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Gustavo Monnerat, Alex S. Maior, Marcio Tannure, Lia K.F.C. Back, and Caleb G.M. Santos

Classical twin studies that presented heritability rates associated with performance in various sports disciplines support the value of genetics in determining the response. In addition, numerous trials involving physiological responses such as hypertrophy, energy expenditure, vasodilation, cardiac output

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Gabriel Rodríguez-Romo, Thomas Yvert, Alfonso de Diego, Catalina Santiago, Alfonso L. Díaz de Durana, Vicente Carratalá, Nuria Garatachea, and Alejandro Lucia

The authors compared ACTN3 R577X genotype and allele frequencies in the majority of all-time-best Spanish judo male athletes (n = 108) and 343 ethnically matched nonathletic men. No between-groups differences were found in allele (P = .077) or genotype distributions (P = .178). Thus, the R577X polymorphism was not significantly associated with the status of being an elite judo athlete, at least in the Spanish population. The contribution of genetics to sports-related phenotype traits is undeniable with some genotypes, of which ACTN3 R577X is currently the leading candidate, partly distinguishing individuals predisposed to either endurance or power sports. However, few athletic events can be categorized as purely power or endurance based. Although genetic testing (ie, for ACTN3 R577X) is already being marketed to predict sports talent and potential of young children, its usefulness is still questionable, at least in competitive judo.

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Sharon Ann Plowman

The last decade has seen a shift in emphasis from the goal of attaining physical fitness (a product) to the behavior of physical activity (a process) to achieve health benefits. A central question is whether the achievement of physical fitness (PF) is necessary or if participation in physical activity (PA) is sufficient. Three basic tenets of this shift are examined by using representative studies. They are: (1) both PA and PF will lead to health benefits; PF is simply a surrogate measure for PA, (2) the impact of genetics will be avoided if PA, not PF, is emphasized and that is desirable, and (3) it is easier to motivate “the masses” to accumulate lifestyle moderate activity than to undergo a vigorous exercise prescription. Results indicate that PA and PF might be independent risk factors, that both have a degree of genetic determination, and that participation rates for PA have changed little and remain insufficient. Both PA and PF need to be evaluated, promoted, and attained.

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Sari Aaltonen, Teemu Palviainen, Richard J. Rose, Urho M. Kujala, Jaakko Kaprio, and Karri Silventoinen

. Genetics of regular exercise and sedentary behaviors . Twin Res Hum Genet . 2014 ; 17 ( 4 ): 262 – 271 . PubMed ID: 25034445 doi:10.1017/thg.2014.42 10.1017/thg.2014.42 14. Lightfoot JT , Geus E. J. C. DE , Booth FW , et al . Biological/genetic regulation of physical activity level: consensus

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Peter J. Whalley, Chey G. Dearing, and Carl D. Paton

. Increases in cycling performance in response to caffeine ingestion are repeatable . Nutr Res . 2012 ; 32 : 78 – 84 . PubMed ID: 22348455 doi:10.1016/j.nutres.2011.12.001 22348455 10.1016/j.nutres.2011.12.001 23. Southward K , Rutherford-Markwick K , Badenhorst C , Ali A . The role of genetics

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Mohanraj Krishnan, Andrew N. Shelling, Clare R. Wall, Edwin A. Mitchell, Rinki Murphy, Lesley M.E. McCowan, and John M.D. Thompson

.healthplace.2016.09.003 27771443 15. Grimm ER , Steinle NI . Genetics of eating behavior: established and emerging concepts . Nutr Rev . 2011 ; 69 ( 1 ): 52 – 60 . PubMed doi:10.1111/j.1753-4887.2010.00361.x 21198635 10.1111/j.1753-4887.2010.00361.x 16. Hill JO , Wyatt HR , Peters JC . Energy

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Gaston Beunen, Martine Thomis, Maarten Peeters, Hermine H. Maes, Albrecht L. Claessens, and Robert Vlietinck

The aim of this study is to quantify the genetic and environmental variation in isometric and explosive strength (power) in children and adolescents, using structural equation models. Arm pull (static strength) and vertical jump (explosive strength, power) were measured in 105 twin pairs from the Leuven Longitudinal Twin Study. Boys and girls were tested at annual intervals between 10 and 16 years and at 18 years. Path models were fitted to the observed strength characteristics and a gender heterogeneity analysis was performed at each age level. A model including additive genetic and specific environmental factors (AE-model) allowing for a difference in total phenotypic variance or in genetic/environmental variance components in boys and girls best explains both strength characteristics at most age levels. The additive genetic contribution for isometric strength varies between a2 = .44 and a2 = .83, and for explosive strength between a2 = .47 and a2 = .92, except at 16 years in males. In conclusion there is good evidence that during the growth period both static and explosive strength are under moderate to moderately strong genetic influence.

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Joey C. Eisenmann and Keith Tolfrey

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Jane A. Kent and Kate L. Hayes

classical molecular biology, genetics, biophysics, biochemistry, and physiology have all contributed to the current understanding of skeletal muscle contraction at the molecular level. At the cellular level, advances in biotechnology have allowed for the novel identification and visualization of cells and

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Erin White, Jennifer D. Slane, Kelly L. Klump, S. Alexandra Burt, and Jim Pivarnik

Background:

Knowing the extent to which genetic and environmental factors influence percent body fatness (%Fat) and physical activity (PA) would be beneficial, since both are tightly correlated with future health outcomes. Thus, the purpose was to evaluate sex differences in genetic and environmental influences on %Fat and physical activity behavior in male and female adolescent twins.

Methods:

Subjects were adolescent (age range 8.3 to 16.6 yr) twins. %Fat (n = 518 twins) was assessed by bioelectrical impedance analysis (BIA) and PA (n = 296 twins) was measured using 3-Day PA Recall. Each activity was converted to total MET-minutes. Univariate twin models were used to examine sex differences in genetic and environmental factors influencing %Fat and PA.

Results:

%Fat was influenced by genetic effects in both boys and girls (88% and 90%, respectively), with slightly higher heritability estimates for girls. PA was influenced solely by environmental effects for both sexes with higher shared environmental influences in boys (66%) and higher nonshared effects in girls (67%).

Conclusions:

When developing interventions to increase PA in adolescents, it is important to consider the environment in which it takes place as it is the primary contributor to PA levels.