Short-term moderate weight loss and resistance training do not affect insulin-stimulated glucose disposal in postmenopausal women

Multitissue responses to exercise: a MoTrPAC feasibility study

We assessed the feasibility of the Molecular Transducers of Physical Activity Consortium (MoTrPAC) human adult clinical exercise protocols, while also documenting select cardiovascular, metabolic, and molecular responses to these protocols. After phenotyping and familiarization sessions, 20 subjects (25 ± 2 yr, 12 M, 8 W) completed an endurance exercise bout (n = 8, 40 min cycling at 70% V̇o2max), a resistance exercise bout (n = 6, ∼45 min, 3 sets of ∼10 repetition maximum, 8 exercises), or a resting control period (n = 6, 40 min rest). Blood samples were taken before, during, and after (10 min, 2 h, and 3.5 h) exercise or rest for levels of catecholamines, cortisol, glucagon, insulin, glucose, free fatty acids, and lactate. Heart rate was recorded throughout exercise (or rest). Skeletal muscle (vastus lateralis) and adipose (periumbilical) biopsies were taken before and ∼4 h following exercise or rest for mRNA levels of genes related to energy metabolism, growth, angiogenesis, and circadian processes. Coordination of the timing of procedural components (e.g., local anesthetic delivery, biopsy incisions, tumescent delivery, intravenous line flushes, sample collection and processing, exercise transitions, and team dynamics) was reasonable to orchestrate while considering subject burden and scientific objectives. The cardiovascular and metabolic alterations reflected a dynamic and unique response to endurance and resistance exercise, whereas skeletal muscle was transcriptionally more responsive than adipose 4 h postexercise. In summary, the current report provides the first evidence of protocol execution and feasibility of key components of the MoTrPAC human adult clinical exercise protocols. Scientists should consider designing exercise studies in various populations to interface with the MoTrPAC protocols and DataHub.NEW & NOTEWORTHY This study highlights the feasibility of key aspects of the MoTrPAC adult human clinical protocols. This initial preview of what can be expected from acute exercise trial data from MoTrPAC provides an impetus for scientists to design exercise studies to interlace with the rich phenotypic and -omics data that will populate the MoTrPAC DataHub at the completion of the parent protocol.

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).

Sarcopenia and Bone Mass Loss as Risks during Aging on Female Elderly with Light Activity

BACKGROUND: Aging is a normal physiological process. The aspect of aging can be delayed by a measurable activity that is carried out early and regularly also intake health nutrition. Measurement of body composition is needed to analyze physiological changes due to aging so it can be used to compile a program of activities also diet to delay the aging process. AIM: The aim of this study is to address the potential risks during aging process in people with light physical activity in Gamping, Patukan. METHODS: Method of this research is the cross-sectional method. Subjects were 190 females with light physical activity that divided into Group 1 (70 females) with an average age 43.71 ± 5.37 years old and Group 2 (120 females) with an average age 61.72 ± 6.82 years old. Body composition was measured by the whole body composition diagnostic scale BG21. RESULTS: The result showed that t-test between Group 1 and Group 2 was significant differences p < 0.05, CI = 0.95 in weight body, body mass index (BMI), muscle mass, bone mass, and active metabolism rate (AMR). The percentage decreasing number for body composition was 13.5%, 12.5%, 8.9%, 4.2%, 25.9%, and 12.8% on weight, BMI, muscle mass, bone mass, and AMR, respectively. CONCLUSION: Female with light activity has a risk as sarcopenia and bone loss during aging. The future programme of this community need to encourage of increasing the physic activity and improving life style to slow the bone loss and muscle loss.

Circulating cytokines as determinants of weight loss-induced improvements in insulin sensitivity

Dietary calorie restriction and exercise promote weight loss and may have additive effects for improving insulin sensitivity, independent of weight loss. It is not known if these effects are attributable to changes in circulating cytokines. We evaluated the hypothesis that modest, matched weight loss induced by calorie restriction and exercise have additive effects on circulating cytokines and these changes correlate with improvements in insulin sensitivity. Overweight and sedentary women and men (n = 52, 45-65 years) were randomized to undergo 7 % weight loss by using 3-6 months of calorie restriction, exercise, or a combination of both calorie restriction and exercise. Concentrations of cytokines and hormones were measured in fasting and oral glucose tolerance test blood samples. Insulin sensitivity was estimated based on oral glucose tolerance test for glucose and insulin. With all groups combined, fasting leptin (p < 0.0001) and high molecular weight adiponectin (p = 0.04) decreased and pentraxin-3 increased (p < 0.0001), in a manner that correlated with improvements in insulin sensitivity (all p ≤ 0.0002). These changes, combined with decreases in glucose-dependent insulinotropic polypeptide from the oral glucose tolerance test, explained 63 % of the variance (p < 0.0001) in insulin sensitivity improvements. Exercise and calorie restriction had additive effects on leptin, with a similar trend for high molecular weight adiponectin. Monocyte chemoattractant protein-1 and C-reactive protein concentrations did not change. Calorie restriction and exercise had opposite effects on soluble tumor necrosis factor receptor-1. Modest weight loss in overweight adults decreases serum leptin and high molecular weight adiponectin, and increases pentraxin-3 concentrations in a manner that correlates with increased insulin sensitivity. Exercise has additive effects to those induced by calorie restriction for reductions in leptin and possibly adiponectin. These changes may contribute to the additive effects of calorie restriction and exercise for improving insulin sensitivity.

Physical Exercise Improves Glucose Metabolism in Lifestyle-Related Diseases

The beneficial effects of physical exercise on the decreased insulin sensitivity caused by detrimental lifestyle were reviewed based on experimental evidences. In epidemiological studies, disease prevention has been considered at three levels: primary (avoiding the occurrence of disease), secondary (early detection and reversal), and tertiary (prevention or delay of complications). The major purpose of physical exercise for primary prevention and treatment of lifestyle-related diseases is to improve insulin sensitivity. It is known that, during physical exercise, glucose uptake by the working muscles rises 7 to 20 times over the basal level, depending on the intensity of the work performed. However, intense exercise provokes the release of insulin-counter regulatory hormones such as glucagons and catecholamines, which ultimately cause a reduction in the insulin action. Continued physical training improves the reduced peripheral tissue sensitivity to insulin in impaired glucose tolerance and Type II diabetes, along with regularization of abnormal lipid metabolism. Furthermore, combination of salt intake restriction and physical training ameliorates hypertension. In practical terms, before diabetic patients undertake any program of physical exercise, various medical examinations are needed to determine whether they have good glycemic control and are without progressive complications. Because the effect of exercise that is manifested in improved insulin sensitivity decreases within 3 days after exercise and is no longer apparent after 1 week, a continued program is needed. For a safety practice, moderate- or low-intensity exercise is preferable. In conclusion, we have found sufficient evidences that support the theory that, combined with other forms of therapy, mild exercise training increases insulin action despite no influence on body mass index or maximal oxygen uptake. Along with evident benefits in health promotion, moderate-intensity exercise might play an important role in facilitating treatment of various diseases.

Prediabetes Phenotype Influences Improvements in Glucose Homeostasis with Resistance Training

Purpose

To determine if prediabetes phenotype influences improvements in glucose homeostasis with resistance training (RT).

Methods

Older, overweight individuals with prediabetes (n = 159; aged 60±5 yrs; BMI 33±4 kg/m²) completed a supervised RT program twice per week for 12 weeks. Body weight and composition, strength, fasting plasma glucose, 2-hr oral glucose tolerance, and Matsuda-Defronza estimated insulin sensitivity index (ISI) were assessed before and after the intervention. Participants were categorized according to their baseline prediabetes phenotype as impaired fasting glucose only (IFG) (n = 73), impaired glucose tolerance only (IGT) (n = 21), or combined IFG and IGT (IFG/IGT) (n = 65).

Results

Chest press and leg press strength increased 27% and 18%, respectively, following the 12-week RT program (both p<0.05). Waist circumference (-1.0%; pre 109.3±10.3 cm, post 108.2±10.6 cm) and body fat (-0.6%; pre 43.7±6.8%, post 43.1±6.8%) declined, and lean body mass (+1.3%; pre 52.0±10.4 kg, post 52.7±10.7 kg) increased following the intervention. Fasting glucose concentrations did not change (p>0.05) following the intervention. However, 2-hr oral glucose tolerance improved in those with IGT (pre 8.94±0.72 mmol/l, post 7.83±1.11 mmol/l, p<0.05) and IFG/IGT (pre 9.66±1.11mmol/l, post 8.60±2.00 mmol/l) but not in those with IFG (pre 6.27±1.28mmol/l, post 6.33± 1.55 mmol/l). There were no significant changes in ISI or glucose area under the curve following the RT program.

Conclusions

RT without dietary intervention improves 2-hr oral glucose tolerance in individuals with prediabetes. However, the improvements in glucose homeostasis with RT appear limited to those with IGT or combined IFG and IGT.

Trial Registration

ClinicalTrials.gov: NCT01112709

Effect of abdominal resistance exercise on abdominal subcutaneous fat of obese women: a randomized controlled trial using ultrasound imaging assessments

OBJECTIVES

The aim of this study was to compare the effect of diet and an abdominal resistance training program to diet alone on abdominal subcutaneous fat thickness and waist circumference of overweight and obese women.

METHODS

This randomized clinical trial included 40 overweight and obese women randomly divided into 2 groups: diet only and diet combined with 12 weeks of abdominal resistance training. Waist and hip circumferences and abdominal skin folds of the subjects were measured at the beginning and 12 weeks after the interventions. In addition, abdominal subcutaneous fat thickness of the subjects was measured using ultrasonography. Percentage body fat and lean body mass of all the subjects were also measured using a bioelectric impedance device.

RESULTS

After 12 weeks of intervention, the weight of participants in both groups decreased; but the difference between the 2 groups was not significant (P = .45). Similarly, other variables including abdominal subcutaneous fat, waist circumference, hip circumference, body mass index, body fat percentage, and skin fold thickness were reduced in both groups; but there were no significant differences between the groups.

CONCLUSIONS

This study found that abdominal resistance training besides diet did not reduce abdominal subcutaneous fat thickness compared to diet alone in overweight or obese women.

Resveratrol supplementation does not improve metabolic function in nonobese women with normal glucose tolerance

Resveratrol has been reported to improve metabolic function in metabolically abnormal rodents and humans, but it has not been studied in nonobese people with normal glucose tolerance. We conducted a randomized, double-blind, placebo-controlled trial to evaluate the metabolic effects of 12 weeks of resveratrol supplementation (75 mg/day) in nonobese, postmenopausal women with normal glucose tolerance. Although resveratrol supplementation increased plasma resveratrol concentration, it did not change body composition, resting metabolic rate, plasma lipids, or inflammatory markers. A two-stage hyperinsulinemic-euglycemic clamp procedure, in conjunction with stable isotopically labeled tracer infusions, demonstrated that resveratrol did not increase liver, skeletal muscle, or adipose tissue insulin sensitivity. Consistent with the absence of in vivo metabolic effects, resveratrol did not affect its putative molecular targets, including AMPK, SIRT1, NAMPT, and PPARGC1A, in either skeletal muscle or adipose tissue. These findings demonstrate that resveratrol supplementation does not have beneficial metabolic effects in nonobese, postmenopausal women with normal glucose tolerance.

The effects of two bouts of high- and low-volume resistance exercise on glucose tolerance in normoglycemic women

The purpose of the study was to determine the efficacy of a low-volume, moderate-intensity bout of resistance exercise (RE) on glucose, insulin, and C-peptide responses during an oral glucose tolerance test (OGTT) in untrained women compared with a bout of high-volume RE of the same intensity. Ten women (age 30.1 ± 9.0 years) were assessed for body composition, maximal oxygen uptake, and 1-repetition maximum (1RM) before completing 3 treatments administered in random order: 1 set of 10 REs (RE1), 3 sets of 10 REs (RE3), and no exercise (C). Twenty-four hours after completing each treatment, an OGTT was performed after an overnight fast. Glucose area under the curve response to an OGTT was reduced after both RE1 (900 ± 113 mmol·L(-1)·min(-1), p = 0.056) and RE3 (827.9 ± 116.3, p = 0.01) compared with C (960.8 ± 152.7 mmol·L(-1)·min(-1)). Additionally, fasting glucose was significantly reduced after RE3 (4.48 ± 0.45 vs. 4.90 ± 0.44 mmol·L(-1), p = 0.01). Insulin sensitivity (IS), as determined from the Cederholm IS index, was improved after RE1 (10.8%) and after RE3 (26.1%). The reductions in insulin and C-peptide areas after RE1 and RE3 were not significantly different from those in the C treatment. In conclusion, greater benefits in glucose regulation appear to occur after higher volumes of RE. However, observed reductions in glucose, insulin, C-peptide areas after RE1 suggest that individuals who may not well tolerate high-volume RE protocols may still benefit from low-volume RE at moderate intensity (65% 1RM).

The effect of the addition of resistance training to a dietary education intervention on apolipoproteins and diet quality in overweight and obese older adults

Objectives

The aim of the study was to examine the additive effect of resistance training (RT) to a dietary education (DE) intervention on emerging coronary heart disease (CHD) risk factors, concentration of apolipoproteins B (apoB) and A-I (apoA-I), and Dietary Approaches to Stop Hypertension (DASH) Diet Index scores in overweight and obese older adults.

Patients and methods

This was an ancillary study of a randomized clinical trial held in the Fall of 2008 at the University of Rhode Island. Participants were overweight or obese subjects (mean body mass index [BMI] of 31.7 kg/m²) randomized into two groups, one participating in DE only (n = 12) and the other participating in DE plus RT (DERT) (n = 15). The intervention involved all subjects participating in 30 minutes of DE per week for 10 weeks. Subjects in the DERT group participated in an additional 40 minutes of RT three times per week for 10 weeks. Measurements taken were anthropometric (height, weight, waist circumference, and body composition using the BOD POD^® [Body Composition System, v 2.14; Life Measurement Instruments, Concord, CA]), clinical (blood pressure), and biochemical (lipid profile and apoB and apoA-I concentrations), and the DASH Diet Index was used to measure diet quality.

Results

27 subjects (11 males, 16 females), with a mean age of 66.6 ± 4.3 years, were included in analyses. The DERT subjects had significantly better triacylglycerol and apoB concentrations and DASH Diet Index scores than the DE subjects post-intervention. Improvements were seen within the DE group in energy intake, fat-free mass, and systolic blood pressure and within the DERT group in body weight, percentage of body fat, BMI, diastolic blood pressure, and oxidized low-density lipoprotein (all P < 0.05).

Conclusion

The addition of RT effectively reduced CHD risk factors, body composition, and diet quality in overweight and obese older adults; DERT was more effective than DE alone in improving DASH Diet Index scores and lowering apoB concentrations but was not more effective in increasing apoA-I concentrations. Future research is needed to determine if apolipoproteins are superior to lipoprotein cholesterol concentrations in predicting CHD risk.

Effect of regional fat loss assessed by DXA on insulin resistance and dyslipidaemia in obese women

OBJECTIVE

To investigate the impact of reduction in total fat mass (FM) and regional FMs on indices of insulin resistance and dyslipidaemia in obese women (BMI > 30 kg/m(2)) after a 1-year weight loss (WL) program; and, secondly, to investigate the potential predictive effect of baseline insulin resistance on reduction in total and regional FMs.

MATERIAL AND METHODS

In 35 women with > 4 kg weight loss, body composition by DXA (dual X-ray absorptiometry), fasting insulin, C-Peptide, insulin resistance (HOMA-IR), insulin sensitivity (QUICKI), metabolic clearance rate (MCRestOGTT) and serum lipids were assessed.

RESULTS

Mean WL was 9.6%; trunk and leg FM were reduced proportionally (14.9-14.7%). Improvement in HOMA-IR was 34.7%, insulin 30.7%, QUICKI 8.6% and MCRest OGTT 74%. The reduction in total, trunk and leg FM were similarly correlated with improvement in indices of insulin resistance (p < 0.001-0.05) and also with initial HOMA-IR (p = 0.000-0.02). In linear regressions improvement in HOMA-IR was similarly related with these FMs (p = 0.008), and initial HOMA predicted loss of trunk FM (p = 0.01). In multivariate analysis improvement in HOMA-IR was explained by loss of total FM (R(2) = 0.20, p = 0.004); improvement of QUICKI by loss of leg FM (R(2) = 0.33, p < 0.001).

CONCLUSION

Loss of leg FM and trunk FM had similar importance for the improvement in insulin resistance. Baseline HOMA-IR predicted the potential for reduction in trunk FM.

Resistance Training During Weight Loss in Overweight and Obese Older Adults: What Are the Benefits?

Obesity and sarcopenia are important public health challenges that affect the healthy aging trajectory of older adults. Although weight loss is recommended for overweight and obese older adults to prevent chronic disease, exercise is an important additional weight management strategy to maximize fat mass loss while retaining lean mass and improving function. Resistance training (RT) is a well-known exercise modality to improve muscle function and lean mass and has been investigated in several recent studies as a potentially powerful strategy to employ along with weight loss in overweight and obese older adults. RT is an important exercise training strategy as outlined in the Physical Activity Guidelines for Americans and is recommended by the American College of Sports Medicine for older adults who are able to safely participate. This brief review will highlight some of the age-related consequences of sarcopenia and obesity and will summarize some of the published research findings of combined RT and weight loss in overweight and obese older adults.

Effect of hyperinsulinemia and very-low-calorie diet on interstitial cytokine levels in subcutaneous adipose tissue of obese women

Type 2 diabetes and obesity are associated with an enhanced release of a number of adipocytokines. Hyperinsulinemia, frequently present in type 2 diabetes and obesity, might be one of the drivers of the enhanced production of adipocytokines. The aim of this study was to investigate the interstitial levels of cytokines in subcutaneous adipose tissue (SCAT) in response to hyperinsulinemia and the effect of weight-reducing hypocaloric diet on this regulation in obese subjects. Thirteen obese premenopausal women participated in the study. Concentrations of seven cytokines were measured in plasma and in AT interstitial fluid collected by microdialysis during a euglycemic-hyperinsulinemic clamp and during control infusion of physiological saline. A subgroup of six women underwent a 4-wk very-low-calorie diet (VLCD). Microdialysis during the clamp was performed before and at the end of VLCD. Hyperinsulinemia induced an increase of monocyte chemoatractant protein (MCP-1) and IL-6 SCAT interstitial and plasma levels and elevated IL-8 levels in SCAT. The relative changes of IL-6 levels in the dialysate correlated with changes of IL-8 and MCP-1. The interstitial and plasma levels of IL-1β, IL-10, TNFα, and plasminogen activator inhibitor (PAI-1) remained unchanged in response to hyperinsulinemia. VLCD resulted in enhancement of the hyperinsulinemia-induced augmentation of MCP-1, IL-6, and IL-8 interstitial levels. In conclusion, hyperinsulinemia upregulates the interstitial levels of MCP-1, IL-6, and IL-8 in SCAT in obese women, whereas it does not affect IL-1β, IL-10, TNFα, and PAI-1 levels. Hypocaloric diet associated with weight reduction enhances the hyperinsulinemia-induced upregulation of MCP-1, IL-6, and IL-8 in SCAT.

Exercise training and dietary glycemic load may have synergistic effects on insulin resistance in older obese adults

BACKGROUND/AIMS

The aim of this study was to assess the combined effects of exercise and dietary glycemic load on insulin resistance in older obese adults.

METHODS

Eleven men and women (62 +/- 2 years; 97.6 +/- 4.8 kg; body mass index 33.2 +/- 2.0) participated in a 12-week supervised exercise program, 5 days/week, for about 1 h/day, at 80-85% of maximum heart rate. Dietary glycemic load was calculated from dietary intake records. Insulin resistance was determined using the euglycemic (5.0 mM) hyperinsulinemic (40 mU/m(2)/min) clamp.

RESULTS

The intervention improved insulin sensitivity (2.37 +/- 0.37 to 3.28 +/- 0.52 mg/kg/min, p < 0.004), increased VO(2max) (p < 0.009), and decreased body weight (p < 0.009). Despite similar caloric intakes (1,816 +/- 128 vs. 1,610 +/- 100 kcal/day), dietary glycemic load trended towards a decrease during the study (140 +/- 10 g before, vs. 115 +/- 8 g during, p < 0.04). The change in insulin sensitivity correlated with the change in glycemic load (r = 0.84, p < 0.009). Four subjects reduced their glycemic load by 61 +/- 8%, and had significantly greater increases in insulin sensitivity (78 +/- 11 vs. 23 +/- 8%, p < 0.003), and decreases in body weight (p < 0.004) and plasma triglycerides (p < 0.04) compared to the rest of the group.

CONCLUSION

The data suggest that combining a low-glycemic diet with exercise may provide an alternative and more effective treatment for insulin resistance in older obese adults.

Substituting food restriction by resistance training prevents liver and body fat regain in ovariectomized rats

OBJECTIVE

Fat mass gain and regain following weight loss are major concerns and may be even more critical after menopause. The present study was undertaken to evaluate the effect of a resistance training protocol on body weight and fat mass in ovariectomized Sprague-Dawley rats following diet-induced weight loss.

DESIGN

Rats were randomly divided into ovariectomized (Ovx) and sham-operated (Sham) groups. Five weeks after ovariectomy, Ovx rats were subjected to a 26% food restriction (OvxFR) for 8 weeks. Following this period, OvxFR rats went back to a normal ad libitum feeding and were divided into two groups: either sedentary or undergoing a resistance training program for an additional 5 weeks, which consisted of climbing a 6-m vertical grill, 20-40 times, with progressively increasing load four times/week.

RESULTS

The food restriction program decreased (p < 0.01) body mass, fat pad weight (intra-abdominal and subcutaneous), and liver triacylglycerol (TAG) levels as compared to normally fed Ovx rats. Stopping the food restriction program over a 5-week period resulted in a partial regain in body weight and intra-abdominal fat pad weight (p < 0.05), and in an almost complete regain in liver TAG compared to normally fed Ovx rats. On the other hand, no significant increases in these variables were noted when the food restriction was replaced by resistance training over the same 5-week period.

CONCLUSION

These results indicate that a resistance training program could be useful in preventing body weight as well as adipose tissue and liver fat regain in Ovx rats, following diet-induced weight loss. It is suggested that changing from a food restriction regimen to a resistance training program can be an interesting strategy to promote successful long-term weight reduction in postmenopausal women.

American College of Sports Medicine Position Stand. Appropriate physical activity intervention strategies for weight loss and prevention of weight regain for adults

Overweight and obesity affects more than 66% of the adult population and is associated with a variety of chronic diseases. Weight reduction reduces health risks associated with chronic diseases and is therefore encouraged by major health agencies. Guidelines of the National Heart, Lung, and Blood Institute (NHLBI) encourage a 10% reduction in weight, although considerable literature indicates reduction in health risk with 3% to 5% reduction in weight. Physical activity (PA) is recommended as a component of weight management for prevention of weight gain, for weight loss, and for prevention of weight regain after weight loss. In 2001, the American College of Sports Medicine (ACSM) published a Position Stand that recommended a minimum of 150 min wk(-1) of moderate-intensity PA for overweight and obese adults to improve health; however, 200-300 min wk(-1) was recommended for long-term weight loss. More recent evidence has supported this recommendation and has indicated more PA may be necessary to prevent weight regain after weight loss. To this end, we have reexamined the evidence from 1999 to determine whether there is a level at which PA is effective for prevention of weight gain, for weight loss, and prevention of weight regain. Evidence supports moderate-intensity PA between 150 and 250 min wk(-1) to be effective to prevent weight gain. Moderate-intensity PA between 150 and 250 min wk(-1) will provide only modest weight loss. Greater amounts of PA (>250 min wk(-1)) have been associated with clinically significant weight loss. Moderate-intensity PA between 150 and 250 min wk(-1) will improve weight loss in studies that use moderate diet restriction but not severe diet restriction. Cross-sectional and prospective studies indicate that after weight loss, weight maintenance is improved with PA >250 min wk(-1). However, no evidence from well-designed randomized controlled trials exists to judge the effectiveness of PA for prevention of weight regain after weight loss. Resistance training does not enhance weight loss but may increase fat-free mass and increase loss of fat mass and is associated with reductions in health risk. Existing evidence indicates that endurance PA or resistance training without weight loss improves health risk. There is inadequate evidence to determine whether PA prevents or attenuates detrimental changes in chronic disease risk during weight gain.

Influence of combined exercise training on indices of obesity, diabetes and cardiovascular risk in type 2 diabetes patients

OBJECTIVE

To investigate the influence of combined exercise training on indices of obesity, diabetes and cardiovascular risk in type 2 diabetes patients.

DESIGN

A double-blind randomized controlled trial with patients receiving either combination (COM), endurance (END) or no training (C).

SETTING

Sint-Jozef hospital (Belgium), general practice (Holland).

SUBJECTS

Forty-six type 2 diabetes patients (17 female, 29 male).

INTERVENTIONS

COM versus END and C. Patients exercised for three months, three times a week for 1 hour.

MAIN MEASURES

Six-minute walk test (6MW T), peak Vo(2), strength in upper and lower limbs, sit-to-stand, height, weight, body mass index, fat mass, glycosylated haemoglobin (HbA1c), glycaemia, triglycerides, high-density lipoprotein (HDL), total cholesterol and quality of life (General Health Survey Short Form (SF-36)).

RESULTS

COM had significant better results on sit-to-stand (P<0.05), 6MW T (P<0.01), strength in upper (P<0.001) and lower limbs (P<0.001) compared with C. A different evolution among COM and C was found for HbA1c (P<0.05) and cholesterol (P<0.01), both decreased in COM and increased in C. HDL increased in COM and decreased in C (P<0.01). END had significant higher results on the 6MW T (P<0.01) compared with C. Compared with END, COM had significantly higher results on strength in upper (P<0.01) and lower limbs (P<0.01). The evolution of SF-36 items was not significantly different between the three groups.

CONCLUSION

In diabetes type 2 patients, COM had significant better effects on indices of physical condition, diabetes and cardiovascular risk compared with C. Compared with END, COM gave a tendency towards better results, however more research with a larger number of participants is needed.

Prevention and treatment of type 2 diabetes: current role of lifestyle, natural product, and pharmacological interventions

Common complications of type 2 diabetes (T2D) are eye, kidney and nerve diseases, as well as an increased risk for the development of cardiovascular disease and cancer. The overwhelming influence of these conditions contributes to a decreased quality of life and life span, as well as significant economic consequences. Although obesity once served as a surrogate marker for the risk of T2D, we know now that excess adipose tissue secretes inflammatory cytokines that left unchecked, accelerate the progression to insulin resistance and T2D. In addition, excess alcohol consumption may also increase the risk of T2D. From a therapeutic standpoint, lifestyle interventions such as dietary modification and/or exercise training have been shown to improve glucose homeostasis but may not normalize the disease process unless weight loss is achieved and increased physical activity patterns are established. Furthermore, utilization of natural products may serve as a significant adjunct in the fight against insulin resistance but further research is needed to ascertain their validity. Since it is clear that pharmaceutical therapy plays a significant role in the treatment of insulin resistance, this review will also discuss some of the newly developed pharmaceutical therapies that may work in conjunction with lifestyle interventions, and lessen the burden of behavioral change as the only strategy against the development of T2D.

Muscle-strengthening activity and its association with insulin sensitivity

OBJECTIVE

Muscle-strengthening activities (MSAs) may increase insulin sensitivity, thereby reducing the risk of diabetes. The purpose of this study was to assess the relationship between MSAs and insulin sensitivity among American adults.

RESEARCH DESIGN AND METHODS

We analyzed data on 4,504 adults without diabetes, aged 20-79 years, who participated in the National Health and Nutrition Examination Survey 1999-2004 and had information on MSAs. Self-reported frequency (times/week) of MSAs was grouped as low (<1), moderate (1-2.9), or high (>or=3). Insulin sensitivity was measured by the fasting quantitative insulin sensitivity check index x 100 (QUICKI).

RESULTS

After adjustment for age, race/ethnicity, physical activity other than MSAs, BMI, smoking, alcohol consumption, and daily total caloric intake, the mean values for QUICKI by low, moderate, and high MSA were 33.6, 33.9, and 34.2, respectively (P for linear trend = 0.008) for men and 34.2, 34.6, 34.6, respectively (P for linear trend = 0.009) for women. Mean fasting insulin (picomols per liter) concentrations were 75.0, 68.9, and 65.9, respectively (P for linear trend = 0.017) for men and 66.9, 63.3, 61.2, respectively (P for linear trend = 0.007) for women. There were no significant differences across MSA groups for fasting glucose among men or women.

CONCLUSIONS

MSA is independently associated with higher insulin sensitivity among U.S. adults. Efforts to increase MSA may be a realistic, feasible, and effective method of reducing insulin resistance among the U.S. population.

Resistance training and dietary protein: effects on glucose tolerance and contents of skeletal muscle insulin signaling proteins in older persons

BACKGROUND

Resistance training (RT) and dietary protein independently influence indexes of whole-body glucose control, though their synergistic effects have not yet been documented.

OBJECTIVE

This study assessed the influence of dietary protein intake on RT-induced changes in systemic glucose tolerance and the contents of skeletal muscle insulin signaling proteins in healthy older persons.

DESIGN

Thirty-six older men and women (age: 61 +/- 1 y) performed RT (3 times/wk for 12 wk) and consumed either 0.9 g protein . kg(-1) . d(-1) [lower-protein (LP) group; approximately 112% of the Recommended Dietary Allowance (RDA)] or 1.2 g protein . kg(-1) . d(-1) [higher-protein (HP) group; approximately 150% of the RDA]; the HP group consumed more total, egg, and dairy proteins.

RESULTS

After RT, body weight was unchanged; whole-body protein and water masses increased, and fat mass decreased with no significantly different responses observed between the LP and HP groups. The RT-induced improvement in oral glucose tolerance (decreased area under the curve, AUC) was not significantly different between the groups (LP: -28%; HP: -25%). The insulin (-21%) and C-peptide (-14%) AUCs decreased in the LP group but did not change significantly in the HP group. Skeletal muscle insulin receptor, insulin receptor substrate-1, and Akt contents were unchanged, and the amount of atypical protein kinase C zeta/lambda (aPKC zeta/lambda), a protein involved with insulin signaling, increased 56% with RT, independent of protein intake.

CONCLUSION

These results support the hypothesis that older persons who consume adequate or moderately high amounts of dietary protein can use RT to improve body composition, oral glucose tolerance, and skeletal muscle aPKC zeta/lambda content without a change in body weight.

Association of insulin sensitivity and muscle strength in overweight and obese sedentary postmenopausal women

The objective of this study was to examine the relationship between insulin sensitivity and lower body muscle strength in overweight and obese sedentary postmenopausal women. The design of the study was cross-sectional. The study population consisted of 82 non-diabetic overweight and obese sedentary postmenopausal women (age: 58.2 ± 5.1 y; body mass index (BMI): 32.4 ± 4.6 kg·m–2). Subjects were classified by dividing the entire cohort into quartiles based on relative insulin sensitivity expressed per kilograms of lean body mass (LBM) (Q1, < 10.3, vs. Q2, 10.3–12.4, vs. Q3, 12.5–14.0, vs. Q4, >14.0 mg·min–1·kg LBM–1). We measured insulin sensitivity (using the hyperinsulinemic–euglycemic clamp technique), body composition (using dual-energy X-ray absorptiometry), visceral fat and muscle attenuation (using computed tomography), and a lower-body muscle strength index expressed as weight lifted in kilograms per kilogram of LBM (kg·kg LBM–1) (using weight-training equipment). A positive and significant relationship was observed between insulin sensitivity and the muscle strength index (r = 0.37; p < 0.001). Moreover, a moderate but significant correlation was observed between the muscle strength index and muscle attenuation (r = 0.22; p < 0.05). Finally, the muscle strength index was significantly higher in the Q4 group compared with the Q2 and Q1 groups, respectively (3.78 ± 1.13 vs. 2.99 ± 0.77 and 2.93 ± 0.91 kg·kg LBM–1; p < 0.05). Insulin sensitivity is positively associated with lower-body muscle strength in overweight and obese sedentary postmenopausal women.

Correlations between measures of insulin sensitivity and weight loss

OBJECTIVE

Many formulas have been proposed to calculate insulin sensitivity and studies have shown their effectiveness. However, few studies have been done to compare formulas.

METHODS

Seventy-two obese participants completed a randomized weight loss study. Weight loss, change in body fat and change in waist circumference were used as surrogates for change in insulin sensitivity. Correlation coefficients were calculated for each of these surrogates with proposed formulas for insulin sensitivity found in the literature.

RESULTS

The change in insulin sensitivity using the formula proposed by McAuley (exp(2.63-0.28 x ln(fasting insulin)-0.31 x ln(fasting triglyceride in mmol/l)) showed the greatest correlation with weight loss (r=-0.59, p<0.0001) and was statistically superior to change in fasting glucose, fasting insulin and homeostasis model assessment (HOMA).

CONCLUSIONS

The insulin sensitivity formula proposed by McAuley provides an accurate means of detecting insulin resistance. As it does not require a glucose tolerance test, it is also easier and less expensive than most other formulas. Use of this formula rather than fasting glucose would detect many more patients with insulin resistance who are at risk for subsequent diabetes and other complications.

Influence of resistance exercise training on glucose control in women with type 2 diabetes

The objective of the study was to evaluate the effects of acute and chronic resistance training on glucose and insulin responses to a glucose load in women with type 2 diabetes. Subjects consisted of type 2 diabetic women (n = 7) and age-matched controls (n = 8) with normal glucose tolerance. All subjects participated in 3 oral glucose tolerance tests: pretraining, 12 to 24 hours after the first exercise session (acute) and 60 to 72 hours after the final training session (chronic). Exercise training consisted of a whole body resistance exercise program using weight-lifting machines 3 days per week for 6 weeks. Resistance training was effective in increasing strength of all muscle groups in all subjects. Integrated glucose concentration expressed as area under the curve (AUC) was 3,355.0 +/- 324.6 mmol/L. min pretraining, improved significantly (P <.01) after the acute bout of exercise (2,868 +/- 324.0 mmol/L. min), but was not improved with chronic training (3,206.0 +/- 337.0 mmol/L. min) in diabetic subjects. A similar pattern of significance was observed with peak glucose concentration (pre: 20.2 +/-1.4 mmol/L; acute: 17.2 +/- 1.7 mmol/L; chronic: 19.9 +/- 1.7 mmol/L). There were no significant changes in insulin concentrations after any exercise bout in the diabetic subjects. There were no changes in glucose or insulin levels in control subjects. An acute bout of resistance exercise was effective in improving integrated glucose concentration, including reducing peak glucose concentrations in women with type 2 diabetes, but not age-matched controls. There were no significant changes in insulin concentrations for either group. Resistance exercise offers an alternative to aerobic exercise for improving glucose control in diabetic patients. To realize optimal glucose control benefits, individuals must follow a regular schedule that includes daily exercise.

Age-related differences in metabolic adaptations following resistance training in women

The purpose of this study was to determine whether aging alters changes in resting metabolic rate, body composition and insulin sensitivity in response to resistance training (RT) in women. The impact of a 6-month controlled RT program on fat-free mass (FFM), resting energy expenditure (REE), and glucose disposal was examined in 19 younger (27.8+/-3.5 yr; range 18-35) and 12 older (66.6+/-4.9 yr, range 55-70) non-obese caucasian women. For younger women, the RT program increased body weight (59.1+/-6.2 to 60.8+/-6.1 kg, p<0.05) due to an increase in FFM (39.2+/-3.7-40.4+/-3.2 kg, p<0.05). REE increased from 1379+/-114 to 1451+/-140 kcal day(-1), p<0.0001), and glucose disposal (from 364.1+/-91.1 to 402.1+/-87.8 mg min(-1), p<0.05). Neither fat mass nor VO2max changed significantly. On the other hand, older women lost fat mass (24.0+/-4.6-23.2+/-5.4 kg, p<0.05) and tended to gain FFM (from 37.3+/-4.0-38.0+/-4.3 kg, +1.9%; p=0.057), whereas no change occurred in body weight, REE, VO(2)max or glucose disposal. Thus, younger women showed greater metabolic changes in body composition, REE and insulin sensitivity in response to RT than older women. These results suggest an age-related alteration in metabolic changes in response to a 6-month RT program in previously untrained women.

Lifestyle intervention of hypocaloric dieting and walking reduces abdominal obesity and improves coronary heart disease risk factors in obese, postmenopausal, African-American and Caucasian women

BACKGROUND

There are few empirical data to support the claim that weight loss improves coronary heart disease (CHD) risk factors in postmenopausal women; nor is it known if there are racial differences in changes of body fat distribution, lipids, glucose tolerance, and blood pressure with weight loss. This study determined the efficacy of a lifestyle weight loss intervention in reducing total and abdominal obesity and improving CHD risk factors in obese Caucasian and African-American postmenopausal women.

METHODS

Body composition (dual-energy x-ray absorptiometry), abdominal fat areas (computed tomography scan), lipoprotein lipids, insulin, glucose tolerance, and blood pressure were measured before and after 6 months of hypocaloric diet and low-intensity walking in 76 overweight or obese (body mass index > 25 kg/m(2)), Caucasian (72%) or African-American (28%), postmenopausal (age = 60 +/- 5 years) women who completed the study.

RESULTS

Absolute amount of body weight lost was similar in Caucasians (-5.4 +/- 3.6 kg) and African Americans (-3.9 +/- 3.6 kg), but Caucasian women lost relatively more fat mass (p <.05). Both groups decreased their subcutaneous abdominal fat, and Caucasian women decreased their visceral fat area, but there were no racial differences in the magnitude of abdominal fat lost. The intervention decreased triglyceride and increased high-density lipoprotein and high-density lipoprotein 2 cholesterol in both races, and it decreased total and low-density lipoprotein cholesterol in Caucasian women (p <.05-.0001). Fasting glucose and glucose area during the oral glucose tolerance test decreased (p <.0001) in Caucasian women, whereas insulin area decreased in both Caucasian (p <.01) and African-American (p <.05) women. Blood pressure decreased the most in women with higher blood pressures at baseline. Changes in lipids, fasting glucose and insulin, their responses during the oral glucose tolerance test, and blood pressure were not different between racial groups.

CONCLUSIONS

Weight loss achieved through a lifestyle intervention of energy restriction and increased physical activity is an equally effective therapy in African-American and Caucasian obese, postmenopausal women for improving glucose and lipid CHD risk factors.