Association between ACTN3 R577X Polymorphism and Trunk Flexibility in 2 Different Cohorts

Area of Science:

• Exercise Physiology
• Human Genetics
• Sports Science

Background:

• The alpha-Actinin-3 (ACTN3) gene provides instructions for making a protein found primarily in fast-twitch muscle fibers.
• The R577X polymorphism in ACTN3 is known to influence muscular strength and power.
• Flexibility is a crucial component of overall physical fitness, yet its genetic underpinnings are less understood.

Purpose of the Study:

• To investigate the association between the ACTN3 R577X polymorphism and flexibility in two independent Japanese cohorts.
• To determine if ACTN3 genotype influences sit-and-reach flexibility measurements.

Main Methods:

• Two cohorts of Japanese adults (totaling 1475 participants) were recruited.
• Participants underwent assessments for grip strength and sit-and-reach flexibility.
• ACTN3 (rs1815739) polymorphism was genotyped using the TaqMan approach.

Main Results:

• In Cohort 1, individuals with the ACTN3 RR genotype exhibited significantly lower sit-and-reach flexibility compared to RX and XX genotypes, even after adjusting for covariates.
• While Cohort 2 showed a trend towards lower flexibility in the RR genotype, the difference was not statistically significant.
• Pooled analysis of both cohorts revealed that the RR genotype was significantly associated with reduced flexibility compared to RX and XX genotypes (P=0.009).

Conclusions:

• The ACTN3 R577X RR genotype is associated with lower flexibility in the general Japanese population.
• These findings suggest a potential genetic influence of ACTN3 on flexibility, complementing its known role in muscular power.