Associations between regional adipose tissue distribution and skeletal muscle bioenergetics in older men and women.

OBJECTIVE: The aim of this study was to examine associations of ectopic adipose tissue (AT) with skeletal muscle (SM) mitochondrial bioenergetics in older adults. METHODS: Cross-sectional data from 829 adults ≥70 years of age were used. Abdominal, subcutaneous, and visceral AT and thigh muscle fat infiltration (MFI) were quantified by magnetic resonance imaging. SM mitochondrial energetics were characterized in vivo (31P-magnetic resonance spectroscopy; ATPmax) and ex vivo (high-resolution respirometry maximal oxidative phosphorylation [OXPHOS]). ActivPal was used to measure physical activity ([PA]; step count). Linear regression adjusted for covariates was applied, with sequential adjustment for BMI and PA. RESULTS: Independent of BMI, total abdominal AT (standardized [Std.] ß = -0.21; R2 = 0.09) and visceral AT (Std. ß = -0.16; R2 = 0.09) were associated with ATPmax (p < 0.01; n = 770) but not following adjustment for PA (p ≥ 0.05; n = 658). Visceral AT (Std. ß = -0.16; R2 = 0.25) and thigh MFI (Std. ß = -0.11; R2 = 0.24) were associated with carbohydrate-supported maximal OXPHOS independent of BMI and PA (p < 0.05; n = 609). Total abdominal AT (Std. ß = -0.19; R2 = 0.24) and visceral AT (Std. ß = -0.17; R2 = 0.24) were associated with fatty acid-supported maximal OXPHOS independent of BMI and PA (p < 0.05; n = 447). CONCLUSIONS: Skeletal MFI and abdominal visceral, but not subcutaneous, AT are inversely associated with SM mitochondrial bioenergetics in older adults independent of BMI. Associations between ectopic AT and in vivo mitochondrial bioenergetics are attenuated by PA.

Chronic exercise improves hepatic acylcarnitine handling.

Exercise mediates tissue metabolic function through direct and indirect adaptations to acylcarnitine (AC) metabolism, but the exact mechanisms are unclear. We found that circulating medium-chain acylcarnitines (AC) (C12-C16) are lower in active/endurance trained human subjects compared to sedentary controls, and this is correlated with elevated cardiorespiratory fitness and reduced adiposity. In mice, exercise reduced serum AC and increased liver AC, and this was accompanied by a marked increase in expression of genes involved in hepatic AC metabolism and mitochondrial ß-oxidation. Primary hepatocytes from high-fat fed, exercise trained mice had increased basal respiration compared to hepatocytes from high-fat fed sedentary mice, which may be attributed to increased Ca2+ cycling and lipid uptake into mitochondria. The addition of specific medium- and long-chain AC to sedentary hepatocytes increased mitochondrial respiration, mirroring the exercise phenotype. These data indicate that AC redistribution is an exercise-induced mechanism to improve hepatic function and metabolism.

Associations between regional adipose tissue distribution and skeletal muscle bioenergetics in older men and women.

Objective: Examine the association of ectopic adipose tissue (AT) with skeletal muscle (SM) mitochondrial bioenergetics in older adults. Methods: Cross-sectional data from 829 older adults ≥70 years was used. Total abdominal, subcutaneous, and visceral AT; and thigh muscle fat infiltration (MFI) was quantified by MRI. SM mitochondrial energetics were characterized using in vivo 31 P-MRS (ATP max ) and ex vivo high-resolution respirometry (maximal oxidative phosphorylation (OXPHOS)). ActivPal was used to measure PA (step count). Linear regression models adjusted for covariates were applied, with sequential adjustment for BMI and PA. Results: Independent of BMI, total abdominal (standardized (Std.) ß=-0.21; R 2 =0.09) and visceral AT (Std. ß=-0.16; R 2 =0.09) were associated with ATP max ( p <0.01), but not after further adjustment for PA (p≥0.05). Visceral AT (Std. ß=-0.16; R 2 =0.25) and thigh MFI (Std. ß=-0.11; R 2 =0.24) were negatively associated with carbohydrate-supported maximal OXPHOS independent of BMI and PA ( p <0.05). Total abdominal AT (Std. ß=-0.19; R 2 =0.24) and visceral AT (Std. ß=-0.17; R 2 =0.24) were associated with fatty acid-supported maximal OXPHOS independent of BMI and PA (p<0.05). Conclusions: Skeletal MFI and abdominal visceral, but not subcutaneous AT, are inversely associated with SM mitochondrial bioenergetics in older adults independent of BMI. Associations between ectopic AT and in vivo mitochondrial bioenergetics are attenuated by PA.

Teaching Kitchens and Culinary Gardens as Integral Components of Healthcare Facilities Providing Whole Person Care: A Commentary.

Child and adult obesity continue to be major health concerns in the United States and can contribute to the development of chronic diseases. Culinary medicine, which incorporates teaching kitchens and gardens, may be a useful strategy for preventing and/or treating obesity-related disease by providing the knowledge and skills that encourage consumption of whole plant-based foods prepared at home. Though emerging research describes the benefits of culinary medicine-based programming, examples of teaching kitchens and culinary gardens being integrated into current clinical practice is minimal. Here, we describe the development of innovative, community-centered culinary medicine programming borne from interdisciplinary collaboration at a leading healthcare system. Preliminary outcomes suggest improvements in anthropometrics, cardiometabolic risk factors, and participation in healthy lifestyle behaviors in pediatric weight management patients, as well as improved confidence, knowledge, and likelihood to prepare whole food, plant-based meals in healthcare employees following participation in culinary medicine workshops. Hospitals and culinary medicine partners can support each other through shared knowledge, vision, and resources to provide value-based care to patients in the community. Collaboration among gardeners, chefs, architects, educators, and healthcare professionals can transfer traditional physician-driven care to patients, empowering them with the tools, resources, and confidence to improve health and wellbeing.

A small change approach on adiposity, lean mass and bone mineral density in adults with overweight and obesity: A randomized controlled trial.

We sought to determine whether small changes in physical activity and diet could prevent adverse changes in body composition over 2 years in adults with overweight and obesity. Previously inactive adults (N = 289) were included in a secondary analysis of data derived from a 3-year, single-centre, two-arm, longitudinal randomized controlled trial. Participants were randomized to a small change approach (N = 144, body mass index: 32.4 ± 4.2 [mean ± standard deviation], age: 52.3 ±. 10.6 years) or usual care (N = 145, body mass index: 32.4 ± 4.2, age: 53.1 ± 10.6 years). Small change approach participants were counselled to make small changes in diet and physical activity, while usual care participants were asked to maintain their usual lifestyle. Adiposity, lean mass and bone mineral density were measured by dual-x-ray absorptiometry. The change in total adiposity was significantly greater in the small change approach group than usual care at 6 and 12 months but did not remain significant at 24 months (mean change [standard error] -0.8 [0.4] vs. -0.7 [0.4] kg; difference 0.6, 95% confidence interval [CI] -1.2 to 1.1). Changes in visceral fat were significantly greater in the small change approach than usual care at 6 and 12 months but did not remain significant at 24 months (-0.04 [0.03] vs. 0.02 [0.03] kg; difference 0.06, 95% CI: -1.5 to 0.3). Changes in lean mass or bone mineral density were not significantly different between groups at any time point (all p > 0.1). The small change approach did not prevent gains in adiposity or losses in lean mass compared to usual care at 2 years in adults with overweight or obesity. No difference from baseline in adiposity, lean mass or bone mineral density was observed in either arm of the trial.

Intermuscular adipose tissue in metabolic disease.

Intermuscular adipose tissue (IMAT) is a distinct adipose depot described in early reports as a 'fatty replacement' or 'muscle fat infiltration' that was linked to ageing and neuromuscular disease. Later studies quantifying IMAT with modern in vivo imaging methods (computed tomography and magnetic resonance imaging) revealed that IMAT is proportionately higher in men and women with type 2 diabetes mellitus and the metabolic syndrome than in people without these conditions and is associated with insulin resistance and poor physical function with ageing. In parallel, agricultural research has provided extensive insight into the role of IMAT and other muscle lipids in muscle (that is, meat) quality. In addition, studies using rodent models have shown that IMAT is a bona fide white adipose tissue depot capable of robust triglyceride storage and turnover. Insight into the importance of IMAT in human biology has been limited by the dearth of studies on its biological properties, that is, the quality of IMAT. However, in the past few years, investigations have begun to determine that IMAT has molecular and metabolic features that distinguish it from other adipose tissue depots. These studies will be critical to further decipher the role of IMAT in health and disease and to better understand its potential as a therapeutic target.

Occupational and leisure-time physical activity and associated factors among shift-working registered nurses: A cross-sectional study.

Background: Lifestyle behaviors, including physical activity, may help to mitigate the chronic disease and mental health consequences of shift work in nurses at the individual level. The physical activity levels of shift-working nurses and factors that predict physical activity in this population are unclear. Objective: The primary aim of this study was to describe work and leisure-time physical activity behaviors in shift-working hospital nurses and determine behavioral, biological, or work-related factors that influence physical activity. Design: Observational; cross-sectional. Settings: Acute care hospital system. Participants: Current registered nurses (N = 112) with a shift work schedule (rotating, mixed, or permanent night shift). Methods: Online validated questionnaires were used to assess work and leisure physical activity levels (International Physical Activity Questionnaire); Theory of Planned Behavior constructs (attitudes, subjective norms, perceived behavioral control, and intention) related to physical activity; and morningness-eveningness. Work-related characteristics were also assessed. Structural equation models were examined for the Theory of Planned Behavior constructs. Results: Shift-working nurses reported 227 (±265) minutes/week of leisure-time and 566 (±868) minutes/week of occupational moderate-to-vigorous physical activity. Attitude (standardized coefficient = 0.63; p < 0.05) was the strongest predictor of physical activity intention, and intention (standardized coefficient = 0.40; p < 0.05) was a significant predictor of leisure-time physical activity behavior. There were no statistically significant differences in physical activity type and amount between those who identified as "morning", "intermediate", or "evening" types. Clinical nurse leaders engaged in statistically significantly less leisure-time physical activity than direct care nurses (703 ± 1142 vs. 1202 ± 1372 MET-minutes/week) (p = 0.013). Conclusions: Our findings suggest that on average, shift-working registered nurses report meeting national physical activity guidelines for leisure and occupational physical activity; however, there is considerable interindividual variability. Theory of Planned Behavior constructs, especially attitude and intention, were significantly associated with leisure-time physical activity but not occupational physical activity, emphasizing the importance of targeting them in interventions to increase physical activity levels among shift-working nurses.

Toward Personalized Exercise Medicine: A Cautionary Tale.

PURPOSE: This study aimed to examine individual exercise response rates across a range of cardiometabolic variables, cardiorespiratory fitness, and body composition in adults. METHODS: A retrospective analysis of data from three randomized controlled trials was used in this study. Participants include those who completed the given trial (control, n = 87; intervention, n = 251). Anthropometric (weight, body mass index, waist circumference), cardiorespiratory fitness (V̇O 2peak ), MRI-measured total adipose tissue (AT), abdominal subcutaneous AT, and visceral AT and common cardiometabolic variables were assessed pre- and postintervention using standard methodologies. The technical error (TE), which includes both the day-to-day variability and instrument error, was calculated using pre- and postintervention data from the time-matched control group. RESULTS: On average, all anthropometric, MRI, and V̇O 2peak variables improved significantly after intervention compared with the control group ( P < 0.05). With the exception of glucose disposal rate (37%), after intervention less than 13% of participants improved cardiometabolic outcome measures beyond the day-to-day variability of measurement. In other words, the individual response for 63%-96% of participants fell within the uncertain range (2 TE). Similarly, for absolute V̇O 2peak (L·min -1 ), only 45% of participants improved beyond 2 TE. By comparison, for MRI-derived variables, the majority of participants (77%, 58%, and 51% for total AT, abdominal subcutaneous AT, and visceral AT, respectively) improved beyond 2 TE. The observed reductions beyond 2 TE for WC and body weight were 53% and 63%, respectively. CONCLUSIONS: The findings suggest extreme caution when inferring that the cardiometabolic and cardiorespiratory fitness response for a given individual is attributable to the exercise dose prescribed.

A small change approach to prevent long-term weight gain in adults with overweight and obesity: a randomized controlled trial.

BACKGROUND: Efforts to manage obesity through weight loss are often unsuccessful as most adults are not able to sustain the major changes in behaviour that are required to maintain weight loss long term. We sought to determine whether small changes in physical activity and diet prevent weight gain in adults with overweight and obesity. METHODS: We randomized 320 sedentary adults with overweight or obesity to monitoring alone (MA, n = 160) or a small change approach (SCA, n = 160). In Phase I (2 yr), MA participants were asked to maintain their normal lifestyle and SCA participants were counselled to make small changes in diet and physical activity, namely a suggested increase in daily step count of 2000 steps with a decrease in energy intake of 100 kcal per day, with group and individual support. Phase II (1 yr) was a passive follow-up period. The difference in change in body weight between groups at 24 and 36 months from baseline was the primary outcome. Additional outcomes included waist circumference and cardiorespiratory fitness. RESULTS: Overall, 268 participants (83.8%) completed the 2-year intervention, and 239 (74.7%) returned at the end of the follow-up period at 3 years. The difference in body weight change between the SCA and MA groups was significant at 3, 6, 12 and 15 months from baseline, but was no longer significant at 24 months (mean change 0.9 [standard error (SE) 0.5] kg v. -0.4 [SE 0.5] kg; difference -0.6, 95% confidence interval [CI] -1.9 to 0.8) or at 36 months (-1.2 [SE 0.8] v. -0.7 [SE 0.8] kg; difference -0.5, 95% CI -2.2 to 1.2). Changes in waist circumference and cardiorespiratory fitness were not significantly different between groups at 24 or 36 months (both p > 0.1). INTERPRETATION: The SCA did not prevent weight gain compared with monitoring alone at 2 or 3 years in adults with overweight or obesity. On average, we observed prevention of weight gain in both arms of the trial. TRIAL REGISTRATION: ClinicalTrials.gov, no. NCT02027077.

Weight Loss and Exercise Differentially Affect Insulin Sensitivity, Body Composition, Cardiorespiratory Fitness, and Muscle Strength in Older Adults With Obesity: A Randomized Controlled Trial.

BACKGROUND: Aging-related disease risk is exacerbated by obesity and physical inactivity. It is unclear how weight loss and increased activity improve risk in older adults. We aimed to determine the effects of diet-induced weight loss with and without exercise on insulin sensitivity, VO2peak, body composition, and physical function in older obese adults. METHODS: Physically inactive older (68.6 ± 4.5 years) obese (body mass index 37.4 ± 4.9 kg/m2) adults were randomized to health education control (HEC; n = 25); diet-induced weight loss (WL; n = 31); or weight loss and exercise (WLEX; n = 28) for 6 months. Insulin sensitivity was measured by hyperinsulinemic-euglycemic clamp, body composition by dual-energy X-ray absorptiometry and MRI, strength by isokinetic dynamometry, and VO2peak by graded exercise test. RESULTS: WLEX improved (p < .05) peripheral insulin sensitivity (+75 ± 103%) versus HEC (+12 ± 67%); WL (+36 ± 47%) versus HEC did not reach statistical significance. WLEX increased VO2peak (+7 ± 12%) versus WL (-2 ± 24%) and prevented reductions in strength and lean mass induced by WL (p < .05). WLEX decreased abdominal adipose tissue (-16 ± 9%) versus HEC (-3 ± 8%) and intermuscular adipose tissue (-15 ± 13%) versus both HEC (+9 ± 15%) and WL (+2 ± 11%; p < .01). CONCLUSIONS: Exercise with weight loss improved insulin sensitivity and VO2peak, decreased ectopic fat, and preserved lean mass and strength. Weight loss alone decreased lean mass and strength. Older adults intending to lose weight should perform regular exercise to promote cardiometabolic and functional benefits, which may not occur with calorie restriction-induced weight loss alone.

Integrating Exercise Counseling Into the Medical School Curriculum: A Workshop-Based Approach Using Behavior Change Techniques.

Objective. Physician physical activity (PA) counseling remains low due partly to lack of knowledge, emphasizing the importance of providing learning opportunities to develop competency, given the strong associations between PA and health. This study aimed to describe the behavior change techniques (BCTs) used in an "Exercise Expo" workshop and examine the workshop's effectiveness for improving social cognitions to discuss exercise with patients. Methods. Second-year medical students (N = 54; Mage ± SD = 25.4 ± 2.95 years) completed questionnaires assessing attitudes, perceived behavior control (PBC), subjective norms, and intentions to provide PA counseling pre- and postworkshop. Repeated-measures analyses of variance evaluated changes in these theory of planned behavior constructs. Results. The most used BCTs included presenting information from credible sources, with opportunities for practicing the behavior and receiving feedback. Significant increases in attitudes, PBC and intentions to discuss PA were observed from pre-post Exercise Expo (P ≤ .01). No statistically significant differences in subjective norms were observed (P = .06). Conclusions. The Exercise Expo significantly improved social cognitions for PA counseling among medical students. Future interventions should target improvements in subjective norms to increase the likelihood the workshop improves PA counseling behavior. The evidence supports the usefulness of a workshop-based educational strategy to enhance medical students' social cognitions for PA counseling.

Individual Response Variation in the Effects of Weight Loss and Exercise on Insulin Sensitivity and Cardiometabolic Risk in Older Adults.

Weight loss induced by decreased energy intake (diet) or exercise generally has favorable effects on insulin sensitivity and cardiometabolic risk. The variation in these responses to diet-induced weight loss with or without exercise, particularly in older obese adults, is less clear. The objectives of our study were to (1) examine the effect of weight loss with or without exercise on the variability of responses in insulin sensitivity and cardiometabolic risk factors and (2) to explore whether baseline phenotypic characteristics are associated with response. Sedentary older obese (BMI 36.3 ± 5.0 kg/m2) adults (68.6 ± 4.7 years) were randomized to one of 3 groups: health education control (HED); diet-induced weight loss (WL); or weight loss and exercise (WL + EX) for 6 months. Composite Z-scores were calculated for changes in insulin sensitivity (C_IS: rate of glucose disposal/insulin at steady state during hyperinsulinemic euglycemic clamp, HOMA-IR, and HbA1C) and cardiometabolic risk (C_CMR: waist circumference, triglycerides, and fasting glucose). Baseline measures included body composition (MRI), cardiorespiratory fitness, in vivo mitochondrial function (ATPmax; P-MRS), and muscle fiber type. WL + EX groups had a greater proportion of High Responders in both C_IS and C_CMR compared to HED and WL only (all p < 0.05). Pre-intervention measures of insulin (r = 0.60) and HOMA-IR (r = 0.56) were associated with change in insulin sensitivity (C_IS) in the WL group (p < 0.05). Pre-intervention measures of glucose (r = 0.55), triglycerides (r = 0.53), and VLDL (r = 0.53) were associated with change in cardiometabolic risk (C_CMR) in the WL group (p < 0.05), whereas triglycerides (r = 0.59) and VLDL (r = 0.59) were associated with C_CMR (all p < 0.05) in WL + EX. Thus, the addition of exercise to diet-induced weight loss increases the proportion of older obese adults who improve insulin sensitivity and cardiometabolic risk. Additionally, individuals with poorer metabolic status are more likely to experience greater improvements in cardiometabolic risk during weight loss with or without exercise.

Individual Response to Standardized Exercise: Total and Abdominal Adipose Tissue.

PURPOSE: (1) Determine the effect of exercise amount and intensity on the proportion of individuals for whom the adipose tissue (AT) response is above the minimal clinically important difference (MCID); and (2) Examine whether clinically meaningful anthropometric changes reflect individual AT responses above the MCID. METHODS: Men (n = 41) and women (n = 62) (52.7 ± 7.6 yr) were randomized to control (n = 20); low amount low intensity (n = 24); high amount low intensity (n = 30); and high amount high intensity (n = 29) treadmill exercise for 24 wk. The AT changes were measured by MRI. 90% confidence intervals for each individual's observed response were calculated as the observed score ±1.64 × TE (technical error of measurement). RESULTS: For visceral AT, HAHI and HALI had a greater proportion of individuals whose AT change and 90% confidence interval were beyond the MCID compared to controls (P < 0.006). For all other AT depots, all exercise groups had significantly more individuals whose changes were beyond the MCID compared with controls. Of those who achieved a waist circumference or body weight reduction ≥ the MCID, 76% to 93% achieved abdominal, abdominal subcutaneous, and visceral AT changes ≥ the MCID. CONCLUSIONS: Increasing exercise amount and/or intensity may increase the proportion of individuals who achieve clinically meaningful visceral AT reductions. Waist circumference or body weight changes beyond a clinically meaningful threshold are predictive of clinically meaningful abdominal adiposity changes.

An appraisal of the SDIR as an estimate of true individual differences in training responsiveness in parallel-arm exercise randomized controlled trials.

Calculating the standard deviation of individual responses (SDIR ) is recommended for estimating the magnitude of individual differences in training responsiveness in parallel-arm exercise randomized controlled trials (RCTs). The purpose of this review article is to discuss potential limitations of parallel-arm exercise RCTs that may confound/complicate the interpretation of the SDIR . To provide context for this discussion, we define the sources of variation that contribute to variability in the observed responses to exercise training and review the assumptions that underlie the interpretation of SDIR as a reflection of true individual differences in training responsiveness. This review also contains two novel analyses: (1) we demonstrate differences in variability in changes in diet and physical activity habits across an intervention period in both exercise and control groups, and (2) we examined participant dropout data from six RCTs and found that significantly (P < 0.001) more participants in control groups (12.8%) dropped out due to dissatisfaction with group assignment compared to exercise groups (3.4%). These novel analyses raise the possibility that the magnitude of within-subject variability may not be equal between exercise and control groups. Overall, this review highlights that potential limitations of parallel-arm exercise RCTs can violate the underlying assumptions of the SDIR and suggests that these limitations should be considered when interpreting the SDIR as an estimate of true individual differences in training responsiveness.

Individual Response to Standardized Exercise: Total and Abdominal Adipose Tissue.

PURPOSE: (1) Determine the effect of exercise amount and intensity on the proportion of adipose tissue (AT) responses likely, very likely, and unlikely above the minimal clinically important difference (MCID); and (2) Examine whether clinically meaningful anthropometric changes reflect individual AT responses above the MCID. METHODS: Men (n=41) and women (n=62) (52.7 ± 7.6 years) were randomized to control (N=20); low amount low intensity (LALI, N=24); high amount low intensity (HALI, N=30); and high amount high intensity (HAHI, N=29) exercise for 24 weeks. AT changes were measured by MRI. The probability that individual responses were > MCID after adjusting for technical error of measurement were calculated for each individual and categorized as: 'Unlikely' = < 25%, 'Possibly' = 25-74%, 'Likely' = 75-94%, 'Very Likely' = 95-100% chance. RESULTS: The HALI (total AT) and HAHI (total AT, visceral AT) groups had a greater proportion of individuals whose response was "very likely" ≥ MCID vs controls (p<0.006). Across the abdominal AT depots, for individuals who reduced WC or body weight ≥ 2 cm or 2 kg, respectively, 51-69% of responses were "likely" or "very likely" beyond the MCID. CONCLUSION: Increasing exercise amount and/or intensity may increase the proportion of individuals deemed 'very likely' to achieve clinically meaningful AT reductions. The use of anthropometric change to identify individual response for adiposity reduction remains a challenge.

Individual Variability in Waist Circumference and Body Weight in Response to Exercise.

PURPOSE: This study aimed to determine the magnitude of exercise-induced individual variability for waist circumference (WC) and body weight change after accounting for biological variability and measurement error. Determinants of response variability were also considered. METHODS: Participants (53 ± 7.5 yr) were 181 adults (61% women) with abdominal obesity randomized to the following: control; low-amount, low-intensity exercise (LALI); high-amount, low-intensity exercise (HALI); or high-amount, high-intensity exercise (HAHI) for 24 wk. Unstructured physical activity was measured by accelerometer. The variability in response to exercise for WC and body weight (SDR) was isolated by subtracting the SD values for the change scores in the exercise group from that of the control group. RESULTS: The variability of response due to exercise (SDR) for change in WC was 3.1, -0.3, and 3.1 cm for LALI, HALI, and HAHI groups, respectively. Corresponding values for body weight were 3.8, 2.0, and 3.5 kg for LALI, HALI, and HAHI, respectively. The high-amount exercise groups yielded the highest proportion of individuals with a clinically meaningful response. No variables predicted the response to exercise (P > 0.05). CONCLUSIONS: Substantial variability in response to standardized exercise was observed for change in both WC and body weight after accounting for the variability not attributed to exercise. Potential determinants of the interindividual variability in response to exercise remain unclear.

Separate Effects of Exercise Amount and Intensity on Adipose Tissue and Skeletal Muscle Mass in Adults with Abdominal Obesity.

OBJECTIVE: To determine the effects of exercise amount (kilocalories per session) and intensity (percent of maximal oxygen consumption [% VO2 peak]) on adipose tissue (AT) and skeletal muscle (SM) in adults with abdominal obesity. METHODS: Participants (n = 103; 52.7 ± 7.6 years) were randomized to the following groups: control; low-amount, low-intensity exercise (180 kcal/session [women] and 300 kcal/session [men] at 50% VO2 peak); high-amount, low-intensity exercise (HALI; 360 kcal/session [women] and 600 kcal/session [men] at 50% VO2 peak); or high-amount, high-intensity exercise (HAHI; 360 kcal/session [women] and 600 kcal/session [men] at 75% VO2 peak) for 24 weeks. Activities of daily living were measured by accelerometry. Magnetic resonance imaging was used to measure tissue mass. RESULTS: Reduction in all AT depots was greater in the exercise groups compared with control (P < 0.002); however, there were no differences between exercise groups (P > 0.05). Visceral and abdominal subcutaneous AT reduction was uniform across the abdomen. Total SM mass did not change with exercise compared with control (P = 0.32). However, while lower-body SM mass was maintained (P = 0.32), upper-body SM mass in the high-amount, high-intensity and the high-amount, low-intensity groups was reduced compared with controls (P < 0.008). CONCLUSIONS: In adults with abdominal obesity, substantial reductions in total, abdominal subcutaneous, and visceral AT with a preservation of total SM mass were observed independent of exercise amount or intensity.

Plasma Metabolite Profiles in Response to Chronic Exercise.

PURPOSE: High-throughput profiling of metabolic status (metabolomics) allows for the assessment of small-molecule metabolites that may participate in exercise-induced biochemical pathways and corresponding cardiometabolic risk modification. We sought to describe the changes in a diverse set of plasma metabolite profiles in patients undergoing chronic exercise training and assess the relationship between metabolites and cardiometabolic response to exercise. METHODS: A secondary analysis was performed in 216 middle-age abdominally obese men and women (mean ± SD, 52.4 ± 8.0 yr) randomized into one of four groups varying in exercise amount and intensity for 6-month duration: high amount high intensity, high amount low intensity, low amount low intensity, and control. One hundred forty-seven metabolites were profiled by liquid chromatography-tandem mass spectrometry. RESULTS: No significant differences in metabolite changes between specific exercise groups were observed; therefore, subsequent analyses were collapsed across exercise groups. There were no significant differences in metabolite changes between the exercise and control groups after 24 wk at a Bonferroni-adjusted statistical significance (P < 3.0 × 10). Seven metabolites changed in the exercise group compared with the control group at P < 0.05. Changes in several metabolites from distinct metabolic pathways were associated with change in cardiometabolic risk traits, and three baseline metabolite levels predicted changes in cardiometabolic risk traits. CONCLUSIONS: Metabolomic profiling revealed no significant plasma metabolite changes between exercise and control after 24 wk at Bonferroni significance. However, we identified circulating biomarkers that were predictive or reflective of improvements in cardiometabolic traits in the exercise group.

Depot-Specific Adipose Tissue Metabolite Profiles and Corresponding Changes Following Aerobic Exercise.

Objectives: Total, visceral, and abdominal subcutaneous adipose tissue (AT) depots have distinct associations with cardiometabolic health; however, the metabolite profiles that characterize each AT depot and its reduction following exercise are poorly understood. Our objectives were to (1) assess the independent associations between identified metabolites and total, visceral and abdominal subcutaneous AT; and (2) examine whether changes in metabolite concentrations and AT mass following aerobic exercise are associated. Methods: A secondary analysis was performed in 103 middle-aged abdominally obese men and women {[mean (SD)], 52.4 (8.0) years} randomized into one of four groups varying in exercise amount and intensity for 6 months duration: high amount high intensity, high amount low intensity, low amount low intensity, and control. One hundred and forty seven metabolites were profiled by liquid chromatography-tandem mass spectrometry. AT mass was measured by magnetic resonance imaging (MRI). Results: Individual metabolite associations with AT depots confirmed several established cross-sectional relationships between the obesity phenotype and metabolic pathways. Collapsed across exercise groups, reduction in visceral AT predicted increases in pyroglutamic acid (B = -0.41) and TCA cycle intermediates [succinic (B = -0.41) and fumaric acid (B = -0.20)], independent of change in total AT. Changes in UDP-GlcNAc (B = 0.43), pyroglutamic acid (B = -0.35), histidine (B = 0.20), citric acid/isocitric acid (B = -0.20), and creatine (B = 0.27) were significantly associated with changes in total AT (false discovery rate = 0.1). Conclusions: Our findings point to potential biomarkers of depot-specific AT reduction that may play a direct role in mediating cardiometabolic improvements.

Abdominal Adiposity, Not Cardiorespiratory Fitness, Mediates the Exercise-Induced Change in Insulin Sensitivity in Older Adults.

Abdominal obesity and low cardiorespiratory fitness (CRF) are associated with insulin resistance in older adults. Exercise is associated with improvement in insulin sensitivity. Whether this association is mediated by change in CRF and/or abdominal obesity is unclear. The current study is a secondary analysis of data from a randomized controlled trial in Kingston, Ontario. Sedentary older adults (60-80 years) (N = 80) who completed the exercise (N = 59) or control (N = 21) conditions for 6 months were included. CRF was measured using a treadmill test, adipose tissue (AT) by magnetic resonance imaging, and insulin sensitivity by hyperinsulinemic-euglycemic clamp. Waist circumference (WC) was measured at the iliac crest. Mediation analyses were used to assess whether abdominal AT and/or CRF mediated the exercise-induced change in insulin sensitivity. By comparison to controls, reduction (mean ± SD) was observed for visceral (-0.4 ± 0.4 kg) and abdominal subcutaneous (-0.4 ± 0.4) AT depots, WC (-4.1 ± 3.2 cm) and BMI (-0.9 ± 0.8 kg/m2) (p < 0.05). Insulin sensitivity (4.2 ± 5.2 M/I) and CRF (0.2 ± 0.3 L/min) improved in the exercise group (p < 0.05). All AT variables, BMI and WC were mediators of the change in insulin sensitivity (p < 0.05). After adjustment for change in total AT, abdominal AT remained a mediator with an effect ratio of 0.79 (p < 0.05), whereas total AT was not significant when adjusted for abdominal AT (p > 0.05). The effect ratio for change in WC and BMI combined (0.63, p<0.05) was greater than either alone. In conclusion, CRF did not mediate the exercise-induced change in insulin sensitivity in older adults. Abdominal adiposity was a strong mediator independent of change in total adiposity.