Genome-wide linkage scan for exercise participation in Dutch sibling pairs

Genetic test for the prescription of diets in support of physical activity

Owing to the fields of nutrigenetics and nutrigenomics today we can think of devising approaches to optimize health, delay onset of diseases and reduce its severity according to our genetic blue print. However this requires a deep understanding of nutritional impact on expression of genes that may result in a specific phenotype. The extensive research and observational studies during last two decades reporting interactions between genes, diet and physical activity suggest a cross talk between various genetic and environmental factors and lifestyle interventions. Although considerable efforts have been made in unraveling the mechanisms of gene-diet interactions the scientific evidences behind developing commercial genetic tests for providing personalized nutrition recommendations are still scarce. In this scenario the current mini-review aims to provide useful insights into salient feature of nutrition based genetic research and its commercial application and the ethical issue and concerns related to its outcome.

Genomewide Association Study of Leisure-Time Exercise Behavior in Japanese Adults

Supplemental digital content is available in the text.

Purpose

Although several genetic factors may play a role in leisure-time exercise behavior, there is currently no evidence of a significant genomewide association, and candidate gene replication studies have produced inconsistent results.

Methods

We conducted a two-stage genomewide association study and candidate single-nucleotide polymorphisms (SNP) association study on leisure-time exercise behavior using 13,980 discovery samples from the Japan Multi-Institutional Collaborative Cohort (J-MICC) study, and 2036 replication samples from the Hospital-based Epidemiologic Research Program at Aichi Cancer Center-2 study. Leisure-time physical activity was measured using a self-administered questionnaire that inquired about the type, frequency and duration of exercise. Participants with ≥4 MET·h·wk⁻¹ of leisure-time physical activity were defined as exhibiting leisure-time exercise behavior. Association testing using mixed linear regression models was performed on the discovery and replication samples, after which the results were combined in a meta-analysis. In addition, we tested six candidate genetic variants derived from previous genomewide association study.

Results

We found that one novel SNP (rs10252228) located in the intergenic region between NPSR1 and DPY19L1 was significantly associated with leisure-time exercise behavior in discovery samples. This association was also significant in replication samples (combined P value by meta-analysis = 2.2 × 10⁻⁹). Several SNP linked with rs10252228 were significantly associated with gene expression of DPY19L1 and DP19L2P1 in skeletal muscle, heart, whole blood, and the nervous system. Among the candidate SNP, rs12612420 in DNAPTP6 demonstrated nominal significance in discovery samples but not in replication samples.

Conclusions

We identified a novel genetic variant associated with regular leisure-time exercise behavior. Further functional studies are required to validate the role of these variants in exercise behavior.

Alleles associated with physical activity levels are estimated to be older than anatomically modern humans

The purpose of this study was to determine the estimated mutation age and conservation of single-nucleotide polymorphisms (SNPs) associated with physical activity (PA) in humans. All human SNPs found to be significantly associated with PA levels in the literature were cross-referenced with the National Heart, Lung, and Blood Institute's Grand Opportunity Exome Sequencing Project to find estimated African-American (AA) and European-American (EA) mutation age. As a secondary measure of mutation age, SNPs were searched for in Hawk's mutation age prediction database which utilizes linkage equilibrium. To determine conservation among hominids, all SNPs were searched in the University of California, Santa Cruz Genome Browser, which contains Neanderthal and chimpanzee reference genomes. Six of the 104 SNPs associated with PA regulation were exon-located missense variants found in IFNAR2, PPARGC1A, PML, CTBP2, IL5RA, and APOE genes. The remaining 98 SNPs were located in non-protein coding regions. Average AA and EA estimated mutation age of the exon-located SNPs were 478.4 ± 327.5 kya and 542.1 ± 369.4 kya, respectively. There were four selective sweeps (suggestive of strong positive selection) of SNPs in humans when compared to Neanderthal or chimpanzee genomes. Exon-located PA candidate SNPs are older than the hypothesized emergence of anatomically modern humans. However, 95% of PA associated SNPs are found in intron and intergenic location. Across all SNPs, there seems to be a high level of conservation of alleles between humans, Neanderthals, and chimpanzees. However, the presence of four selective sweeps suggests there were selection pressures or drift unique to Homo sapiens that influenced the development of mutations associated with PA regulation.

Genetic Factors Associated With Human Physical Activity: Are Your Genes Too Tight To Prevent You Exercising?

The benefits of physical activity (PA) on health and fitness are well known. It has become apparent from studies of heritability that there is a considerable genetic component to PA. However, PA is such a complex phenotype that the measurement and quantification of it provide a challenge to a clearer understanding of its genetic basis. In this review, we assessed available evidence from family and twin studies that have estimated the heritability of PA. Heritability is greater when evaluated by accelerometry compared with questionnaires, and for questionnaires higher in twin than family studies. Accelerometry studies suggest heritability of PA is 51% to 56%. There have been many genome-wide linkage studies, candidate gene studies, and four genome-wide association studies that have highlighted specific genetic factors linked to different PA levels. These studies have generally failed to replicate identified loci, with the exception of the melanocortin 4 receptor, and this may be because of the variability in the measurement techniques used to characterize the behavior. Future work should aim to standardize the procedures used to measure PA in the context of trying to identify genetic causes. The link of genetics to physical exercise is not so tight that it prevents voluntary interventions.

Biological/Genetic Regulation of Physical Activity Level: Consensus from GenBioPAC

PURPOSE

Physical activity unquestionably maintains and improves health; however, physical activity levels globally are low and not rising despite all the resources devoted to this goal. Attention in both the research literature and the public policy domain has focused on social-behavioral factors; however, a growing body of literature suggests that biological determinants play a significant role in regulating physical activity levels. For instance, physical activity level, measured in various manners, has a genetic component in both humans and nonhuman animal models. This consensus article, developed as a result of an American College of Sports Medicine-sponsored round table, provides a brief review of the theoretical concepts and existing literature that supports a significant role of genetic and other biological factors in the regulation of physical activity.

CONCLUSIONS

Future research on physical activity regulation should incorporate genetics and other biological determinants of physical activity instead of a sole reliance on social and other environmental determinants.

Genetic Determinants for Leisure-Time Physical Activity

PURPOSE

Leisure-time physical activity (LTPA) is a well-established modifiable lifestyle determinant for multiple cardiometabolic outcomes. However, current understanding of the genetic architecture that may determine LTPA remains very limited. Therefore, we aimed to examine the role of genetic factors in affecting LTPA, which has yet to be investigated comprehensively and in-depth.

METHODS

We conducted a genomewide analysis using 1000 Genomes Project imputed data from the Women's Health Initiative (n = 11,865), the Jackson Heart Study (n = 3015), and the Framingham Heart Study (n = 7339). A series of secondary analyses, including candidate gene analysis, sequence kernel association tests, pathway analysis, functional annotation, and expression quantitative trait loci analysis, were performed to follow-up on the primary findings.

RESULTS

Ethnicity-specific genetic signals were investigated, respectively, for African Americans and European Americans. Two variants, rs116550874 (meta-analysis: P = 1.63 × 10) and rs3792874 (meta-analysis: P = 8.33 × 10), were associated with LTPA in African Americans; rs28524846 (meta-analysis: P = 1.30 × 10) was identified for EA. We also replicated four previously reported loci (GABRG3, CYP19A1, PAPSS2, and CASR; P for lead single nucleotide polymorphisms < 0.005). Further fine-mapping and functional annotation suggested that several identified loci (novel and replicated) are involved in 1) the homeostatic drive coupled with the reward system and 2) the development and regulation of the capacity to perform LTPA.

CONCLUSIONS

To our knowledge, our analysis is the first to comprehensively investigate the genomewide signals for LTPA in multiple ethnicities. These findings support the notion that genetic predisposition plays a critical role in determining LTPA, of which the biological and clinical implications warrants further investigation.

A genetic variant in IL-15Rα correlates with physical activity among European-American adults

BACKGROUND

Interleukin-15 (IL-15) is a myokine associated with muscle strength, possibly by attenuating protein breakdown. A variant in the alpha-receptor (IL-15Rα 1775 A>C, rs2228059) partially modulates the muscle strength and size response to resistance training. We examined if this polymorphism associated with habitual physical activity among European-American adults.

METHODS

Men (n = 240, 23.7 ± 0.3 year, body mass index [BMI] 25.3 ± 0.3 kg/m2 ) and women (n = 292, 23.2 ± 0.3 year, 24.0 ± 0.3 kg/m2 ) were genotyped. Physical activity phenotypes were derived from the Paffenbarger Physical Activity Questionnaire. Analysis of covariance (ancova) tested log-transformed differences between the IL-15Rα genotype and physical activity phenotypes by gender with age and BMI as covariates.

RESULTS

Men with the IL-15Rα 1775AA genotype spent more time in light intensity physical activity (39.4 ± 2.4 hr/week) than men with the CC genotype (28.6 ± 2.3 hr/week, (p = .009).

CONCLUSION

Further research is needed to confirm our finding and determine the possible mechanisms by which the IL-15Rα variant modulates light intensity physical activity.

The Genetics of Physical Activity

PURPOSE OF REVIEW

Physical activity (PA) is a well-established modifiable lifestyle determinant for multiple cardio-metabolic outcomes. While many psychosocial and environmental correlates of PA have been identified, current understanding of the genetic architecture that contributes to PA is still very limited, especially when compared to other phenotypes such as obesity and diabetes.

RECENT FINDINGS

This review systematically and comprehensively assesses available evidence from animal experiments, family studies, population-based candidate gene analyses, and genome-wide association studies (GWAS) studying the genetics of physical activity patterns. It discusses the scientific evolution in the field of PA genetics, including the recognition of increased sample sizes, the shift from early family-based approaches to association-based design, and the rapidly advancement of enabling genotyping and sequencing technologies. In addition, this review points to the gaps in the current knowledge base, including the general lack of GWAS and whole-genome sequence analyses particularly understudied populations, and the need for large-scale collaborative effort in both observational and experimental settings. In this review, we also call for research utilizing systems biology strategies for PA genetic research and accounting for complex gene-environment interactions that may vary by race/ethnicity. The epidemic of physical inactivity has been a public health nemesis, encompassing a large burden of diseases and high societal costs. A better understanding of the genetic basis of PA can inform public health policies for the prevention, control, and treatment of many chronic diseases related to physical inactivity.

Genomics and genetics in the biology of adaptation to exercise

This article is devoted to the role of genetic variation and gene-exercise interactions in the biology of adaptation to exercise. There is evidence from genetic epidemiology research that DNA sequence differences contribute to human variation in physical activity level, cardiorespiratory fitness in the untrained state, cardiovascular and metabolic response to acute exercise, and responsiveness to regular exercise. Methodological and technological advances have made it possible to undertake the molecular dissection of the genetic component of complex, multifactorial traits, such as those of interest to exercise biology, in terms of tissue expression profile, genes, and allelic variants. The evidence from animal models and human studies is considered. Data on candidate genes, genome-wide linkage results, genome-wide association findings, expression arrays, and combinations of these approaches are reviewed. Combining transcriptomic and genomic technologies has been shown to be more powerful as evidenced by the development of a recent molecular predictor of the ability to increase VO2max with exercise training. For exercise as a behavior and physiological fitness as a state to be major players in public health policies will require that the role of human individuality and the influence of DNA sequence differences be understood. Likewise, progress in the use of exercise in therapeutic medicine will depend to a large extent on our ability to identify the favorable responders for given physiological properties to a given exercise regimen.

Heritability of objectively assessed daily physical activity and sedentary behavior

BACKGROUND

Twin and family studies that estimated the heritability of daily physical activity have been limited by poor measurement quality and a small sample size.

OBJECTIVE

We examined the heritability of daily physical activity and sedentary behavior assessed objectively by using combined heart rate and movement sensing in a large twin study.

DESIGN

Physical activity traits were assessed in daily life for a mean (± SD) 6.7 ± 1.1 d in 1654 twins from 420 monozygotic and 352 dizygotic same-sex twin pairs aged 56.3 ± 10.4 y with body mass index (in kg/m(2)) of 26.1 ± 4.8. We estimated the average daily movement, physical activity energy expenditure, and time spent in moderate-to-vigorous intensity physical activity and sedentary behavior from heart rate and acceleration data. We used structural equation modeling to examine the contribution of additive genetic, shared environmental, and unique environmental factors to between-individual variation in traits.

RESULTS

Additive genetic factors (ie, heritability) explained 47% of the variance in physical activity energy expenditure (95% CI: 23%, 53%) and time spent in moderate-to-vigorous intensity physical activity (95% CI: 29%, 54%), 35% of the variance in acceleration of the trunk (95% CI: 0%, 44%), and 31% of the variance in the time spent in sedentary behavior (95% CI: 9%, 51%). The remaining variance was predominantly explained by unique environmental factors and random error, whereas shared environmental factors played only a marginal role for all traits with a range of 0-15%.

CONCLUSIONS

The between-individual variation in daily physical activity and sedentary behavior is mainly a result of environmental influences. Nevertheless, genetic factors explain up to one-half of the variance, suggesting that innate biological processes may be driving some of our daily physical activity.

Genetic determinants of voluntary exercise

Variation in voluntary exercise behavior is an important determinant of long-term human health. Increased physical activity is used as a preventative measure or therapeutic intervention for disease, and a sedentary lifestyle has generally been viewed as unhealthy. Predisposition to engage in voluntary activity is heritable and induces protective metabolic changes, but its complex genetic/genomic architecture has only recently begun to emerge. We first present a brief historical perspective and summary of the known benefits of voluntary exercise. Second, we describe human and mouse model studies using genomic and transcriptomic approaches to reveal the genetic architecture of exercise. Third, we discuss the merging of genomic information and physiological observations, revealing systems and networks that lead to a more complete mechanistic understanding of how exercise protects against disease pathogenesis. Finally, we explore potential regulation of physical activity through epigenetic mechanisms, including those that persist across multiple generations.

Genomics of elite sporting performance: what little we know and necessary advances

Numerous reports of genetic associations with performance- and injury-related phenotypes have been published over the past three decades; these studies have employed primarily the candidate gene approach to identify genes that associate with elite performance or with variation in performance-and/or injury-related traits. Although generally with small effect sizes and heavily prone to type I statistic error, the number of candidate genetic variants that can potentially explain elite athletic status, injury predisposition, or indeed response to training will be much higher than that examined by numerous biotechnology companies. Priority should therefore be given to applying whole genome technology to sufficiently large study cohorts of world-class athletes with adequately measured phenotypes where it is possible to increase statistical power. Some of the elite athlete cohorts described in the literature might suffice, and collectively, these cohorts could be used for replication purposes. Genome-wide association studies are ongoing in some of these cohorts (i.e., Genathlete, Russian, Spanish, Japanese, United States, and Jamaican cohorts), and preliminary findings include the identification of one single nucleotide polymorphism (SNP; among more than a million SNPs analyzed) that associates with sprint performance in Japanese, American (i.e., African American), and Jamaican cohorts with a combined effect size of ~2.6 (P-value <5×10(-7)) and good concordance with endurance performance between select cohorts. Further replications of these signals in independent cohorts will be required, and any replicated SNPs will be taken forward for fine-mapping/targeted resequencing and functional studies to uncover the underlying biological mechanisms. Only after this lengthy and costly process will the true potential of genetic testing in sport be determined.

Variants of the ankyrin repeat domain 6 gene (ANKRD6) and muscle and physical activity phenotypes among European-derived American adults

Ankyrin repeat domain 6 (ANKRD6) is a ubiquitous protein that associates with early development in mammals and is highly expressed in the brain, spinal cord, and heart of humans. We examined the role of 8 ANKRD6 single-nucleotide polymorphisms (SNPs) on muscle performance and habitual physical activity (PA). Single-nucleotide polymorphisms were 545 T>A (rs9362667), 485 M>L (rs61736690), 233 T>M (rs2273238), 128 I>L (rs3748085), 631 P>L (rs61739327), 122 Q>E (rs16881983), 197805 G>A (rs9344950), and 710 L>X (NOVEL). This study consisted of 922 healthy, untrained, European-derived American men (n = 376, 23.6 ± 0.3 years, 25.0 ± 0.2 kg·m(-2)) and women (n = 546, 23.2 ± 0.2 years, 24.0 ± 0.2 kg·m(-2)). Muscle strength (maximum voluntary contraction [MVC] and 1 repetition maximum [1RM]) and size (cross-sectional area [CSA]) were assessed before and after 12 weeks of unilateral resistance training (RT). A subsample (n = 536, 23.4 ± 0.2 years, 24.6 ± 0.2 kg·m(-2)) completed the Paffenbarger Physical Activity Questionnaire. Associations among ANKRD6 genotypes and muscle phenotypes were tested with repeated measure analysis of covariance (ANCOVA) and PA phenotypes with multivariate ANCOVA, with age and body mass index as covariates. ANKRD6 122 Q>E was associated with increased baseline biceps CSA. ANKRD6 545 A>T and ANKRD6 710 L>X were associated with increased 1RM and MVC in response to RT, respectively. ANKRD6 631 P>L was associated with increased biceps CSA response to RT and time spent in moderate-intensity PA among the total sample and women. ANKRD6 genetic variants were associated with the muscle size and strength response to RT and habitual PA levels. Further research is needed to validate our results and explore mechanisms for the associations we observed.

Determinants of physical activity and exercise in healthy older adults: a systematic review

Background

The health benefits of regular physical activity and exercise have been widely acknowledged. Unfortunately, a decline in physical activity is observed in older adults. Knowledge of the determinants of physical activity (unstructured activity incorporated in daily life) and exercise (structured, planned and repetitive activities) is needed to effectively promote an active lifestyle. Our aim was to systematically review determinants of physical activity and exercise participation among healthy older adults, considering the methodological quality of the included studies.

Methods

Literature searches were conducted in PubMed/Medline and PsycINFO/OVID for peer reviewed manuscripts published in English from 1990 onwards. We included manuscripts that met the following criteria: 1) population: community dwelling healthy older adults, aged 55 and over; 2) reporting determinants of physical activity or exercise. The outcome measure was qualified as physical activity, exercise, or combination of the two, measured objectively or using self-report. The methodological quality of the selected studies was examined and a best evidence synthesis was applied to assess the association of the determinants with physical activity or exercise.

Results

Thirty-four manuscripts reporting on 30 studies met the inclusion criteria, of which two were of high methodological quality. Physical activity was reported in four manuscripts, exercise was reported in sixteen and a combination of the two was reported in fourteen manuscripts. Three manuscripts used objective measures, twenty-two manuscripts used self-report measures and nine manuscripts combined a self-report measure with an objective measure. Due to lack of high quality studies and often only one manuscript reporting on a particular determinant, we concluded "insufficient evidence" for most associations between determinants and physical activity or exercise.

Conclusions

Because physical activity was reported in four manuscripts only, the determinants of physical activity particularly need further study. Recommendations for future research include the use of objective measures of physical activity or exercise as well as valid and reliable measures of determinants.

Genome-wide association study of exercise behavior in Dutch and American adults

INTRODUCTION

The objective of this study was to identify genetic variants that are associated with adult leisure time exercise behavior using genome-wide association (GWA) in two independent samples.

METHODS

Exercise behavior was measured in 1644 unrelated Dutch and 978 unrelated American adults of European ancestry with detailed questions about type, frequency, and duration of exercise. Individuals were classified into regular exercisers or nonexercisers using a threshold of 4 MET·h (metabolic equivalents-hours per week). GWA analyses of ∼1.6 million observed and imputed Single Nucleotide Polymorphism (SNP) were conducted in both samples independently using logistic regression in SNPTEST, including sex, age, and body mass index as covariates. A meta-analysis of the results was performed using the weighted inverse variance method in METAL.

RESULTS

Thirty-seven novel SNPs in the PAPSS2 gene and in two intergenic regions on chromosomes 2q33.1 and 18p11.32 were associated with exercise participation (pooled P values <1.0 × 10(-5)). Previously reported associations (ACE, CASR, CYP19A1, DRD2, LEPR, and MC4R genes) or linkage findings (2p22.3, 4q28, 4q31.21 7p13, 9q31, 11p15, 13q22, 15q13, 18q12.2, 18q21.1, 19p13.3, and 20q12) were not replicated, although suggestive evidence was found for association to rs12405556 in the LEPR gene (pooled P value 9.7 × 10(-4); American sample, P value 9.8 × 10(-5)) and for association to rs8036270 in the GABRG3 gene (pooled P value 4.6 × 10(-5)) in the linkage region 15q12-13.

CONCLUSIONS

The heritability of leisure time exercise behavior is likely to be accounted for by many genetic variants with small effect size. These can be detected by GWA as was shown here for the PAPSS2 gene, but larger samples with genome-wide genotypes and high-quality exercise data are needed for further progress.

Effect of the melanocortin-3 receptor Thr6Lys and Val81Ile genetic variants on body composition and substrate oxidation in Chilean obese children

Mice genetically deficient in the melanocortin-3 receptor gene are characterized by normal body weight, increased body fat, mild hypophagia, reduced locomotor activity, and increased respiratory quotient compared with wild-type mice. In humans, the 6Lys-81Ile haplotype of melanocortin-3 receptor (MC3R) gene has been associated with childhood obesity, higher body fat percentage, and reduced fat oxidation compared to non-carriers. The aim of this study was to evaluate the association between MC3R 6Lys-81Ile haplotype with body composition and substrate oxidation in response to moderate exercise in obese children. Eight Chilean obese children (aged 8-12) carriers of MC3R 6Lys-81Ile haplotype were compared with eight age-gender-matched obese non-carriers. Children were identified through a previous cross-sectional study on genetic determinants of childhood obesity (n = 229). Genotypes for MC3R Thr6Lys and Val81Ile were determined by polymerase chain reaction-restriction fragment length polymorphism. Body composition was assessed by the four-compartment model (dual-energy X-ray absorptiometry, total body water by the deuterium dilution technique, and total fat mass by air-displacement plethysmography). Substrate oxidation was assessed by indirect calorimetry in response to moderate exercise (60% VO(2 max)). Wilcoxon matched-pairs test was used to compare quantitative variables. No significant differences among carriers and non-carriers were found in anthropometrical and body composition measurements. The Carriers of the 6Lys-81Ile haplotype showed higher respiratory quotient (p = 0.06) and a significantly higher glucose oxidation (p = 0.01) compared with non-carriers after standardization for fat-free mass. Our results are consistent with a possible participation of MC3R 6Lys-81Ile variants in glucose oxidation in response to moderate exercise.

Genetic Influences on Individual Differences in Exercise Behavior during Adolescence

The aim of this study was to investigate the degree to which genetic and environmental influences affect variation in adolescent exercise behavior. Data on regular leisure time exercise activities were analyzed in 8,355 adolescent twins, from three-age cohorts (13-14, 15-16, and 17–19 years). Exercise behavior was assessed with survey items about type of regular leisure time exercise, frequency, and duration of the activities. Participants were classified as sedentary, regular exercisers, or vigorous exercisers. The prevalence of moderate exercise behavior declined from age 13 to 19 years with a parallel increase in prevalence of sedentary behavior, whereas the prevalence of vigorous exercise behavior remained constant across age cohorts. Variation in exercise behavior was analyzed with genetic structural equation modeling employing a liability threshold model. Variation was largely accounted for by genetic factors (72% to 85% of the variance was explained by genetic factors), whereas shared environmental factors only accounted for a substantial part of the variation in girls aged 13-14 years (46%). We hypothesize that genetic effects on exercise ability may explain the high heritability of exercise behavior in this phase of life.

Genetic architecture of voluntary exercise in an advanced intercross line of mice

Exercise is essential for health, yet the amount, duration, and intensity that individuals engage in are strikingly variable, even under prescription. Our focus was to identify the locations and effects of quantitative trait loci (QTL) controlling genetic predisposition for exercise-related traits, utilizing a large advanced intercross line (AIL) of mice. This AIL (G(4)) population originated from a reciprocal cross between mice with genetic propensity for increased voluntary exercise [high-runner (HR) line, selectively bred for increased wheel running] and the inbred strain C57BL/6J. After adjusting for family structure, we detected 32 significant and 13 suggestive QTL representing both daily running traits (distance, duration, average speed, and maximum speed) and the mean of these traits on days 5 and 6 (the selection criteria for HR) of a 6-day test conducted at 8 wk of age, with many co-localizing to similar genomic regions. Additionally, seven significant and five suggestive QTL were observed for the slope and intercept of a linear regression across all 6 days of running, some representing a combination of the daily traits. We also observed two significant and two suggestive QTL for body mass before exercise. These results, from a well-defined animal model, reinforce a genetic basis for the predisposition to engage in voluntary exercise, dissect this predisposition into daily segments across a continuous time period, and present unique QTL that may provide insight into the initiation, continuation, and temporal pattern of voluntary activity in mammals.

Exercise therapy in type 2 diabetes

Structured exercise is considered an important cornerstone to achieve good glycemic control and improve cardiovascular risk profile in Type 2 diabetes. Current clinical guidelines acknowledge the therapeutic strength of exercise intervention. This paper reviews the wide pathophysiological problems associated with Type 2 diabetes and discusses the benefits of exercise therapy on phenotype characteristics, glycemic control and cardiovascular risk profile in Type 2 diabetes patients. Based on the currently available literature, it is concluded that Type 2 diabetes patients should be stimulated to participate in specifically designed exercise intervention programs. More attention should be paid to cardiovascular and musculoskeletal deconditioning as well as motivational factors to improve long-term treatment adherence and clinical efficacy. More clinical research is warranted to establish the efficacy of exercise intervention in a more differentiated approach for Type 2 diabetes subpopulations within different stages of the disease and various levels of co-morbidity.

Parent-of-origin effects on voluntary exercise levels and body composition in mice

Despite the health-related benefits of exercise, many people do not engage in enough activity to realize the rewards, and little is known regarding the genetic or environmental components that account for this individual variation. We created and phenotyped a large G(4) advanced intercross line originating from reciprocal crosses between mice with genetic propensity for increased voluntary exercise (HR line) and the inbred strain C57BL/6J. G(4) females (compared to males) ran significantly more when provided access to a running wheel and were smaller with a greater percentage of body fat pre- and postwheel access. Change in body composition resulting from a 6-day exposure to wheels varied between the sexes with females generally regulating energy balance more precisely in the presence of exercise. We observed parent-of-origin effects on most voluntary wheel running and body composition traits, which accounted for 3-13% of the total phenotypic variance pooled across sexes. G(4) individuals descended from progenitor (F(0)) crosses of HRfemale symbol and C57BL/6Jmale symbol ran greater distances, spent more time running, ran at higher maximum speeds/day, and had lower percent body fat and higher percent lean mass than mice descended from reciprocal progenitor crosses (C57BL/6Jfemale symbol x HRmale symbol). For some traits, significant interactions between parent of origin and sex were observed. We discuss these results in the context of sex dependent activity and weight loss patterns, the contribution of parent-of-origin effects to predisposition for voluntary exercise, and the genetic (i.e., X-linked or mtDNA variations), epigenetic (i.e., genomic imprinting), and environmental (i.e., in utero environment or maternal care) phenomena potentially modulating these effects.