Personalized preventive medicine: genetics and the response to regular exercise in preventive interventions

Combined exercise training decreases blood pressure in OLDER women with NOS3 polymorphism providing changes in differentially methylated regions (DMRs)

The mechanisms by which the ageing process is associated to an unhealthy lifestyle and how they play an essential role in the aetiology of systemic arterial hypertension have not yet been completely elucidated. Our objective is to investigate the influence of NOS3 polymorphisms [-786T > C and (Glu298Asp)] on systolic blood pressure (SBP) and diastolic blood pressure (DBP) response, differentially methylated regions (DMRs), and physical fitness of adult and older women after a 14-week combined training intervention. The combined training was carried out for 14 weeks, performed 3 times a week, totalling 180 minutes weekly. The genotyping experiment used Illumina Infinium Global Screening Array version 2.0 (GSA V2.0) and Illumina's EPIC Infinium Methylation BeadChip. The participants were separated into SNP rs2070744 in TT (59.7 ± 6.2 years) and TC + CC (60.0 ± 5.2 years), and SNP rs17999 in GluGlu (58.8 ± 5.7 years) and GluAsp + AspAsp (61.6 ± 4.9 years). We observed an effect of time for variables BP, physical capacities, and cholesterol. DMRs related to SBP and DBP were identified for the rs2070744 and rs17999 groups pre- and decreased numbers of DMRs post-training. When we analysed the effect of exercise training in pre- and post-comparisons, the GluGlu SNP (rs17999) showed 10 DMRs, and after enrichment, we identified several biological biases. The combined training improved the SBP and DBP values of the participants regardless of the SNPs. In addition, exercise training affected DNA methylation differently between the groups of NOS3 polymorphisms.

Standard Deviation of Individual Response for VO2max Following Exercise Interventions: A Systematic Review and Meta-analysis

BACKGROUND

Although numerous attempts to demonstrate inter-individual differences in trainability across various outcomes have been unsuccessful, the investigation of maximal oxygen consumption (VO2max) trainability warrants further study.

OBJECTIVE

Our objective was to conduct the first systematic review and meta-analysis to evaluate inter-individual differences in VO2max trainability across aerobic exercise training protocols utilizing non-exercising comparator groups.

METHODS

We conducted a literature search across three databases: EMBASE, PubMed and SCOPUS. The search strategy incorporated two main concepts: aerobic exercise training and VO2max. Studies were included if they used human participants, employed standardized and supervised exercise training, reported absolute or relative VO2max, included a non-exercise comparator group, reported VO2max change scores for non-exercise and exercise groups and provided the standard deviation (SD) of change for all groups. We calculated the SD of individual response (SDIR) to estimate the presence of inter-individual differences in trainability across all studies.

RESULTS

The literature search generated 32,968 studies, 24 of which were included in the final analysis. Our findings indicated that (1) the majority of variation in observed change scores following an intervention is due to measurement error, (2) calculating SDIR within a single study would not yield sufficient accuracy of SDIR due to generally small sample sizes and (3) meta-analysis of SD IR 2 across studies does not provide strong evidence for a positive value.

CONCLUSION

Overall, our meta-analysis demonstrated that there is not strong evidence supporting the existence of VO2max trainability across single interventions. As such, it appears unlikely that clinically relevant predictors of VO2max response will be discovered. Registration can be found online ( https://doi.org/10.17605/OSF.IO/X9VU3 ).

Understanding the variation in exercise responses to guide personalized physical activity prescriptions

Understanding the factors that contribute to exercise response variation is the first step in achieving the goal of developing personalized exercise prescriptions. This review discusses the key molecular and other mechanistic factors, both extrinsic and intrinsic, that influence exercise responses and health outcomes. Extrinsic characteristics include the timing and dose of exercise, circadian rhythms, sleep habits, dietary interactions, and medication use, whereas intrinsic factors such as sex, age, hormonal status, race/ethnicity, and genetics are also integral. The molecular transducers of exercise (i.e., genomic/epigenomic, proteomic/post-translational, transcriptomic, metabolic/metabolomic, and lipidomic elements) are considered with respect to variability in physiological and health outcomes. Finally, this review highlights the current challenges that impede our ability to develop effective personalized exercise prescriptions. The Molecular Transducers of Physical Activity Consortium (MoTrPAC) aims to fill significant gaps in the understanding of exercise response variability, yet further investigations are needed to address additional health outcomes across all populations.

Bone marrow metabolism is affected by body weight and response to exercise training varies according to anatomical location

AIM

High body weight is a protective factor against osteoporosis, but obesity also suppresses bone metabolism and whole-body insulin sensitivity. However, the impact of body weight and regular training on bone marrow (BM) glucose metabolism is unclear. We studied the effects of regular exercise training on bone and BM metabolism in monozygotic twin pairs discordant for body weight.

METHODS

We recruited 12 monozygotic twin pairs (mean ± SD age 40.4 ± 4.5 years; body mass index 32.9 ± 7.6, mean difference between co-twins 7.6 kg/m2 ; eight female pairs). Ten pairs completed the 6-month long training intervention. We measured lumbar vertebral and femoral BM insulin-stimulated glucose uptake (GU) using 18 F-FDG positron emission tomography, lumbar spine bone mineral density and bone turnover markers.

RESULTS

At baseline, heavier co-twins had higher lumbar vertebral BM GU (p < .001) and lower bone turnover markers (all p < .01) compared with leaner co-twins but there was no significant difference in femoral BM GU, or bone mineral density. Training improved whole-body insulin sensitivity, aerobic capacity (both p < .05) and femoral BM GU (p = .008). The training response in lumbar vertebral BM GU was different between the groups (time × group, p = .02), as GU tended to decrease in heavier co-twins (p = .06) while there was no change in leaner co-twins.

CONCLUSIONS

In this study, regular exercise training increases femoral BM GU regardless of weight and genetics. Interestingly, lumbar vertebral BM GU is higher in participants with higher body weight, and training counteracts this effect in heavier co-twins even without reduction in weight. These data suggest that BM metabolism is altered by physical activity.

Personalized redox biology: Designs and concepts

Personalized interventions are regarded as a next-generation approach in almost all fields of biomedicine, such as clinical medicine, exercise, nutrition and pharmacology. At the same time, an increasing body of evidence indicates that redox processes regulate, at least in part, multiple aspects of human physiology and pathology. As a result, the idea of applying personalized redox treatments to improve their efficacy has gained popularity among researchers in recent years. The aim of the present primer-style review was to highlight some crucial yet underappreciated methodological, statistical, and interpretative concepts within the redox biology literature, while also providing a physiology-oriented perspective on personalized redox biology. The topics addressed are: (i) the critical issue of investigating the potential existence of inter-individual variability; (ii) the importance of distinguishing a genuine and consistent response of a subject from a chance finding; (iii) the challenge of accurately quantifying the effect of a redox treatment when dealing with 'extreme' groups due to mathematical coupling and regression to the mean; and (iv) research designs and analyses that have been implemented in other fields, and can be reframed and exploited in a redox biology context.

Genetics and athletic performance: a systematic SWOT analysis of non-systematic reviews

Exercise genetics/genomics is a growing research discipline comprising several Strengths and Opportunities but also deals with Weaknesses and Threats. This "systematic SWOT overview of non-systematic reviews" (sSWOT) aimed to identify the Strengths, Weaknesses, Opportunities, and Threats linked to exercise genetics/genomics. A systematic search was conducted in the Medline and Embase databases for non-systematic reviews to provide a comprehensive overview of the current literature/research area. The extracted data was thematically analyzed, coded, and categorized into SWOT clusters. In the 45 included reviews five Strengths, nine Weaknesses, six Opportunities, and three Threats were identified. The cluster of Strengths included "advances in technology", "empirical evidence", "growing research discipline", the "establishment of consortia", and the "acceptance/accessibility of genetic testing". The Weaknesses were linked to a "low research quality", the "complexity of exercise-related traits", "low generalizability", "high costs", "genotype scores", "reporting bias", "invasive methods", "research progress", and "causality". The Opportunities comprised of "precision exercise", "omics", "multicenter studies", as well as "genetic testing" as "commercial"-, "screening"-, and "anti-doping" detection tool. The Threats were related to "ethical issues", "direct-to-consumer genetic testing companies", and "gene doping". This overview of the present state of the art research in sport genetics/genomics indicates a field with great potential, while also drawing attention to the necessity for additional advancement in methodological and ethical guidance to mitigate the recognized Weaknesses and Threats. The recognized Strengths and Opportunities substantiate the capability of genetics/genomics to make significant contributions to the performance and wellbeing of athletes.

Differences in the Anthropometric and Physiological Profiles of Hungarian Male Rowers of Various Age Categories, Rankings and Career Lengths: Selection Problems

Background: Little is known about the anthropometric and physiological profiles of lower-ranking athletes who aspire to rise to the pinnacle of their profession.

Aim: The aim of this study was to create anthropometric and physiological profiles of Hungarian male rowers of different age categories (15–16, 17–18, and over 18 years), sports rankings and career lengths.

Materials and Methods: Anthropometric and physiological profiles were created for 55 juniors, 52 older juniors and 23 seniors representing seven of the largest Hungarian rowing clubs. One-way independent analysis of variance (ANOVA) was used to compare arithmetic means.

Results: Rowers in older age categories were significantly taller (185.0 ± 5.0 cm vs. 183.0 ± 7.3 cm vs. 178.7 ± 7.2 cm) and heavier (81.1 ± 8.8 kg vs. 73.7 ± 8.4 kg vs. 66.8 ± 12.3 kg) than their younger peers, with significantly higher BMI values and larger body dimensions. Compared to younger athletes, rowers in older age categories also covered 2,000 m significantly faster (6.6 ± 0.3 min vs. 6.9 ± 0.4 min vs. 7.5 ± 0.5 min) while developing significantly more power (372.2 ± 53.0 W vs. 326.8 ± 54.5 W vs. 250.6 ± 44.6 W). Similarly, seniors and older juniors had higher values of maximal oxygen uptake and force max (by 6.2 and 7.0 ml/kg/min, and by 263.4 and 169.8 N). Within the older juniors, internationally ranked rowers had significantly greater body height (+ 5.9 cm), body mass (+ 6.1 kg), sitting height (+ 2.7 cm), arm span (+ 7.9 cm), limb length (+ 3.73 cm) and body surface area (+ 0.21 m²). They also rowed 2,000 m significantly faster (–0.43 min, p < 0.001) and had significantly higher values of power (+ 58.3 W), relative power (+ 0.41 W/kg), jump height (+ 4.5 cm), speed max (+ 0.18 m/s) and force max (+ 163.22 N).

Conclusion: The study demonstrated that potential differences in anthropometric and physiological profiles are more difficult to capture in non-elite rowers, and that the final outcome may be determined by external factors. Therefore, athletes with superior aptitude for rowing are more difficult to select from among lower-ranking rowers, and further research is needed to determine specific training requirements to achieve the maximum rowing performance.

Personalized Exercise Programs Based upon Remote Assessment of Motor Fitness: A Pilot Study among Healthy People Aged 65 Years and Older

BACKGROUND

The World Health Organization has recently updated exercise guidelines for people aged >65 years, emphasizing the inclusion of multiple fitness components. However, without adequate recognition of individual differences, these guidelines may be applied using an approach that "one-size-fits-all." Within the shifting paradigm toward an increasingly personalized approach to medicine and health, it is apparent that fitness components display a significant age-related increase in variability. Therefore, it is both logical and necessary to perform an accurate individualized assessment of multiple fitness components prior to optimal prescription for a personalized exercise program.

OBJECTIVE

The aim of the study was to test the feasibility and effectiveness of a novel tool able to remotely assess balance, flexibility, and strength using smartphone sensors (accelerometer/gyroscope), and subsequently deliver personalized exercise programs via the smartphone.

METHODS

We enrolled 52 healthy volunteers (34 females) aged 65+ years, with normal cognition and low fall risk. Baseline data from remote smartphone fitness assessment were analyzed to generate 42 fitness digital markers (DMs), used to guide personalized exercise programs (×5/week for 6 weeks) delivered via smartphone. Programs included graded exercises for upper/lower body, flexibility, strength, and balance (dynamic, static, and vestibular). Participants were retested after 6 weeks.

RESULTS

Average age was 74.7 ± 6.4 years; adherence was 3.6 ± 1.7 exercise sessions/week. Significant improvement for pre-/posttesting was observed for 10/12 DMs of strength/flexibility for upper/lower body (sit-to-stand repetitions/duration; arm-lift duration; torso rotation; and arm extension/flexion). Balance improved significantly for 6/10 measures of tandem stance, with consistent (nonsignificant) trends observed across 20 balance DMs of tandem walk and 1 leg stance. Balance tended to improve among the 37 participants exercising ≥3/week.

DISCUSSION

These preliminary results provide a proof of concept, with high adherence and improved fitness confirming the benefits of remote fitness assessment for guiding home personalized exercise programs among healthy adults aged >65 years. Further examination of the application within a randomized control study is necessary, comparing the personalized exercise program to general guidelines among healthy older adults, as well as specific populations, such as those with frailty, deconditioning, cognitive, or functional impairment. The study tool offers the opportunity to collect big data, including additional variables, with subsequent utilization of artificial intelligence to optimize the personalized exercise program.

Causes and Consequences of Interindividual Response Variability: A Call to Apply a More Rigorous Research Design in Acute Exercise-Cognition Studies

The different responses of humans to an apparently equivalent stimulus are called interindividual response variability. This phenomenon has gained more and more attention in research in recent years. The research field of exercise-cognition has also taken up this topic, as shown by a growing number of studies published in the past decade. In this perspective article, we aim to prompt the progress of this research field by (i) discussing the causes and consequences of interindividual variability, (ii) critically examining published studies that have investigated interindividual variability of neurocognitive outcome parameters in response to acute physical exercises, and (iii) providing recommendations for future studies, based on our critical examination. The provided recommendations, which advocate for a more rigorous study design, are intended to help researchers in the field to design studies allowing them to draw robust conclusions. This, in turn, is very likely to foster the development of this research field and the practical application of the findings.

Genome wide association study of response to interval and continuous exercise training: the Predict-HIIT study

BACKGROUND

Low cardiorespiratory fitness (V̇O_2peak) is highly associated with chronic disease and mortality from all causes. Whilst exercise training is recommended in health guidelines to improve V̇O_2peak, there is considerable inter-individual variability in the V̇O_2peak response to the same dose of exercise. Understanding how genetic factors contribute to V̇O_2peak training response may improve personalisation of exercise programs. The aim of this study was to identify genetic variants that are associated with the magnitude of V̇O₂peak response following exercise training.

METHODS

Participant change in objectively measured V̇O₂peak from 18 different interventions was obtained from a multi-centre study (Predict-HIIT). A genome-wide association study was completed (n = 507), and a polygenic predictor score (PPS) was developed using alleles from single nucleotide polymorphisms (SNPs) significantly associated (P < 1 × 10^-5) with the magnitude of V̇O₂peak response. Findings were tested in an independent validation study (n = 39) and compared to previous research.

RESULTS

No variants at the genome-wide significance level were found after adjusting for key covariates (baseline V̇O₂peak_, individual study, principal components which were significantly associated with the trait). A Quantile-Quantile plot indicates there was minor inflation in the study. Twelve novel loci showed a trend of association with V̇O₂peak response that reached suggestive significance (P < 1 × 10^-5). The strongest association was found near the membrane associated guanylate kinase, WW and PDZ domain containing 2 (MAGI2) gene (rs6959961, P = 2.61 × 10^-7). A PPS created from the 12 lead SNPs was unable to predict V̇O₂peak response in a tenfold cross validation, or in an independent (n = 39) validation study (P > 0.1). Significant correlations were found for beta coefficients of variants in the Predict-HIIT (P < 1 × 10^-4) and the validation study (P <  × 10^-6), indicating that general effects of the loci exist, and that with a higher statistical power, more significant genetic associations may become apparent.

CONCLUSIONS

Ongoing research and validation of current and previous findings is needed to determine if genetics does play a large role in V̇O₂peak response variance, and whether genomic predictors for V̇O₂peak response trainability can inform evidence-based clinical practice. Trial registration Australian New Zealand Clinical Trials Registry (ANZCTR), Trial Id: ACTRN12618000501246, Date Registered: 06/04/2018, http://www.anzctr.org.au/Trial/Registration/TrialReview.aspx?id=374601&isReview=true .

NOS3 Polymorphisms Can Influence the Effect of Multicomponent Training on Blood Pressure, Nitrite Concentration and Physical Fitness in Prehypertensive and Hypertensive Older Adult Women

Associations of endothelial nitric oxide synthase (NOS3) polymorphisms with hypertension and response to exercise training in prehypertensive and hypertensive older adult women remain unclear. This study used a multicomponent program (various capacities and motor skills) in the physical training intervention. It analyzed the influence of NOS3 polymorphisms [−786T > C, 894G > T (Glu298Asp), and intron 4b/a] on the response of blood pressure (BP), nitrite concentration, and physical fitness in older adult women. Fifty-two participants aged between 50 and 80 underwent body mass index, BP, 6-min walk, elbow flexion, and sit and stand-up tests to assess physical fitness. The intervention duration was 12 weeks, twice a week, on non-consecutive days. Each session lasted 90 min, maintaining an intensity between 13 (moderate) and 15 (intense), controlled by the Subjective Effort Perception Scale. Plasma/blood samples were collected to assess nitrite concentration and genotyping. The statistical analysis included Fisher’s exact test and linear mixed-effects models. The multicomponent training’s positive effect was observed with a similar response in both prehypertensive and hypertensive groups. However, carriers of different genotypes demonstrated different responses to training: the decreases in systolic and diastolic BP and increases in nitrite expected from the physical training were smaller in variant genotype than ancestral genotype carriers, especially in the hypertensive group. At positions −786T > C and Glu298Asp, only the ancestral genotypes showed a decrease in diastolic BP (Δ% = −8.1, and Δ% = −6.5, respectively) and an increase on nitrite (Δ% = 19.1, and Δ% = 24.1, respectively) in the hypertensive group. Our results show that the benefits of a multicomponent training intervention seem to be genotype-dependent. It should be possible to consider genetic variants when selecting an exercise treatment intervention.

Systemic cross-talk between brain, gut, and peripheral tissues in glucose homeostasis: effects of exercise training (CROSSYS). Exercise training intervention in monozygotic twins discordant for body weight

BACKGROUND

Obesity and physical inactivity are major global public health concerns, both of which increase the risk of insulin resistance and type 2 diabetes. Regulation of glucose homeostasis involves cross-talk between the central nervous system, peripheral tissues, and gut microbiota, and is affected by genetics. Systemic cross-talk between brain, gut, and peripheral tissues in glucose homeostasis: effects of exercise training (CROSSYS) aims to gain new systems-level understanding of the central metabolism in human body, and how exercise training affects this cross-talk.

METHODS

CROSSYS is an exercise training intervention, in which participants are monozygotic twins from pairs discordant for body mass index (BMI) and within a pair at least the other is overweight. Twins are recruited from three population-based longitudinal Finnish twin studies, including twins born in 1983-1987, 1975-1979, and 1945-1958. The participants undergo 6-month-long exercise intervention period, exercising four times a week (including endurance, strength, and high-intensity training). Before and after the exercise intervention, comprehensive measurements are performed in Turku PET Centre, Turku, Finland. The measurements include: two positron emission tomography studies (insulin-stimulated whole-body and tissue-specific glucose uptake and neuroinflammation), magnetic resonance imaging (brain morphology and function, quantification of body fat masses and organ volumes), magnetic resonance spectroscopy (quantification of fat within heart, pancreas, liver and tibialis anterior muscle), echocardiography, skeletal muscle and adipose tissue biopsies, a neuropsychological test battery as well as biosamples from blood, urine and stool. The participants also perform a maximal exercise capacity test and tests of muscular strength.

DISCUSSION

This study addresses the major public health problems related to modern lifestyle, obesity, and physical inactivity. An eminent strength of this project is the possibility to study monozygotic twin pairs that share the genome at the sequence level but are discordant for BMI that is a risk factor for metabolic impairments such as insulin resistance. Thus, this exercise training intervention elucidates the effects of obesity on metabolism and whether regular exercise training is able to reverse obesity-related impairments in metabolism in the absence of the confounding effects of genetic factors.

TRIAL REGISTRATION

ClinicalTrials.gov , NCT03730610 . Prospectively registered 5 November 2018.

Postprandial skeletal muscle metabolism following a high-fat diet in sedentary and endurance-trained males

Our objective was to determine the influence of a high-fat diet (HFD) on fasting and postprandial skeletal muscle substrate metabolism in endurance-trained (ET) compared with sedentary (SED) humans. SED (n = 17) and ET (n = 7) males were control-fed a 10-day moderate-fat diet followed by a 5-day isocaloric HFD (55% fat, 30% carbohydrate). Skeletal muscle biopsies were taken in the fasted condition and 4 h after a high-fat meal (820 kcals; 63% fat and 25% carbohydrate). Palmitate-induced suppression of pyruvate oxidation, an indication of substrate preference, and oxidation of fat and glucose were measured in homogenized skeletal muscle in fasted and fed states. Postprandial responses were calculated as percent changes from fasting to fed states. Postprandial suppression of pyruvate oxidation was maintained after the HFD in ET, but not SED skeletal muscle, suggesting greater adaptability to dietary intake changes in the former. Fasting total fat oxidation increased due to the HFD in ET skeletal muscle (P = 0.006), which was driven by incomplete fat oxidation (P = 0.008). Fasting fat oxidation remained unchanged in skeletal muscle of SED individuals. Yet, postprandial fat oxidation was similar between groups. Fasting glucose oxidation was elevated after the HFD in ET (P = 0.036), but not SED, skeletal muscle. Postprandial glucose oxidation was reduced due to the HFD in SED (P = 0.002), but not ET, skeletal muscle. These findings provide insight into differing substrate metabolism responses between SED and ET individuals and highlight the role that the prevailing diet may play in modulating fasting and postprandial metabolic responses in skeletal muscle.NEW & NOTEWORTHY The relationship between high dietary fat intake and physical activity level and their combined effect on skeletal muscle substrate metabolism remains unclear. We assessed the influence of the prevailing diet in modulating substrate oxidation in skeletal muscle of endurance-trained compared with sedentary humans during a high-fat challenge meal. Collectively, our findings demonstrate the adaptability of skeletal muscle in endurance-trained individuals to high dietary fat intake.

Effects of aerobic and inspiratory training on skeletal muscle microRNA-1 and downstream-associated pathways in patients with heart failure

BACKGROUND

The exercise intolerance in chronic heart failure with reduced ejection fraction (HFrEF) is mostly attributed to alterations in skeletal muscle. However, the mechanisms underlying the skeletal myopathy in patients with HFrEF are not completely understood. We hypothesized that (i) aerobic exercise training (AET) and inspiratory muscle training (IMT) would change skeletal muscle microRNA-1 expression and downstream-associated pathways in patients with HFrEF and (ii) AET and IMT would increase leg blood flow (LBF), functional capacity, and quality of life in these patients.

METHODS

Patients age 35 to 70 years, left ventricular ejection fraction (LVEF) ≤40%, New York Heart Association functional classes II-III, were randomized into control, IMT, and AET groups. Skeletal muscle changes were examined by vastus lateralis biopsy. LBF was measured by venous occlusion plethysmography, functional capacity by cardiopulmonary exercise test, and quality of life by Minnesota Living with Heart Failure Questionnaire. All patients were evaluated at baseline and after 4 months.

RESULTS

Thirty-three patients finished the study protocol: control (n = 10; LVEF = 25 ± 1%; six males), IMT (n = 11; LVEF = 31 ± 2%; three males), and AET (n = 12; LVEF = 26 ± 2%; seven males). AET, but not IMT, increased the expression of microRNA-1 (P = 0.02; percent changes = 53 ± 17%), decreased the expression of PTEN (P = 0.003; percent changes = -15 ± 0.03%), and tended to increase the p-AKT^ser473 /AKT ratio (P = 0.06). In addition, AET decreased HDAC4 expression (P = 0.03; percent changes = -40 ± 19%) and upregulated follistatin (P = 0.01; percent changes = 174 ± 58%), MEF2C (P = 0.05; percent changes = 34 ± 15%), and MyoD expression (P = 0.05; percent changes = 47 ± 18%). AET also increased muscle cross-sectional area (P = 0.01). AET and IMT increased LBF, functional capacity, and quality of life. Further analyses showed a significant correlation between percent changes in microRNA-1 and percent changes in follistatin mRNA (P = 0.001, rho = 0.58) and between percent changes in follistatin mRNA and percent changes in peak VO₂ (P = 0.004, rho = 0.51).

CONCLUSIONS

AET upregulates microRNA-1 levels and decreases the protein expression of PTEN, which reduces the inhibitory action on the PI3K-AKT pathway that regulates the skeletal muscle tropism. The increased levels of microRNA-1 also decreased HDAC4 and increased MEF2c, MyoD, and follistatin expression, improving skeletal muscle regeneration. These changes associated with the increase in muscle cross-sectional area and LBF contribute to the attenuation in skeletal myopathy, and the improvement in functional capacity and quality of life in patients with HFrEF. IMT caused no changes in microRNA-1 and in the downstream-associated pathway. The increased functional capacity provoked by IMT seems to be associated with amelioration in the respiratory function instead of changes in skeletal muscle. ClinicalTrials.gov (Identifier: NCT01747395).

Impacts of exercise interventions on different diseases and organ functions in mice

Background

In recent years, much evidence has emerged to indicate that exercise can benefit people when performed properly. This review summarizes the exercise interventions used in studies involving mice as they are related to special diseases or physiological status. To further understand the effects of exercise interventions in treating or preventing diseases, it is important to establish a template for exercise interventions that can be used in future exercise-related studies.

Methods

PubMed was used as the data resource for articles. To identify studies related to the effectiveness of exercise interventions for treating various diseases and organ functions in mice, we used the following search language: (exercise [Title] OR training [Title] OR physical activity [Title]) AND (mice [title/abstract] OR mouse [title/abstract] OR mus [title/abstract]). To limit the range of search results, we included 2 filters: one that limited publication dates to "in 10 years" and one that sorted the results as "best match". Then we grouped the commonly used exercise methods according to their similarities and differences. We then evaluated the effectiveness of the exercise interventions for their impact on diseases and organ functions in 8 different systems.

Results

A total of 331 articles were included in the analysis procedure. The articles were then segmented into 8 systems for which the exercise interventions were used in targeting and treating disorders: motor system (60 studies), metabolic system (45 studies), cardio-cerebral vascular system (58 studies), nervous system (74 studies), immune system (32 studies), respiratory system (7 studies), digestive system (1 study), and the system related to the development of cancer (54 studies). The methods of exercise interventions mainly involved the use of treadmills, voluntary wheel-running, forced wheel-running, swimming, and resistance training. It was found that regardless of the specific exercise method used, most of them demonstrated positive effects on various systemic diseases and organ functions. Most diseases were remitted with exercise regardless of the exercise method used, although some diseases showed the best remission effects when a specific method was used.

Conclusion

Our review strongly suggests that exercise intervention is a cornerstone in disease prevention and treatment in mice. Because exercise interventions in humans typically focus on chronic diseases, national fitness, and body weight loss, and typically have low intervention compliance rates, it is important to use mice models to investigate the molecular mechanisms underlying the health benefits from exercise interventions in humans.

Using Physiologic, Genetic, and Epigenetic Information to Provide Care to Clients Who Are Obese

The pathology of obesity is a complex process involving interactions among behavioral, environmental, immunologic, genetic, and epigenetic factors. This article gives a broad overview of obesity. The physiology of fat storage, influence of eating behaviors on obesity, and the genetic relationship between eating and food sources are discussed. Specific genes that have been associated with obesity are introduced, with information on leptin and genes such as FTO, GLUT4, and others. This synopsis of obesity expands into environmental influences and epigenetic factors. These include food selection, gut microbiota, pregnancy, and exercise. The nurse will gain specific knowledge to assist in tailoring therapies specific to clients who are working to overcome the long-term effects of this disorder.

Dose-Response Matters! - A Perspective on the Exercise Prescription in Exercise-Cognition Research

In general, it is well recognized that both acute physical exercises and regular physical training influence brain plasticity and cognitive functions positively. However, growing evidence shows that the same physical exercises induce very heterogeneous outcomes across individuals. In an attempt to better understand this interindividual heterogeneity in response to acute and regular physical exercising, most research, so far, has focused on non-modifiable factors such as sex and different genotypes, while relatively little attention has been paid to exercise prescription as a modifiable factor. With an adapted exercise prescription, dosage can be made comparable across individuals, a procedure that is necessary to better understand the dose-response relationship in exercise-cognition research. This improved understanding of dose-response relationships could help to design more efficient physical training approaches against, for instance, cognitive decline.

Variability in exercise physiology: Can capturing intra-individual variation help better understand true inter-individual responses?

Exploring individual responses to exercise training is a growing area of interest. Understanding reasons behind true observed inter-individual responses may help personalise exercise training to maximise the benefits received. While numerous factors have been explored, an often underappreciated consideration in the sport and exercise science field is the influence intra-individual variation, both in a single measurement and in response to an intervention, may have on training outcomes. Several study designs and statistical approaches are available to incorporate intra-individual variation into interventions and accordingly provide information on whether 'true' inter-individual responses are present or if they are an artefact of intra-individual variation. However, such approaches are sparingly applied. Moreover, intra-individual variation may also be important when true inter-individual response differences are present. In this perspective piece, the concept of intra-individual variation is described before briefly summarising study designs and statistical practices to account for intra-individual variation. We then outline two examples of physiological practices (stratified randomisation and prescribing exercise programmes upon training parameters) to demonstrate why sport and exercise scientists should acknowledge intra-individual variation prior to the implementation of an intervention, which potentially offers an additional explanation behind observed true inter-individual responses to training. Repeated testing pre-implementation of exercise training would conceptually provide more confident estimates of training parameters, which if utilised in a study design will help attenuate biases that may dictate inter-individual differences. Moreover, the incorporation of intra-individual differences will facilitate insights into alternative factors that may predict and/or explain true observed individual responses to an exercise training programme.

Functional DNA variations associated with Saudi female with low VO2max: a pilot microarray study

The study aims to explore the genetic predispositions and molecular pathways of low cardiorespiratory fitness (VO2max) in young Saudi females (n = 70). Young females were grouped based on the level of VO2max according to the specification of the physical fitness specialist certification as low VO2max (< 28.9; n = 19) and high VO2max (> 33; n = 14) and genotyped for 243345 putative functional exonic variants. The CYFIP2&FNDC9-rs10037485T, C1R-rs75380747G and TOP2A-rs13695C SNPs on chromosome 5, 12 and 17, respectively were found to be the most significant among young Saudi females with low VO2max (P < 8.01 × 10-05). Linkage disequilibrium (LD) analysis among the significant SNPs (P < 0.001) have revealed risk and protective haplotypes with high degree (p-value < 1.0 × 10-4) of LD. The most significant risk haplotypes with the low VO2max in young Saudi females are: Chromosome 1: LOC112268276-rs10800201G; LOC112268276-rs4657537A; rs4657583T (p-value = 2.00 × 10-04); Chromosome 3: rs978979G; CCDC66-rs7637449A; CCDC66-rs111934125T; FAM208A-rs9835332G (p-value = 5.00 × 10-04) and Chromosome 17: STX2-rs13696C; TNS4-rs1901187C (p-value = 1.00 × 10-04). Functional Enrichment Analysis revealed that the genes with SNPs P < 0.001 have significantly involved in the heart rate (P = 0.00442), body weight (P = 0.00629), breath tests (P = 0.0147), proteolysis (P = 0.00623) and cardiac muscle fiber development (P = 0.0263). In conclusion we could say that the identified genetic predispositions and gene-annotation enrichment in low VO2max in young Saudi females revealed that they are at high risk for developing cardiovascular complications.

Short-term pre-operative high-intensity interval training does not improve fitness of colorectal cancer patients

Background

Pre‐operative cardiorespiratory fitness (CRF) in colorectal cancer (CRC) patients has been shown to affect post‐operative outcomes. The aim of this study was to test the feasibility of high‐intensity interval training (HIIT) for improving fitness in pre‐operative CRC patients within the 31‐day cancer waiting‐time targets imposed in the UK.

Methods

Eighteen CRC patients (13 males, mean age: 67 years (range: 52‐77 years) participated in supervised HIIT on cycle ergometers 3 or 4 times each week prior to surgery. Exercise intensity during 5 × 1‐minute HIIT intervals (interspersed with 90‐second recovery) was 100%‐120% maximum wattage achieved at a baseline cardiopulmonary exercise test (CPET). CPET before and after HIIT was used to assess CRF.

Results

Patients completed a mean of eight HIIT sessions (range 6‐14) over 19 days (SD 7). There was no significant increase in VO₂ peak (23.9 ± 7.0 vs 24.2 ± 7.8 mL/kg/min (mean ± SD), P = 0.58) or anaerobic threshold (AT: 14.0 ± 3.4 vs 14.5 ± 4.5 mL/kg/min, P = 0.50) after HIIT. There was a significant reduction in resting systolic blood pressure (152 ± 19 vs 142 ± 19 mm Hg, P = 0.0005) and heart rate at submaximal exercise intensities after HIIT.

Conclusions

Our pragmatic HIIT exercise protocol did not improve the pre‐operative fitness of CRC patients within the 31‐day window available in the UK to meet cancer surgical waiting‐time targets.

A Multi-Center Comparison of O2peak Trainability Between Interval Training and Moderate Intensity Continuous Training

There is heterogeneity in the observed O_2peak response to similar exercise training, and different exercise approaches produce variable degrees of exercise response (trainability). The aim of this study was to combine data from different laboratories to compare O_2peak trainability between various volumes of interval training and Moderate Intensity Continuous Training (MICT). For interval training, volumes were classified by the duration of total interval time. High-volume High Intensity Interval Training (HIIT) included studies that had participants complete more than 15 min of high intensity efforts per session. Low-volume HIIT/Sprint Interval Training (SIT) included studies using less than 15 min of high intensity efforts per session. In total, 677 participants across 18 aerobic exercise training interventions from eight different universities in five countries were included in the analysis. Participants had completed 3 weeks or more of either high-volume HIIT (n = 299), low-volume HIIT/SIT (n = 116), or MICT (n = 262) and were predominately men (n = 495) with a mix of healthy, elderly and clinical populations. Each training intervention improved mean O_2peak at the group level (P < 0.001). After adjusting for covariates, high-volume HIIT had a significantly greater (P < 0.05) absolute O_2peak increase (0.29 L/min) compared to MICT (0.20 L/min) and low-volume HIIT/SIT (0.18 L/min). Adjusted relative O_2peak increase was also significantly greater (P < 0.01) in high-volume HIIT (3.3 ml/kg/min) than MICT (2.4 ml/kg/min) and insignificantly greater (P = 0.09) than low-volume HIIT/SIT (2.5 mL/kg/min). Based on a high threshold for a likely response (technical error of measurement plus the minimal clinically important difference), high-volume HIIT had significantly more (P < 0.01) likely responders (31%) compared to low-volume HIIT/SIT (16%) and MICT (21%). Covariates such as age, sex, the individual study, population group, sessions per week, study duration and the average between pre and post O_2peak explained only 17.3% of the variance in O_2peak trainability. In conclusion, high-volume HIIT had more likely responders to improvements in O_2peak compared to low-volume HIIT/SIT and MICT.

Inter-individual differences in weight change following exercise interventions: a systematic review and meta-analysis of randomized controlled trials

Previous reports of substantial inter-individual differences in weight change following an exercise intervention are often based solely on the observed responses in the intervention group. Therefore, we aimed to quantify the magnitude of inter-individual differences in exercise-mediated weight change. We synthesized randomized controlled trials (RCTs) of structured, supervised exercise interventions. Fourteen electronic databases were searched for relevant studies published up to March 2017. Search terms focused on structured training, RCTs and body weight. We then sifted these results for those RCTs (n = 12, 1500 participants) that included relevant comparator group data. Standard deviations (SDs) of weight change were extracted, thereby allowing the SD for true inter-individual differences in weight loss to be calculated for each study. Using a random effects meta-analysis, the pooled SD (95% CI) for true individual responses was 0.8 (-0.9 to 1.4) kg. The 95% prediction interval (based on 2SDs) for true inter-individual responses was -2.8 to 3.6 kg. The probability (% chance) that the true individual response variability would be clinically meaningful (>2.5 kg) in a future study in similar settings was 23% ('unlikely'). Therefore, we conclude that evidence is limited for the notion that there are clinically important individual differences in exercise-mediated weight change.

Inter-Individual Responses of Maximal Oxygen Uptake to Exercise Training: A Critical Review

It has recently been reported how to quantify inter-individual differences in the response to an exercise intervention using the standard deviation of the change scores, as well as how to appraise these differences for clinical relevance. In a parallel-group randomised controlled trial, the key trigger for further investigation into inter-individual responses is when the standard deviation of change in the intervention sample is substantially larger than the same standard deviation derived from a suitable comparator sample. 'True' and clinically relevant inter-individual differences in response can then be plausibly expected, and potential moderators and mediators of the inter-individual differences can be explored. We now aim to critically review the research on the inter-individual differences in response to exercise training, focusing on maximal oxygen uptake (VO₂max). A literature search through the relevant bibliographic databases resulted in the identification of six relevant studies that were published prior to the influential HEalth, RIsk factors, exercise Training And GEnetics (HERITAGE) Family Study. Only one of these studies was found to include a comparator arm. Re-analysis of the data from this study, accounting for random within-subjects variation, revealed an absence of clinically important inter-individual differences in the response of VO₂max to exercise training. The standard deviation of change was, in fact, larger (±5.6 mL/kg/min) for the comparator than the intervention group (±3.7 mL/kg/min). We located over 180 publications that resulted from the HERITAGE Family Study, but we could not find a comparator arm in any of these studies. Some authors did not explain this absence, while others reasoned that only inter-individual differences in exercise response were of interest, thus the intervention sample was investigated solely. We also found this absence of a comparator sample in on-going studies. A perceived high test-retest reliability is offered as a justification for the absence of a comparator arm, but the test-retest reliability analysis for the HERITAGE Family Study was over a much shorter term than the length of the actual training period between baseline and follow-up measurements of VO₂max. We also scrutinised the studies in which twins have been investigated, resulting in concerns about how genetic influences on the magnitude of general within-subjects variability has been partitioned out (again in the absence of a comparator no-training group), as well as with the intra-class correlation coefficient approach to data analysis. Twin pairs were found to be sometimes heterogeneous for the obviously influential factors of sex, age and fitness, thereby inflating an unadjusted coefficient. We conclude that most studies on inter-individual differences in VO₂max response to exercise training have no comparator sample. Therefore, true inter-individual differences in response cannot be quantified, let alone appraised for clinical relevance. For those studies with a comparator sample, we found that the inter-individual differences in training response were not larger than random within-subjects variation in VO₂max over the same time period as the training intervention.

Inter-individual variation in adaptations to endurance and resistance exercise training: genetic approaches towards understanding a complex phenotype

Exercise training which meets the recommendations set by the National Physical Activity Guidelines ensues a multitude of health benefits towards the prevention and treatment of various chronic diseases. However, not all individuals respond well to exercise training. That is, some individuals have no response, while others respond poorly. Genetic background is known to contribute to the inter-individual (human) and -strain (e.g., mice, rats) variation with acute exercise and exercise training, though to date, no specific genetic factors have been identified that explain the differential responses to exercise. In this review, we provide an overview of studies in human and animal models that have shown a significant contribution of genetics in acute exercise and exercise training-induced adaptations with standardized endurance and resistance training regimens, and further describe the genetic approaches which have been used to demonstrate such responses. Finally, our current understanding of the role of genetics and exercise is limited primarily to the nuclear genome, while only a limited focus has been given to a potential role of the mitochondrial genome and its interactions with the nuclear genome to predict the exercise training-induced phenotype(s) responses. We therefore discuss the mitochondrial genome and literature that suggests it may play a significant role, particularly through interactions with the nuclear genome, in the inherent ability to respond to exercise.

Myopenia and precision (P4) medicine

Precision (P4) medicine represents a new medical paradigm that focuses on Personalized, Predictive, Preventive and Participatory approaches. The P4 paradigm is particularly appropriate for moving the care of persons with myopenia forward. Muscular dystrophies are clearly a set of genetically different diseases where genomics are the basis of diagnosis, and genetic modulation via DNA, oligonucleotides and clustered regularly interspaced short palendronic repeats hold great potential for a cure. The utility of personalized genomics for sarcopenia coupled with utilizing a predictive approach for the diagnosis with early preventive strategies is a key to improving sarcopenic outcomes. The importance of understanding different levels of patient enthusiasm and different responses to exercise should guide the participatory phase of sarcopenic treatment. In the case of cachexia, understanding the effects of the different therapies now available through the P4 approach on muscle wasting is a key to management strategies.

Circulating MiRNAs as biomarkers of gait speed responses to aerobic exercise training in obese older adults

Gait speed is a useful predictor of adverse outcomes, including incident mobility disability and mortality in older adults. While aerobic exercise training (AEX) is generally an effective therapy to improve gait speed, individual responses are highly variable. Circulating microRNAs (miRNAs) may contribute to inter-individual changes in gait speed with AEX. We examined whether plasma miRNAs are associated with gait speed changes (dGaitSp) in 33 obese older adults (age: 69.3±3.6 years, BMI: 34.0±3.1 kg/m², 85% white, 73% women) who performed treadmill walking, 4 days/week for 5 months. Gait speed (baseline: 1.02±0.19 m/s; range of response: −0.2 to 0.35 m/s) was assessed using a 400 meter-fast-paced walk test. Using Nanostring technology, 120 out of 800 miRNAs were found to be abundantly expressed in plasma and 4 of these were significantly changed after AEX: miR-376a-5p increased, while miR-16-5p, miR-27a-3p, and miR-28-3p all decreased. In addition, baseline miR-181a-5p levels (r=-0.40, p=0.02) and percent changes in miR-92a-3p (r=-0.44, p=0.009) associated negatively with dGaitSp. Linear regression combined baseline miR-181a-5p and miR-92a-3p levels showed even stronger associations with dGaitSp (r=-0.48, p=0.005). These results suggest that circulating miR-181a-5p and miR-92a-3p may predict and/or regulate AEX-induced gait speed changes in obese older adults.

Genetic testing for exercise prescription and injury prevention: AIS-Athlome consortium-FIMS joint statement

BACKGROUND

There has been considerable growth in basic knowledge and understanding of how genes are influencing response to exercise training and predisposition to injuries and chronic diseases. On the basis of this knowledge, clinical genetic tests may in the future allow the personalisation and optimisation of physical activity, thus providing an avenue for increased efficiency of exercise prescription for health and disease.

RESULTS

This review provides an overview of the current status of genetic testing for the purposes of exercise prescription and injury prevention. As such there are a variety of potential uses for genetic testing, including identification of risks associated with participation in sport and understanding individual response to particular types of exercise. However, there are many challenges remaining before genetic testing has evidence-based practical applications; including adoption of international standards for genomics research, as well as resistance against the agendas driven by direct-to-consumer genetic testing companies. Here we propose a way forward to develop an evidence-based approach to support genetic testing for exercise prescription and injury prevention.

CONCLUSION

Based on current knowledge, there is no current clinical application for genetic testing in the area of exercise prescription and injury prevention, however the necessary steps are outlined for the development of evidence-based clinical applications involving genetic testing.

Genes to predict VO2max trainability: a systematic review

Background

Cardiorespiratory fitness (VO_2max) is an excellent predictor of chronic disease morbidity and mortality risk. Guidelines recommend individuals undertake exercise training to improve VO_2max for chronic disease reduction. However, there are large inter-individual differences between exercise training responses. This systematic review is aimed at identifying genetic variants that are associated with VO_2max trainability.

Methods

Peer-reviewed research papers published up until October 2016 from four databases were examined. Articles were included if they examined genetic variants, incorporated a supervised aerobic exercise intervention; and measured VO_2max/VO_2peak pre and post-intervention.

Results

Thirty-five articles describing 15 cohorts met the criteria for inclusion. The majority of studies used a cross-sectional retrospective design. Thirty-two studies researched candidate genes, two used Genome-Wide Association Studies (GWAS), and one examined mRNA gene expression data, in addition to a GWAS. Across these studies, 97 genes to predict VO_2max trainability were identified. Studies found phenotype to be dependent on several of these genotypes/variants, with higher responders to exercise training having more positive response alleles than lower responders (greater gene predictor score). Only 13 genetic variants were reproduced by more than two authors. Several other limitations were noted throughout these studies, including the robustness of significance for identified variants, small sample sizes, limited cohorts focused primarily on Caucasian populations, and minimal baseline data. These factors, along with differences in exercise training programs, diet and other environmental gene expression mediators, likely influence the ideal traits for VO_2max trainability.

Conclusion

Ninety-seven genes have been identified as possible predictors of VO_2max trainability. To verify the strength of these findings and to identify if there are more genetic variants and/or mediators, further tightly-controlled studies that measure a range of biomarkers across ethnicities are required.

Characterization of the Rotating Exercise Quantification System (REQS), a novel Drosophila exercise quantification apparatus

Obesity is a disease that has reached epidemic proportions in the United States and has prompted international legislation in an attempt to curtail its prevalence. Despite the fact that one of the most prescribed treatment options for obesity is exercise, the genetic mechanisms underlying exercise response in individuals are still largely unknown. The fruit fly Drosophila melanogaster is a promising new model for studying exercise genetics. Currently, the lack of an accurate method to quantify the amount of exercise performed by the animals is limiting the utility of the Drosophila model for exercise genetics research. To address this limitation, we developed the Rotational Exercise Quantification System (REQS), a novel apparatus that is able to simultaneously induce exercise in flies while recording their activity levels. Thus, the REQS provides a method to standardize Drosophila exercise and ensure that all animals irrespective of genotype and sex experience the same level of exercise. Here, we provide a basic characterization of the REQS, validate its measurements using video-tracking technology, illustrate its potential use by presenting a comparison of two different exercise regimes, and demonstrate that it can be used to detect genotype-dependent variation in activity levels.

Effect of Multicomponent Training on Blood Pressure, Nitric Oxide, Redox Status, and Physical Fitness in Older Adult Women: Influence of Endothelial Nitric Oxide Synthase (NOS3) Haplotypes

The purpose of this study was to verify the influence of the genotype or haplotype (interaction) of the NOS3 polymorphisms [-786T>C, 894G>T (Glu298Asp), and intron 4b/a] on the response to multicomponent training (various capacities and motor skills) on blood pressure (BP), nitrite concentration, redox status, and physical fitness in older adult women. The sample consisted of 52 participants, who underwent body mass index and BP assessments. Physical fitness was evaluated by six-minute walk, elbow flexion, and sit and stand up tests. Plasma/blood samples were used to evaluate redox status, nitrite concentration, and genotyping. Associations were observed between isolated polymorphisms and the response of decreased systolic and diastolic BP and increased nitrite concentration and antioxidant activity. In the haplotype analysis, the group composed of ancestral alleles (H1) was the only one to present improvement in all variables studied (decrease in systolic and diastolic BP, improvement in nitrite concentration, redox status, and physical fitness), while the group composed of variant alleles (H8) only demonstrated improvement in some variables of redox status and physical fitness. These findings suggest that NOS3 polymorphisms and physical training are important interacting variables to consider in evaluating redox status, nitric oxide availability and production, and BP control.

Influence of Accelerometer Placement and/or Heart Rate on Energy Expenditure Prediction during Uphill Exercise

Studies using a triaxial accelerometer and heart rate (HR) simultaneously for estimating energy expenditure (EE) during uphill exercise are rare. Exploring the optimal location for placing the accelerometer for predicting EE during uphill exercise is essential. Sixteen healthy male participants (M ± SEM; age 25.00 ± 0.61 years; body weight 74.13 ± 2.51 kg; body height 1.74 ± 0.01 m; body mass index 24.30 ± 0.63 kg/m²) exercised on a treadmill under 12 conditions (4 speeds and 3 gradients) on 3 days. Triaxial accelerometers, an HR recorder, and a metabolic measurement system were simultaneously used. Accelerometer outputs from various anatomical locations (upper arm, chest, lower back, waist, thigh, and instep) showed significant positive correlations with EE (0.819, 0.846, 0.816, 0.820, 0.672, and 0.669, respectively; p < .05). The linear regression equation for changes in HR showed the highest coefficient of determination (r²) of .837 with 87.9% reliability. When the HR signal was included, the r² value (> .842) and reliability (87.9%) between the accelerometer outputs and EE improved. Accelerometer outputs from the waist position alone provide highly accurate EE values. Using both accelerometer outputs and HR for EE estimation during uphill exercise is feasible and improves the accuracy of EE prediction.

The Beneficial Effects of Physical Activity: Is It Down to Your Genes? A Systematic Review and Meta-Analysis of Twin and Family Studies

Background

There is evidence for considerable heterogeneity in the responsiveness to regular physical activity (PA) which might reflect the influence of genetic factors. The aim of this systematic review was to assess whether the response to a PA intervention for measures of body composition and cardiorespiratory fitness is (i) correlated within twin pairs and/or families and (ii) more correlated in monozygotic twins (MZ) compared to dizygotic twins (DZ), which would be consistent with genetic effects.

Methods

We performed electronic database searches, combining key words relating to “physical activity” and “genetics”, in MEDLINE, CINAHL, EMBASE, SPORTS Discuss, AMED, PsycINFO, WEB OF SCIENCE, and SCOPUS from the earliest records to March 2016.

Twin and family studies were included if they assessed body composition and/or cardiorespiratory fitness following a PA intervention, and provided a heritability estimate, maximal heritability estimate, or within MZ twin pair correlation (r_MZ).

Data on heritability (twin studies), maximal heritability (family studies), and the r_MZ were extracted from included studies, although heritability estimates were not reported as small sample sizes made them uninformative.

Results

After screening 224 full texts, nine twin and five family studies were included in this review. The pooled r_MZ in response to PA was significant for body mass index (r_MZ = 0.69, n = 58), fat mass (r_MZ = 0.58, n = 48), body fat percentage (r_MZ = 0.55, n = 72), waist circumference (r_MZ = 0.50, n = 27), and VO₂max (r_MZ = 0.39, n = 48), where “n” represents the total number of twin pairs from all studies. Maximal heritability estimates ranged from 0–21% for measures of body composition, and 22–57% for cardiorespiratory fitness.

Twin studies differed in sample age, baseline values, and PA intervention, although the exclusion of any one study did not affect the results.

Conclusions

Shared familial factors, including genetics, are likely to be a significant contributor to the response of body composition and cardiorespiratory fitness following PA.

Genetic factors may explain individual variation in the response to PA.

Trial Registrations

PROSPERO Registration No CRD42015020056.

Electronic supplementary material

The online version of this article (doi:10.1186/s40798-016-0073-9) contains supplementary material, which is available to authorized users.

The TreadWheel: A Novel Apparatus to Measure Genetic Variation in Response to Gently Induced Exercise for Drosophila

Obesity is one of the dramatic health issues affecting developed and developing nations, and exercise is a well-established intervention strategy. While exercise-by-genotype interactions have been shown in humans, overall little is known. Using the natural negative geotaxis of Drosophila melanogaster, an important model organism for the study of genetic interactions, a novel exercise machine, the TreadWheel, can be used to shed light on this interaction. The mechanism for inducing exercise with the TreadWheel is inherently gentle, thus minimizing possible confounding effects of other stressors. Using this machine, we were able to assess large cohorts of adult flies from eight genetic lines for their response to exercise after one week of training. We measured their triglyceride, glycerol, protein, glycogen, glucose content, and body weight, as well as their climbing ability and feeding behavior in response to exercise. Exercised flies showed decreased stored triglycerides, glycogen, and body weight, and increased stored protein and climbing ability. In addition to demonstrating an overall effect of TreadWheel exercise on flies, we found significant interactions of exercise with genotype, sex, or genotype-by-sex effects for most of the measured phenotypes. We also observed interaction effects between exercise, genotype, and tissue (abdomen or thorax) for metabolite profiles, and those differences can be partially linked to innate differences in the flies' persistence in maintaining activity during exercise bouts. In addition, we assessed gene expression levels for a panel of 13 genes known to be associated with respiratory fitness and found that many responded to exercise. With this study, we have established the TreadWheel as a useful tool to study the effect of exercise in flies, shown significant genotype-specific and sex-specific impacts of exercise, and have laid the ground work for more extensive studies of how genetics, sex, environment, and aging interact with exercise to influence metabolic fitness in Drosophila.

The P4 Health Spectrum - A Predictive, Preventive, Personalized and Participatory Continuum for Promoting Healthspan

Chronic diseases (i.e., noncommunicable diseases), mainly cardiovascular disease, cancer, respiratory diseases and type-2-diabetes, are now the leading cause of death, disability and diminished quality of life on the planet. Moreover, these diseases are also a major financial burden worldwide, significantly impacting the economy of many countries. Healthcare systems and medicine have progressively improved upon the ability to address infectious diseases and react to adverse health events through both surgical interventions and pharmacology; we have become efficient in delivering reactive care (i.e., initiating interventions once an individual is on the verge of or has actually suffered a negative health event). However, with slowly progressing and often 'silent' chronic diseases now being the main cause of illness, healthcare and medicine must evolve into a proactive system, moving away from a merely reactive approach to care. Minimal interactions among the specialists and limited information to the general practitioner and to the individual receiving care lead to a fragmented health approach, non-concerted prescriptions, a scattered follow-up and a suboptimal cost-effectiveness ratio. A new approach in medicine that is predictive, preventive, personalized and participatory, which we label here as "P4" holds great promise to reduce the burden of chronic diseases by harnessing technology and an increasingly better understanding of environment-biology interactions, evidence-based interventions and the underlying mechanisms of chronic diseases. In this concept paper, we propose a 'P4 Health Continuum' model as a framework to promote and facilitate multi-stakeholder collaboration with an orchestrated common language and an integrated care model to increase the healthspan.

EFEITOS DO EXERCÍCIO RESISTIDO DE ALTA INTENSIDADE EM RATOS QUE RECEBERAM DEXAMETASONA

RESUMO Introdução: A dexametasona administrada cronicamente promove alterações deletérias no metabolismo dos carboidratos. Objetivo: Avaliar os efeitos do exercício resistido de alta intensidade sobre a sensibilidade à insulina, tolerância à glicose e força muscular de ratos submetidos ao uso crônico de dexametasona. Métodos: Foram utilizados 40 ratos machos divididos randomicamente em quatro grupos: 1) Controle Sedentário (CS); 2) Controle Treinado (CT); 3) Dexametasona Sedentário (DS) e 4) Dexametasona Treinado (DT). O exercício resistido foi realizado em aparelho de agachamento composto por três séries, 10 repetições, com intensidade de 75% de 1 RM durante quatro semanas. Concomitantemente, os grupos DS e DT recebiam diariamente dexametasona intraperitoneal (0,2 g/kg) e os grupos CS e CT recebiam somente solução salina (0,9%). Ao final do protocolo foram realizados testes de tolerância à glicose, sensibilidade à insulina e teste de força máxima. Resultados: Nos grupos treinados (CT e DT) houve aumento da força muscular de 14,78% e 36,87% respectivamente, sem ganho significativo nos grupos sedentários. No teste de tolerância à glicose, os grupos treinados (CT e DT) apresentaram amplitudes atenuadas da glicose plasmática quando comparados aos grupos sedentários (CS e DS). No teste de sensibilidade à insulina, o grupo DT apresentou menor área sob a curva em relação ao grupo DS. Conclusão: O exercício resistido de alta intensidade melhora a sensibilidade à insulina, tolerância à glicose e a força muscular em ratos que receberam a dexametasona.

Cardiopulmonary Exercise Testing in Children and Adolescents with High Body Mass Index

Consensus has yet to be achieved on whether obesity is inexorably tied to poor fitness. We tested the hypothesis that appropriate reference of cardiopulmonary exercise testing (CPET) variables to lean body mass (LBM) would eliminate differences in fitness between high-BMI (≥ 95th percentile, n = 72, 50% female) and normal-BMI (< 85th percentile, n = 142, 49% female), otherwise-healthy children and adolescents typically seen when referencing body weight. We measured body composition with dual x-ray absorptiometry (DXA) and CPET variables from cycle ergometry using both peak values and submaximal exercise slopes (peak VO2, ΔVO2/ΔHR, ΔWR/ΔHR, ΔVO2/ΔWR, and ΔVE/ΔVCO2). In contrast to our hypothesis, referencing to LBM tended to lessen, but did not eliminate, the differences (peak VO2 [p < .004] and ΔVO2/ΔHR [p < .02]) in males and females; ΔWR/ΔHR differed between the two groups in females (p = .041) but not males (p = .1). The mean percent predicted values for all CPET variables were below 100% in the high-BMI group. The pattern of CPET abnormalities suggested a pervasive impairment of O2 delivery in the high-BMI group (ΔVO2/ΔWR was in fact highest in normal-BMI males). Tailoring lifestyle interventions to the specific fitness capabilities of each child (personalized exercise medicine) may be one of the ways to stem what has been an intractable epidemic.

Genomic and transcriptomic predictors of triglyceride response to regular exercise

AIM

We performed genome-wide and transcriptome-wide profiling to identify genes and single nucleotide polymorphisms (SNPs) associated with the response of triglycerides (TG) to exercise training.

METHODS

Plasma TG levels were measured before and after a 20-week endurance training programme in 478 white participants from the HERITAGE Family Study. Illumina HumanCNV370-Quad v3.0 BeadChips were genotyped using the Illumina BeadStation 500GX platform. Affymetrix HG-U133+2 arrays were used to quantitate gene expression levels from baseline muscle biopsies of a subset of participants (N=52). Genome-wide association study (GWAS) analysis was performed using MERLIN, while transcriptomic predictor models were developed using the R-package GALGO.

RESULTS

The GWAS results showed that eight SNPs were associated with TG training-response (ΔTG) at p<9.9×10(-6), while another 31 SNPs showed p values <1×10(-4). In multivariate regression models, the top 10 SNPs explained 32.0% of the variance in ΔTG, while conditional heritability analysis showed that four SNPs statistically accounted for all of the heritability of ΔTG. A molecular signature based on the baseline expression of 11 genes predicted 27% of ΔTG in HERITAGE, which was validated in an independent study. A composite SNP score based on the top four SNPs, each from the genomic and transcriptomic analyses, was the strongest predictor of ΔTG (R(2)=0.14, p=3.0×10(-68)).

CONCLUSIONS

Our results indicate that skeletal muscle transcript abundance at 11 genes and SNPs at a number of loci contribute to TG response to exercise training. Combining data from genomics and transcriptomics analyses identified a SNP-based gene signature that should be further tested in independent samples.

Looking Ahead Perspective: Where Will the Future of Exercise Biology Take Us?

The health-promoting benefits of exercise have been recognized for centuries, yet the molecular and cellular mechanisms for the acute and chronic adaptive response to a variety of physical activities remain incompletely described. This Perspective will take a forward view to highlight emerging questions and frontiers in the ever-changing landscape of exercise biology. The biology of exercise is complex, highly variable, and involves a myriad of adaptive responses in multiple organ systems. Given the multitude of changes that occur in each organ during exercise, future researchers will need to integrate tissue-specific responses with large-scale omics to resolve the integrated biology of exercise. The ultimate goal will be to understand how these system-wide, tissue-specific exercise-induced changes lead to measurable physiological outcomes at the whole-body level to improve health and well-being.

True and false interindividual differences in the physiological response to an intervention

NEW FINDINGS

What is the topic of this review? In 'personalized medicine', various plots and analyses are purported to quantify individual differences in intervention response, identify responders/non-responders and explore response moderators or mediators. What advances does it highlight? We highlight the impact of within-subject random variation, which is inevitable even with 'gold-standard' measurement tools/protocols and sometimes so substantial that it explains all apparent individual response differences. True individual response differences are quantified only by comparing the SDs of changes between intervention and comparator arms. When these SDs are similar, true individual response differences are clinically unimportant and further analysis unwarranted. Within the 'hot topic' of personalized medicine, we scrutinize common approaches for presenting and quantifying individual differences in the physiological response to an intervention. First, we explain how popular plots used to present individual differences in response are contaminated by random within-subject variation and the regression to the mean artefact. Using a simulated data set of blood pressure measurements, we show that large individual differences in physiological response can be suggested by some plots and analyses, even when the true magnitude of response is exactly the same in all individuals. Second, we present the appropriate designs and analysis approaches for quantifying the true interindividual variation in physiological response. It is imperative to include a comparator arm/condition (or derive information from a prior relevant repeatability study) to quantify true interindividual differences in response. The most important statistic is the SD of changes in the intervention arm, which should be compared with the same SD in the comparator arm or from a prior repeatability study in the same population conducted over the same duration as the particular intervention. Only if the difference between these SDs is clinically relevant is it logical to go on to explore any moderators or mediators of the intervention effect that might explain the individual response. To date, very few researchers have compared these SDs before making claims about individual differences in physiological response and their importance to personalized medicine.