laboratory, Camilo José Cela University, C/Castillo de Alarcon, 49, Villafranca del Castillo, 28692, Madrid, Spain. jdelcoso@ucjc.edu.
Juan
J
Del Coso
Exercise Physiology Laboratory, Camilo José Cela University, C/Castillo de Alarcon, 49, Villafranca del Castillo, 28692, Madrid, Spain.
Marjorie
M
Valero
Exercise Physiology Laboratory, Camilo José Cela University, C/Castillo de Alarcon, 49, Villafranca del Castillo, 28692, Madrid, Spain.
Juan José
JJ
Salinero
Exercise Physiology Laboratory, Camilo José Cela University, C/Castillo de Alarcon, 49, Villafranca del Castillo, 28692, Madrid, Spain.
Beatriz
B
Lara
Sport Training Laboratory, European University of Madrid, Madrid, Spain.
Germán
G
Díaz
Exercise Physiology Laboratory, Camilo José Cela University, C/Castillo de Alarcon, 49, Villafranca del Castillo, 28692, Madrid, Spain.
César
C
Gallo-Salazar
Exercise Physiology Laboratory, Camilo José Cela University, C/Castillo de Alarcon, 49, Villafranca del Castillo, 28692, Madrid, Spain.
Diana
D
Ruiz-Vicente
Exercise Physiology Laboratory, Camilo José Cela University, C/Castillo de Alarcon, 49, Villafranca del Castillo, 28692, Madrid, Spain.
Francisco
F
Areces
Exercise Physiology Laboratory, Camilo José Cela University, C/Castillo de Alarcon, 49, Villafranca del Castillo, 28692, Madrid, Spain.
Carlos
C
Puente
Chair of Genomic Medicine, Camilo José Cela University, Madrid, Spain.
Juan Carlos
JC
Carril
Chair of Genomic Medicine, Camilo José Cela University, Madrid, Spain.
Ramón
R
Cacabelos
D000185:Actinin / Q000235:genetics*; D000293:Adolescent; D000328:Adult; D000368:Aged; D003402:Creatine Kinase / Q000097:blood; D005260:Female; D005838:Genotype; D006720:Homozygote; D006801:Humans; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction / Q000235:genetics; D018482:Muscle, Skeletal / Q000378:metabolism / Q000502:physiology*; D063806:Myalgia / Q000097:blood / Q000235:genetics*; D009211:Myoglobin / Q000097:blood; D020641:Polymorphism, Single Nucleotide; D012420:Running
C118456:ACTN3 protein, human; D009211:Myoglobin; D000185:Actinin; D003402:Creatine Kinase
Endurance exercise; Genetics; Muscle pain; Rhabdomyolysis; Single-nucleotide polymorphism.; α-Actinins