The human gene map for performance and health-related fitness phenotypes: the 2002 update

Higher resistance training volume offsets muscle hypertrophy nonresponsiveness in older individuals

The magnitude of muscle hypertrophy in response to resistance training (RT) is highly variable between individuals (response heterogeneity). Manipulations in RT variables may modulate RT-related response heterogeneity; yet, this remains to be determined. Using a within-subject unilateral design, we aimed to investigate the effects of RT volume manipulation on whole muscle hypertrophy [quadriceps muscle cross-sectional area (qCSA)] among nonresponders and responders to a low RT dose (single-set). We also investigated the effects of RT volume manipulation on muscle strength in these responsiveness groups. Eighty-five older individuals [41M/44F, age = 68 ± 4 yr; body mass index (BMI) = 26.4 ± 3.7 kg/m2] had one leg randomly allocated to a single (1)-set and the contralateral leg allocated to four sets of unilateral knee-extension RT at 8-15 repetition maximum (RM) for 10-wk 2 days/wk. Pre- and postintervention, participants underwent magnetic resonance imaging (MRI) and unilateral knee-extension 1-RM strength testing. MRI typical error (2× TE = 3.27%) was used to classify individuals according to responsiveness patterns. n = 51 were classified as nonresponders (≤2× TE) and n = 34 as responders (>2× TE) based on pre- to postintervention change qCSA following the single-set RT protocol. Nonresponders to single-set training showed a dose response, with significant time × set interactions for qCSA and 1-RM strength, indicating greater gains in response to the higher volume prescription (time × set: P < 0.05 for both outcomes). Responders improved qCSA (time: P < 0.001), with a tendency toward higher benefit from the four sets RT protocol (time × set: P = 0.08); on the other hand, 1-RM increased similarly irrespectively of RT volume prescription (time × set: P > 0.05). Our findings support the use of higher RT volume to mitigate nonresponsiveness among older adults.NEW & NOTEWORTHY Using a within-subject unilateral design, we demonstrated that increasing resistance training (RT) volume may be a simple, effective strategy to improve muscle hypertrophy and strength gains among older adults who do not respond to low-volume RT. In addition, it could most likely be used to further improve hypertrophic outcomes in responders.

Associations between ACE Genotypes, +8.5 Gz Tolerance, and Body Composition in F-15 Pilot Candidates

INTRODUCTION

Pilots' +8.5Gz tolerance is related with their selection, safety and special mission suitability. The preliminary study about F-15 pilot candidates were rare, especially related with genetic effect like ACE (angiotensin converting enzyme) gene.

BACKGROUND

This study aimed to investigate the associations between the +8.5 Gz test qualification and angiotensin converting enzyme (ACE) genotypes in Korean F-15 pilot candidates for pilot special mission suitability and cadet body composition education.

MATERIALS AND METHODS

We performed +8.5Gz test (15 seconds), target gene (ACE) identified and body composition measurements from twenty Korean F-15 pilot candidates (ages 23.0-28.6 years). The +8.5Gz test results (pass and not-passed), body composition parameters and their relationship with the ACE genotype were evaluated.

RESULTS

Four (20%), six (30%), and 10 (50%) pilots had the DD, DI, and II genotypes based on the ACE gene identification results, respectively. Ten (50%) pilots passed by maintaining consciousness during the +Gz test. Of them, three (75%, 3/4), four (66.7%, 4/6), and three (30%, 3/10) had the DD, DI, and II genotypes (P < .05, DD > II), respectively. Compared with other genotypes, the DD genotype was associated with overall higher values of body composition indices, and this association was more prominent among pilots who passed the +8.5 Gz test.

DISCUSSION

In some ethnic groups, the DD genotype has been found to have an effect on elite players' high-intensity performance, including muscle power and strength. The DD genotype exhibited the highest performance in terms of passing rate, longest mean breathing interval(s), and higher values of body composition parameters in pilots who passed the +8.5 Gz test.

CONCLUSIONS

In this study, the group with the DD genotype exhibited a higher pass rate and heavier body composition parameters than the group with the II genotype. These results require further investigation to determine their significance and applicability in other ethnic groups.

Molecular Portrait of an Athlete

Sequencing of the human genome and further developments in "omics" technologies have opened up new possibilities in the study of molecular mechanisms underlying athletic performance. It is expected that molecular markers associated with the development and manifestation of physical qualities (speed, strength, endurance, agility, and flexibility) can be successfully used in the selection systems in sports. This includes the choice of sports specialization, optimization of the training process, and assessment of the current functional state of an athlete (such as overtraining). This review summarizes and analyzes the genomic, proteomic, and metabolomic studies conducted in the field of sports medicine.

Associations Between Fast-Food Consumption and Body Mass Index: A Cross-Sectional Study in Adult Twins

Obesity is a substantial health problem in the United States, and is associated with many chronic diseases. Previous studies have linked poor dietary habits to obesity. This cross-sectional study aimed to identify the association between body mass index (BMI) and fast-food consumption among 669 same-sex adult twin pairs residing in the Puget Sound region around Seattle, Washington. We calculated twin-pair correlations for BMI and fast-food consumption. We next regressed BMI on fast-food consumption using generalized estimating equations (GEE), and finally estimated the within-pair difference in BMI associated with a difference in fast-food consumption, which controls for all potential genetic and environment characteristics shared between twins within a pair. Twin-pair correlations for fast-food consumption were similar for identical (monozygotic; MZ) and fraternal (dizygotic; DZ) twins, but were substantially higher in MZ than DZ twins for BMI. In the unadjusted GEE model, greater fast-food consumption was associated with larger BMI. For twin pairs overall, and for MZ twins, there was no association between within-pair differences in fast-food consumption and BMI in any model. In contrast, there was a significant association between within-pair differences in fast-food consumption and BMI among DZ twins, suggesting that genetic factors play a role in the observed association. Thus, although variance in fast-food consumption itself is largely driven by environmental factors, the overall association between this specific eating behavior and BMI is largely due to genetic factors.

Association of Angiotensin Converting Enzyme I/D and α-actinin-3 R577X Genotypes with Growth Factors and Physical Fitness in Korean Children

This study analyzed the differences in aerobic and anaerobic exercise ability and growth-related indicators, depending on the polymorphism of the ACE and the ACTN3 genes, to understand the genetic influence of exercise ability in the growth process of children. The subjects of the study consisted of elementary school students (n=856, age 10.32±0.07 yr). The anthropometric parameters, physical fitness and growth factors were compared among groups of the ACE I/D or the ACTN3 R577X polymorphisms. There were no significant differences between the anthropometric parameters, physical fitness and growth factors for the ACE gene ID or the ACTN3 gene R577X polymorphism. However, the DD type of ACE gene was highest in the side step test (p<0.05), and the DD type was significantly higher than the II+ID type (p<0.05) in the early bone age. The combined group of the ACE gene II+ID and the ACTN3 gene XX type significantly showed lower early bone age (p< 0.05). This study did not find any individual or compounding effects of the polymorphism in the ACE I/D or the ACTN3 R577X polymorphisms on the anthropometric parameters, physical fitness and growth factors of Korean children. However, the exercise experience and the DD type of the ACE gene may affect the early maturity of the bones.

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.

Endocrine crosstalk between muscle and bone

The musculoskeletal system is a complex organ comprised of the skeletal bones, skeletal muscles, tendons, ligaments, cartilage, joints, and other connective tissue that physically and mechanically interact to provide animals and humans with the essential ability of locomotion. This mechanical interaction is undoubtedly essential for much of the diverse shape and forms observed in vertebrates and even in invertebrates with rudimentary musculoskeletal systems such as fish. It makes sense from a historical point of view that the mechanical theories of musculoskeletal development have had tremendous influence of our understanding of biology, because these relationships are clear and palpable. Less visible to the naked eye or even to the microscope is the biochemical interaction among the individual players of the musculoskeletal system. It was only in recent years that we have begun to appreciate that beyond this mechanical coupling of muscle and bones, these 2 tissues function at a higher level through crosstalk signaling mechanisms that are important for the function of the concomitant tissue. Our brief review attempts to present some of the key concepts of these new concepts and is outline to present muscles and bones as secretory/endocrine organs, the evidence for mutual genetic and tissue interactions, pathophysiological examples of crosstalk, and the exciting new directions for this promising field of research aimed at understanding the biochemical/molecular coupling of these 2 intimately associated tissues.

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.

The use of Angiotensin-I converting enzyme i/d genetic polymorphism as a biomarker of athletic performance in humans

Angiotensin II is a key regulator of blood pressure and cardiovascular function in mammals. The conversion of angiotensin into its active form is carried out by Angiotensin I-Converting Enzyme (ACE). The measurement of ACE concentration in plasma or serum, its enzymatic activity, and the correlation between an insertion/deletion (I/D) genetic polymorphism of the ACE gene have been investigated as possible indicators of superior athletic performance in humans. In this context, other indicators of superior adaptation to exercise resulting in better athletic performance (such as ventricular hypertrophy, VO₂ max, and competition results) were mostly used to study the association between ACE I/D polymorphism and improved performance. Despite the fact that the existing literature presents little consensus, there is sufficient scientific evidence to warrant further investigation on the usage of ACE activity and the I/D ACE gene polymorphism as biomarkers of superior athletic performance in humans of specific ethnicities or in athletes involved in certain sports. In this sense, a biomarker would be a substance or genetic component that could be measured to provide a degree of certainty, or an indication, of the presence of a certain trait or characteristic that would be beneficial to the athlete’s performance. Difficulties in interpreting and comparing the results of scientific research on the topic arise from dissimilar protocols and variation in study design. This review aims to investigate the current literature on the use of ACE I/D polymorphism as a biomarker of performance in humans through the comparison of scientific publications.

Aging has greater impact on anaerobic versus aerobic power in trained masters athletes

This study measured the relative rates of change of the three human energy systems across a 30-year age range. A cross-section of highly trained masters cyclists (n = 156 males and 17 females; 35-64 years) were tested for maximal cycling performance. There were 50 (29%) track sprint cyclists and the remaining (71%) were predominantly road cycling specialists. A 10 s peak power test measured anaerobic power, a 30 s test measured anaerobic capacity, and a progressive test to volitional fatigue was used to determine peak aerobic power. Participants' exercise patterns were recorded using a physical activity recall questionnaire. Linear regression showed significant changes in anaerobic performance with aging. Peak anaerobic power (W · kg⁻¹) declined at a rate (mean ± SEE) of 8.1 ± 4.1% per decade (P < 0.0001) and anaerobic capacity (kJ · kg⁻¹) declined at 8.0 ± 3.3% per decade (P < 0.0001). Peak aerobic power [W · kg⁻¹] did not change significantly with age [-1.8 ± 1.5% per decade (P = 0.218)]. This cross-sectional study showed performance of the two anaerobic energy systems declined significantly across the age spectrum with no change in aerobic capacity.

The Psychological Benefits of Vigorous Exercise: A Study of Discordant MZ Twin Pairs

The physiological benefits of vigorous exercise are well established. The existence of psychological benefits is less clear, however, due to methodological limitations common to investigatory studies. Two of these limitations are the difficulty of establishing appropriate control groups and the large variety of highly specific measures of psychological function available for consideration of effects. To address these limitations, we identified 63 pairs of monozygotic twins from the National Survey of Midlife Development in the United States who were discordant for the amount of vigorous exercise in which they engaged regularly. The twins who regularly engaged in vigorous exercise experienced greater positive psychological functioning than their nonexercising co-twins as measured by the latent factor representing the variance common to 8 measures of mood, optimism, control over life, and interpersonal aspects of personality. The magnitude of the difference was in excess of .4 standard deviations.

Inverse but independent trends in obesity and fitness levels among Greek children: a time-series analysis from 1997 to 2007

OBJECTIVE

We examined secular trends in physical fitness and BMI status in 8- to 9-year-old Greek children during an 11-year period (1997-2007).

METHODS

Population data derived from a yearly health survey performed in over 85% of Greek schools. Anthropometric measurements and physical fitness tests from 651,582 children were analyzed. The gender- and age-specific BMI cut-off points by the International Obesity Task Force were used to define overweight/obesity.

RESULTS

Aerobic performance decreased by 4.9% (p < 0.001) for boys and 4.4% (p < 0.001) for girls between 1997 and 2007 while obesity increased by approximately 50% in both genders (p < 0.001). Time-series analyses revealed that the increasing trends in obesity were independent of the reduction in fitness levels. An increase from 21% in 1997 to 48.2% in 2007 was observed in the prevalence of the low quartile of aerobic performance for girls (p < 0.001) and from 25.7% in 1997 to 38.7% in 2007 (p < 0.001) for boys. Approximately 80% and 85% of obese boys and girls, respectively, failed to pass the low quartile of all aerobic tests in 2007.

CONCLUSIONS

Inverse but independent trends in obesity and fitness levels were observed among Greek children during an 11-year period (1997-2007), a fact that predisposes our children to serious health risks as they grow older.

Optimal health and function among the elderly: lessening severity of ADL disability

Despite mounting evidence implicating sedentary behavior as a significant risk factor among the elderly, there is a limited amount of information on the type and amount of activity needed to promote optimal health and function in older people. Overall muscle strength and mass decline 30–50% between the ages of 30 and 80. The loss of muscle mass accounts for most of the observed loss of strength. The loss of muscle tissue is due to a decrease in the number of muscle fibers and to atrophy of the type II muscle fibers. The declining strength reduces the capacity to carry out basic activities of daily life and puts people at risk for falls and dependence on others. The objective of the present review is to examine the role of exercise training as a primary tool for increasing cardiopulmonary and muscular fitness in order to lessen the severity of disability in activities of daily living and to attain optimal health and functioning among the elderly.

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.

Strong inverse association between physical fitness and overweight in adolescents: a large school-based survey

Background

Studies examining the relationship between physical fitness and obesity in children have had mixed results despite their interrelationship making intuitive sense. We examined the relationship between physical fitness and overweight and obesity in a large sample of adolescents in the Republic of Seychelles (Indian Ocean, African region).

Methods

All students of four grades of all secondary schools performed nine physical fitness tests. These tests assessed agility, strength and endurance, and included the multistage shuttle run, a validated measure of maximal oxygen uptake. Weight and height were measured, body mass index (BMI) calculated, and "overweight" and "obesity" were defined based on the criteria of the International Obesity Task Force. We defined "lean" weight as age- and sex-specific BMI <10^th percentile. Age- and sex-specific percentiles for each fitness test were calculated. "Good" performance was defined as a result ≥75^th percentile.

Results

Data were available in 2203 boys and 2143 girls from a total of 4599 eligible students aged 12–15 years. The prevalence of overweight (including obesity) was 11.2% (95% confidence interval: 9.9–12.4) in boys and 17.5% (15.9–19.1) in girls. For 7 of the 9 tests, the relationship between BMI and fitness score, as assessed by locally weighted regression, was characterized by a marked inverse J shape. Students with normal body weight achieved "good" performance markedly more often than overweight or obese students on 7 of the 9 tests of fitness and more often than lean children. For example, good performance for the multistage shuttle run was achieved by 25.6% (SE: 2.1) of lean students, 29.6% (0.8) of normal weight students, 7.9% (1.3) of overweight students and 1.2% (0.9) of obese students.

Conclusion

This cross-sectional study shows a strong inverse relationship between fitness and excess body weight in adolescents. Improving fitness in adolescents, likely through increasing physical activity, might need special interventions that are responsive to the ability and needs of overweight children.

Improved resolution of the comparative horse–human map: Investigating markers with in silico and linkage mapping approaches

Genetic maps are extremely important tools for tracing the genes that govern economically significant traits, and microsatellites are a significant component of these. In this study, we isolated 2346 novel horse microsatellites as resources for the construction of high-density horse genetic maps. Of these 2346 markers, 339 (14.5%) horse sequences showed sequence homology to DNA sequences in the human genome, demonstrating that microsatellites as type II markers are valuable resources for developing linkage maps and that they have a potential equal to that of type I markers for developing comparative maps. Of the 339 markers, 206 (60.8%) were assigned to horse chromosomes using the Animal Health Trust (AHT) full-sib reference family, and 195 (94.6%) of these localized to the expected syntenic locations on the human genome. These results confirmed the high level of accuracy of in silico mapping. Thus, the 339 markers that exhibited homology to the human genome increased the density of markers on the horse-human comparative map. The resulting comparative map will facilitate the use of horse microsatellites as genetic markers for the identification of quantitative trait loci (QTL) that have been mapped on the human genome. In addition, although the in silico and linkage mapping data did not agree for the other 11 (5.4%) of the assigned 206 markers, these may represent new putative regions of horse-human synteny.

Response of high-sensitivity C-reactive protein to exercise training in an at-risk population

BACKGROUND

High-sensitivity C-reactive protein (hsCRP) is promoted as an independent predictor of atherosclerotic risk. In addition, cardiorespiratory fitness is inversely related to hsCRP in single-sex cross-sectional analyses. Our objective was to determine if modulating fitness with exercise training imposes changes in high-sensitivity C-reactive protein in a mixed-sex population at risk for cardiovascular disease.

METHODS

We studied baseline and postintervention plasma hsCRP in 193 sedentary, overweight to mildly obese, dyslipidemic men and women who were randomized to 6 months of inactivity or 1 of 3 aerobic exercise groups: low amount-moderate intensity (energy equivalent of approximately 19.3 km/wk at 40%-55% peak VO2), low amount-high intensity (energy equivalent of approximately 19.3 km/wk at 65%-80% peak VO2), or high amount-high intensity (energy equivalent of approximately 32.2 km/wk at 65%-80% peak VO2).

RESULTS

At baseline, the study population was at intermediate to high cardiovascular risk as defined by hsCRP. Cardiorespiratory fitness was inversely related to hsCRP (P < .001) even after adjusting for significant and expected sex differences. Fitness, hormone replacement therapy use, and high-density lipoprotein cholesterol accounted for the sex difference in baseline hsCRP. Fitness, high-density lipoprotein cholesterol, fasting insulin, hormone replacement therapy, and visceral adiposity were all independent predictors for baseline hsCRP (r2 = 0.34 for the entire model, P < .0001). However, despite significant improvements in fitness, visceral adiposity, subcutaneous adiposity, and insulin sensitivity, hsCRP did not change in response to exercise training (P > .20).

CONCLUSIONS

Cardiorespiratory fitness is inversely related to hsCRP independent of sex and accounts for most of the large sex disparity in hsCRP. Nonetheless, in the absence of a significant change in diet, 6 months of aerobic exercise training does not produce a significant change in hsCRP in an at-risk population.

Body mass index gain, fast food, and physical activity: effects of shared environments over time

OBJECTIVE

The magnitude of environmental vs. genetic effects on BMI, diet, and physical activity (PA) is widely debated. We followed a sibling cohort (where individuals shared households in childhood and adolescence) to young adulthood (when some continued sharing households and others lived apart) to examine the role of discordant environments in adult twins' divergent trends in BMI and health behaviors and to quantify the variation in BMI and behavior among all siblings that is attributable to environmental and additive genetic effects.

RESEARCH METHODS AND PROCEDURES

In the National Longitudinal Study of Adolescent Health, siblings sharing households for > or =10 years as adolescents (mean age = 16.5 +/- 1.7 years; N = 5524) were followed into adulthood (mean = 22.4 +/- 1.8 years; N = 4368), self-reporting PA, sedentary behavior, and dietary characteristics. Adult BMI and adolescent z scores were derived from measured height and weight.

RESULTS

Compared with those living together, twins living apart exhibited greater discordance in change in BMI, PA, and fast food intake from adolescence to adulthood. Adolescent household environments accounted for 8% to 10% of variation in adolescent fast food intake and sedentary behaviors and 50% of variation in adolescent overweight. Adolescent household effects on PA were substantially greater in young adulthood (accounting for 50% of variation) vs. adolescence. Young adult fast food intake was significantly affected by young adult household environment, accounting for 12% of variation.

DISCUSSION

These findings highlight important environmental influences on BMI, PA, and fast food intake during the transition to adulthood. Household and physical environments play an important role in establishing long-term behavior patterns.

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.

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.

From genetics to genomics: using gene-based medicine to prevent disease and promote health in children

The remarkable achievements of the Human Genome Project promise great opportunities for disease prediction, treatment, and prevention. In this paper, we discuss the continuum of genetic variation as medical practice begins to shift focus from the study of single genes (genetics) to the study of the entire genome (genomics). Pediatricians should anticipate an influx of genetic information and will need to become as facile in interpreting this type of predictive information as they are with other types of medical data, while recognizing the unique ethical, legal, and social implications of genetic testing in children. We discuss an approach to assist pediatricians in decision-making that emphasizes the need for knowledge about the analytic performance of genetic tests, their validity in predicting health outcomes, and the utility of the genetic information in improving health and preventing disease.

Mitochondrial DNA lineages of elite Ethiopian athletes

Previous studies have hypothesised that mitochondrial DNA (mtDNA) polymorphisms may influence aerobic performance. The matrilineal inheritance and accumulation of polymorphisms in mtDNA means that mtDNA haplogroups, characterised by key polymorphisms, are often represented at different frequencies in different populations. The present study aimed to compare the mtDNA haplogroup distribution of elite Ethiopian athletes relative to the general Ethiopian population. The haplogroup distribution of 76 endurance athletes (E), members of the Ethiopian national athletics team, was compared to 108 members of the general Ethiopian population (C). DNA was extracted from buccal swabs and haplogroups assigned by sequencing part of the hypervariable sequence (HVS-I), followed by analysis of key coding-region polymorphisms. A high proportion of African 'L' haplogroups was found in athletes and controls (C=53%; E=55%). Haplogroup distribution of endurance runners did not differ from that of C (P=0.63). Elite Ethiopian athletes are not a mitochondrially distinct group relative to the Ethiopian population. It appears that environment and, perhaps, polymorphisms in the nuclear genome are more important determinants of Ethiopian running success than mtDNA polymorphisms.

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.

Exercise training increases electron and substrate shuttling proteins in muscle of overweight men and women with the metabolic syndrome

Aerobic conditioned muscle shows increased oxidative metabolism or glucose relative to untrained muscle at a given absolute exercise intensity. The studies of a targeted risk reduction intervention through defined exercise (STRRIDE) study is an aerobic exercise intervention in men and women with features of metabolic syndrome (Kraus WE, Torgan CE, Duscha BD, Norris J, Brown SA, Cobb FR, Bales CW, Annex BH, Samsa GP, Houmard JA, and Slentz CA, Med Sci Sports Exerc 33: 1774–1784, 2001), with four muscle biopsies taken during training and detraining time points. Here, we expanded a previous study (Hittel DS, Kraus WE, and Hoffman EP, J Physiol 548: 401–410, 2003) and used mRNA profiling to investigate gene transcripts associated with energy and substrate metabolism in STRRIDE participants. We found coordinate regulation of key metabolic enzymes with aerobic training in metabolic syndrome (aspartate aminotransferase 1, lactate dehydrogenase B, and pyruvate dehydrogenase-α1). All were also quickly downregulated by detraining, although the induction was not an acute response to activity. Protein and enzymatic assays were used to validate mRNA induction with aerobic training and loss with detraining (96 h to 2 wk) in 10 male and 10 female STRRIDE subjects. We propose that training coordinately increases the levels of aspartate aminotransferase 1, lactate dehydrogenase B, and pyruvate dehydrogenase-α1subunit, increasing glucose metabolism in muscle by liberating pyruvate for oxidative metabolism and, therefore, limiting lactate efflux. Serial measurement of fasting plasma lactate from 62 subjects from the same exercise group demonstrated a significant decrease of circulating lactate with training. We also found evidence for sex-specific molecular remodeling of muscle with ubiquinol-cytochrome c reductase core protein II, a component of mitochondrial respiratory complex III, which showed an increase after training that was specific to women. These biochemical adaptations complement existing molecular models for improved glucose tolerance with exercise intervention in prediabetic individuals.

Strain-dependent differences in responses to exercise training in inbred and hybrid mice

The aim of this study was to characterize the response to exercise training in several mouse strains and estimate the genetic contribution to phenotypic variation in the responses to exercise training. Male mice from three inbred strains [C57Bl/6J (BL6), FVB/NJ (FVB), and Balb/cJ (Balb/c)] and three hybrid F(1) strains [CB6F1/J (CB6 = female Balb/c x male BL6), B6F F(1) (female BL6 x male FVB), and FB6 F(1) (female FVB x male BL6)] completed an exercise performance test before and after a 4-wk treadmill running program. Distance was used as the primary estimate of endurance exercise performance. FVB mice showed the greatest response to training, with five- to sevenfold greater increases in distance run compared with BL6 and Balb/c strains. Specifically, BL6, FVB, and Balb/c strains increased distance by 33, 172, and 23%, respectively. A similar pattern of changes across strains was observed for run time (17, 87, and 11%) and work (99, 287, and 57%). As a group, F(1) hybrid mice derived from BL6 and FVB strains showed an intermediate response to training (61%). However, further analysis indicated that training responses in FB6 F(1) mice (80%) were approximately 2.5-fold greater than responses in B6F F(1) mice (33%, P = 0.08). A similar pattern of changes between FB6 and B6F F(1) mice was observed for run time (44.5 and 17%) and work (141 and 59%). These data demonstrate that there are large strain-dependent differences in training responses among inbred mouse strains, suggesting that genetic background contributes significantly to adaptation to exercise. Furthermore, the contrasting responses in B6F and FB6 F(1) strains show that a maternal component strongly influences strain-dependent differences in training responses.

Parent-child physical activity relationships in 12-year old French students do not depend on family socioeconomic status

OBJECTIVES

Regular physical activity (PA) in young needs to be promoted to prevent obesity and subsequent diabetes. Influences of parental PA on adolescents' activity level have been studied with discordant results and the effect of socioeconomic status (SES) on these relationships is not clarified.

METHODS

Cross-sectional population-based survey of about 3000 12-year old French students and their parents. Familial associations were assessed with logistic regression models taking into account SES and children's and parents' corpulence. Sport involvement and sedentary behaviors were assessed by standardized questionnaires filled out separately by children and parents, the latter also reporting their educational data and family income tax.

RESULTS

Participation in structured PA outside school was higher for boys (74%) than for girls (58%, p<10-5) and a high sedentary behavior (watching television, playing computer/video games and reading > or =2h/day) was observed in one-third of the sample, both in boys and in girls. Children were more likely to participate in structured PA outside school when both parents practiced sport as compared to neither parent practicing it, with an odd ratio OR (95%CI) of 1.97 (1.4-2.8) for boys and 1.56 (1.2-2.1) for girls. Familial associations of inactivity were significant for boys only. A greater percentage of adolescents had a high level of sedentary behavior when both parents versus no parents watched television > 2h/day (OR 1.95 (1.52.6)). Parent-child physical activity relationships were not modified by the family SES or the children's or parents' weight status.

CONCLUSION

Parental involvement in sport is an important correlate of a young adolescent's participation in structured PA outside school, whatever the family SES or corpulence of the family members.

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

This review presents the 2003 update of the human gene map for physical performance and health-related fitness phenotypes. It is based on peer-reviewed papers published by the end of 2003 and includes association studies with candidate genes, genome-wide scans with polymorphic markers, and single-gene defects causing exercise intolerance to variable degrees. The genes and markers with evidence of association or linkage with a performance or fitness phenotype in sedentary or active people, in adaptation to acute exercise, or for training-induced changes are positioned on the genetic map of all autosomes and the X chromosome. Negative studies are reviewed but a gene or locus must be supported by at least one positive study before being inserted on the map. By the end of 2000, 29 loci were depicted on the first edition of the map. In contrast, the 2003 human gene map for physical performance and health-related phenotypes includes 109 autosomal gene entries and QTL, plus two on the X chromosome. Moreover, there are 15 mitochondrial genes in which sequence variants have been shown to influence relevant fitness and performance phenotypes.

Intensive lifestyle modification: impact on cardiovascular disease risk factors in subjects with and without clinical cardiovascular disease

Intensive lifestyle modification programs are intended to stabilize or promote regression of coronary artery disease; however, clinical response is often nonuniform, complicating appropriate utilization of resources and prediction of outcome. This study assessed physiological and psychological benefits to 72 persons participating in a prospective, nonrandomized, four-component lifestyle change program and compared response between patients with clinical cardiovascular disease (CVD) and patients with elevated risk factors for CVD but without clinical manifestations of disease. Subjects entering the program due to elevated risk factor levels alone demonstrated equal or greater benefit, in terms of improvement in primary CVD risk factors and reduction in measures of coronary disease risk developed in the Framingham Heart Study, than those with clinical CVD. These findings suggest that intensive lifestyle change programs may be important for primary prevention in individuals at increased risk of CVD.

Y chromosome haplogroups of elite Ethiopian endurance runners

Favourable genetic endowment has been proposed as part of the explanation for the success of East African endurance athletes, but no evidence has yet been presented. The Y chromosome haplogroup distribution of elite Ethiopian athletes (n=62) was compared with that of the general Ethiopian population (n=95) and a control group from Arsi (a region producing a disproportionate number of athletes; n=85). Athletes belonged to three groups: marathon runners (M; n=23), 5-km to 10-km runners (5-10K; n=21) and other track and field athletes (TF; n=18). DNA was extracted from buccal swabs and haplogroups were assigned after the typing of binary markers in multiplexed minisequencing reactions. Frequency differences between groups were assessed by using contingency exact tests and showed that Y chromosome haplogroups are not distributed amongst elite Ethiopian endurance runners in the same proportions as in the general population, with statistically significant (P<0.05) differences being found in four of the individual haplogroups. The geographical origins and languages of the athletes and controls suggest that these differences are less likely to be a reflection of population structure and that Y chromosome haplogroups may play a significant role in determining Ethiopian endurance running success.

Interleukin-1 polymorphisms are associated with the inflammatory response in human muscle to acute resistance exercise

Inflammation appears to play an important role in the repair and regeneration of skeletal muscle after damage. We tested the hypothesis that the severity of the inflammatory response in muscle after an acute bout of resistance exercise is associated with single nucleotide polymorphisms (SNPs) previously shown to alter interleukin-1 (IL-1) activity. Using a double-blind prospective design, sedentary young men were screened (n = 100) for enrolment (n = 24) based upon having 1 of 4 haplotype patterns composed of five polymorphic sites in the IL-1 gene cluster: IL-1A (+4845), IL-1B (+3954), IL-1B (-511), IL-1B (-3737) and IL-1RN (+2018). Subjects performed a standard bout of resistance leg exercise and vastus lateralis biopsies were obtained pre-, and at 24, and 72 h post-exercise. Inflammatory marker mRNAs (IL-1beta, IL-6 and tumor necrosis factor-alpha (TNF-alpha)) and the number of CD68(+) macrophages were quantified. Considerable variation was observed in the expression of these gene products between subjects. At 72 h post-exercise, IL-1beta had increased in a number of subjects (n = 10) and decreased (n = 4) or did not change (n = 10) in others. Inflammatory responses were significantly associated with specific haplotype patterns and were also influenced by individual SNPs. Subjects with genotypes 1.1 at IL-1B (+3954) or 2.2 at IL-1B (-3737) had approximately a 2-fold higher median induction of several markers, but no increase in macrophages, suggesting that cytokine gene expression is elevated per macrophage. The IL-1RN (+2018) SNP maximized the response specifically within these groups and was associated with increased macrophage recruitment. This is the first report that IL-1 genotype is associated with the inflammation of skeletal muscle following acute resistance exercise that may potentially affect the adaptations to chronic resistance exercise.

Does the association of habitual physical activity with the metabolic syndrome differ by level of cardiorespiratory fitness?

OBJECTIVE

Cardiovascular fitness (VO(2max)) and physical activity are both related to risk of metabolic disease. It is unclear, however, whether the metabolic effects of sedentary living are the same in fit and unfit individuals. The purpose of this study was, therefore, to describe the association between physical activity and the metabolic syndrome and to test whether fitness level modifies this relationship.

RESEARCH DESIGN AND METHODS

Physical activity was measured objectively using individually calibrated heart rate against energy expenditure. VO(2max) was predicted from a submaximal exercise stress test. Fat mass and fat-free mass (FFM) were calculated using impedance biometry. A metabolic syndrome score was computed by summing the standardized values for obesity, hypertension, hyperglycemia, insulin resistance, hypertriglyceridemia, and the inverse level of HDL cholesterol and was expressed as a continuously distributed outcome. To correct for exposure measurement error, a random subsample (22% of cohort) re-attended for three repeat measurements in the year following the first assessment.

RESULTS

The relationship of VO(2max) (ml O2.kg(FFM)(-1).min(-1)) and the metabolic syndrome score was of borderline significance after adjusting for age, sex, physical activity, and measurement error (beta = -0.58, P = 0.06). The magnitude of the association between physical activity (kJ.d(-1).kg(FFM)(-1)) and the metabolic syndrome was more than three times greater than for VO(2max) (standardized beta = -1.83, P = 0.0042). VO(2max), however, modified the relationship between physical activity energy expenditure and metabolic syndrome (P = 0.036).

CONCLUSIONS

This study demonstrates a strong inverse association between physical activity and metabolic syndrome, an association that is much steeper in unfit individuals. Thus, prevention of metabolic disease may be most effective in the subset of unfit inactive people.