Abstract
ABSTRACT We aimed to investigate the influence of alpha-actinin-3 (ACTN3) R577X polymorphism on responsiveness to post-activation performance enhancement (PAPE) of countermovement jumps (CMJ) in untrained subjects. Sixteen untrained men were allocated into two groups according to their ACTN3 gene alleles: homozygous for the X allele (XX, n = 9) or homozygous for the R allele (RR, n = 7). CMJ height, mean power output and vertical force were determined twice (CMJ1 and CMJ2) in two conditions: control (CON) and potentiated (PAPE). In the CON condition, CMJ were performed before and after a 15-min rest. In the PAPE condition, CMJ were performed 15 min before and 4 min following five squats with a 5-repetition maximum (5RM) load. Different conditions were applied on separate days in a randomized order. Statistical analysis involved three-way ANOVAs to compare the differences between conditions (CON and PAPE), time (CMJ1 and CMJ2), and groups (XX and RR). Significance level considered was p < 0.05. Effect sizes were calculated as Cohen’s d. The effect sizes for changes in CMJ height for CON and following pre-activation for PAPE were 0.04 and 0.08, respectively. No significant differences were found for CMJ height between XX and RR at baseline (1.07 ± 2.54 cm e -0.82 ± 2.56 cm, respectively). No differences were found (p>0.05) in responsiveness to PAPE between the groups (XX = -0.20 ± 1.6 cm and RR = -0.81 ± 2.7 cm). We conclude that ACTN3 gene polymorphisms does not influence responsiveness to PAPE.
Highlights
Post-activation performance enhancement (PAPE) is a phenomenon that temporarily increases power generation capacity, and it is often induced by performing pre-activation exercise at maximal or near maximal intensity[1]
Sixteen untrained young men who had not engaged in any type of strength training in the previous 6 months and were homozygous to the R577X and R577R ACTN3 gene polymorphisms participated in this study
No significant differences between the groups were found for baseline values or any of the assessed anthropometric characteristics or 5-RM squats load (Table 1)
Summary
Post-activation performance enhancement (PAPE) is a phenomenon that temporarily increases power generation capacity, and it is often induced by performing pre-activation exercise at maximal or near maximal intensity[1]. PAPE is best observed when analyzing changes in force, especially rate of force development[1,2,3,4,5], previous studies have shown improvements in jumping performance (e.g. jump height) following pre-activation activities (e.g., backsquat and halfsquat)[2,3,4,5]. Previous studies have indicated the phosphorylation of the myosin regulatory light chain (RLC) as a mechanism that might determine PAPE magnitude. The magnitude of myosin RLC phosphorylation seems to be related to muscle fiber type, with greater RLC phosphorylation occurring in type II muscle fibers[9]. Individuals and muscle groups with greater type II muscle fiber distribution are more responsive to PAPE than those with greater distribution of type I muscle fibers[6,9]
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