The human gene map for performance and health-related fitness phenotypes: the 2003 update

Sex differences and athletic performance. Where do trans individuals fit into sports and athletics based on current research?

There are well known sex differences in parameters of physical fitness/performance due to changes occurring during sexual development. Thus, many sport and athletic events have regulations separating male and female participants. However, the inclusion or exclusion of transgender individuals in athletics has recently received outsized attention despite relatively few cases of transgender athletes. When determining which athletic gender category trans individuals should be permitted to compete in, it is important to understand the level of physical fitness/performance these individuals possess relative to their cisgender counterparts. Unfortunately, there are few studies investigating this topic, and several complications that confound this research. The current review seeks to discuss sex and gender as concepts, review sex differences in fitness/performance and how they develop, and then, consider how current evidence suggests that trans individuals compare to cis individuals. Finally, this review seeks to offer considerations for whether trans individuals should be excluded from sports and athletics, and how future research should proceed to better understand this marginalized population.

Genetic variations underlying self-reported physical functioning: a review

PURPOSE

Genetic associations with self-reported physical functioning (SPF) are less well-studied than genetic associations with performance-measured physical functioning (PPF). We review the literature on the associations of genetic variations on SPF. We provide an overview of SPF assessment, genetic contributions to SPF including heritability, effects of genetic variations and mutations, and effects of interventions on the gene-SPF relationship. We also aim to provide directions for future research.

METHODS

A computerized literature search using PubMed, Web of Science, and PsychInfo was conducted to select relevant literature published up to November 2013. Inclusion criteria were the use of an SPF questionnaire, original articles in English on human subjects, published in peer-reviewed journals and reporting significant associations between SPF and the genome.

RESULTS

Nineteen articles were included. SPF was commonly assessed with the Short Form-36 questionnaire involving mainly convenience samples of either older persons or chronically ill. Heritability estimates were 10-30 %. Candidate genes associated with SPF could be ascribed to biological pathways associated with neurodegeneration, physiological systems regulation, or cell regulation. The APOE gene associated with neurodegeneration was most studied (n = 3). Three papers included both SPF and PPF assessments. No genome-wide association study on SPF has been conducted.

CONCLUSIONS

Associations between SPF and the genome have been investigated in selected populations in a limited number of publications. Future research should consider increasing sample variation and incorporate both SPF and PPF assessments. Also, longitudinal studies should be conducted in order to elicit stronger conclusions regarding the genetic associations with SPF.

Playing with heart and soul…and genomes: sports implications and applications of personal genomics

Whether the integration of genetic/omic technologies in sports contexts will facilitate player success, promote player safety, or spur genetic discrimination depends largely upon the game rules established by those currently designing genomic sports medicine programs. The integration has already begun, but there is not yet a playbook for best practices. Thus far discussions have focused largely on whether the integration would occur and how to prevent the integration from occurring, rather than how it could occur in such a way that maximizes benefits, minimizes risks, and avoids the exacerbation of racial disparities. Previous empirical research has identified members of the personal genomics industry offering sports-related DNA tests, and previous legal research has explored the impact of collective bargaining in professional sports as it relates to the employment protections of the Genetic Information Nondiscrimination Act (GINA). Building upon that research and upon participant observations with specific sports-related DNA tests purchased from four direct-to-consumer companies in 2011 and broader personal genomics (PGx) services, this anthropological, legal, and ethical (ALE) discussion highlights fundamental issues that must be addressed by those developing personal genomic sports medicine programs, either independently or through collaborations with commercial providers. For example, the vulnerability of student-athletes creates a number of issues that require careful, deliberate consideration. More broadly, however, this ALE discussion highlights potential sports-related implications (that ultimately might mitigate or, conversely, exacerbate racial disparities among athletes) of whole exome/genome sequencing conducted by biomedical researchers and clinicians for non-sports purposes. For example, the possibility that exome/genome sequencing of individuals who are considered to be non-patients, asymptomatic, normal, etc. will reveal the presence of variants of unknown significance in any one of the genes associated with hypertrophic cardiomyopathy (HCM), long QT syndrome (LQTS), Marfan's syndrome, and other conditions is not inconsequential, and how this information is reported, interpreted, and used may ultimately prevent the individual from participation in competitive sports. Due to the distribution of genetic diversity that reflects our evolutionary and demographic history (including the discernible effects of restricted gene flow and genetic drift associated with cultural constructs of race) and in recognition of previous policies for "leveling" the playing field in competitive sports based on "natural" athletic abilities, preliminary recommendations are provided to discourage genetic segregation of sports and to develop best practice guidelines for genomic sports medicine programs that will facilitate player success, promote player safety, and avoid genetic discrimination within and beyond the program.

Lifestyle modifies the relationship between body composition and adrenergic receptor genetic polymorphisms, ADRB2, ADRB3 and ADRA2B: a secondary analysis of a randomized controlled trial of physical activity among postmenopausal women

Genetic variations in the adrenergic receptor (ADR) have been associated with body composition in cross-sectional studies. Recent findings suggest that ADR variants may also modify body composition response to lifestyle. We assessed the role of ADR variants in body composition response to 12 months of resistance training versus control in previously sedentary postmenopausal women. Randomized trial completers were genotyped for A2B (Glu9/12) by fragment length analysis, and B2 (Gln27Glu) and B3 (Trp64Arg) by TaqMan (n = 148, 54% hormone therapy users). Associations between genotypes and body composition, by dual energy X-ray absorptiometry, were analyzed using univariate models. There was no main effect of individual genes on change in body composition, however, gene x exercise interactions were observed for A2B (Glu9/12) and B2 (Gln27Glu) on change in lean soft tissue (LST, p = 0.02); exercisers on the A2B (Glu9-) background gained LST compared to a loss among controls over 12 months (p < 0.05), with no significant intervention effect on the A2B (Glu9+) background. Similarly, there was a significant LST gain with exercise on the B2 (Glu27+) background compared to loss among controls and no intervention effect on the B2 (Glu27-) background. A non-significant association between total body fat (TBF) and B3 (Trp64Arg) persisted among sedentary controls only when intervention groups were separated (%TBF gain with B3 (Arg64+) carriage, p = 0.03); exercisers lost TBF regardless of genotype. In summary, effect modification by lifestyle was demonstrated on ADRA2B, B2, and B3 genetic backgrounds. Individuals with certain ADR genotypes may be more vulnerable to adverse changes in body composition with sedentary behavior, thus these candidate genes warrant further study.

Decreased muscle ACE activity enhances functional response to endurance training in rats, without change in muscle oxidative capacity or contractile phenotype

In the present study, we tested the hypothesis that chronic ANG I-converting enzyme (ACE) inhibition could improve the training-induced improvement in endurance exercise performance and that this could be related to enhanced skeletal muscle metabolic efficiency. Female Wistar rats were assigned to four groups comprising animals either maintained sedentary or endurance trained (Sed and Tr, respectively), and treated or not for 10 wk with an ACE inhibitor, perindopril (2 mg·kg−1·day−1) (Per and Ct, respectively) ( n = 8 each). Trained rats underwent an 8-wk treadmill training protocol that consisted of 2 h/day running at 30 m/min on a 8% decline. Before the start of and 1 wk before the end of experimental conditioning, the running time to exhaustion of rats was measured on a treadmill. The training program led to an increase in endurance time, higher in Tr-Per than in Tr-Ct group (125% in Tr-Ct vs. 183% in Tr-Per groups, P < 0.05). Oxidative capacity, measured in saponin-permeabilized fibers of slow soleus and fast plantaris muscles, increased with training, but less in Tr-Per than in Tr-Ct rats. The training-induced increase in citrate synthase activity also was less in soleus from Tr-Per than Tr-Ct rats. The training-induced increase in the percentage of the type IIa isoform of myosin heavy chain (MHC) (45%, P < 0.05) and type IIx MHC (25%, P < 0.05) associated with decreased type IIb MHC (34%, P < 0.05) was minimized by perindopril administration. These findings demonstrate that the enhancement in physical performance observed in perindopril-treated animals cannot be explained by changes in mitochondrial respiration and/or MHC distribution within muscles involved in running exercise.

Association between angiotensin-converting enzyme gene polymorphisms and exercise performance in patients with COPD

BACKGROUND AND OBJECTIVE

Recent studies have shown that polymorphisms of the angiotensin-converting enzyme (ACE) gene are closely associated with pulmonary disorders. The ACE gene is involved in the regulation of inflammatory reactions to lung injury, respiratory drive, erythropoiesis and tissue oxygenation. The hypothesis for this study was that the ACE gene may be associated with the ventilatory response to exercise and the aerobic work efficiency of skeletal muscle in patients with COPD.

METHODS

Sixty-one Chinese Han COPD patients and 57 healthy control subjects performed incremental cardiopulmonary exercise testing on a cycle ergometer. ACE genotypes were determined using PCR amplification.

RESULTS

Resting lung function and blood gas index were not significantly different among the three ACE genotype COPD groups. Similarly, there were no significant differences in AT, maximal O(2) uptake, maximal O(2) pulse, maximal dyspnoea index, ventilatory response (DeltaVE/DeltaVCO(2)), O(2) cost of ventilation (VO(2)/W/VE), end-tidal partial pressure of carbon dioxide at maximal exercise and maximal SaO(2) among the three ACE genotype COPD patients. Maximal work load and aerobic work efficiency were higher in the COPD group with the II genotype than in those with the ID or DD genotype. There were no significant differences in resting lung function and cardiopulmonary exercise testing parameters among the three ACE genotype control groups.

CONCLUSIONS

The ACE gene may be involved in the regulation of skeletal muscle aerobic work efficiency, but is not associated with the ventilatory responses to exercise in COPD patients.

Genome-wide linkage scan for athlete status in 700 British female DZ twin pairs

Association studies, comparing elite athletes with sedentary controls, have reported a number of genes that may be related to athlete status. The present study reports the first genome wide linkage scan for athlete status. Subjects were 4488 adult female twins from the TwinsUK Adult Twin Registry (793 monozygotic [MZ] and 1000 dizygotic [DZ] complete twin pairs, and single twins). Athlete status was measured by asking the twins whether they had ever competed in sports and what was the highest level obtained. Twins who had competed at the county or national level were considered elite athletes. Using structural equation modeling in Mx, the heritability of athlete status was estimated at 66%. Seven hundred DZ twin pairs that were successfully genotyped for 1946 markers (736 microsatellites and 1210 SNPs) were included in the linkage analysis. Identical-by-descent probabilities were estimated in Merlin for a 1 cM grid, taking into account the linkage disequilibrium of correlated SNPs. The linkage scan was carried out in Mx using the [Formula: see text]-approach. Suggestive linkages were found on chromosomes 3q22-q24 and 4q31-q34. Both areas converge with findings from previous studies using exercise phenotypes. The peak on 3q22-q24 was found at the SLC9A9 gene. The region 4q31-q34 overlaps with the region for which suggestive linkages were found in two previous linkage studies for physical fitness (FABP2 gene; Bouchard et al., 2000) and physical activity (UCP1 gene; Simonen et al., 2003). Future association studies should further clarify the possible role of these genes in athlete status.

Mitochondrial haplogroup T is negatively associated with the status of elite endurance athlete

Mitochondrial function is absolutely necessary to supply the energy required for muscles, and germ line mutations in mitochondrial genes have been related with impaired cardiac function and exercise intolerance. In addition, alleles at several polymorphic sites in mtDNA define nine common haplogroups, and some of these haplogroups have been implicated in the risk of developing several diseases. In this study, we analysed the association between mtHaplogroups and the capacity to reach the status of elite endurance athlete. DNA was obtained from blood leukocytes of 95 Spanish elite endurance athletes and 250 healthy male population controls. We analysed eight mitochondrial polymorphisms and the frequencies were statistically compared between elite athletes and controls. Haplogroup T, specifically defined by 13368A, was significantly less frequent among elite endurance athletes (p =0.012, Fisher's exact test). Our study suggests that allele 13368A and mitochondrial haplogroup T might be a marker negatively associated with the status of elite endurance athlete. This mitochondrial variant could be related with a lower capacity to respond to endurance training, through unknown mechanisms involving a less efficient mitochondrial workload.

Gene doping: a review of performance-enhancing genetics

Unethical athletes and their mentors have long arrogated scientific and medical advances to enhance athletic performance, thus gaining a dishonest competitive advantage. Building on advances in genetics, a new threat arises from athletes using gene therapy techniques in the same manner that some abused performance-enhancing drugs were used. Gene doping, as this is known, may produce spectacular physiologic alterations to dramatically enhance athletic abilities or physical appearance. Furthermore, gene doping may present pernicious problems for the regulatory agencies and investigatory laboratories that are entrusted to keep sporting events fair and ethical. Performance-enhanced genetics will likewise present unique challenges to physicians in many spheres of their practice.

Genetic effects in common on maximal walking speed and muscle performance in older women

The purpose was to examine whether maximal walking speed, maximal isometric knee extensor strength, and leg extensor power share genetic or environmental effects in common. The data was collected from 103 monozygotic and 114 dizygotic female twin pairs aged 63-76 years. Maximal walking speed over 10 m was measured in the laboratory corridor using photocells for timing. Isometric knee extensor strength and leg extensor power were measured using an adjustable dynamometer. The genetic models showed that strength, power, and walking speed had a genetic effect in common which accounted for 52% of the variance in strength, 36% in power, and 34% in walking speed. Strength and power had a non-shared environmental effect in common explaining 13% of variation in strength and 14% in power. The remaining variance was accounted for by trait-specific effects. Some people may be more prone to functional limitation in old age due to their genetic disposition, but this does not rule out that changes in the lifestyle of predisposed subjects may also have a major effect. Approximately half of the variation in each trait was explained by environmental effects, which suggests the importance of the physical activity to improve performance and prevent functional limitation.

Current anti-doping policy: a critical appraisal

BACKGROUND

Current anti-doping in competitive sports is advocated for reasons of fair-play and concern for the athlete's health. With the inception of the World Anti Doping Agency (WADA), anti-doping effort has been considerably intensified. Resources invested in anti-doping are rising steeply and increasingly involve public funding. Most of the effort concerns elite athletes with much less impact on amateur sports and the general public.

DISCUSSION

We review this recent development of increasingly severe anti-doping control measures and find them based on questionable ethical grounds. The ethical foundation of the war on doping consists of largely unsubstantiated assumptions about fairness in sports and the concept of a "level playing field". Moreover, it relies on dubious claims about the protection of an athlete's health and the value of the essentialist view that sports achievements reflect natural capacities. In addition, costly antidoping efforts in elite competitive sports concern only a small fraction of the population. From a public health perspective this is problematic since the high prevalence of uncontrolled, medically unsupervised doping practiced in amateur sports and doping-like behaviour in the general population (substance use for performance enhancement outside sport) exposes greater numbers of people to potential harm. In addition, anti-doping has pushed doping and doping-like behaviour underground, thus fostering dangerous practices such as sharing needles for injection. Finally, we argue that the involvement of the medical profession in doping and anti-doping challenges the principles of non-maleficience and of privacy protection. As such, current anti-doping measures potentially introduce problems of greater impact than are solved, and place physicians working with athletes or in anti-doping settings in an ethically difficult position. In response, we argue on behalf of enhancement practices in sports within a framework of medical supervision.

SUMMARY

Current anti-doping strategy is aimed at eradication of doping in elite sports by means of all-out repression, buttressed by a war-like ideology similar to the public discourse sustaining international efforts against illicit drugs. Rather than striving for eradication of doping in sports, which appears to be an unattainable goal, a more pragmatic approach aimed at controlled use and harm reduction may be a viable alternative to cope with doping and doping-like behaviour.

A transdisciplinary model integrating genetic, physiological, and psychological correlates of voluntary exercise

OBJECTIVE

Physical inactivity contributes to as many as 250,000 premature deaths per year (R. R. Pate et al., 1995). The authors' objective was to test a transdisciplinary model of the ways in which genetic variants, physiological factors, and psychological factors are thought to influence exercise with 64 healthy, regular exercisers.

DESIGN

In a within-subjects design, psychological and physiological responses to exercise were compared with responses to a sedentary activity.

MAIN OUTCOME MEASURES

The authors measured affective state, perceived exertion, heart rate, and temperature change in response to moderate exercise versus sedentary activity. They also quantified genotypes on a single nucleotide polymorphism in the brain-derived neurotrophic factor (BDNF) gene.

RESULTS AND CONCLUSIONS

The data show a relation between increases in positive affective states and acute exercise behavior, as opposed to a sedentary control. The BDNF gene moderated the effect of exercise on mood, heart rate, and perceived exertion. Physiological factors were, in turn, related to mood response, and mood response was a significant correlate of motivation to exercise in the future and of current exercise behavior. The model has potential as a framework for the basic study of the genetic, physiological, and psychological processes involved with voluntary exercise and as a tool for the applied examination of tailored exercise interventions and their efficacy for different subsets of individuals.

Genetic influences on exercise participation in 37,051 twin pairs from seven countries

BACKGROUND

A sedentary lifestyle remains a major threat to health in contemporary societies. To get more insight in the relative contribution of genetic and environmental influences on individual differences in exercise participation, twin samples from seven countries participating in the GenomEUtwin project were used.

METHODOLOGY

Self-reported data on leisure time exercise behavior from Australia, Denmark, Finland, Norway, The Netherlands, Sweden and United Kingdom were used to create a comparable index of exercise participation in each country (60 minutes weekly at a minimum intensity of four metabolic equivalents).

PRINCIPAL FINDINGS

Modest geographical variation in exercise participation was revealed in 85,198 subjects, aged 19-40 years. Modeling of monozygotic and dizygotic twin resemblance showed that genetic effects play an important role in explaining individual differences in exercise participation in each country. Shared environmental effects played no role except for Norwegian males. Heritability of exercise participation in males and females was similar and ranged from 48% to 71% (excluding Norwegian males).

CONCLUSIONS

Genetic variation is important in individual exercise behavior and may involve genes influencing the acute mood effects of exercise, high exercise ability, high weight loss ability, and personality. This collaborative study suggests that attempts to find genes influencing exercise participation can pool exercise data across multiple countries and different instruments.

Blood doping: present procedures and detection techniques

Blood doping represents a serious risk in endurance athletes. Blood transfusion practices (either autologous or homologous) have been used since 1960 and, despite the significant improvement in the laboratory methods, only homologous blood transfusion can be detected currently, while for autologous blood transfusion, no validated methods exist. In the last 15 years, a number of drugs have been developed to treat anemic patients. From recombinant erythropoietin to synthetic hemoglobin, all the developed tools are potentially useful to increase the oxygen transport to peripheral tissues in endurance athletes. Thus, the availability of doping-detection methods can only be sustained by the knowledge of any novel therapeutic approach in this field. The identification of the doping molecule is the gold standard of any antidoping campaign; despite this, indirect methods based on the detection of the effects induced by the doping procedure will be a very powerful tool in the near future. Nevertheless, while direct methods are only affected by the sensitivity and the specificity of the method itself (deterministic methods), indirect approaches are affected by the statistic weight of the results (probabilistic methods). Thus, blood doping will be better controlled by the combination of the two approaches.

Computational disease gene identification: a concert of methods prioritizes type 2 diabetes and obesity candidate genes

Genome-wide experimental methods to identify disease genes, such as linkage analysis and association studies, generate increasingly large candidate gene sets for which comprehensive empirical analysis is impractical. Computational methods employ data from a variety of sources to identify the most likely candidate disease genes from these gene sets. Here, we review seven independent computational disease gene prioritization methods, and then apply them in concert to the analysis of 9556 positional candidate genes for type 2 diabetes (T2D) and the related trait obesity. We generate and analyse a list of nine primary candidate genes for T2D genes and five for obesity. Two genes, LPL and BCKDHA, are common to these two sets. We also present a set of secondary candidates for T2D (94 genes) and for obesity (116 genes) with 58 genes in common to both diseases.

The associations of ACE polymorphisms with physical, physiological and skill parameters in adolescents

Genetic variation in the human Angiotensin I-Converting Enzyme (ACE) gene has been associated with many heritable traits, including physical performance. Herein we report the results of a study of several physical, physiological and skill parameters and lifestyle in 1,027 teenage Greeks. We show that there is a strong association (P < 0.001) between the ACE I/D (insertion/deletion) polymorphism and both handgrip strength and vertical jump in females, homozygotes for the I-allele exhibiting higher performance-related phenotype scores, accounting for up to 4.5% of the phenotypic variance. The association is best explained by a model in which the D-allele is dominant, with the mean phenotypic value in the I/D heterozygotes being close to that of the mean of the DD homozygotes. The association acts across the phenotype distribution in a classical polygenic manner. Other polymorphisms that define major ACE haplotypes in European populations (rs4424958, rs4311) show weaker associations with these performance-related phenotypes than does I/D. Similarly, diplotypes defined by these polymorphisms do not explain significantly larger amounts of the variance than I/D alone. As ACE I/D is the polymorphism most strongly associated with circulating ACE activity in European populations, we propose that the functional allelic differences that influence ACE activity also mediate the associations with the performance-related phenotypes studied here.

What makes a champion?

Variation in human athletic performance is determined by a complex interaction of socio-cultural, psychological, and proximate physiological factors. Human physiological trait variance has both an environmental and genetic basis, although the classic gene-environment dichotomy is clearly too simplistic to understand the full range of variation for most proximate determinants of athletic performance, e.g., body composition. In other words, gene and environment interact, not just over the short term, but also over the lifetime of an individual with permanent effects on the adult phenotype. To further complicate matters, gene and environment may also be correlated. That is, genetically gifted individuals may be identified as children and begin training pulmonary, cardiovascular, and muscle systems at an early critical age. This review covers evidence in support of a genetic basis to human athletic performance, with some emphasis on the recent explosion of candidate gene studies. In addition, the review covers environmental influences on athletic performance with an emphasis on irreversible environmental effects, i.e., developmental effects that may accrue during critical periods of development either before conception (epigenetic effects), during fetal life (fetal programming), or during childhood and adolescence. Throughout, we emphasize the importance of gene-environment interaction (G x E) as a means of understanding variation in human physiological performance and we promote studies that integrate genomics with developmental biology.

Growth hormone 1 (GH1) gene and performance and post-race rectal temperature during the South African Ironman triathlon

BACKGROUND

Some studies have suggested that the insertion allele of the ACE gene is associated with endurance performance, including the Ironman triathlon. It is possible that this association is due to genetic linkage between the ACE I/D locus and the T/A variant in intron 4 of the neighbouring GH1 gene. The A variant is associated with lower levels of growth hormone production. Growth hormone has multiple effects, especially on metabolism during exercise and recovery from exercise. Its production during exercise has also been shown to stimulate sweat rate and heat loss.

OBJECTIVE

To determine whether the GH1 gene is associated with the performance and/or post-race rectal temperatures of competitors in the South African Ironman triathlon.

METHODS

A total of 169 of the fastest finishing white male triathletes who completed the 2000 and/or 2001 South African Ironman triathlon and 155 control subjects were genotyped for the T/A variant in the GH1 gene. Post-race rectal temperature was also determined in 103 of these triathletes.

RESULTS

There was no significant difference in the frequency of this polymorphism in the GH1 gene when the fastest finishing triathletes were compared with the control subjects. Post-race rectal temperatures were, however, significantly higher in those triathletes with an AA genotype (mean (SD) 37.7 (0.8) degrees C) compared with those with a TT genotype (37.2 (0.8) degrees C) (p = 0.019).

CONCLUSIONS

The T/A polymorphism in intron 4 of the GH1 gene was not associated with performance of the fastest finishers of the South African Ironman triathlon. Post-race rectal temperatures were, however, significantly higher in the fastest finishing athletes, who were homozygous for a GH1 genotype associated with lower growth hormone production.

Gene hunting in hypoxia and exercise

New technologies in genomics and proteomics are revolutionizing the study of adaptation to environmental stress. These approaches provide a comprehensive overview of the responses of thousands of genes/proteins to stress and enormously expand our view of the molecular and metabolic changes that underlie physiological responses. Several new technologies can help physiological labs to become gene hunters. DNA array screening is particularly effective for two purposes: (1) identifying coordinated responses by functional groups of gene/proteins such as multiple members of a signal transduction cascade or enzymes of a metabolic pathway, and (2) highlighting cell functions that have never before been linked with the stress under consideration. We have shown that heterologous screening of DNA arrays can be a highly effective method of gene hunting for the comparative biochemist provided that it is followed up by species-specific analyses including PCR to quantify transcript levels and Western blotting to analyze protein responses. Recent work in my lab has used cDNA array screening to evaluate responses to low oxygen by multiple hypoxia/anoxia tolerant systems, revealing common gene responses across phylogeny. Analysis of vertebrate facultative anaerobiosis in freshwater turtles reveals an interesting mixture of gene responses, including up-regulation of antioxidant enzymes, protease inhibitors, and proteins of iron metabolism; a few of these are coordinated by the hypoxia inducible factor in other systems but most are not. Array screening is also providing new insights into how exercise stimulates the growth of differentiated muscle cells and studies in our lab are identifying the gene responses associated with "anti-exercise"--gene up-regulation that aids hibernating mammals to maintain their muscle mass despite months of inactivity.

Individual differences in the responses to endurance and resistance training

Large individual differences in the responsiveness of cardiorespiratory fitness (VO2peak) to endurance training have been observed in healthy subjects. We tested the hypothesis that subjects with a poor responsiveness to endurance training might benefit from resistance training in terms of aerobic fitness. The study population consisted of sedentary healthy male and female subjects (n=91, 42+/-5 year) assigned to either a training (n=73) or a control group (n=18). The randomized cross-over study design included a 2-week laboratory-controlled endurance or resistance training period with a 2-month detraining period between the interventions. Large individual differences were observed in the changes of VO2peak (DeltaVO2peak) after both the endurance (average 8+/-6 %, P<0.001, range -5 to +22%) and resistance training (average 4+/-5%, P<0.001, range -8 to +16%). The average increase in DeltaVO2peak between genders was similar after both the endurance (8+/-6% for both genders, P=ns) and resistance training (3+/-5% for males and 5+/-6% for females, P=ns). There was no linear relationship between the changes in VO2peak after each training intervention (r=-.09, P=ns). On the contrary, when the study group was divided into quartiles according to the endurance training response (1+/-3, 6+/-1, 9+/-1, and 16+/-3% increase in VO2peak), the group with the lowest response to endurance training increased VO2peak after the resistance training intervention (DeltaVO2peak 7+/-5%, P<0.001). The individual responsiveness of VO2peak to exercise training is related to the mode of training. The healthy males and females whose training response is low after endurance training seem to result in a marked improvement in their cardiorespiratory fitness by resistance training.

Nondisease genetic testing: reporting of muscle SNPs shows effects on self-concept and health orientation scales

The purpose of this study was to assess the impact of genetic self-knowledge (nondisease genotype information) on individual self-concept and Health Orientation Scale (HOS). Adult volunteers (n=257) were recruited from an ongoing genetic association study identifying muscle quantitative trait loci (QTLs). Participants completed psychosocial assessments before and after 12 weeks of resistance training of the nondominant arm. At study exit, a genetic counselor informed participants of genetic test results on three to four genes that have an association with muscle-related traits, and counseled subjects on the potential significance of these findings. The second psychosocial assessment was performed immediately following this counseling session. The Tennessee Self-Concept Scale v.2 (TSCS:2) and the HOS showed female subjects to have a significantly greater positive change between first and second assessments, relative to male subjects. Most self-concept subscales improved significantly, when 'neutral' genotypes (no anticipated beneficial or deleterious impact) were reported, compared to positive genotypes. TSCS:2 subscales showing improvement included: total (P=0.013); physical (P=0.004); satisfaction (P=0.019); and behavioral (P=0.047). HOS subscales showing improvement included health image concern (P=0.006); and health expectations (P=0.047). In conclusion, these results suggest that genetic self-knowledge affects self-concept, consistent with the 'attribution' theory. Individuals who received neutral genetic information attributed positive changes from the exercise program to their own abilities, while those who received positive information were more likely to attribute positive changes to their genetics. This study is limited by the ability to determine the direction of the impact of nondisease genetic information presented to participants.

The EPAS1 gene influences the aerobic-anaerobic contribution in elite endurance athletes

EPAS1 is a gene involved in complex oxygen sensing. It is expressed in microvascular endothelial cells, lung epithelial cells, cardiac myocytes and the brain. An association study was undertaken comparing elite endurance athletes classified into two groups according to a power-time model of performance intensity: power-time-maximum (PT-MAX; N=242, event duration 50 s to 10 min) and power-time-steady state (PT-SS; N=151, event duration ~2-10 h), with normal controls (N=444) using 12 SNPs across EPAS1. Ordinal regression analysis of allele frequencies revealed significant differences at SNPs 2 and 3 (P=0.01). Haplotype analysis revealed the presence of haplotypes involving SNPs 2-5 that significantly differentiated (P<0.05) the groups based on an ordinal ranking using the power-time classification. These same haplotypes differentiated the PT-MAX group in which a significant decrease in a haplotype (F: G-C-C-G; OR=0.57, P=0.02, 95% CI 0.36-0.92) and increase in a second haplotype (G: A-T-G-G; OR=1.75, P=0.03, 95% CI 1.05-2.91) was observed compared to controls. The PT-SS group was differentiated from the PT-MAX group by a third haplotype (H: A-T-G-A; OR=0.46, P=0.04, 95% CI 0.22-0.96). Since EPAS1 has a role as a sensor capable of integrating cardiovascular function, energetic demand, muscle activity and oxygen availability into physiological adaptation, we propose that DNA variants in EPAS1 influence the relative contribution of aerobic and anaerobic metabolism and hence the maximum sustainable metabolic power for a given event duration.

No association between Angiotensin Converting Enzyme (ACE) gene variation and endurance athlete status in Kenyans

East African runners are continually successful in international distance running. The extent to which genetic factors influence this phenomenon is unknown. The insertion (I) rather than deletion (D) of a 287 bp fragment in the human angiotensin converting enzyme (ACE) gene is associated with lower circulating and tissue ACE activity and with endurance performance amongst Caucasians. To assess the association between ACE gene variation and elite endurance athlete status in an African population successful in distance running, DNA samples were obtained from 221 national Kenyan athletes (N), 70 international Kenyan athletes (I), and 85 members of the general Kenyan population (C). Blood samples were obtained from C and assayed for circulating ACE activity. ACE I/D (rs????--from NCBI SNPdb first time poly mentioned) genotype was determined, as was genotype at A22982GD (rs????--from NCBI SNPdb first time poly mentioned) which has been shown to associate more closely with ACE levels in African subjects than the I/D polymorphism. ACE I/D and A22982G genotypes explained 13 and 24% of variation in circulating ACE activity levels (P = 0.034 and <0.001 respectively). I/D genotype was not associated with elite endurance athlete status (df = 4, chi(2) = 4.1, P=0.39). In addition, genotype at 22982 was not associated with elite endurance athlete status (df = 4, chi(2) = 5.7, P = 0.23). Nor was the A allele at 22982, which is associated with lower ACE activity, more prevalent in N (0.52) or I (0.41) relative to C (0.53). We conclude that ACE I/D and A22982G polymorphisms are not strongly associated with elite endurance athlete status amongst Kenyans.

Body maintenance and repair: how food and exercise keep the musculoskeletal system in good shape

This article provides a personal view of how feeding and exercise acutely modify protein metabolism of human skeletal muscle, with discussion of the anabolic signalling mechanisms involved and some new findings on the metabolism of the turnover of collagen, tendon and bone.

Genes and human elite athletic performance

Physical fitness is a complex phenotype influenced by a myriad of environmental and genetic factors, and variation in human physical performance and athletic ability has long been recognised as having a strong heritable component. Recently, the development of technology for rapid DNA sequencing and genotyping has allowed the identification of some of the individual genetic variations that contribute to athletic performance. This review will examine the evidence that has accumulated over the last three decades for a strong genetic influence on human physical performance, with an emphasis on two sets of physical traits, viz. cardiorespiratory and skeletal muscle function, which are particularly important for performance in a variety of sports. We will then review recent studies that have identified individual genetic variants associated with variation in these traits and the polymorphisms that have been directly associated with elite athlete status. Finally, we explore the scientific implications of our rapidly growing understanding of the genetic basis of variation in performance.

PPARGC1A genotype (Gly482Ser) predicts exceptional endurance capacity in European men

Animal and human data indicate a role for the peroxisome proliferator-activated receptor-gamma coactivator 1alpha (PPARGC1A) gene product in the development of maximal oxygen uptake (V(O2 max)), a determinant of endurance capacity, diabetes, and early death. We tested the hypothesis that the frequency of the minor Ser482 allele at the PPARGC1A locus is lower in World-class Spanish male endurance athletes (cases) [n = 104; mean (SD) age: 26.8 (3.8) yr] than in unfit United Kingdom (UK) Caucasian male controls [n = 100; mean (SD) age: 49.3 (8.1) yr]. In cases and controls, the Gly482Ser genotype met Hardy-Weinberg expectations (P > 0.05 in both groups tested separately). Cases had significantly higher V(O2 max) [73.4 (5.7) vs. 29.4 ml x kg(-1) x min(-1) (3.8); P < 0.0001] and were leaner [body mass index: 20.6 (1.5) vs. 27.6 kg/m2 (3.9); P < 0.0001] than controls. In unadjusted chi2 analyses, the frequency of the minor Ser482 allele was significantly lower in cases than in controls (29.1 vs. 40.0%; P = 0.01). To assess the possibility that genetic stratification could confound these observations, we also compared Gly482Ser genotype frequencies in Spanish (n = 164) and UK Caucasian men (n = 381) who were unselected for their level of fitness. In these analyses, Ser482 allele frequencies were very similar (36.9% in Spanish vs. 37.5% in UK Caucasians, P = 0.83), suggesting that confounding by genetic stratification is unlikely to explain the association between Gly482Ser genotype and endurance capacity. In summary, our data indicate a role for the Gly482Ser genotype in determining aerobic fitness. This finding has relevance from the perspective of physical performance, but it may also be informative for the targeted prevention of diseases associated with low fitness such as Type 2 diabetes.