Impact of ACTN3 R577X Polymorphism on Muscle Damage Susceptibility Following Aerobic or Strength Exercises: A Systematic Review.

This study compares muscle damage levels in individuals with and without the ACTN3 R577X polymorphism after engaging in aerobic or strength exercises. A systematic review was performed using articles from PubMed, SciELO, ScienceDirect, Cochrane Library, Medline, and Lilacs. The keywords were "muscle damage" and "muscle injury" combined with "ACTN3," "R577X," and "alpha-actinin-3," following the guidelines of the Preferred Reporting Items for Systematic Reviews (PRISMA). A total of 421 articles were identified, of which 10 were considered eligible. In total, 411 individuals were investigated considering all studies included in this review. Of the five studies with strength exercises, four found no differences between genotypes post exercise. On the contrary, of the five studies that evaluated muscle damage in aerobic exercise, three (that monitored this aspect in long-duration and strenuous sporting events: marathon, half ironman, and ultra-endurance adventure race) observed that individuals with the ACTN3 R577X polymorphism presented higher levels of muscle damage (measured by creatine kinase, myoglobin, and lactate dehydrogenase). To conclude, the ACTN3 R577X polymorphism can make an individual more susceptible to muscle damage after more high-volume aerobic exercise. As far as strength exercises are concerned, such a relationship does not appear to be observed. In this sense, individuals with this polymorphism require a longer recovery time from aerobic training sessions with long duration, as well as specific strategies for distributing training throughout the week.