Endurance training per se increases metabolic health in young, moderately overweight men

Potent incretin-based therapy for obesity: A systematic review and meta-analysis of the efficacy of semaglutide and tirzepatide on body weight and waist circumference, and safety

Potent incretin-based therapy shows promise for the treatment of obesity along with reduced incidence of cardiovascular events in patients with preexisting cardiovascular disease and obesity. This study assessed the efficacy and safety of the incretin-based obesity treatments, once-weekly subcutaneous semaglutide 2.4 mg and tirzepatide 10 or 15 mg, in people with obesity without diabetes. Of the 744 records identified, seven randomized controlled trials (n = 5140) were included. Five studies (n = 3288) investigated semaglutide and two studies (n = 1852) investigated tirzepatide. The treatment effect, shown as placebo-subtracted difference, on body weight was -15.0% (95% CI, -17.8 to -12.2) with -12.9% (95% CI, -14.7 to -11.1) for semaglutide and -19.2% (95% CI, -22.2 to -16.2) for tirzepatide. The treatment effect on waist circumference was -11.4 cm (95% CI, -13.7 to -9.2) with -9.7 cm (95% CI, -10.8 to -8.5) for semaglutide and -14.6 cm (95% CI, -15.8 to -13.4) for tirzepatide. The adverse events related to semaglutide and tirzepatide were primarily of mild-to-moderate severity and mostly gastrointestinal, which was more frequent during the dose-titration period and leveled off during the treatment period. This emphasizes that once-weekly subcutaneous semaglutide 2.4 mg and tirzepatide 10 or 15 mg induce large reductions in body weight and waist circumference and are generally well-tolerated.

Myokines: A central point in managing redox homeostasis and quality of life

Redox homeostasis is a crucial phenomenon that is obligatory for maintaining the healthy status of cells. However, the loss of redox homeostasis may lead to numerous diseases that ultimately result in a compromised quality of life. Skeletal muscle is an endocrine organ that secretes hundreds of myokines. Myokines are peptides and cytokines produced and released by muscle fibers. Skeletal muscle secreted myokines act as a robust modulator for regulating cellular metabolism and redox homeostasis which play a prime role in managing and improving metabolic function in multiple organs. Further, the secretory myokines maintain redox homeostasis not only in muscles but also in other organs of the body via stabilizing oxidants and antioxidant levels. Myokines are also engaged in maintaining mitochondrial dynamics as mitochondria is a central point for the generation of reactive oxygen species (ROS). Ergo, myokines also act as a central player in communicating signals to other organs, including the pancreas, gut, liver, bone, adipose tissue, brain, and skin via their autocrine, paracrine, or endocrine effects. The present review provides a comprehensive overview of skeletal muscle-secreted myokines in managing redox homeostasis and quality of life. Additionally, probable strategies will be discussed that provide a solution for a better quality of life.

Accumulated Short Bouts of Walking in Older Adults With Type 2 Diabetes: Effects on Glycosylated Hemoglobin (HbA1c) and Homeostasis Model Assessment of Insulin Resistance (HOMA-IR)

The current study examined the effects of accumulated short bouts of walking on glycosylated hemoglobin (HbA1c) and homeostasis model assessment of insulin resistance (HOMA-IR) of older adults with type 2 diabetes. Differences in variables between models of accumulated bouts of walking and 10,000 steps were also investigated. Sedentary participants (N = 38) were randomized into one of three groups: accumulated 10-minute bouts of walking at 100 steps/min (10/100MW), accumulated 10,000 steps (10KS), or control. HbA1c, HOMA-IR, blood lipids, and cardiorespiratory fitness (VO2max) were assessed before and after the intervention. VO2max, HbA1c, and HOMA-IR in the 10/100MW and 10KS groups showed significant and comparable improvements postintervention compared to preintervention (p < 0.05). Furthermore, the change in average daily step count was significantly associated with the change in HbA1c of the two walking groups (r = -0.61 for 10KS and r = -0.63 for 10/100MW; p < 0.05). Accumulated short bouts of walking at 100 steps/min and 10,000 steps daily improved HbA1c and HOMA-IR of older adults with type 2 diabetes. [Research in Gerontological Nursing, 16(5), 250-258.].

GDF15 increases insulin action in the liver and adipose tissue via a β-adrenergic receptor-mediated mechanism

Growth differentiation factor 15 (GDF15) induces weight loss and increases insulin action in obese rodents. Whether and how GDF15 improves insulin action without weight loss is unknown. Obese rats were treated with GDF15 and displayed increased insulin tolerance 5 h later. Lean and obese female and male mice were treated with GDF15 on days 1, 3, and 5 without weight loss and displayed increased insulin sensitivity during a euglycemic hyperinsulinemic clamp on day 6 due to enhanced suppression of endogenous glucose production and increased glucose uptake in WAT and BAT. GDF15 also reduced glucagon levels during clamp independently of the GFRAL receptor. The insulin-sensitizing effect of GDF15 was completely abrogated in GFRAL KO mice and also by treatment with the β-adrenergic antagonist propranolol and in β1,β2-adrenergic receptor KO mice. GDF15 activation of the GFRAL receptor increases β-adrenergic signaling, in turn, improving insulin action in the liver and white and brown adipose tissue.

Dose-response effects of exercise and caloric restriction on visceral adiposity in overweight and obese adults: a systematic review and meta-analysis of randomised controlled trials

OBJECTIVE

To determine and compare the dose-response effects of exercise and caloric restriction on visceral adipose tissue in overweight and obese adults, while controlling for the weekly energy deficit induced by the interventions.

METHODS

PubMed, Embase, CINAHL and Web of Science were searched for randomised controlled trials comparing exercise or caloric restriction against eucaloric controls in overweight or obese adults. The primary outcome was the change in visceral fat measured by CT or MRI. Meta-analyses and meta-regressions were performed to determine the overall effect size (ES) and the dose-dependent relationship of exercise and caloric restriction on visceral fat. Heterogeneity, risk of bias and the certainty of evidence were also assessed.

RESULTS

Forty randomised controlled trials involving 2190 participants were included. Overall, exercise (ES -0.28 (-0.37 to -0.19); p<0.001; I2=25%) and caloric restriction (ES -0.53 (-0.71 to -0.35); p<0.001; I2=33%) reduced visceral fat compared with the controls. Exercise demonstrated a dose-response effect of -0.15 ((-0.23 to -0.07); p<0.001) per 1000 calories deficit per week, whereas the effect of caloric restriction was not dose-dependent (ES 0.03 (-0.12 to 0.18); p=0.64). Most of the studies showed a moderate risk of bias.

CONCLUSIONS

These findings support the dose-dependent effects of exercise to reduce visceral fat in overweight and obese adults. Caloric restriction did not demonstrate a dose-response relationship, although this may be attributed to the smaller number of studies available for analysis, compared with exercise studies.

PROSPERO REGISTRATION NUMBER

CRD42020210096.

Effect of exercise training on insulin-stimulated glucose disposal: a systematic review and meta-analysis of randomized controlled trials

BACKGROUND AND OBJECTIVE

The effect of exercise training on whole-body insulin sensitivity has not been systematically summarized. We aimed to summarize the data from randomized controlled trials evaluating the effect of exercise training on insulin action, in adults.

SUBJECTS

MEDLINE, EMBASE, and CENTRAL databases were searched until January 2021. Randomized controlled trials lasting ≥4 weeks, including adults, and evaluating the effect of exercise on insulin-stimulated glucose disposal measured using the hyperinsulinemic euglycemic clamp, were included.

METHODS

Three reviewers extracted summary data from published trials. The primary outcome was insulin-stimulated glucose disposal. Standardized weighted mean differences (SMD) in glucose disposal between intervention and control were compared. The PEDro scale was used to assess risk of bias.

RESULTS

We included 25 trials (36 interventions, N = 851). Exercise increased insulin-stimulated glucose disposal relative to control, SMD = 0.52 (95% confidence interval [CI]: 0.39, 0.65; p < 0.001; I2 = 47%) without significantly suppressing hepatic glucose production. In trials without isotopic tracers, exercise increased glucose disposal (SMD = 0.63; 95% CI: 0.48, 0.77; p < 0.001, I2 = 55%). In trials with isotopic tracers, exercise increased glucose disposal only when tracers were added to the exogenous glucose used for clamping (SMD = 0.34; 95% CI: 0.03, 0.66, p = 0.034. I2 = 0%). In a meta-regression model including aerobic exercise, weight change, and tracer technique, only percent weight change explained between trial heterogeneity (β = 0.069; 95% CI: 0.005, 0.013). The PEDro rating indicated relatively low risk of bias (5.8 ± 0.22).

CONCLUSIONS

Exercise training for at least four weeks significantly increases insulin-stimulated glucose disposal. Weight loss maximizes the effect and may be needed to improve hepatic insulin sensitivity. Differences in tracer methodology contribute to divergent outcomes and should be considered when assessing conclusions from research examining the effect of exercise on insulin action.

REGISTRATION

PROSPERO (CRD42019124381).

Long-Term Effect of Weight Regain Following Behavioral Weight Management Programs on Cardiometabolic Disease Incidence and Risk: Systematic Review and Meta-Analysis

BACKGROUND

Behavioral weight management programs (BWMPs) enhance weight loss in the short term, but longer term cardiometabolic effects are uncertain as weight is commonly regained. We assessed the impact of weight regain after BWMPs on cardiovascular risk factors, diabetes, and cardiovascular disease.

METHODS

Trial registries, 11 databases, and forward-citation searching (latest search, December 19) were used to identify articles published in English, from any geographical region. Randomized trials of BWMPs in adults with overweight/obesity reporting cardiometabolic outcomes at ≥12 months at and after program end were included. Differences between more intensive interventions and comparator groups were synthesized using mixed-effects, meta-regression, and time-to-event models to assess the impact of weight regain on cardiovascular disease incidence and risk.

RESULTS

One hundred twenty-four trials reporting on ≥1 cardiometabolic outcomes with a median follow-up of 28 (range, 11-360) months after program end were included. Median baseline participant body mass index was 33 kg/m2; median age was 51 years. Eight and 15 study arms (7889 and 4202 participants, respectively) examined the incidence of cardiovascular disease and type 2 diabetes, respectively, with imprecise evidence of a lower incidence for at least 5 years. Weight regain in BWMPs relative to comparators reduced these differences. One and 5 years after program end, total cholesterol/HDL (high-density lipoprotein) ratio was 1.5 points lower at both times (82 studies; 19 003 participants), systolic blood pressure was 1.5 mm mercury and 0.4 mm lower (84 studies; 30 836 participants), and HbA1c (%) 0.38 lower at both times (94 studies; 28 083 participants). Of the included studies, 22% were judged at high risk of bias; removing these did not meaningfully change results.

CONCLUSIONS

Despite weight regain, BWMPs reduce cardiometabolic risk factors with effects lasting at least 5 years after program end and dwindling with weight regain. Evidence that they reduce the incidence of cardiovascular disease or diabetes is less certain. Few studies followed participants for ≥5 years.

REGISTRATION

URL: https://www.crd.york.ac.uk/PROSPERO/; Unique identifier: CRD42018105744.

The impact of exercise and cumulative physical activity on energy intake and diet quality in adults enrolled in the Midwest Exercise Trial for the Prevention of Weight Regain

The purpose of this study was to assess impact of different volumes of exercise as well as cumulative moderate to vigorous physical activity (MVPA) on energy intake (EI) and diet quality, as assessed by the Healthy Eating Index-2010(HEI-2010), across a 12-month weight maintenance intervention. Participants were asked to attend group behavioural sessions, eat a diet designed for weight maintenance and exercise either 150, 225 or 300 min/week. Dietary intake was assessed by 3-d food records, and MVPA was assessed by accelerometry. Two hundred and twenty-four participants (42·5 years of age, 82 % female) provided valid dietary data for at least one time point. There was no evidence of group differences in EI, total HEI-2010 score or any of the HEI-2010 component scores (all P > 0·05). After adjusting for age, sex, time, group and group-by-time interactions, there was an effect of cumulative MVPA on EI (1·08, P = 0·04), total HEI-2010 scores (-0·02, P = 0·003), Na (-0·006, P = 0·002) and empty energy scores (-0·007, P = 0·004. There was evidence of a small relationship between cumulative daily EI and weight (β: 0·00187, 95 % CI 0·001, P = 0·003). However, there was no evidence for a relationship between HEI total score (β: -0·006, 95 % CI 0·07, 0·06) or component scores (all P > 0·05) and change in weight across time. The results of this study suggest that increased cumulative MVPA is associated with clinically insignificant increases in EI and decreases in HEI.

Differential Effects of Amount, Intensity, and Mode of Exercise Training on Insulin Sensitivity and Glucose Homeostasis: A Narrative Review

As type 2 diabetes remains a leading cause of morbidity and mortality, identifying the most appropriate preventive treatment early in the development of disease is an important public health matter. In general, lifestyle interventions incorporating exercise and weight loss via caloric restriction improve cardiometabolic risk by impacting several key markers of insulin sensitivity and glucose homeostasis. However, variations in the effects of specific types of exercise interventions on these markers have led to conflicting results surrounding the optimal amount, intensity, and mode of exercise for optimal effects. Moreover, the addition of weight loss via caloric restriction to exercise interventions appears to differentially impact changes in body composition, metabolism, and insulin sensitivity compared to exercise alone. Determining the optimal amount, intensity, and mode of exercise having the most beneficial impact on glycemic status is both: (1) clinically important to provide guidelines for appropriate exercise prescription; and (2) physiologically important to understand the pathways by which exercise—with and without weight loss—impacts glycemic status to enhance precision lifestyle medicine. Thus, the purposes of this narrative review are to: (1) summarize findings from the three Studies of a Targeted Risk Reduction Intervention through Defined Exercise (STRRIDE) randomized trials regarding the differential effects of exercise amount, intensity, and mode on insulin action and glucose homeostasis markers; and (2) compare the STRRIDE findings to other published dose–response exercise trials in order to piece together the various physiologic pathways by which specific exercise interventions—with or without weight loss—impact glycemic status.

High-refined carbohydrate diet alters different metabolic functions in female rats

A diet containing refined carbohydrate (HCD) caused obesity and white adipose tissue (WAT) abnormalities, but it is unclear if HCD is linked with other metabolic dysfunctions in female models. Thus, we assessed whether HCD results in WAT, pancreas, liver, skeletal muscle (SM) and thyroid (TH) abnormalities in female rats. Female rats were fed with HCD for 15 days and metabolic morphophysiology, inflammation, oxidative stress (OS), and fibrosis markers were assessed. HCD rats presented large adipocytes, hyperleptinemia, and WAT OS. HCD caused irregular glucose metabolism, low insulin levels, and large pancreatic isle. Granulomas, reduced glycogen, and OS were observed in HCD livers. HCD caused hypertrophy and increased in glycogen in SM. HCD caused irregular TH morphophysiology, reduced colloid area and high T3 levels. In all selected tissues, inflammation and fibrosis were observed in HCD rats. Collectively, these data suggest that the HCD impairs metabolic function linked with irregularities in WAT, pancreas, liver, SM and TH in female rats.

Maintenance of cardiorespiratory fitness, body composition, and a physically active lifestyle after structured exercise interventions in individuals with overweight and obesity: A mixed-method follow-up study

Objectives

The aim of this mixed-method study was to explore maintenance of physical activity and health effects one year after completion of exercise interventions in transport and leisure-time domains of everyday life. We hypothesised that routinisation of active commuting would lead to better maintenance of physical activity and health effects compared with leisure-time exercise.

Study design

Mixed-methods follow-up study.

Methods

Individuals with overweight/obesity, who completed a 6-month exercise intervention (active commuting by bike (BIKE), moderate (MOD) or vigorous intensity leisure-time exercise (VIG)), were after one year invited to participate in a follow-up visit which included measurements of cardiorespiratory fitness during an incremental bicycle test and body composition using dual-energy X-ray absorptiometry. Variability in maintenance practices was assessed in a sub-sample of participants who experienced the greatest improvements ('VO₂peak improvers') and reductions ('VO₂peak reducers'), respectively, in cardiorespiratory fitness. Semi-structured interviews were conducted (15-30 min) and analysed using systematic text condensation to identify barriers and facilitators associated with maintenance of physical activity.

Results

Out of the 74 participants completing an exercise intervention, 46 (62%) completed follow-up (BIKE: n = 14; MOD: n = 14; VIG: n = 18). Improvements in VO₂peak and reductions in fat mass were maintained in BIKE and VIG. Body weight decreased in BIKE and fat free mass increased in VIG. Changes in VO₂peak and anthropometry at follow-up did not differ between BIKE and MOD + VIG. Fat mass decreased and recreational physical activity increased in 'VO₂peak improvers'. Findings from the interviews suggested that self-monitoring, collective exercising, and new personal exercise challenges facilitate maintenance of a physically active lifestyle.

Conclusion

Completion of a structured exercise intervention consisting of 6 months of active commuting or vigorous intensity leisure-time exercise was associated with long-term maintenance of improvements in VO₂peak and body composition, whereas moderate intensity leisure-time exercise was not. In contrast to our hypothesis, active commuting was not associated with better maintenance of physical activity and health effects after the intervention compared with leisure-time exercise.

The effect of exercise training on adipose tissue insulin sensitivity: A systematic review and meta-analysis

This systematic review and meta-analysis determined the impact of exercise training on adipose tissue insulin sensitivity in adults. Its scope extended to studies measuring whole-body and localized subcutaneous adipose tissue insulin sensitivity using validated techniques. Consensus from four studies demonstrates that exercise training improved whole-body adipose tissue insulin sensitivity when measured via stable-isotope lipid tracers (rate of appearance suppression in response to hyperinsulinemia). Meta-analysis of 20 studies (26 intervention arms) employing the adipose tissue insulin resistance index (ADIPO-IR) supported these findings (-10.63 [-14.12 to -7.15] pmol·L^-1  × mmol·L^-1 ). With ADIPO-IR, this response was greater in studies documenting weight loss and shorter sampling time (≤48 h) post-training. Overall, exercise training did not affect whole-body adipose tissue insulin sensitivity in seven studies (11 intervention arms) measuring the suppression of circulating non-esterified fatty acids in response to insulin infusion (1.51 [-0.12 to 3.14]%); however, subgroup analysis identified an enhanced suppression post-training in trials reporting weight loss. From four microdialysis studies, consensus indicates no effect of exercise training on localized (abdominal/femoral) adipose tissue insulin sensitivity, potentially suggesting that enhanced whole-body responses are related to improvements in central adipose depots. However, heterogeneity within microdialysis protocols dictates that findings must be viewed with caution.

Preserved stem cell content and innervation profile of elderly human skeletal muscle with lifelong recreational exercise

Abstract

Muscle fibre denervation and declining numbers of muscle stem (satellite) cells are defining characteristics of ageing skeletal muscle. The aim of this study was to investigate the potential for lifelong recreational exercise to offset muscle fibre denervation and compromised satellite cell content and function, both at rest and under challenged conditions. Sixteen elderly lifelong recreational exercisers (LLEX) were studied alongside groups of age‐matched sedentary (SED) and young subjects. Lean body mass and maximal voluntary contraction were assessed, and a strength training bout was performed. From muscle biopsies, tissue and primary myogenic cell cultures were analysed by immunofluorescence and RT‐qPCR to assess myofibre denervation and satellite cell quantity and function. LLEX demonstrated superior muscle function under challenged conditions. When compared with SED, the muscle of LLEX was found to contain a greater content of satellite cells associated with type II myofibres specifically, along with higher mRNA levels of the beta and gamma acetylcholine receptors (AChR). No difference was observed between LLEX and SED for the proportion of denervated fibres or satellite cell function, as assessed in vitro by myogenic cell differentiation and fusion index assays. When compared with inactive counterparts, the skeletal muscle of lifelong exercisers is characterised by greater fatigue resistance under challenged conditions in vivo, together with a more youthful tissue satellite cell and AChR profile. Our data suggest a little recreational level exercise goes a long way in protecting against the emergence of classic phenotypic traits associated with the aged muscle.

Key points

The detrimental effects of ageing can be partially offset by lifelong self‐organized recreational exercise, as evidence by preserved type II myofibre‐associated satellite cells, a beneficial muscle innervation status and greater fatigue resistance under challenged conditions.

Satellite cell function (in vitro), muscle fibre size and muscle fibre denervation determined by immunofluorescence were not affected by recreational exercise.

Individuals that are recreationally active are far more abundant than master athletes, which sharply increases the translational perspective of the present study. Future studies should further investigate recreational activity in relation to muscle health, while also including female participants.

Physical Activity and Total Daily Energy Expenditure in Older US Adults: Constrained versus Additive Models

PURPOSE

This study aimed to examine the shape of the relationship between physical activity (PA) and total energy expenditure (TEE) and to explore the role of energy balance status (negative, stable, positive) in influencing this association.

METHODS

Cross-sectional. Participants were 584 older adults (50-74 yr) participating in the Interactive Diet and Activity Tracking in AARP study. TEE was assessed by doubly labeled water and PA by accelerometer. The relationship between PA and TEE was assessed visually and using nonlinear methods (restricted cubic splines). Percent weight change (>3%) over a 6-month period was used as a proxy measurement of energy balance status.

RESULTS

TEE generally increased with increasing deciles of PA averaging 2354 (SD, 351) kcal·d-1 in the bottom decile to 2693 (SD, 480) kcal·d-1 in the top decile. Cubic spline models showed an approximate linear association between PA and TEE (linear relation, P < 0.0001; curvature, P = 0.920). Results were similar in subgroup analyses for individuals classified as stable or positive energy balance. For those in negative energy balance, TEE was generally flat with increasing deciles of PA averaging 2428 (SD, 285) kcal·d-1 in the bottom decile to 2372 (SD, 560) kcal·d-1 in the top decile.

CONCLUSIONS

Energy balance status seems to play an important role in the relationship between PA and TEE. When in a positive energy balance, the relationship between TEE and PA was consistent with an additive model; however, when energy balance was negative, TEE seems to be consistent with a constrained model. These findings support PA for weight gain prevention by increasing TEE; however, the effect of PA on TEE during periods of weight loss may be limited. An adequately powered, prospective study is warranted to confirm these exploratory findings.

Physiological Changes and Pathological Pain Associated with Sedentary Lifestyle-Induced Body Systems Fat Accumulation and Their Modulation by Physical Exercise

A sedentary lifestyle is associated with overweight/obesity, which involves excessive fat body accumulation, triggering structural and functional changes in tissues, organs, and body systems. Research shows that this fat accumulation is responsible for several comorbidities, including cardiovascular, gastrointestinal, and metabolic dysfunctions, as well as pathological pain behaviors. These health concerns are related to the crosstalk between adipose tissue and body systems, leading to pathophysiological changes to the latter. To deal with these health issues, it has been suggested that physical exercise may reverse part of these obesity-related pathologies by modulating the cross talk between the adipose tissue and body systems. In this context, this review was carried out to provide knowledge about (i) the structural and functional changes in tissues, organs, and body systems from accumulation of fat in obesity, emphasizing the crosstalk between fat and body tissues; (ii) the crosstalk between fat and body tissues triggering pain; and (iii) the effects of physical exercise on body tissues and organs in obese and non-obese subjects, and their impact on pathological pain. This information may help one to better understand this crosstalk and the factors involved, and it could be useful in designing more specific training interventions (according to the nature of the comorbidity).

Effect of exercise training on skeletal muscle protein expression in relation to insulin sensitivity: Per-protocol analysis of a randomized controlled trial (GO-ACTIWE)

Exercise training improves peripheral insulin sensitivity and leads to molecular adaptations in the skeletal muscle. We investigated changes in the expression of key muscle proteins in the glucose metabolic pathway following active commuting by bike or leisure-time exercise at two different intensities. In addition, potential associations between insulin sensitivity and muscle protein expression were examined. This per-protocol analysis included 72 out of 130 physically inactive, healthy women and men (20-45 years) with overweight/obesity (BMI: 25-35 kg/m2 ) who completed 6 months of no intervention (CON, n = 12), active commuting by bike (BIKE, n = 14), or leisure-time exercise of moderate (MOD, n = 28) or vigorous (VIG, n = 18) intensity. Exercise was prescribed 5 days/week with a weekly exercise energy expenditure of 1,600 kcal for women and 2,100 kcal for men. Insulin sensitivity was determined by a hyperinsulinemic euglycemic clamp and skeletal muscle biopsies were obtained from m. vastus lateralis and analyzed for protein expression at baseline and after 3 and 6 months of intervention. We found an increased expression of pyruvate dehydrogenase (PDH) in the exercise groups compared with the control group following 6 months of training. No differential effects were observed on the protein expression following moderate versus vigorous intensity exercise. In addition, we found a positive association between insulin sensitivity and the expression of glucose transporter type 4 as well as PDH. The positive association and the increase in expression of PDH after exercise training points toward a role for PDH in the training-induced enhancement of insulin sensitivity.

Physical inactivity from youth to adulthood and adult cardiometabolic risk profile

Adults with a low physical activity (PA) level are at increased risk for cardiometabolic diseases, but little is known on the association between physical inactivity since youth and cardiometabolic health in adulthood. We investigated the association of persistent physical inactivity from youth to adulthood with adult cardiometabolic risk factors. Data were drawn from the ongoing Cardiovascular Risk in Young Finns Study with seven follow-ups between 1980 and 2011 (baseline age 3-18 years, n = 1961). Physical activity data from a standardized questionnaire was expressed as a PA-index. Using the PA-index, four groups were formed: 1)persistently physically inactive (n = 246), 2)decreasingly active (n = 305), 3)increasingly active (n = 328), and 4)persistently active individuals (n = 1082). Adulthood cardiometabolic risk indicators included waist circumference, body mass index (BMI), blood pressure, and fasting lipids, insulin, and glucose. Clustered cardiometabolic risk was defined using established criteria for metabolic syndrome. Persistently physically inactive group was used as a reference. Compared to the persistently physically inactive group, those who were persistently active had lower risk for adult clustered cardiometabolic risk (RR = 0.67;CI95% = 0.53-0.84; Harmonized criteria), obesity (BMI > 30 kg/m², RR = 0.76;CI95% = 0.59-0.98), high waist circumference (RR = 0.82;CI95% = 0.69-0.98), and high triglyceride (RR = 0.60;CI95% = 0.47-0.75), insulin (RR = 0.58;CI95% = 0.46-0.74) and glucose (RR = 0.77;CI95% = 0.62-0.96) concentrations as well as low high-density lipoprotein cholesterol (HDLC) concentration (RR = 0.78;CI95% = 0.66-0.93). Comparable results were found when persistently physically inactive individuals were compared with those who increased PA. The results remained essentially similar after adjustment for education, diet, smoking, and BMI. Persistently physically inactive lifestyle since youth is associated with an unfavorable cardiometabolic risk profile in adulthood. Importantly, even minor increase in PA lowers the cardiometabolic risk.

Improved Sleep Quality and Depressive Symptoms With Exercise Training in Obese Women From a Low Socioeconomic Community: A Randomized Controlled Trial

BACKGROUND

Improving sleep quality and reducing depressive symptoms may be target mechanisms for intervention-based research aimed at reducing cardiometabolic risk in low-income communities. This study assessed the effects of exercise training on depressive symptoms and sleep in obese women for a low socioeconomic community. The secondary aim explored associations between changes in depressive symptoms and sleep with changes in cardiorespiratory fitness and cardiometabolic risk factors.

METHODS

Participants were randomized into exercise (n = 20) or control (n = 15) groups. The exercise group completed 12 weeks of combined resistance and aerobic training (40-60 min, 4 d/wk), and the control group maintained habitual diet and activity. Preintervention and postintervention testing included questionnaires on symptoms of depression, psychological distress, and sleep quality. Sedentary time, peak oxygen consumption, body mass index, and insulin sensitivity were measured objectively. Sleep duration (accelerometry) was assessed at preintervention and weeks 4, 8, and 12.

RESULTS

Exercise training reduced depressive symptoms (P = .002) and improved sleep quality (P < .001) and sleep efficiency (P = .005). Reduced depressive symptoms were associated with improved peak oxygen consumption (rho = -.600, P < .001), and improved sleep quality correlated with reduced sedentary time (rho = .415, P = .018).

CONCLUSION

These results highlight the potential for community-based exercise interventions to simultaneously address multiple comorbidities in a low-income setting.

Adipose Tissue Distribution Predicts Prognosis of Cirrhotic Patients Undergoing Hepatectomy for Hepatocellular Carcinoma

BACKGROUND

Body composition data are reportedly correlated with patient prognosis for various cancers. However, little is known about the prognostic impact of adipose tissue distribution among patients with hepatocellular carcinoma (HCC).

METHODS

Data for 181 consecutive cirrhotic patients who underwent hepatectomy for HCC were retrospectively reviewed. The clinical significance of the visceral-to-subcutaneous adipose tissue ratio (VSR) was investigated through analysis of short- and long-term surgical outcomes.

RESULTS

Of the 181 patients, 60 (33%) were classified as the high-VSR group and 121 (67%) as the low-VSR group. Although VSR was not correlated with a risk of postoperative morbidity, multivariate analysis confirmed that a higher VSR was significantly correlated with a shorter time to interventional failure (hazard ratio [HR] 2.24; P = 0.008) and overall survival (HR 2.65; P = 0.001) independently of American Joint Committed on Cancer stage or preoperative nutritional status. Analysis of the recurrence patterns showed that the proportion of unresectable recurrence at the initial recurrence event was significantly higher in the high-VSR group (39% vs. 18%; P = 0.025). The yearly transition probabilities, defined by a Markov model from postoperative R0 status to advanced disease or death (7.6% vs. 1.5%, P < 0.001) and early recurrence stage to advanced disease or death (15.4% vs. 2.8%, P = 0.004), were higher in the high-VSR group, suggesting that patients with a higher VSR are vulnerable to disease progression.

CONCLUSION

A high VSR was found to be an independent predictor of disease progression and poor prognosis for HCC patients with underlying liver cirrhosis having resection for HCC.

Muscle-Organ Crosstalk: Focus on Immunometabolism

Skeletal muscle secretes several hundred myokines that facilitate communication from muscle to other organs, such as, adipose tissue, pancreas, liver, gut, and brain. The biological roles of myokines include effects on e.g., memory and learning, as well as glucose and lipid metabolism. The present minireview focuses on recent developments showing that exercise-induced myokines are involved in immunometabolism of importance for the control of e.g., tumor growth and chronic inflammation. In this review, immunometabolism is discussed as the non-immune related pathologies leading to an immune response and some degree of inflammation, which promotes metabolic abnormalities.

Muscle-Organ Crosstalk: The Emerging Roles of Myokines

Physical activity decreases the risk of a network of diseases, and exercise may be prescribed as medicine for lifestyle-related disorders such as type 2 diabetes, dementia, cardiovascular diseases, and cancer. During the past couple of decades, it has been apparent that skeletal muscle works as an endocrine organ, which can produce and secrete hundreds of myokines that exert their effects in either autocrine, paracrine, or endocrine manners. Recent advances show that skeletal muscle produces myokines in response to exercise, which allow for crosstalk between the muscle and other organs, including brain, adipose tissue, bone, liver, gut, pancreas, vascular bed, and skin, as well as communication within the muscle itself. Although only few myokines have been allocated to a specific function in humans, it has been identified that the biological roles of myokines include effects on, for example, cognition, lipid and glucose metabolism, browning of white fat, bone formation, endothelial cell function, hypertrophy, skin structure, and tumor growth. This suggests that myokines may be useful biomarkers for monitoring exercise prescription for people with, for example, cancer, diabetes, or neurodegenerative diseases.

Effects of exercise training and detraining on atheromatous matrix metalloproteinase activity in mice

BACKGROUND AND AIMS

Exercise training (ET) helps treat atherosclerosis. However, many patients stop regular ET for various reasons. The effect of detraining on atherosclerosis is not well studied. We examined the effects of ET vs. short-term detraining on atheromatous matrix-metalloproteinase (MMP) activity in preexisting plaque and circulating cytokines/lipids.

METHODS AND RESULTS

Eighteen-week-old apolipoprotein-E^-/- mice (n = 56) on a Western diet underwent: 1) ET for 6-weeks (ET5+1), 2) ET for 5-weeks and detraining for 1-week (ET5+0), 3) ET for the last 1-week (ET0+1), or 4) no treadmill ET at all for 6-weeks (ET0+0). Atheromatous MMP-activity was visualized using molecular imaging with an MMP-2/9-activatable near-infrared-fluorescent probe. Compared with no ET (ET0+0), regular ET (ET5+1) decreased carotid atheromatous MMP activity, but this protective effect was significantly blunted by short-term detraining (ET5+0). Short-term detraining after longer-term ET showed a reduction in MMP-activity similar to short-term ET (ET0+1). Blood levels of lipids and cytokines paralleled the molecular imaging results: exercise caused higher levels of high-density lipoprotein, adiponectin, and interleukin-10 and lower levels of vascular cell adhesion molecule, monocyte chemoattractant protein-1, interleukin-1β, and low-density lipoprotein. However, this beneficial effect was short-lived, with the ET5+0 group being similar to the ET0+0 group, and the ET0+1 group being similar to the ET5+1 group. The effect of exercise can be modeled with an exponential-decay of the protective factor of about 15%/day.

CONCLUSIONS

Even short-term detraining reduces atheroprotective effects, and tips the balance towards atherosclerosis. This suggests that ET, to be effective, needs to be prolonged and regular, and that detraining should be avoided.

Changes in body composition with a hypocaloric diet combined with sedentary, moderate and high-intense physical activity: a randomized controlled trial

BACKGROUND

There is evidence showing the effectiveness of a hypocaloric diet and the increase in physical activity on weight loss. However, the combined role of these factors, not only on weight loss but also body composition, remains unclear. The purpose of this study was to investigate the effect of a hypocaloric diet on the body composition of obese adult women throughout different degrees of physical activity during a weight loss program.

METHODS

One hundred and seventeen healthy female volunteers were randomly assigned to one of the experimental groups: a control group with a low-level prescription of physical activity (1-4 METs), moderate physical activity group that performed 10.000 steps walking (5-8 METs) and intense physical activity group that trained exercises by at least 70% of VO2max three times a week (> 8 METs). All subjects followed a hypocaloric diet designed with a reduction of 500 kcal/day. Nutritional counseling was provided throughout the study period to help ensure dietary adherence.

RESULTS

We found no differences in body weight compared to moderate and intense physical activity (ßstand. = - 0.138 vs. ßstand. = - 0.139). Body fat was lower in women following an intense activity (ßstand. = - 0.436) than those with moderate exercise (ßstand. = - 0.231). The high-intense activity also increased muscle mass at the end of the intervention, standing out above the moderate activity (ßstand. = 0.182 vs. ßstand. = 0.008).

CONCLUSIONS

These findings indicate that a hypocaloric diet, without prescription of physical activity, is adequate to lose weight in the short term (12 weeks), but physical activity is vital to modify the body composition in women with obesity. Body fat was lower when women practiced a moderate exercise compared to hypocaloric diet only, but an intense physical activity was the most effective protocol to obtain a reduction of body fat and maintain muscle mass.

TRIAL REGISTRATION

The study protocol complied with the Declaration of Helsinki for medical studies, it was approved by the bioethical committee of Córdoba University, in the Department of Health at the Regional Government of Andalusia (Act n°284, ref.4156) and retrospectively registered in clinicaltrials.gov (NCT03833791). Registered 2 January 2019.

Protocol for a randomised controlled trial of the combined effects of the GLP-1 receptor agonist liraglutide and exercise on maintenance of weight loss and health after a very low-calorie diet

INTRODUCTION

The success rate of weight loss maintenance is limited. Therefore, the purpose of this study is to investigate the maintenance of weight loss and immunometabolic health outcomes after diet-induced weight loss followed by 1-year treatment with a glucagon-like peptide-1 receptor agonist (liraglutide), physical exercise or the combination of both treatments as compared with placebo in individuals with obesity.

METHODS AND ANALYSIS

This is an investigator-initiated, randomised, placebo-controlled, parallel group trial. We will enrol expectedly 200 women and men (age 18-65 years) with obesity (body mass index 32-43 kg/m2) to adhere to a very low-calorie diet (800 kcal/day) for 8 weeks in order to lose at least 5% of body weight. Subsequently, participants will be randomised in a 1:1:1:1 ratio to one of four study groups for 52 weeks: (1) placebo, (2) exercise 150 min/week+placebo, (3) liraglutide 3.0 mg/day and (4) exercise 150 min/week+liraglutide 3.0 mg/day. The primary endpoint is change in body weight from randomisation to end-of-treatment.

ETHICS AND DISSEMINATION

The trial has been approved by the ethical committee of the Capital Region of Denmark and the Danish Medicines Agency. The trial will be conducted in agreement with the Declaration of Helsinki and monitored to follow the guidelines for good clinical practice. Results will be submitted for publication in international peer-reviewed scientific journals.

TRIAL REGISTRATION NUMBER

2015-005585-32.

Age-Dependent Impairment in Endothelial Function and Arterial Stiffness in Former High Class Male Athletes Is No Different to That in Men With No History of Physical Training

Background

Physical activity is generally considered to exert positive effects on the cardiovascular system in humans. However, surprisingly little is known about the delayed effect of professional physical training performed at a young age on endothelial function and arterial stiffness in aging athletes. The present study aimed to assess the impact of long‐lasting professional physical training (endurance and sprint) performed at a young age on the endothelial function and arterial stiffness reported in older age in relation to glycocalyx injury, prostacyclin and nitric oxide production, inflammation, basal blood lipid profile, and glucose homeostasis.

Methods and Results

This study involved 94 male subjects with varied training backgrounds, including young athletes (mean age ∼25 years), older former high class athletes (mean age ∼60 years), and aged‐matched untrained control groups. Aging increased arterial stiffness, as reflected by an enhancement in pulse wave velocity, augmentation index, and stiffness index (P<10⁻⁴), as well as decreased endothelial function, as judged by the attenuation of flow‐mediated vasodilation (FMD) in the brachial artery (P=0.03). Surprisingly, no effect of the training performed at a young age on endothelial function and arterial stiffness was observed in the former athletes. Moreover, no effect of training performed at a young age (P>0.05) on blood lipid profile, markers of inflammation, and glycocalyx shedding were observed in the former athletes.

Conclusions

Our study clearly shows that aging, but not physical training history, represents the main contributing factor responsible for decline in endothelial function and increase in arterial stiffness in former athletes.

PPARG Pro12Ala Ala carriers exhibit greater improvements in peripheral insulin sensitivity in response to 12 weeks of aerobic exercise training

The Ala allele of PPARG Pro12Ala ( rs1801282 ) is associated with greater improvements to the glucose metabolism in exercise studies, but whether this extends to peripheral insulin sensitivity is unknown. Our objective was to investigate the effect of PPARG Pro12Ala on exercise-induced changes in peripheral insulin sensitivity. A total of 124 (91 Pro homozygotes and 33 Ala carriers) previously physically inactive healthy young men and women with overweight or class 1 obesity who completed a 12 wk aerobic exercise intervention were included in the analysis. All participants underwent a hyperinsulinemic euglycemic clamp before and after the 12 wk intervention. The prescribed exercise frequency was 5–7 days/wk, and the exercise energy expenditure was 2,100 4,200 kcal/wk for men and 1,600 kcal/wk for women. Insulin sensitivity improved significantly in both genotype groups. However, Ala carriers had a 1.13-fold (95% confidence interval 1.01; 1.26, P = 0.032) greater improvement in insulin sensitivity from baseline compared with Pro homozygotes. Our data support that PPARG Pro12Ala modifies the effect of aerobic exercise on peripheral insulin sensitivity.

Insulin sensitivity improvement with exercise training is mediated by body weight loss in subjects with metabolic syndrome

AIM

To determine whether exercise training improves insulin actions through concomitant body weight loss (BWL).

METHODS

Subjects (aged 55±8 years) with metabolic syndrome (MetS), prediabetes (fasting blood glucose: 111±2mg·dL^-1, HbA1c: 5.85±0.05%) and abdominal obesity (waist circumference: 104±7.9cm) were randomly allocated to either a group performing aerobic interval training (EXER; n=76) or a sedentary group receiving lifestyle counselling (CONT; n=20) for 16 weeks.

RESULTS

At baseline, insulin sensitivity (according to HOMA2 and intravenous glucose tolerance test; CS_I), body composition and VO_2max were similar between the groups. After the intervention, both groups had similar BWL (1-2%), but only the EXER group showed decreased [mean (95% CI)] trunk fat mass [from 18.2 (17.4-18.9) to 17.3kg (16.6-17.9); P<0.001] and HOMA2 scores [from 1.6 (1.5-1.7) to 1.4 (1.3-1.5); P=0.001], and increased VO_2max [from 2.07 (1.92-2.21) to 2.28 (2.11-2.45) LO₂·min^-1; P<0.001]. However, CS_I did not improve in any group. Within-group subdivision by BWL (≤0%, 0-3%, ≥3%) revealed higher CS_I in those with BWL≥3% in both groups. Trunk fat mass reductions were closely associated with CS_I and HOMA-IR improvement (r=-0.452-0.349; P<0.001).

CONCLUSION

In obese MetS subjects with prediabetes, 3% BWL is required for consistent improvement in insulin sensitivity. Thus, exercise-training programmes should be combined with calorie restriction to achieve BWL levels that prevent the development of diabetes.

Exercise-Induced Changes in Visceral Adipose Tissue Mass Are Regulated by IL-6 Signaling: A Randomized Controlled Trial

Visceral adipose tissue is harmful to metabolic health. Exercise training reduces visceral adipose tissue mass, but the underlying mechanisms are not known. Interleukin-6 (IL-6) stimulates lipolysis and is released from skeletal muscle during exercise. We hypothesized that exercise-induced reductions in visceral adipose tissue mass are mediated by IL-6. In this randomized placebo-controlled trial, we assigned abdominally obese adults to tocilizumab (IL-6 receptor antibody) or placebo during a 12-week intervention with either bicycle exercise or no exercise. While exercise reduced visceral adipose tissue mass, this effect of exercise was abolished in the presence of IL-6 blockade. Changes in body weight and total adipose tissue mass showed similar tendencies, whereas lean body mass did not differ between groups. Also, IL-6 blockade increased cholesterol levels, an effect not reversed by exercise. Thus, IL-6 is required for exercise to reduce visceral adipose tissue mass and emphasizes a potentially important metabolic consequence of IL-6 blockade.

How does 6 months of active bike commuting or leisure-time exercise affect insulin sensitivity, cardiorespiratory fitness and intra-abdominal fat? A randomised controlled trial in individuals with overweight and obesity

Objectives

To evaluate effects of active bike commuting or leisure-time exercise of two intensities on peripheral insulin sensitivity (primary outcome), cardiorespiratory fitness and intra-abdominal adipose tissue mass (secondary outcomes).

Methods

188 physically inactive, healthy women and men (20-45 years) with overweight or class 1 obesity were recruited. In the 6-month trial, 130 participants were randomised to either: no intervention (CON), active commuting (BIKE) or leisure-time exercise of moderate (MOD, 50% VO2peak) or vigorous (VIG, 70% VO2peak) intensity. 100 completed follow-up testing. Exercise prescription was 5 days/week with a weekly exercise energy expenditure of 1600 kcal for women and 2100 kcal for men. Testing was performed at baseline, 3 months and 6 months.

Results

Peripheral insulin sensitivity (ml/min/pmol insulin/L) increased (improved) by 24% (95% CI 6% to 46%, p=0.01) in VIG compared with CON at 3 months. Peripheral insulin sensitivity increased (improved) by 20% in BIKE (95% CI 1% to 43%, p=0.04) and 26% in VIG (95% CI 7% to 47%, p<0.01) compared with CON at 6 months. Cardiorespiratory fitness increased in all exercise groups compared with CON at 6 months; but the increase was higher in those that undertook vigorous exercise than those who did moderate exercise. Intra-abdominal adipose tissue mass diminished across all exercise groups in comparison to CON at 6 months.

Conclusions

Active bike commuting improved cardiometabolic health; as did leisure-time exercise. Leisure-time exercise of vigorous intensity conferred more rapid effects on peripheral insulin sensitivity as well as additional effects on cardiorespiratory fitness than did moderate intensity exercise.

Trial registration

NCT01962259

Effects of active commuting and leisure-time exercise on appetite in individuals with overweight and obesity

Acute exercise is associated with a transient suppression of appetite. The effects of regular exercise on appetite are not well understood. We aimed to determine the effects of active commuting and leisure-time exercise on appetite. One hundred thirty physically inactive women and men (20-45 yr) with overweight and obesity were randomized to 6 mo of habitual lifestyle (CON, n = 18), active commuting (BIKE, n = 35), or leisure-time exercise of moderate [MOD, 50% peak oxygen uptake (V̇o_2peak)-reserve, n = 39] or vigorous (VIG, 70% V̇o_2peak-reserve, n = 38) intensity. Appetite ratings, acylated ghrelin, cholecystokinin (CCK), glucagon-like peptide-1 (GLP-1), peptide YY (PYY), and glucagon were assessed in the basal state and in response to meal and exercise challenges at baseline and 3 and 6 mo. Ad libitum energy intake was determined during test meals. Data from 90 participants (per protocol) were available, and results are comparisons with CON. At 3 mo, ad libitum energy intake was lower in VIG (-22%, P < 0.01), basal glucagon was lower in BIKE ( P < 0.05) and VIG ( P = 0.01), and postprandial ratings of prospective food consumption were lower in MOD ( P = 0.02) and VIG ( P < 0.001). In VIG, ratings of hunger ( P = 0.01) and prospective food consumption ( P = 0.03) were lower after acute exercise at 3 mo. At 6 mo, basal and postprandial GLP-1 were higher ( P ≤ 0.04) whereas postexercise PYY was lower ( P = 0.03) in VIG and postexercise CCK was lower in BIKE ( P = 0.03). Vigorous-intensity exercise training leads to a transient suppression of energy intake and subjective appetite (3 mo) but a more long-term increase in basal and postprandial GLP-1 (6 mo) in individuals with overweight and obesity. NEW & NOTEWORTHY This is the first randomized controlled trial, to our knowledge, investigating long-term effects of exercise domain and intensity on subjective and hormonal markers of appetite and ad libitum energy intake in individuals with overweight and obesity. Appetite was assessed in response to meal and exercise challenges at baseline and at 3 and 6 mo. Anorexigenic effects of exercise vary with the duration of intervention and are restricted to regular leisure-time exercise of vigorous intensity in individuals with overweight and obesity.

Effects of Exercise Domain and Intensity on Sleep in Women and Men with Overweight and Obesity

Inadequate sleep is associated with cardiometabolic risk and adiposity. Exercise has been suggested as an efficient strategy to improve sleep; however, the effects of different types of exercise on sleep in individuals with overweight and obesity are not well understood. We examined effects of active commuting and leisure-time exercise on sleep in individuals with overweight or obesity. 130 physically inactive adults (20-45 years) with overweight or class 1 obesity (body mass index: 25-35 kg/m²) were randomized to 6 months of habitual lifestyle (CON, n = 18), active commuting by bike (BIKE, n = 35), or leisure-time exercise of moderate intensity (MOD, 50% VO₂peak-reserve, n = 39) or vigorous intensity (VIG, 70% VO₂peak-reserve, n = 38), 5 days/week. Sleep was assessed from 7-day/night accelerometry and questionnaires at baseline, 3 months, and 6 months. 92 participants were included in a per protocol analysis. At 3 months, sleep duration was longer in VIG (29 min/night [3; 55] (mean [95% CI]), p=0.03) but not in BIKE and MOD (p ≥ 0.11) compared with CON and was not different between groups at 6 months (p ≥ 0.36 vs. CON). At 6 months, sleep duration variability was lower in MOD (-31% [-50; -3], p=0.03) and numerically lower in VIG (-28% [-49; 1], p=0.06) relative to CON but was unchanged in BIKE (p=0.17 vs. CON). The effects were, however, primarily attributable to shorter and more irregular sleep in CON over time. Our findings suggest that effects of exercise on sleep in individuals with overweight and obesity may be restricted to leisure-time exercise with a short-term effect on sleep duration after vigorous intensity exercise (3 months) but a more regular sleep pattern after 6 months of moderate and vigorous intensity exercise compared with physically inactive controls. This trial was registered at clinicaltrials.gov with ID NCT01962259.

Accumulated or continuous exercise for glycaemic regulation and control: a systematic review with meta-analysis

OBJECTIVE

To compare the effectiveness of accumulating exercise in multiple bouts of at least 10 min throughout a day with exercise completed in a single bout (continuous or interval), or no exercise, on glycaemic control and regulation in inactive people without diagnosed glycaemic dysfunction.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

Seven electronic databases were searched: CINAHL (EBSCO), Cochrane Library, EMBASE (Ovid), MEDLINE 1948-(Ovid), SCOPUS (Elsevier), SPORTDiscus (EBSCO) and Web of Science (ISI) with no restrictions on date and included all titles indexed up to February 2018.

ELIGIBILITY CRITERIA FOR SELECTING STUDIES

Articles reporting insufficiently active adults (19 to 64 years) without metabolic dysfunction, measuring glycaemic control or regulation following at least 6 weeks of aerobic exercise.

RESULTS

Only one study compared accumulated exercise to single-bout exercise with no significant effect on fasting glucose (95% CI: -0.04 to 0.24 mmol·L-1) or fasting insulin (95% CI: -1.79 to 9.85 pmol·L-1) reported 48 hours after the final bout. No studies compared accumulated exercise with no-exercise. Compared with no-exercise, single-bout exercise reduces insulin resistance (mean difference (MD): -0.53 pmol·L-1; 95% CI: -0.93 to -0.13). Insulin resistance was clearly reduced with moderate-intensity (-0.68 (-1.28 to -0.09)) but not with high-intensity (-0.38 (-1.20 to 0.44)) exercise. Single-bout exercise was not statistically more beneficial than no-exercise for glycated haemoglobin (HbA1c) (MD: -0.11 %; 95% CI: -0.24 to 0.02) in metabolically healthy individuals.

SUMMARY/CONCLUSION

The glycaemic response to accumulated exercise or single-bout exercise might not be different, however exercise intensity might influence the mechanisms generating the response.

PROSPERO REGISTRATION NUMBER

CRD42015025042.

Effects of 6 months supervised physical training on muscle strength and aerobic capacity in patients undergoing Roux-en-Y gastric bypass surgery: a randomized controlled trial

Obesity and physical inactivity are major health problems. Roux-en-Y gastric bypass (RYGB) surgery results in significant weight loss and reduces obesity-related morbidity and mortality. Physical activity lowers the risk of cardiovascular disease and premature death. The aims of this study were to elucidate the effects of RYGB followed by 6 months of supervised physical training on physical capacity. In a randomized controlled trial, 60 participants eligible for RYGB were randomized 6 months post-surgery to either two weekly physical training sessions for 26 weeks (INT) or a control group (CON). Aerobic capacity (VO₂ max), muscle strength (MS) of the shoulder and hip and physical function were measured pre-surgery and 6, 12 and 24 months post-surgery. RYGB per se decreased MS in all tested muscle groups, had no effects on VO₂ max but improved physical function. After the intervention, INT had a significant 0.33 L min^-1 increase in VO₂ max compared to CON (95% CI: 0.07-0.57, P = 0.013). Furthermore, MS in the hip adductor increased significantly with 13 N (95% CI: 3.6-22.4, P = 0.007) and a between-group difference was found in the Stair Climb Test (0.46 repetitions [95% CI: 0.02-0.91, P = 0.042]). The effects were not maintained at follow-up. Supervised physical training following RYGB improved VO₂ max, hip MS and physical function, but the positive effects were not maintained at follow-up. While activities of daily life may become easier as a result of RYGB, the observed extensive post-operative loss of MS requires more attention to increase the patient's physical capacity prospectively.

An Exercise Intervention to Unravel the Mechanisms Underlying Insulin Resistance in a Cohort of Black South African Women: Protocol for a Randomized Controlled Trial and Baseline Characteristics of Participants

Background

The pathogenesis of type 2 diabetes (T2D) in black African women is complex and differs from that in their white counterparts. However, earlier studies have been cross-sectional and provide little insight into the causal pathways. Exercise training is consistently used as a model to examine the mechanisms underlying insulin resistance and risk for T2D.

Objective

The objective of the study was to examine the mechanisms underlying the changes in insulin sensitivity and secretion in response to a 12-week exercise intervention in obese black South African (SA) women.

Methods

A total of 45 obese (body mass index, BMI: 30-40 kg/m²) black SA women were randomized into a control (n=22) or experimental (exercise; n=23) group. The exercise group completed 12 weeks of supervised combined aerobic and resistance training (40-60 min, 4 days/week), while the control group maintained their typical physical activity patterns, and both groups were requested not to change their dietary patterns. Before and following the 12-week intervention period, insulin sensitivity and secretion (frequently sampled intravenous glucose tolerance test) and its primary and secondary determinants were measured. Dietary intake, sleep quality and quantity, physical activity, and sedentary behaviors were measured every 4 weeks.

Results

The final sample included 20 exercise and 15 control participants. Baseline sociodemographics, cardiorespiratory fitness, anthropometry, cardiometabolic risk factors, physical activity, and diet did not differ between the groups (P>.05).

Conclusions

The study describes a research protocol for an exercise intervention to understand the mechanisms underlying insulin sensitivity and secretion in obese black SA women and aims to identify causal pathways underlying the high prevalence of insulin resistance and risk for T2D in black SA women, targeting specific areas for therapeutic intervention.

Trial Registration

Pan African Clinical Trial Registry PACTR201711002789113; http://www.pactr.org/ATMWeb/ appmanager/atm/atmregistry?_nfpb=true&_pageLabel=portals_app_atmregistry_portal_page_13 (Archived by WebCite at http://www.webcitation.org/6xLEFqKr0)

Exercise and weight loss effects on cardiovascular risk factors in overweight men

Both exercise training and weight loss reduce cardiovascular risk, but the independent importance of the two strategies is unclear. We aimed to investigate independent and combined effects of exercise training and weight loss on lipoproteins and dyslipidemia in overweight sedentary men. Sixty individuals were randomized to 12 wk of endurance training (T), energy-reduced diet (D), training and energy increased diet (T-iD), or control (C). Equal energetic deficits (-600 kcal/day) were prescribed by exercise for T and caloric restriction for D. T-iD completed similar exercise but remained in energy balance due to the dietary replacement of calories expended during exercise. Total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), high-density lipoprotein cholesterol (HDL-C), apolipoprotein (apo)B and A1, pre-β-HDL, and susceptibility of LDL-C to oxidation were measured. Body weight was reduced similarly between T (-5.9 ± 0.7 kg) and D (-5.2 ± 0.8 kg), whereas T-iD (-1.0 ± 0.5 kg) and C (0.1 ± 0.6 kg) remained weight stable. Plasma TC, LDL-C, and apolipoprotein B were reduced in T compared with C ( P < 0.001 for both), but this was not observed for D ( P > 0.17). Changes in TC and LDL-C were associated with changes in body weight and body fat ( P < 0.01). In T-iD, increases in HDL-C and apolipoprotein A1 were observed ( P < 0.001). In conclusion, an exercise-induced decline in body weight reduces proatherogenic apoB-containing lipoproteins, whereas exercise compensated by energy intake increases the key component of reverse cholesterol transport, i.e., apoA1-containing HDL-C. NEW & NOTEWORTHY Exercise has additive effects in lowering plasma lipoprotein particles to diet-induced weight loss in individuals with increased cardiovascular risk. In the present study, we investigated whether training per se would have beneficial cardiovascular effects. We found that 3 mo of exercise-induced weight loss reduced proatherogenic lipoproteins, whereas endurance training without weight loss improved factors involved in reverse cholesterol transport in a group of overweight sedentary men.

Enhanced insulin sensitivity in successful, long-term weight loss maintainers compared with matched controls with no weight loss history

Background:

Weight gain is associated with deterioration in metabolic health, whereas weight loss improves insulin sensitivity. This study assesses the impact of long-term, successfully maintained weight loss and weight-loss relapse on measures of insulin sensitivity and identifies factors that explain variability in insulin sensitivity.

Methods:

Women (20–45 years) were recruited into four groups: reduced-overweight/obese (RED, n=15); body mass index (BMI)-matched controls (stable low-weight, n=19), BMI⩽27 kg m⁻²; relapsed-overweight/obese subjects (REL, n=11); and BMI-matched controls (obese stable weight, n=11), BMI⩾27 kg m⁻². A 75 g oral glucose tolerance test determined fasting and 2 h plasma glucose and insulin. Homeostatic Model Assessment (HOMA-IR) and insulin sensitivity index (ISI_(0,120)) assessed insulin sensitivity. Anthropometric measurements, fasting resting metabolic rate (RMR) and respiratory quotient (RQ) were measured. Questionnaires and dietary intake were recorded, and physical activity was measured using accelerometers.

Results:

RED were more insulin sensitive, characterised by lower fasting (P=0.001) and 2 h insulin (P=0.003) levels compared with all other groups. There were no significant differences in dietary intake, sedentary, light and moderate activity, RMR or RQ in the RED compared with the other three groups. % Body weight (BW) lost (P<0.001), % BW regained (P<0.05), body fat %, light activity (P<0.05, only log HOMA), vigorous activity (P<0.05) and RQ (P<0.01) predicted 61.4% and 59.7% of variability in log HOMA and log ISI_(0,120), respectively, in multiple linear regression models.

Conclusion:

This study showed sustained enhanced insulin sensitivity in successful weight loss maintainers compared with BMI-matched controls with no weight loss history. Weight-loss-relapsed individuals were indistinguishable from controls. Weight loss itself was the strongest predictor of improved insulin sensitivity, whereas weight regain significantly predicted reduced insulin sensitivity. Weight-loss maintenance programs are essential to retaining metabolic benefits acquired through weight loss. Being physically active, reducing sedentary behaviour and, in particular, including small amounts of vigorous physical activity significantly predicted improved insulin sensitivity.

Relationship between volition, physical activity and weight loss maintenance: Study rationale, design, methods and baseline characteristics

AIMS

To investigate the relationship between volition, physical activity and weight loss maintenance.

METHODS

We recruited 84 sedentary (maximal oxygen uptake: 25 ± 5 ml/min), overweight and obese (Body mass index (BMI) 38 ± 7 m/h², fat 44 ± 7 %) women ( n = 55) and men ( n = 29) for an interdisciplinary prospective study with follow-up. The change in lifestyle and weight loss is promoted via a 3-month intensive lifestyle intervention at a private health school. The intervention consists of supervised training (1-3 hours/day), a healthy hypo-caloric diet (-500 to -700 kCal/day) and education in healthy lifestyle in classes/groups. The participants' body weight and composition (Dual Energy X-ray absorptiometry), volitional skills (questionnaire), physical activity level (heart rate accelerometer/questionnaire) and maximal oxygen uptake (indirect calorimetry) are to be monitored before, after, and 3 and 12 months after the intervention.

RESULTS

At the 12-month follow-up, three different groups will be established: Clinical weight loss maintenance (> 10% weight loss from baseline), moderate weight loss maintenance (1-10% weight loss) and no weight loss (or weight regain). A linear mixed model analysis will be used to compare levels of volitional skills, physical activity and maximal oxygen uptake over time, between the three groups. Correlational analyses will be used to investigate possible associations between volition, maximal oxygen uptake, physical activity level and weight loss maintenance.

CONCLUSIONS

If specific volitional skills are identified as predictors of adherence to physical activity and success in clinical weight loss maintenance, these can be trained in future intensive lifestyle interventions in order to optimize the success rate.

AJS1669, a novel small-molecule muscle glycogen synthase activator, improves glucose metabolism and reduces body fat mass in mice

Impaired glycogen synthesis and turnover are common in insulin resistance and type 2 diabetes. As glycogen synthase (GS) is a key enzyme involved in the synthetic process, it presents a promising therapeutic target for the treatment of type 2 diabetes. In the present study, we identified a novel, potent and orally available GS activator AJS1669 {sodium 2-[[5-[[4-(4,5-difluoro-2-methylsulfanyl-phenyl) phenoxy] methyl]furan-2-carbonyl]-(2-furylmethyl)amino] acetate}. In vitro, we performed a glycogen synthase 1 (GYS1) activation assay for screening GS activators and identified that the activity of AJS1669 was further potentiated in the presence of glucose-6-phosphate (G6P). In vivo, we used ob/ob mice to evaluate the novel anti-diabetic effects of AJS1669 by measuring basal blood glucose levels, glucose tolerance and body fat mass index. Repeated administration of AJS1669 over 4 weeks reduced blood glucose and hemoglobin A1c (HbA1c) levels in ob/ob mice. AJS1669 also improved glucose tolerance in a dose-dependent manner, and decreased body fat mass. The mRNA levels of genes involved in mitochondrial fatty acid oxidation and mitochondrial biogenesis were elevated in skeletal muscle tissue following AJS1669 treatment. Hepatic tissue of treated mice also exhibited elevated expression of genes associated with fatty acid oxidation. In contrast to ob/ob mice, in C57Bl/6 mice AJS1669 administration did not alter body weight or reduce glucose levels. These results demonstrate that pharmacological agents that activate GYS1, the main GS subtype found in skeletal muscle, have potential for use as novel treatments for diabetes that improve glucose metabolism in skeletal muscle.

The GO-ACTIWE randomized controlled trial - An interdisciplinary study designed to investigate the health effects of active commuting and leisure time physical activity

Regular physical activity is efficacious for improving metabolic health in overweight and obese individuals, yet, many adults lead sedentary lives. Most exercise interventions have targeted leisure time, but physical activity also takes place in other domains of everyday life. Active commuting represents a promising alternative to increase physical activity, but it has yet to be established whether active commuting conveys health benefits on par with leisure time physical activity (LTPA). A 6-month randomized controlled trial was designed to investigate the effects of increased physical activity in transport (bicycling) or leisure time domains (moderate or vigorous intensity endurance exercise). We included 188 overweight and class 1 obese sedentary women and men (20-45years) of which 130 were randomized to either sedentary controls (n=18), active commuting (n=35) or moderate (n=39) or vigorous (n=38) intensity LTPA. At baseline and after 3 and 6months, participants underwent a rigorous 3-day biomedical test regimen followed by free-living measurements. In a sub-sample, physical activity level and energy expenditure were monitored by means of personal assistive technology and the doubly labeled water technique. Additionally, the delivery, reception and routinization of the exercise regimens were investigated by ethnological fieldwork. One year after termination of the intervention, participants will be invited for a follow-up visit to investigate sustained health effects and continuous physical activity adherence. By combining biomedical, technological and humanistic approaches, we aim to understand the health benefits of physical activity in different domains of everyday life, as well as how to improve adherence to physical activity.

Muscle fiber type diversification during exercise and regeneration

The plasticity of skeletal muscle can be traced down to extensive metabolic, structural and molecular remodeling at the single fiber level. Skeletal muscle is comprised of different fiber types that are the basis of muscle plasticity in response to various functional demands. Resistance and endurance exercises are two external stimuli that differ in their duration and intensity of contraction and elicit markedly different responses in muscles adaptation. Further, eccentric contractions that are associated with exercise-induced injuries, elicit varied muscle adaptation and regenerative responses. Most adaptive changes are fiber type-specific and are highly influenced by diverse structural, metabolic and functional characteristics of individual fiber types. Regulation of signaling pathways by reactive oxygen species (ROS) and oxidative stress also plays an important role in muscle fiber adaptation during exercise. This review focuses on cellular and molecular responses that regulate the adaptation of skeletal muscle to exercise and exercise-related injuries.

A systematic review and meta-analysis on the effects of exercise training versus hypocaloric diet: distinct effects on body weight and visceral adipose tissue

Exercise training ('exercise') and hypocaloric diet ('diet') are frequently prescribed for weight loss in obesity. Whilst body weight changes are commonly used to evaluate lifestyle interventions, visceral adiposity (VAT) is a more relevant and stronger predictor for morbidity and mortality. A meta-analysis was performed to assess the effects of exercise or diet on VAT (quantified by radiographic imaging). Relevant databases were searched through May 2014. One hundred seventeen studies (n = 4,815) were included. We found that both exercise and diet cause VAT loss (P < 0.0001). When comparing diet versus training, diet caused a larger weight loss (P = 0.04). In contrast, a trend was observed towards a larger VAT decrease in exercise (P = 0.08). Changes in weight and VAT showed a strong correlation after diet (R(2)  = 0.737, P < 0.001), and a modest correlation after exercise (R(2)  = 0.451, P < 0.001). In the absence of weight loss, exercise is related to 6.1% decrease in VAT, whilst diet showed virtually no change (1.1%). In conclusion, both exercise and diet reduce VAT. Despite a larger effect of diet on total body weight loss, exercise tends to have superior effects in reducing VAT. Finally, total body weight loss does not necessarily reflect changes in VAT and may represent a poor marker when evaluating benefits of lifestyle-interventions.

Energy and Macronutrient Intake in the Midwest Exercise Trial 2 (MET-2)

PURPOSE

This study aimed to examine the effect of exercise training over 10 months at two levels of energy expenditure on energy and macronutrient intake in a sample of previously sedentary, overweight/obese young adults.

METHODS

We conducted a 10-month trial in 141 young adults who were randomized to either supervised exercise 5 d·wk(-1) at 400 and 600 kcal per session or nonexercise control. Participants were instructed to maintain their usual ad libitum diet. Energy/macronutrient intake was assessed at baseline and 3.5, 7, and 10 months over 7-d periods of ad libitum eating in a university cafeteria using digital photography. Foods consumed outside the cafeteria were assessed using multiple-pass recalls.

RESULTS

There were no significant between-group differences in absolute energy intake at baseline or at any other time point in the total sample or in men. In women, absolute energy intake was significantly greater in the 600-kcal-per-session group versus controls at both 3.5 and 7 months. There were no significant between-group differences in relative energy intake (kcal·kg·d(-1)) at any time point in the total sample, in men or women. There were no significant within- or between-group differences of change in absolute or relative energy intake in any of the three study groups in the total sample or in men or women. No clinically relevant changes in macronutrient intake were observed.

CONCLUSIONS

Aerobic exercise training does not significantly alter energy or macronutrient intake in overweight and obese young adults. The possibility of a threshold level beyond which increased exercise energy expenditure fails to produce a more negative energy balance and potential sex differences in the energy intake response to increased levels of exercise are potentially important.

Energy intake, nonexercise physical activity, and weight loss in responders and nonresponders: The Midwest Exercise Trial 2

OBJECTIVE

To compare energy intake, total daily energy expenditure (TDEE), nonexercise energy expenditure (NEEx), resting metabolic rate (RMR), nonexercise physical activity (NEPA), and sedentary time between participants with weight loss <5% (nonresponders) vs. ≥5% (responders) in response to exercise.

METHODS

Adults (18-30 years) with overweight/obesity (BMI 25-40 kg/m(2) ) were randomized to exercise: 5 days/week, 400 or 600 kcal/session, 10 months.

RESULTS

Of the participants, 40 responded and 34 did not respond to the exercise protocol. Nonresponder energy intake was higher vs. responders, significant only in men (P=0.034). TDEE increased only in responders (P=0.001). NEEx increased in responders and decreased in nonresponders, significant only in men (P=0.045). There were no within- or between-group differences for change in RMR. NEPA increased in responders and decreased in nonresponders (group-by-time interactions: total sample, P=0.049; men, P=0.016). Sedentary time decreased in both groups, significant only in men.

CONCLUSIONS

Men who did not lose weight in response to exercise (<5%) had higher energy intake and lower NEEx when compared with men losing ≥5%. No significant differences in any parameters assessed were observed between women who lost <5% vs. those losing ≥5%. Factors associated with the weight loss response to exercise in women warrant additional investigation.

Effects of Exercise Training on Cardiorespiratory Fitness and Biomarkers of Cardiometabolic Health: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

BACKGROUND

Guidelines recommend exercise for cardiovascular health, although evidence from trials linking exercise to cardiovascular health through intermediate biomarkers remains inconsistent. We performed a meta-analysis of randomized controlled trials to quantify the impact of exercise on cardiorespiratory fitness and a variety of conventional and novel cardiometabolic biomarkers in adults without cardiovascular disease.

METHODS AND RESULTS

Two researchers selected 160 randomized controlled trials (7487 participants) based on literature searches of Medline, Embase, and Cochrane Central (January 1965 to March 2014). Data were extracted using a standardized protocol. A random-effects meta-analysis and systematic review was conducted to evaluate the effects of exercise interventions on cardiorespiratory fitness and circulating biomarkers. Exercise significantly raised absolute and relative cardiorespiratory fitness. Lipid profiles were improved in exercise groups, with lower levels of triglycerides and higher levels of high-density lipoprotein cholesterol and apolipoprotein A1. Lower levels of fasting insulin, homeostatic model assessment-insulin resistance, and glycosylated hemoglobin A1c were found in exercise groups. Compared with controls, exercise groups had higher levels of interleukin-18 and lower levels of leptin, fibrinogen, and angiotensin II. In addition, we found that the exercise effects were modified by age, sex, and health status such that people aged <50 years, men, and people with type 2 diabetes, hypertension, dyslipidemia, or metabolic syndrome appeared to benefit more.

CONCLUSIONS

This meta-analysis showed that exercise significantly improved cardiorespiratory fitness and some cardiometabolic biomarkers. The effects of exercise were modified by age, sex, and health status. Findings from this study have significant implications for future design of targeted lifestyle interventions.

Predictors of Energy Compensation during Exercise Interventions: A Systematic Review

Weight loss from exercise-induced energy deficits is usually less than expected. The objective of this systematic review was to investigate predictors of energy compensation, which is defined as body energy changes (fat mass and fat-free mass) over the total amount of exercise energy expenditure. A search was conducted in multiple databases without date limits. Of 4745 studies found, 61 were included in this systematic review with a total of 928 subjects. The overall mean energy compensation was 18% ± 93%. The analyses indicated that 48% of the variance of energy compensation is explained by the interaction between initial fat mass, age and duration of exercise interventions. Sex, frequency, intensity and dose of exercise energy expenditure were not significant predictors of energy compensation. The fitted model suggested that for a shorter study duration, lower energy compensation was observed in younger individuals with higher initial fat mass (FM). In contrast, higher energy compensation was noted for younger individuals with lower initial FM. From 25 weeks onward, energy compensation was no longer different for these predictors. For studies of longer duration (about 80 weeks), the energy compensation approached 84%. Lower energy compensation occurs with short-term exercise, and a much higher level of energy compensation accompanies long-term exercise interventions.

Independent effects of endurance training and weight loss on peak fat oxidation in moderately overweight men: a randomized controlled trial

Endurance training increases peak fat oxidation (PFO) during exercise, but whether this is independent of changes in body weight is not known. The aim of the present study was to investigate the effects of endurance training with or without weight loss or a diet-induced weight loss on PFO and on key skeletal muscle mitochondrial proteins involved in fat oxidation. Sixty moderately overweight, sedentary but otherwise healthy men were randomized to 12 wk of training (T), diet (D), training and increased caloric intake (T-iD), or continuous sedentary control (C). Isoenergetic deficits corresponding to 600 kcal/day were comprised of endurance exercise for T and caloric restriction for D. T-iD completed similar training but was not in 600 kcal deficit because of dietary replacement. PFO and the exercise intensity at which this occurred (FatMax) were measured by a submaximal exercise test and calculated by polynomial regression. As intended by study design, a similar weight loss was observed in T (−5.9 ± 0.7 kg) and D (−5.2 ± 0.8 kg), whereas T-iD (−1.0 ± 0.5 kg) and C (0.1 ± 0.6 kg) remained weight stable. PFO increased to a similar extent with 42% in T [0.16 g/min; 95% confidence intervals (CI): 0.02; 0.30, P = 0.02] and 41% in T-iD (0.16 g/min; 95% CI: 0.01; 0.30, P = 0.04) compared with C, but did not increase in D ( P = 0.96). In addition, the analysis of covariance showed that changes in both PFO (0.10 g/min; 95% CI: 0.03; 0.17, P = 0.03) and FatMax (6.3% V̇o2max; 95% CI: 1.4; 11.3, P < 0.01) were independently explained by endurance training. In conclusion, endurance training per se increases PFO in moderately overweight men.