Effect of ACTN3 R577X Genotype on Injury Epidemiology in Elite Endurance Runners

Area of Science:

• Sports Medicine
• Human Genetics
• Exercise Physiology

Background:

• The ACTN3 gene encodes α-actinin-3, a protein crucial for muscle function.
• The R577X polymorphism (rs1815739) in ACTN3 results in a deficiency of functional α-actinin-3 in individuals with the XX genotype.
• Previous studies suggested XX genotype athletes are more susceptible to non-contact muscle injuries.

Purpose of the Study:

• To investigate the association between the ACTN3 R577X polymorphism and the epidemiology of running-related injuries in elite endurance athletes.
• To determine if the ACTN3 genotype influences injury incidence, location, onset, severity, or type in this population.

Main Methods:

• A cross-sectional study involving 89 Spanish elite endurance runners.
• Recording of running-related injuries over one season.
• Determination of ACTN3 R577X genotype using genomic DNA samples.

Main Results:

• Injury incidence was significantly higher in RR genotype runners (3.2 injuries/1000 h) compared to RX (2.0) and XX (2.2) genotypes (p=0.030).
• Injury locations differed by genotype: RR runners had more Achilles tendon injuries, RX runners had more knee injuries, and XX runners had more groin injuries (p=0.025).
• The ACTN3 genotype did not impact injury onset, severity, or type.

Conclusions:

• The ACTN3 R577X polymorphism slightly influences injury epidemiology in elite endurance athletes, with RR genotype associated with a higher overall injury rate.
• Specific genotypes are linked to distinct injury locations, challenging the notion that XX genotype confers higher muscle injury risk in endurance runners.