The Impact of ACTN3 Gene Polymorphisms on Susceptibility to Exercise-Induced Muscle Damage and Changes in Running Economy Following Downhill Running

Abstract

This study aimed to investigate if ACTN3 gene polymorphism impacts the susceptibility to exercise-induced muscle damage (EIMD) and changes in running economy (RE) following downhill running. Thirty-five healthy men were allocated to the two groups based on their ACTN3 gene variants: RR and X allele carriers. Neuromuscular function [knee extensor isometric peak torque (IPT), rate of torque development (RTD), and countermovement, and squat jump height], indirect markers of EIMD [muscle soreness, mid-thigh circumference, knee joint range of motion, and serum creatine kinase (CK) activity], and RE (oxygen uptake, minute ventilation, blood lactate concentration, and perceived exertion) for 5-min of running at a speed equivalent to 80% of individual maximal oxygen uptake speed were assessed before, immediately after, and 1–4 days after a 30-min downhill run (−15%). Neuromuscular function was compromised (P < 0.05) following downhill running with no differences between the groups, except for IPT, which was more affected in the RR individuals compared with the X allele carriers immediately (−24.9 ± 6.9% vs. −16.3 ± 6.5%, respectively) and 4 days (−16.6 ± 14.9% vs. −4.2 ± 9.5%, respectively) post-downhill running. EIMD manifested similarly for both the groups except for serum CK activity, which was greater for RR (398 ± 120 and 452 ± 126 U L–1 at 2 and 4 days following downhill running, respectively) compared with the X allele carriers (273 ± 121 and 352 ± 114 U L–1 at the same time points). RE was compromised following downhill running (16.7 ± 8.3% and 11 ± 7.5% increases in oxygen uptake immediately following downhill running for the RR and X allele carriers, respectively) with no difference between the groups. We conclude that although RR individuals appear to be more susceptible to EIMD following downhill running, this does not extend to the changes in RE.

Effects of muscle fatigue on exercise-induced hamstring muscle damage: a three-armed randomized controlled trial

“…This shows that CK varies widely between trained individuals that perform the same training regimen. One of the main factors affecting CK values after muscle damage is presumed to be the individual polymorphism of the ACTN3 gene (Koch et al 2014 ), which was recently confirmed by de Lima et al ( 2021 ). The results of their study showed that the CK response after muscle damage is attributed to the ACTN3 polymorphism, rather than load exposure itself.…”

Slow or fast: Implications of myofibre type and associated differences for manifestation of neuromuscular disorders

“…The loss of αactinin-3 changes the overall protein composition and elastic properties of fast myofibre Z-bands, resulting in loss of force generation and increased susceptibility to eccentric damage in αactinin-3-deficient individuals. 170,171 Other effects of the ACTN3 XX genotype related to altered muscle function and adaptation to physical demands and atrophy are observed and have been widely investigated in various human populations, with the ACTN3 XX genotype associated with age-related loss of human muscle and bone 172 and considered a disease modifier for inherited myopathies such as McArdle disease and DMD 173…”

“…While this α‐actinin‐3 deficiency is not associated with any overt disease, it is associated with athletic performance: with detriment to optimal sprint and power performance in elite athletes and the general population, while it was initially considered beneficial for endurance athletes such as marathon runners. The loss of α‐actinin‐3 changes the overall protein composition and elastic properties of fast myofibre Z‐bands, resulting in loss of force generation and increased susceptibility to eccentric damage in α‐actinin‐3‐deficient individuals 170,171 . Other effects of the ACTN3 XX genotype related to altered muscle function and adaptation to physical demands and atrophy are observed and have been widely investigated in various human populations, with the ACTN3 XX genotype associated with age‐related loss of human muscle and bone 172 and considered a disease modifier for inherited myopathies such as McArdle disease and DMD 173 …”