ACTN3 R577X Genotype and Exercise Phenotypes in Recreational Marathon Runners.
Loading...
Identifiers
Publication date
2019
Start date of the public exhibition period
End date of the public exhibition period
Advisors
Journal Title
Journal ISSN
Volume Title
Publisher
Genes
Share
Abstract
Homozygosity for the X-allele in the ACTN3 R577X (rs1815739) polymorphism
results in the complete absence of -actinin-3 in sarcomeres of fast-type muscle fibers. In elite athletes,
the ACTN3 XX genotype has been related to inferior performance in speed and power-oriented sports;
however, its influence on exercise phenotypes in recreational athletes has received less attention. We
sought to determine the influence of ACTN3 genotypes on common exercise phenotypes in recreational
marathon runners. Methods: A total of 136 marathoners (116 men and 20 women) were subjected to
laboratory testing that included measurements of body composition, isometric muscle force, muscle
flexibility, ankle dorsiflexion, and the energy cost of running. ACTN3 genotyping was performed
using TaqMan probes. Results: 37 runners (27.2%) had the RR genotype, 67 (49.3%) were RX and 32
(23.5%) were XX. There was a di erence in body fat percentage between RR and XX genotype groups
(15.7 5.8 vs. 18.8 5.5%; e ect size, ES, = 0.5 0.4, p = 0.024), whereas the distance obtained in
the sit-and-reach-test was likely lower in the RX than in the XX group (15.3 7.8 vs. 18.4 9.9 cm;
ES = 0.4 0.4, p = 0.046). Maximal dorsiflexion during the weight-bearing lunge test was di erent in
the RR and XX groups (54.8 5.8 vs. 57.7 5.1 degree; ES = 0.5 0.5, p = 0.044). Maximal isometric
force was higher in the RR than in the XX group (16.7 4.7 vs. 14.7 4.0 N/kg; ES = �����0.5 0.3,
p = 0.038). There was no di erence in the energy cost of running between genotypes (~4.8 J/kg/min
for all three groups, ES ~0.2 0.4). Conclusions: The ACTN3 genotype might influence several
exercise phenotypes in recreational marathoners. Deficiency in -actinin-3 might be accompanied
by higher body fatness, lower muscle strength and higher muscle flexibility and range of motion.
Although there is not yet a scientific rationale for the use of commercial genetic tests to predict sports
performance, recreational marathon runners who have performed such types of testing and have
the ACTN3 XX genotype might perhaps benefit from personalized strength training to improve their
performance more than their counterparts with other ACTN3 genotypes.
Doctoral program
Description
Keywords
Exercise, Performance, Endurance, Genetics, Single nucleotide polymorphism