Aerobic versus strength training for risk factor intervention in middle-aged men at high risk for coronary heart disease

Exercise, Physical Activity, and Cardiometabolic Health: Insights into the Prevention and Treatment of Cardiometabolic Diseases

Physical activity (PA) and exercise are widely recognized as essential components of primary and secondary cardiovascular disease (CVD) prevention efforts and are emphasized in the health promotion guidelines of numerous professional societies and committees. The protean benefits of PA and exercise extend across the spectrum of CVD, and include the improvement and reduction of risk factors and events for atherosclerotic CVD (ASCVD), cardiometabolic disease, heart failure, and atrial fibrillation (AF), respectively. Here, we highlight recent insights into the salutary effects of PA and exercise on the primary and secondary prevention of ASCVD, including their beneficial effects on both traditional and nontraditional risk mediators; exercise "prescriptions" for ASCVD; the role of PA regular exercise in the prevention and treatment of heart failure; and the relationships between, PA, exercise, and AF. While our understanding of the relationship between exercise and CVD has evolved considerably, several key questions remain including the association between extreme volumes of exercise and subclinical ASCVD and its risk; high-intensity exercise and resistance (strength) training as complementary modalities to continuous aerobic exercise; and dose- and intensity-dependent associations between exercise and AF. Recent advances in molecular profiling technologies (ie, genomics, transcriptomics, proteomics, and metabolomics) have begun to shed light on interindividual variation in cardiometabolic responses to PA and exercise and may provide new opportunities for clinical prediction in addition to mechanistic insights.

Effects of resistance training on insulin sensitivity in the elderly: A meta-analysis of randomized controlled trials

We performed a systematic review and meta-analysis of randomized controlled trials (RCTs) assessing the effect of resistance training in older adults on insulin sensitivity.

METHODS

Cochrane, Embase, PubMed, Web of Science and EBSCO were searched from inception to April 2021. We integrated randomized controlled trials published in English, and participants were non-athletic and aged ≥60 years. The outcome of interest was the change in insulin sensitivity, derived from the homeostatic model of insulin resistance (HOMA-IR) and hemoglobin A1c (HbA1c).

RESULTS

12 RCTs were included in this meta-analysis comparing resistance training (n = 232) with control (n = 209). Resistance exercise significantly reduced HOMA-IR level (d = -0.25, 95% CI, -0.43 to -0.06; P < 0.05) and HbA1c levels of (d = -0.51, 95% CI, -0.84 to -0.18; P < 0.05). Subgroup analysis of HOMA-IR revealed that the variables "population", "training intensity" and "period" had significant effects on HOMA-IR, with the largest effect sizes for high-intensity (d = -0.43, 95%CI, -0.85 to -0.22, P < 0.05) and long-term (more than 12 weeks) (d = -0.43, 95%CI, -0.85 to -0.22, P < 0.05) training programs in older adults without type 2 diabetes (T2D) (d = -0.23, 95%CI, -0.42 to -0.04, P < 0.05). Subgroup analysis of HbA1c suggested that resistance training programs with moderate intensity (d = -0.51, 95%CI, -0.90 to -0.12, P < 0.05) and short term (less than or equal to 12 weeks) (d = -0.49, 95%CI, -0.84 to -0.14, P < 0.05) have greater effects on HbA1c.

CONCLUSION

The findings of this meta-analysis suggest that resistance training is effective for inducing improvement in insulin sensitivity for elderly. Subgroup analysis showed that high intensity and long period of resistance exercise improve HOMA-IR in healthy old adults, and that resistance training with moderate intensity and short period improve HbA1c in T2D old people. More studies with high methodological qualities and large sample sizes need to be done to further confirm our conclusion.

Determining the effect size of aerobic exercise training on the standard lipid profile in sedentary adults with three or more metabolic syndrome factors: a systematic review and meta-analysis of randomised controlled trials

OBJECTIVES

To estimate the change in the standard lipid profile (SLP) of adults diagnosed with ≥3 metabolic syndrome (MetS) factors following aerobic exercise training (AET); and to investigate whether study/intervention covariates are associated with this change.

DESIGN

Systematic review with univariate meta-analysis and meta-regression.

DATA SOURCES

English language searches of online databases from inception until July 2020. ELIGIBILITY CRITERIA: (1) Published randomised controlled human trials with study population ≥10 per group; (2) sedentary adults with ≥3 MetS factors but otherwise free of chronic disease, not pregnant/lactating; (3) AET-only intervention with duration ≥12 weeks; and (4) reporting pre-post intervention SLP outcomes.

RESULTS

Various univariate meta-analyses pooled 48 data sets of 2990 participants. Aerobic exercise training significantly (P<.001) improved all lipids (mmol/L mean difference ranges, 95% CIs): total cholesterol, -0.19 (-0.26 to -0.12) to -0.29 (-0.36 to -0.21); triglycerides, -0.17 (-0.19 to -0.14) to -0.18 (-0.24 to -0.13); high-density lipoprotein-cholesterol (HDL-C), 0.05 (0.03 to 0.07) to 0.10 (0.05 to 0.15); and low-density lipoprotein-cholesterol (LDL-C), -0.12 (-0.16 to -0.9) to -0.20 (-0.25 to -0.14). Meta-regression showed that intensity may explain change in triglycerides and volume may explain change in HDL-C and LDL-C.

CONCLUSION

Aerobic exercise training positively changes the SLP of sedentary and otherwise healthy adults with ≥3 MetS factors. Adjusting AET intervention training variables may increase the effects of AET on triglycerides and HDL-C.

PROSPERO REGISTRATION NUMBER

CRD42020151925.

Cardioprotective effects of resistance training add to those of total activity in Americans

BACKGROUND

Resistance training is cardioprotective independent of total activity in experimental research and is prescribed to clinical populations, but is often largely neglected at population scale. Here we determine whether these benefits are relevant to general practice.

METHODS

A total of 6947 Americans over 20 years old (51% male) from NHANES 2003-2006 reported resistance training and objectively tracked 1-week total activity. Activity measures were modeled as five-level predictors of objectively measured binary heart-disease risks (hypertension, dyslipidemia, overweight, and diabetes) corrected for age, ethnicity, gender, and smoking. Significance was defined as Pfor trend less than .10 that the lowest activity category differed from the average of all others. If both activity measures predicted the same risk, mutually corrected models were run.

RESULTS

Average total activity was 20 minutes/day (SD 24). About 30% of subjects had resistance trained in the past month, reporting up to 7 sessions/day. Prevalences of hypertension, dyslipidemia, overweight, and diabetes were 32%, 46%, 68%, and 7.2%, respectively. All significant associations for resistance training (but not total activity) exhibited a threshold in dose-response curve, with comparable benefits from any dose above "none." Resistance trainers had significantly lower odds of hypertension (ORs, 0.55-0.85), overweight (ORs, 0.55-0.74), and diabetes (ORs, 0.51-0.80), but not dyslipidemia (ORs, 0.55-0.74). For total activity there was no significant trend in risk of either hypertension or dyslipidemia, but there were for overweight (ORs for each quintile above the lowest 1.04, 0.89, 0.78, and 0.49) and diabetes (ORs, 0.83, 0.68, 0.50, and 0.23; all Pfor trend <.01). Associations of resistance training with diabetes and obesity attenuated only slightly after correction for total activity, and vice versa.

CONCLUSIONS

Cardioprotective associations of resistance training were comparable to those of total activity and clinically relevant at low doses. Largest benefits accrued to those who combined any dose of resistance training with high total activity.

Diabetes and Composition of Weight Lifting and Cardio in Exercise

The prevalence of type-2 diabetes(T2D) has increased globally. This has led to greater mortality, morbidity and disability in the general population. It is thus crucial to identify methods to prevent its onset among the healthy, and to also discover solutions to adequately manage the complications among those affected. Most research in this area has focused on the role of diet and exercise. More recently, different exercise types and their relationship with T2D has received considerable attention. In our work, we investigate the association between T2D (primary outcome) and two types of exercises: cardio (CR) and weight lifting (WL). Specifically, the relationship between duration of time spent in the two exercises and the odds of T2D is explored. Data are obtained from the Behavioural Risk Factor Surveillance System (BRFSS) survey, USA. Three ethnic populations are considered: White American, Black American and Hispanic American. Both WL and CR are found to be associated with negative log-odds of diabetes across all three ethnicities (WL: p <; 0.0001 and CR: p=0.00431). The association between WL and T2D is found to be modified for females (interaction-term coefficient: -0.096 (p=0.0115)).

Perspective: Pragmatic Exercise Recommendations for Older Adults: The Case for Emphasizing Resistance Training

Optimal health benefits from exercise are achieved by meeting both aerobic and muscle strengthening guidelines, however, most older adults (OAs) do not exercise and the majority of those who do only perform one type of exercise. A pragmatic solution to this problem may be emphasizing a single exercise strategy that maximizes health benefits. The loss of muscle mass and strength at an accelerated rate are hallmarks of aging that, without intervention, eventually lead to physical disability and loss of independence. Additionally, OAs are at risk of developing several chronic diseases. As such, participating in activities that can maintain or increase muscle mass and strength, as well as decrease chronic disease risk, is essential for healthy aging. Unfortunately, there is a widely held belief that adaptations to aerobic and resistance exercise are independent of each other, requiring the participation of both types of exercise to achieve optimal health. However, we argue that this assertion is incorrect, and we discuss crossover adaptations of both aerobic and resistance exercise. Aerobic exercise can increase muscle mass and strength, though not consistently and may be limited to exercise that overloads a particular muscle group, such as stationary bicycling. In contrast, resistance exercise is effective at maintaining muscle health with increasing age, and also has significant effects on cardiovascular disease (CVD) risk factors, type 2 diabetes (T2D), cancer, and mortality. We posit that resistance exercise is the most effective standalone exercise strategy for improving overall health in OAs and should be emphasized in future guidelines.

Cardiorespiratory Fitness, Body Mass Index, and Markers of Insulin Resistance in Apparently Healthy Women and Men

BACKGROUND

Insulin resistance may be present in healthy adults and is associated with poor health outcomes. Obesity is a risk factor for insulin resistance, but most obese adults do not have insulin resistance. Fitness may be protective, but the association between fitness, weight, and insulin resistance has not been studied in a large population of healthy adults.

METHODS

A cross-sectional analysis of cardiorespiratory fitness, body mass index, and markers of insulin resistance was performed. Study participants were enrolled at the Cooper Clinic in Dallas, Texas. The analysis included 19,263 women and 48,433 men with no history of diabetes or cardiovascular disease. Cardiorespiratory fitness was measured using exercise treadmill testing. Impaired fasting glucose (100-125 mg/dL) and elevated fasting triglycerides (≥150 mg/dL) were used as a markers of insulin resistance.

RESULTS

Among individuals with normal weight, poor fitness was associated with 2.2-fold higher odds of insulin resistance in women (1.4-3.6; P = .001) and 2.8-fold higher odds in men (2.1-3.6; P <.001). The impact of fitness remained significant for overweight and obese individuals, with the highest risk group being the unfit obese. Among obese women, the odds ratio for insulin resistance was 11.0 for fit women (8.7-13.9; P <.001) and 20.3 for unfit women (15.5-26.5; P <.001). Among obese men, the odds ratio for insulin resistance was 7.4 for fit men (6.7-8.2; P < .001) and 12.9 for unfit men (11.4-14.6; P < .001).

CONCLUSIONS

Independent of weight, poor fitness is associated with risk of insulin resistance. Obese individuals, particularly women, may benefit from the greatest absolute risk reduction by achieving moderate fitness.

Resistance Exercise Training as a Primary Countermeasure to Age-Related Chronic Disease

Age is a primary risk factor for a number of chronic diseases including mobility disability, cardiovascular disease (CVD), type 2 diabetes (T2D), and cancer. Most physical activity guidelines emphasize the performance of 150 min of moderate-to-vigorous or 75 min of vigorous aerobic exercise training (AET) weekly for reduction of chronic disease risk. Nonetheless, there is an emerging body of evidence showing that resistance exercise training (RET) appears to be as effective as AET in reducing risk of several chronic diseases. It may also be that RET is more effective than AET in some regards; the converse is likely also true. We posit that the perceived divergent exercise mode-dependent health benefits of AET and RET are likely small in most cases. In this short review, our aim is to examine evidence of associations between the performance of RET and chronic health disease risk (mobility disability, T2D, CVD, cancer). We also postulate on how RET may be influencing chronic disease risk and how it is a critical component for healthy aging. Accumulating evidence points to RET as a potent and robust preventive strategy against a number of chronic diseases traditionally associated with the performance of AET, but evidence favors RET as a potent countermeasure against declines in mobility. On the basis of this review we propose that the promotion of RET should assume a more prominent position in exercise guidelines particularly for older persons.

Effect of Strength Training on Lipid and Inflammatory Outcomes: Systematic Review With Meta-Analysis and Meta-Regression

Background: The aim of this study was to perform a systematic review with meta-analysis and meta-regressions evaluating the effects of isolated strength training (ST), compared with a control group, on total cholesterol (TC), triglycerides (TG), low-density (LDL), high-density lipoprotein (HDL), C-reactive protein (CRP), and adiponectin of adults. Methods: Embase, PubMed, Cochrane, and Scopus data sources were searched up to May 2017. Clinical trials that compared ST with a control group of adults older than 18 years, which evaluated blood TC, TG, LDL, HDL, CRP, or adiponectin as an outcome were included. Random effect was used and the effect size (ES) was calculated by using the standardized mean difference with a 95% confidence interval. Results: ST promotes a reduction in TC (ES: -0.399; P < .001), TG (ES: -0.204; P = .002), LDL (ES: -0.451; P < .001), and CRP (ES: -0.542; P = .01) levels. In addition, ST is associated to an increase in HDL (ES: 0.363; P < .001) and adiponectin concentrations (ES: 1.105; P = .01). Conclusion: ST promotes decreases in TC, TG, LDL, and CRP levels and increases HDL and adiponectin concentrations. Thus, progressive ST could be a potential therapeutic option for improving abnormalities in lipid and inflammatory outcomes in adults.

Better lung function with increased handgrip strength, as well as maximum oxygen uptake, in congenital heart disease across the lifespan

Background

The respiratory benefits of muscle strength are well-known in heart-healthy populations, but recommendations and research often focus instead on aerobic fitness (peak oxygen uptake) or total activity. Independent benefits of strength thus may be underestimated, especially in congenital heart disease where perceived dangers of certain types of exercise may outweigh perceived benefits. To assess whether it is plausible that pulmonary benefits of strength in heart-healthy populations also apply in congenital heart disease, we simultaneously correlated these patients’ lung function with fitness, strength, and cardiac diagnosis.

Methods

Lung function (forced expiratory volume in one second percentage predicted (FEV1%pred)) was modeled as function of handgrip strength, congenital heart disease diagnosis, peak oxygen uptake and the interactions of handgrip with sex and diagnosis in 538 Germans (58% male, ages 6–82 years) in linear models corrected for age, sex, height and weight. Congenital heart disease diagnoses were: complex cyanotic; Fallot/Truncus arteriosus communis (common arterial trunk) (TAC); shunts; transposition of the great arteries (TGA); left heart; and other/none.

Results

Each kg of handgrip was associated with 0.74% higher FEV1%pred ( p < 0.001) and handgrip explained almost 10% of variance in FEV1%pred. While some groups had higher FEV1%pred than others ( p for global null <0.0001), all experienced similar associations with strength ( p for interaction with handgrip >0.10 for both sex and diagnosis.) Correction for peak oxygen uptake eliminated the association with congenital heart disease, but not handgrip.

Conclusion

Strength was associated with better lung function in all ages even after correction for peak oxygen uptake, regardless of sex and congenital heart disease. This suggests that strength may be at least as important for lung function as aerobic fitness. Heart-safe strength training may improve pulmonary function in congenital heart disease.

Comparison of time-matched aerobic, resistance, or concurrent exercise training in older adults

A supervised 12-week intervention of time-matched aerobic vs resistance versus concurrent exercise training was employed to investigate mode- and time course-specific effects of exercise training in older adults. Community-dwelling men and women (n = 84; M/F, 45/39; 69.3 ± 3.5 years; 26.4 ± 3.8 kg m^-2 ) were randomly assigned (n = 21 each) to either non-exercise control (CON), aerobic exercise only (AER), resistance exercise only (RES), or concurrent aerobic and resistance exercise (CEX). Training groups trained three times per week, each performing 72 minutes of active exercise time per week. Body composition, physical and cognitive function, and markers of metabolic health were assessed before (PRE), and after 6 (MID) and 12 (POST) weeks of exercise training. Hand-grip strength, 1RM chest press, and arm LBM were improved by both RES and CEX, but not AER. Aerobic fitness increased in AER and RES, but not CEX. Cognitive function improved in all groups, but occurred earlier (ie, at MID) in AER. CEX improved gait speed and lower limb strength and reduced trunk fat compared to either AER or RES. Leg LBM was unchanged in any group. Temporal patterns were observed as early as 6 weeks of training (gait speed, upper and lower limb strength, aerobic fitness), whereas others were unchanged until 12 weeks (hand-grip strength, timed up-and-go, sit-to-stand). Compared to either aerobic or resistance exercise training alone, concurrent exercise training is as efficacious for improving a range of health-related parameters and is more efficacious for increasing gait speed and lower limb strength, and decreasing trunk fat in older adults.

Association of baseline level of physical activity and its temporal changes with incident hypertension and diabetes mellitus

Background The association between baseline and temporal changes in physical activity and incident hypertension or diabetes mellitus in initially non-hypertensive or non-diabetic subjects is rarely known. Methods Among individuals who underwent consecutive comprehensive health screenings, their physical activity level was measured using a self-reported international physical activity questionnaire. First, subjects were classified into four categories: no regular physical activity with a sedentary lifestyle; minimal physical activity (<75 min/week); insufficient physical activity (≥75 min but <150 min/week); and sufficient physical activity (≥150 min/week). Second, subjects were sub-grouped, based on temporal changes in physical activity level between baseline and consecutive follow-up: increase, no change, and decrease. Results Finally, among 174,314 subjects (mean age 36.7 ± 6.9 years), 5544 (3.18%) and 21,276 (12.2%) developed incident diabetes mellitus and arterial hypertension, respectively. After a multivariate adjustment, sufficient baseline physical activity was associated with significantly lower risk for incident hypertension (hazard ratio 0.89; 95% confidence interval (CI) 0.81 to 0.97), but the difference was not significant, and showed a lower trend in diabetes mellitus incidence (hazard ratio 0.87; 95% CI 0.69 to 1.04) in reference to no regular physical activity group. Regardless of the baseline physical activity level, subjects with a temporal increase in physical activity showed significantly decreased risk for incident hypertension (hazard ratio 0.93; 95% CI 0.87 to 0.99) and diabetes mellitus (hazard ratio 0.83; 95% CI 0.74 to 0.92) compared with those with a temporal decrease in their physical activity level. Conclusion Both sufficient baseline physical activity level and its temporal increase were associated with a lower risk of incident hypertension and diabetes mellitus in a large, relatively healthy, cohort.

Dehydroepiandrosterone supplementation combined with Weight-Loading Whole-Body Vibration Training (WWBV) affects exercise performance and muscle glycogen storage in middle-aged C57BL/6 mice

Background: Adequate nutritional intake and an optimal training program are important elements of any strategy to preserve or increase muscle mass and strength during aging. Purpose: In the current study, we investigate the effects of Dehydroepiandrosterone (DHEA), one of the most abundant circulating steroids in humans and a precursor hormone, supplementation combined with a weight-loading whole-body vibration (WWBV) on exercise performance, physical fatigue-related biochemical responses and testosterone content in middle-aged 9 months old C57BL/6 mice. Methods: Male middle-aged C57BL/6 mice were divided into 3 groups (n = 8 per group) and treated for 4 weeks with the following: 1) Sedentary control (SC) with vehicle 2) DHEA supplementation (DHEA, 10.2 mg/kg) and 3) DHEA supplementation with WWBV training (DHEA: 10.2 mg/kg; WBV: 5.6 Hz, 2 mm, 0.13 g). Exercise performance was evaluated by forelimb grip strength and time to exhaustion, as well as changes in body composition and anti-fatigue levels after a 15-min swimming exercise. Fatigue-related biochemical responses of serum lactate, ammonia, glucose, creatine kinase (CK), and blood urea nitrogen (BUN) were measured following the swimming exercise. In addition, the biochemical parameters and the testosterone levels were measured at the end of the experiment. Results: DHEA supplementation combined with WWBV training for 4 weeks significantly decreased the amount of white adipose tissue and increased the food and water intake. Additionally, WWBV+DHEA supplementation improved exercise performance, testosterone levels and glycogen contents of both liver and muscle. WWBV+DHEA supplementation also decreased serum lactate, ammonia and BUN levels, while increasing glucose levels following the 15-min swim test. Conclusion: Taken together, our results suggest that combining the WWBV training program with DHEA supplementation could provide an anti-fatigue pharmacological effect for elderly populations.

Dynamic Resistance Training as Stand-Alone Antihypertensive Lifestyle Therapy: A Meta-Analysis

Background

Aerobic exercise (AE) is recommended as first‐line antihypertensive lifestyle therapy based on strong evidence showing that it lowers blood pressure (BP) 5 to 7 mm Hg among adults with hypertension. Because of weaker evidence showing that dynamic resistance training (RT) reduces BP 2 to 3 mm Hg among adults with hypertension, it is recommended as adjuvant lifestyle therapy to AE training. Yet, existing evidence suggests that dynamic RT can lower BP as much or more than AE.

Methods and Results

We meta‐analyzed 64 controlled studies (71 interventions) to determine the efficacy of dynamic RT as stand‐alone antihypertensive therapy. Participants (N=2344) were white (57%), middle‐aged (47.2±19.0 years), and overweight (26.8±3.4 kg/m²) adults with prehypertension (126.7±10.3/76.8±8.7 mm Hg); 15% were on antihypertensive medication. Overall, moderate‐intensity dynamic RT was performed 2.8±0.6 days/week for 14.4±7.9 weeks and elicited small‐to‐moderate reductions in systolic BP (SBP; d₊=−0.31; 95% CIs, −0.43, −0.19; −3.0 mm Hg) and diastolic BP (DBP; d₊=−0.30; 95% CIs, −0.38, −0.18; −2.1 mm Hg) compared to controls (Ps<0.001). Greater BP reductions occurred among samples with higher resting SBP/DBP: ≈6/5 mm Hg for hypertension, ≈3/3 mm Hg for prehypertension, and ≈0/1 mm Hg for normal BP (Ps<0.023). Furthermore, nonwhite samples with hypertension experienced BP reductions that were approximately twice the magnitude of those previously reported following AE training (−14.3 mm Hg [95% CIs, −19.0, −9.4]/−10.3 mm Hg [95% CIs, −14.5, −6.2]).

Conclusions

Our results indicate that for nonwhite adult samples with hypertension, dynamic RT may elicit BP reductions that are comparable to or greater than those reportedly achieved with AE training. Dynamic RT should be further investigated as a viable stand‐alone therapeutic exercise option for adult populations with high BP.

Adoption and maintenance of gym-based strength training in the community setting in adults with excess weight or type 2 diabetes: a randomized controlled trial

Background

Participant adoption and maintenance is a major challenge in strength training (ST) programs in the community-setting. In adults who were overweight or with type 2 diabetes (T2DM), the aim of this study was to compare the effectiveness of a standard ST program (SST) to an enhanced program (EST) on the adoption and maintenance of ST and cardio-metabolic risk factors and muscle strength.

Methods

A 12-month cluster-randomized controlled trial consisting of a 6-month adoption phase followed by a 6-month maintenance phase. In 2008–2009, men and women aged 40–75 years (n = 318) with T2DM (n = 117) or a BMI >25 (n = 201) who had not participated in ST previously were randomized into either a SST or an EST program (which included additional motivationally-tailored behavioral counselling). Adoption and maintenance were defined as undertaking ≥ 3 weekly gym-based exercise sessions during the first 6-months and from 6–12 months respectively and were assessed using a modified version of the CHAMPS (Community Healthy Activity Models Program for Seniors) instrument.

Results

Relative to the SST group, the adjusted odds ratio (OR) of adopting ST for all participants in the EST group was 3.3 (95 % CI 1.2 to 9.4). In stratified analyses including only those with T2DM, relative to the SST group, the adjusted OR of adopting ST in the EST group was 8.2 (95 % CI 1.5–45.5). No significant between-group differences were observed for maintenance of ST in either pooled or stratified analyses. In those with T2DM, there was a significant reduction in HbA1c in the EST compared to SST group during the adoption phase (net difference, -0.13 % [-0.26 to -0.01]), which persisted after 12-months (-0.17 % [-0.3 to -0.05]).

Conclusions

A behaviorally-focused community-based EST intervention was more effective than a SST program for the adoption of ST in adults with excess weight or T2DM and led to greater improvements in glycemic control in those with T2DM.

Trial registration

Registered at ACTRN12611000695909 (Date registered 7/7/2011).

The effects of electrical stimulation on body composition and metabolic profile after spinal cord injury--Part II

Diet and exercise are cornerstones in the management of obesity and associated metabolic complications, including insulin resistance, type 2 diabetes, and disturbances in the lipid profile. However, the role of exercise in managing body composition adaptations and metabolic disorders after spinal cord injury (SCI) is not well established. The current review summarizes evidence about the efficacy of using neuromuscular electrical stimulation or functional electrical stimulation in exercising the paralytic lower extremities to improve body composition and metabolic profile after SCI. There are a number of trials that investigated the effects on muscle cross-sectional area, fat-free mass, and glucose/lipid metabolism. The duration of the intervention in these trials varied from 6 weeks to 24 months. Training frequency ranged from 2 to 5 days/week. Most studies documented significant increases in muscle size but no noticeable changes in adipose tissue. While increases in skeletal muscle size after twice weekly training were greater than those trials that used 3 or 5 days/week, other factors such as differences in the training mode, i.e. resistance versus cycling exercise and pattern of muscle activation may be responsible for this observation. Loading to evoke muscle hypertrophy is a key component in neuromuscular training after SCI. The overall effects on lean mass were modest and did not exceed 10% and the effects of training on trunk or pelvic muscles remain unestablished. Most studies reported improvement in glucose metabolism with the enhancement of insulin sensitivity being the major factor following training. The effect on lipid profile is unclear and warrants further investigation.

Effects of strength training on blood lipoprotein concentrations in postmenopausal women

Strength training is often identified as a contributing factor in prevention of diseases and as a non-pharmacological treatment for metabolic disorders and for control of body mass. Its protective effects and utility for management of disease are amplified in people at risk of diabetes mellitus and dyslipidemias, and cardiovascular diseases (CVD). Recently the benefits of strength training have been used to reduce the risk of these diseases emerging in postmenopausal women, who are at greater risk of CVD than men of the same age. Notwithstanding, little is known about the effects of strength training on metabolism of blood lipoproteins. The objective of this review was to compare the results of articles that have investigated the effects on lipoprotein concentrations of strength training in postmenopausal women. Current articles dealing with the subject, with publication dates from 1979 to 2012 and large numbers of citations by well-known researchers were identified on the Pubmed, Scopus and EBSCO databases. It was concluded that strength training possibly has an action that affects lipoprotein metabolism and concentrations in postmenopausal women.

Do statins increase and Mediterranean diet decrease the risk of breast cancer?

BACKGROUND

Physical exercise and healthy dietary habits are recommended to prevent breast cancer.

DISCUSSION

Increased intake of omega-3 fatty acids associated with decreased omega-6 - resulting in higher omega-3 to omega-6 ratio compared with Western-type diet - is inversely associated with breast cancer risk. The modernized Mediterranean diet with high omega-3 to omega-6 ratio, high fiber and polyphenol intake, and consumption of low-glycemic index foods reduces overall cancer risk and specifically breast cancer risk. It has been suggested that consuming no more than one alcoholic drink per day, preferably wine, is preferable. Eliminating environmental contaminants, including endocrine disruptors, and favoring organic foods to increase polyphenol intake and the omega-3 to omega-6 ratios were also shown to be beneficial. Cholesterol-lowering statins may decrease antitumor defenses; are toxic for the mitochondria; decrease the omega-3 to omega-6 ratio; increase body mass index, insulin resistance and diabetic risk; and have been associated with an increased breast cancer risk.

SUMMARY

Therefore, as well as making lifestyle changes to decrease breast cancer risk, we argue that physicians should carefully consider (and often avoid) therapies that may increase breast cancer or diabetes risk in high-risk women and women who wish to decrease their breast cancer risk.

Impact of diet and exercise on lipid management in the modern era

Unfortunately, many patients as well as the medical community, continue to rely on coronary revascularization procedures and cardioprotective medications as a first-line strategy to stabilize or favorably modify established risk factors and the course of coronary artery disease. However, these therapies do not address the root of the problem, that is, the most proximal risk factors for heart disease, including unhealthy dietary practices, physical inactivity, and cigarette smoking. We argue that more emphasis must be placed on novel approaches to embrace current primary and secondary prevention guidelines, which requires attacking conventional risk factors and their underlying environmental causes. The impact of lifestyle on the risk of cardiovascular disease has been well established in clinical trials, but these results are often overlooked and underemphasized. Considerable data also strongly support the role of lifestyle intervention to improve glucose and insulin homeostasis, as well as physical inactivity and/or low aerobic fitness. Accordingly, intensive diet and exercise interventions can be highly effective in facilitating coronary risk reduction, complementing and enhancing medications, and in some instances, even outperforming drug therapy.

Modification of insulin sensitivity and glycemic control by activity and exercise

Type 2 diabetes has progressed into a major contributor to preventable death, and developing optimal therapeutic strategies to prevent future type 2 diabetes and its primary clinical manifestation of cardiovascular disease is a major public health challenge. This article will provide a brief overview of the role of activity and exercise in modulating insulin sensitivity and will outline the effect of physical activity, high-intensity interval training, and resistance training on insulin sensitivity and glycemic control.

Resistance exercise at variable volume does not reduce postprandial lipemia in postmenopausal women

The aim of this study was to investigate the acute effects of resistance exercise sessions (RESs) performed at different levels of high-volume resistance exercise (HVRE) and low-volume resistance exercise (LVRE) on postprandial lipemia (PPL) in postmenopausal women. Thirty-nine healthy unconditioned postmenopausal women (59.5 ± 4.8 years of age, body mass 69.6 ± 9.1 kg, height 157.9 ± 7.2 cm, BMI 27.6 ± 4.1 kg m(-2), waist circumference 76.1 ± 9.7 cm, VO2max 18.7 ± 1.4 mL kg(-1) min(-1)) were assigned to a LVRE (n = 12), HVRE (n = 14), and control group (CG, n = 13). Experimental groups performed one RES involving eight exercises. The HVRE group performed three sets with a maximum of 15 repetitions, and the LVRE group performed one set with a maximum of 15 repetitions. Approximately 16 h after a RES, all of the groups were given an oral fat tolerance test (OFTT). During the RES, we evaluated the energy expenditure (EE) of the resistance session and excess postexercise oxygen consumption (EPOC); following the RES and the OFTT, we evaluated lipid profiles (total cholesterol, HDL, LDL, and triglycerides). While the study groups did not demonstrate significant differences in lipid profiles, the total energy expenditure (EE + EPOC) of the session exercise treatments was significantly higher for HVRE than for LVRE (0.60 ± 0.12 and 0.31 ± 0.11 MJ, respectively, p < 0.001). Different levels of resistance exercise do not lower basal triglyceride concentration and postprandial lipid profile parameters at approximately 16 h following resistance exercise in untrained postmenopausal women.

Impact of different training modalities on anthropometric and metabolic characteristics in overweight/obese subjects: a systematic review and network meta-analysis

Background

The aim of this systematic review of randomized controlled trials was to compare the effects of aerobic training (AET), resistance training (RT), and combined aerobic and resistance training (CT) on anthropometric parameters, blood lipids, and cardiorespiratory fitness in overweight and obese subjects.

Methods

Electronic searches for randomized controlled trials were performed in MEDLINE, EMBASE and the Cochrane Trial Register. Inclusion criteria were: Body Mass Index: ≥25 kg/m², 19+ years of age, supervised exercise training, and a minimum intervention period of 8 weeks. Anthropometric outcomes, blood lipids, and cardiorespiratory fitness parameters were included. Pooled effects were calculated by inverse-variance random effect pairwise meta-analyses and Bayesian random effects network meta-analyses.

Findings

15 trials enrolling 741 participants were included in the meta-analysis. Compared to RT, AET resulted in a significantly more pronounced reduction of body weight [mean differences (MD): -1.15 kg, p = 0.04], waist circumference [MD: -1.10 cm, p = 0.004], and fat mass [MD: -1.15 kg, p = 0.001] respectively. RT was more effective than AET in improving lean body mass [MD: 1.26 kg, p<0.00001]. When comparing CT with RT, MD in change of body weight [MD: -2.03 kg, p<0.0001], waist circumference [MD: -1.57 cm, p = 0.0002], and fat mass [MD: -1.88 kg, p<0.00001] were all in favor of CT. Results from the network meta-analyses confirmed these findings.

Conclusion

Evidence from both pairwise and network meta-analyses suggests that CT is the most efficacious means to reduce anthropometric outcomes and should be recommended in the prevention and treatment of overweight, and obesity whenever possible.

Metabolic syndrome and insulin resistance: underlying causes and modification by exercise training

Metabolic syndrome (MS) is a collection of cardiometabolic risk factors that includes obesity, insulin resistance, hypertension, and dyslipidemia. Although there has been significant debate regarding the criteria and concept of the syndrome, this clustering of risk factors is unequivocally linked to an increased risk of developing type 2 diabetes and cardiovascular disease. Regardless of the true definition, based on current population estimates, nearly 100 million have MS. It is often characterized by insulin resistance, which some have suggested is a major underpinning link between physical inactivity and MS. The purpose of this review is to: (i) provide an overview of the history, causes and clinical aspects of MS, (ii) review the molecular mechanisms of insulin action and the causes of insulin resistance, and (iii) discuss the epidemiological and intervention data on the effects of exercise on MS and insulin sensitivity.

Lower maternal body condition during pregnancy affects skeletal muscle structure and glut-4 protein levels but not glucose tolerance in mature adult sheep

Suboptimal maternal nutrition and body composition are implicated in metabolic disease risk in adult offspring. We hypothesized that modest disruption of glucose homeostasis previously observed in young adult sheep offspring from ewes of a lower body condition score (BCS) would deteriorate with age, due to changes in skeletal muscle structure and insulin signaling mechanisms. Ewes were fed to achieve a lower (LBCS, n = 10) or higher (HBCS, n = 14) BCS before and during pregnancy. Baseline plasma glucose, glucose tolerance and basal glucose uptake into isolated muscle strips were similar in male offspring at 210 ± 4 weeks. Vastus total myofiber density (HBCS, 343 ± 15; LBCS, 294 ± 14 fibers/mm(2), P < .05) and fast myofiber density (HBCS, 226 ± 10; LBCS 194 ± 10 fibers/mm(2), P < .05), capillary to myofiber ratio (HBCS, 1.5 ± 0.1; LBCS 1.2 ± 0.1 capillary:myofiber, P < .05) were lower in LBCS offspring. Vastus protein levels of Akt1 were lower (83% ± 7% of HBCS, P < .05), and total glucose transporter 4 was increased (157% ± 6% of HBCS, P < .001) in LBCS offspring, Despite the reduction in total myofiber density in LBCS offspring, glucose tolerance was normal in mature adult life. However, such adaptations may lead to complications in metabolic control in an overabundant postnatal nutrient environment.

The Cooperative Lifestyle Intervention Program-II (CLIP-II): design and methods

A complication of cardiovascular disease (CVD) and the metabolic syndrome (MetS) among older adults is loss of mobility. The American Heart Association has identified weight management as a core component of secondary prevention programs for CVD and is an important risk factor for physical disability. The American Society for Nutrition and the Obesity Society have highlighted the need for long-term randomized clinical trials to evaluate the independent and additive effects of diet-induced weight loss (WL) and physical activity in older persons on outcomes such as mobility, muscle function, and obesity related diseases. Here we describe the rationale, design, and methods of a translational study, the Cooperative Lifestyle Intervention Program-II (CLIP-II). CLIP-II will randomize 252 obese, older adults with CVD or MetS to a weight loss only treatment (WL), aerobic exercise training (AT)+WL, or resistance exercise training (RT)+WL for 18 months. The dual primary outcomes are mobility and knee extensor strength. The interventions will be delivered by YMCA community partners with our staff as trainers and advisers. This study will provide the first large scale trial to evaluate the effects of diet-induced WL on mobility in obese, older adults with CVD or MetS as compared to WL combined with two different modes of physical activity (AT and RT). Because uncertainty exists about the best approach for promoting WL in older adults due to concerns with the loss of lean mass, the design also permits a contrast between AT+WL and RT+WL on muscle strength.

The effect of exercise on the cardiovascular risk factors constituting the metabolic syndrome: a meta-analysis of controlled trials

Background

Numerous meta-analyses have investigated the effect of exercise in different populations and for single cardiovascular risk factors, but none have specifically focused on the metabolic syndrome (MetS) patients and the concomitant effect of exercise on all associated cardiovascular risk factors.

Objective

The aim of this article was to perform a systematic review with a meta-analysis of randomized and clinical controlled trials (RCTs, CTs) investigating the effect of exercise on cardiovascular risk factors in patients with the MetS.

Methods

RCTs and CTs ≥4 weeks investigating the effect of exercise in healthy adults with the MetS and published in a peer-reviewed journal up to November 2011 were included. Primary outcome measures were changes in waist circumference (WC), systolic and diastolic blood pressure, high-density lipoprotein cholesterol (HDL-C), triglycerides and fasting plasma glucose. Peak oxygen uptake (\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ {\dot{{V}}\text{O}}_{{ 2 {\text{peak}}}} $$\end{document}) was a secondary outcome. Random and fixed-effect models were used for analyses and data are reported as means and 95% confidence intervals (CIs).

Results

Seven trials were included, involving nine study groups and 206 participants (128 in exercise group and 78 in control group). Significant mean reductions in WC −3.4 (95% CI −4.9, −1.8) cm, blood pressure −7.1 (95% CI −9.03, −5.2)/−5.2 (95% CI −6.2, −4.1) mmHg and a significant mean increase in HDL-C +0.06 (95% CI +0.03, +0.09) mmol/L were observed after dynamic endurance training. Mean plasma glucose levels −0.31 (95% CI −0.64, 0.01; p = 0.06) mmol/L and triglycerides −0.05 (95% CI −0.20, 0.09; p = 0.47) mmol/L remained statistically unaltered. In addition, a significant mean improvement in \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$ {\dot{{V}}\text{O}}_{{ 2 {\text{peak}}}} $$\end{document} of +5.9 (95% CI +3.03, +8.7) mL/kg/min or 19.3% was found.

Conclusions

Our results suggest that dynamic endurance training has a favourable effect on most of the cardiovascular risk factors associated with the MetS. However, in the search for training programmes that optimally improve total cardiovascular risk, further research is warranted, including studies on the effects of resistance training and combined resistance and endurance training.

Resistance training decreases 24-hour blood pressure in women with metabolic syndrome

BACKGROUND

The purpose of this study was to verify the effects of eight weeks of resistance training (RT) on 24 hour blood pressure (BP) in patients with and without metabolic syndrome (MetS).

METHODS

Seventeen women volunteered to participate in this study, 9 with MetS (37.0 ± 8.7 yrs; body mass 77.3 ± 9.7 kg; body mass index 30.3 ± 4.2 kg · m(-2)) and 8 without MetS (35.1 ± 7.2 yrs; body mass 61.3 ± 8.1 kg; body mass index 24.2 ± 2.5 kg · m(-2)). Individuals were subjected to eight weeks (3 times/week) of whole body RT comprised of one exercise for each main muscle group with three sets of 8-12 repetitions of each subject's maximal load . A rest interval of one minute was allowed between sets and exercises. Twenty-four hour BP was measured by ambulatory blood pressure monitoring.

RESULTS

Mean and diastolic night-time BP decreased (-3.9 mmHg, p = 0.04; -5.5 mmHg, p = 0.03, respectively) after eight weeks of training in MetS patients. This decrease was observed at 11:00 pm, 02:00 am (only diastolic), 07:00 am, and 6:00 pm. There was no training effect on BP in women without MetS.

CONCLUSIONS

Considering the elevation of BP as a contributor to the pathogenesis of MetS, and also to the increase of cardiovascular risk, this study supports RT as a non-pharmacological therapy in the management of BP control for MetS.

Intensidades de treinamento resistido e pressão arterial de idosas hipertensas - um estudo piloto

INTRODUÇÃO: Observa-se que a literatura apresenta uma lacuna acerca da intensidade ideal de treinamento resistido para idosos hipertensos, os poucos estudos existentes utilizam treinamentos com diferentes intensidades. OBJETIVO: Verificar o efeito de duas intensidades de treinamento resistido sobre a pressão arterial de idosas hipertensas controladas. Métodos: Dezesseis idosas hipertensas, controladas por medicação anti-hipertensiva, foram divididas em dois grupos através de sorteio. Nove pacientes foram submetidas a treinamento resistido moderado (G1) e sete, a treinamento resistido leve (G2). As pacientes realizaram oito semanas de treinamento resistido, com frequência de três vezes por semana em dias alternados, no período vespertino. Os exercícios realizados foram respectivamente: leg press, supino reto, extensão de joelhos, puxada frontal, flexão de joelhos, abdução de ombro, abdução unilateral de quadril com cross over e rosca direta com barra. RESULTADOS: As pacientes do G1 apresentaram redução tanto nos valores de repouso da pressão arterial diastólica (PAD) p < 0,03, como da pressão arterial média (PAM) p < 0,03. O G2, por sua vez, apresentou redução nos valores de repouso da PAM (p < 0,03) e uma tendência à redução na PAD (p < 0,06). A magnitude de queda em ambos os grupos foi superior aos valores apresentados na literatura. CONCLUSÂO: Tanto o treinamento resistido moderado quanto o leve, mesmo quando iniciados na terceira idade, promoveram benefícios cardiovasculares. Ambos podem ser indicados como tratamento coadjuvante para idosas hipertensas controladas por medicação.

Commentary on the clinical management of metabolic syndrome: why a healthy lifestyle is important

Metabolic syndrome (MS) is associated with an increased risk of type 2 diabetes mellitus and cardiovascular diseases. There is no recognized method to manage MS. Many physicians treat the individual characteristics of MS (high blood pressure, high triglycerides, and so on) instead of the syndrome as a whole, placing particular emphasis on those components that are easily amenable to drug treatment. However, regular physical exercise and a healthy diet have been demonstrated to improve the health of a number of populations, but few studies have assessed their effects in patients with MS. A meta-analysis by Yamaoka and Tango in BMC Medicine found that a lifestyle change program (dietary counseling and encouragement to exercise) resulted in improvements in components of MS and in reducing the proportion of patients with MS. The effects may not be impressive in absolute terms, but the data should be interpreted with the heterogeneity of the included studies in mind. Because of the many adverse side effects of the drugs used to correct individual aspects of MS, this meta-analysis provides strong evidence that lifestyle changes must be the first-line approach to manage MS.See related article http://www.biomedcentral.com/1741-7015/10/138/abstract.

Physical activity, health benefits, and mortality risk

A plethora of epidemiologic evidence from large studies supports unequivocally an inverse, independent, and graded association between volume of physical activity, health, and cardiovascular and overall mortality. This association is evident in apparently healthy individuals, patients with hypertension, type 2 diabetes mellitus, and cardiovascular disease, regardless of body weight. Moreover, the degree of risk associated with physical inactivity is similar to, and in some cases even stronger than, the more traditional cardiovascular risk factors. The exercise-induced health benefits are in part related to favorable modulations of cardiovascular risk factors observed by increased physical activity or structured exercise programs. Although the independent contribution of the exercise components, intensity, duration, and frequency to the reduction of mortality risk is not clear, it is well accepted that an exercise volume threshold defined at caloric expenditure of approximately 1,000 Kcal per week appears to be necessary for significant reduction in mortality risk. Further reductions in risk are observed with higher volumes of energy expenditure. Physical exertion is also associated with a relatively low and transient increase in risk for cardiac events. This risk is significantly higher for older and sedentary individuals. Therefore, such individuals should consult their physician prior to engaging in exercise.

“Walking is man’s best medicine”

Hippocrates

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).

Resistance exercise and aerobic exercise when paired with dietary energy restriction both reduce the clinical components of metabolic syndrome in previously physically inactive males

The purpose of this study was to compare resistance exercise training (RT) to aerobic exercise training (AE) on the clinical risk factors for metabolic syndrome (MetSyn) in physically inactive overweight males (age 27-48 years). Subjects with at least one risk factor for MetSyn performed RT (n = 13, age 35.1 ± 4.7 years, BMI 31.2 ± 2.7 kg/m(2)) or AE (n = 9, age 37.6 ± 4.9 years, BMI, 31.2 ± 3.2 kg/m(2)) for 6 months. Training frequency and exercise session duration were equal and by 3 months the subjects exercised 4 day/week for 45 min/session. Blood lipids and glucose, waist circumference, and mean arterial blood pressure (MAP) were measured at 0, 3, and 6 months. A MetSyn z score was calculated for each subject from triglycerides, HDL cholesterol, fasting glucose, waist circumference, and MAP. Statistical significance was set at p ≤ 0.05. No significant differences existed between RT and AE groups at 0 month. AE showed a significant reduction in MetSyn z score from 0 (0.91 ± 3.57) to 6 months (-1.35 ± 2.95), while RT approached significance (p = 0.07) from 0 (0.09 ± 2.62) to 6 months (-1.30 ± 2.22). Triglycerides (mmol/L) significantly decreased in AE from 0 (1.93 ± 0.90) to 6 months (1.41 ± 0.70). Waist circumference (cm) significantly decreased in AE from 0 (106.8 ± 7.3) to 6 months (101.2 ± 6.5), and in RT from 0 (108.4 ± 9.0) to 6 months (105.7 ± 7.0). MAP (mmHg) decreased in RT from 0 (93.8 ± 5.8) to 6 months (87.5 ± 6.1) and in AE from 0 (97.6 ± 7.0) to 6 months (91.3 ± 6.8). With equal training frequency and exercise session duration, both RT and AE training, when paired with energy restriction improve the clinical risk factor profile for MetSyn.

Strength training as a countermeasure to aging muscle and chronic disease

Strength training (ST) has long been considered a promising intervention for reversing the loss of muscle function and the deterioration of muscle structure associated with advanced age but, until recently, the evidence was insufficient to support its role in the prevention or treatment of disease. In recent decades, there has been a long list of quality reviews examining the effects of ST on functional abilities and a few on risk factors for specific diseases, but none have provided a comprehensive assessment of ST as an intervention for a broad range of diseases. This review provides an overview of research addressing the effectiveness of ST as an intervention for the prevention or treatment of the adverse consequences of (i) aging muscle; (ii) the metabolic syndrome (MetS) and its components, i.e. insulin resistance, abdominal obesity, hyperlipidaemia and hypertension; (iii) fibromyalgia; (iv) rheumatoid arthritis; and (v) Alzheimer's disease. Collectively, these studies indicate that ST may serve as an effective countermeasure to some of the adverse consequences of the MetS, fibromyalgia and rheumatoid arthritis. Evidence in support of the hypothesis that ST reduces insulin resistance or improves insulin action comes both from indirect biomarkers, such as glycosylated haemoglobin (HbA(1c)), and insulin responses to oral glucose tolerance tests, as well as from more direct procedures such as hyperglycaemic and hyperinsulinaemic-euglycaemic clamp techniques. The evidence for the use of ST as a countermeasure of abdominal obesity is less convincing. Although some reports show statistically significant reductions in visceral fat, it is unclear if the magnitude of these changes are physiologically meaningful and if they are independent of dietary influences. The efficacy of ST as an intervention for reducing dyslipidaemia is at best inconsistent, particularly when compared with other pharmacological and non-pharmacological interventions, such as aerobic exercise training. However, there is more consistent evidence for the effectiveness of ST in reducing triglyceride levels. This finding could have clinical significance, given that elevated triglyceride is one of the five criterion measures for the diagnosis of the MetS. Small to moderate reductions in resting and exercise blood pressure have been reported with some indication that this effect may be genotype dependent. ST improves or reverses some of the adverse effects of fibromyalgia and rheumatoid arthritis, particularly pain, inflammation, muscle weakness and fatigue. Investigations are needed to determine how these effects compare with those elicited from aerobic exercise training and/or standard treatments. There is no evidence that ST can reverse any of the major biological or behavioural outcomes of Alzheimer's disease, but there is evidence that the prevalence of this disease is inversely associated with muscle mass and strength. Some indicators of cognitive function may also improve with ST. Thus, ST is an effective countermeasure for some of the adverse effects experienced by patients of many chronic diseases, as discussed in this review.

Physical inactivity and mortality risk

In recent years a plethora of epidemiologic evidence accumulated supports a strong, independent and inverse, association between physical activity and the fitness status of an individual and mortality in apparently healthy individuals and diseased populations. These health benefits are realized at relatively low fitness levels and increase with higher physical activity patterns or fitness status in a dose-response fashion. The risk reduction is at least in part attributed to the favorable effect of exercise or physical activity on the cardiovascular risk factors, namely, blood pressure, diabetes mellitus and obesity. In this review, we examine evidence from epidemiologic and interventional studies in support of the association between exercise and physical activity and health. In addition, we present the exercise effects on the aforementioned risk factors. Finally, we include select dietary approaches and their impact on risk factors and overall mortality risk.

Evidence for resistance training as a treatment therapy in obesity

Over the last decade, investigators have paid increasing attention to the effects of resistance training (RT) on several metabolic syndrome variables. Evidence suggests that skeletal muscle is responsible for up to 40% of individuals' total body weight and may be influential in modifying metabolic risk factors via muscle mass development. Due to the metabolic consequences of reduced muscle mass, it is understood that normal aging and/or decreased physical activity may lead to a higher prevalence of metabolic disorders. The purpose of this review is to (1) evaluate the potential clinical effectiveness and biological mechanisms of RT in the treatment of obesity and (2) provide up-to-date evidence relating to the impact of RT in reducing major cardiovascular disease risk factors (including dyslipidaemia and type 2 diabetes). A further aim of this paper is to provide clinicians with recommendations for facilitating the use of RT as therapy in obesity and obesity-related metabolic disorders.

Motivation of fitness center participants toward resistance training

There is a need to better understand the behavior and sense of motivation of fitness center participants. The purpose of this study was to assess whether or not demographic characteristics and health self-determinism (intrinsic or extrinsic motivation) of fitness center participants were predictive of their levels of resistance training. A cross-sectional design was used; participants were recruited via the Internet to complete an online survey. There were 185 participants (age = 39.1 +/- 11.3 years) in the study. The majority of respondents reported having carried out levels of resistance training that met national health organization recommendations. Regression analysis of the data revealed that health self-determinism predicted quantity of resistance training reported (p = 0.014), whereas demographics did not. Being intrinsically motivated to health self-determinism predicted meeting national resistance training recommendations compared to participants extrinsically motivated (p = 0.007). For those who work with fitness center participants, our findings are useful by identifying participants as a predominantly intrinsically motivated group of people that performs adequate quantities of resistance training; the methodology employed in this study can be used to identify participants in need of increased levels of resistance training and heightened sense of motivation to do so.

Aging, resistance training, and diabetes prevention

With the aging of the baby-boom generation and increases in life expectancy, the American population is growing older. Aging is associated with adverse changes in glucose tolerance and increased risk of diabetes; the increasing prevalence of diabetes among older adults suggests a clear need for effective diabetes prevention approaches for this population. The purpose of paper is to review what is known about changes in glucose tolerance with advancing age and the potential utility of resistance training (RT) as an intervention to prevent diabetes among middle-aged and older adults. Age-related factors contributing to glucose intolerance, which may be improved with RT, include improvements in insulin signaling defects, reductions in tumor necrosis factor-α, increases in adiponectin and insulin-like growth factor-1 concentrations, and reductions in total and abdominal visceral fat. Current RT recommendations and future areas for investigation are presented.

Resistance training in the treatment of the metabolic syndrome: a systematic review and meta-analysis of the effect of resistance training on metabolic clustering in patients with abnormal glucose metabolism

Over the last decade, investigators have given increased attention to the effects of resistance training (RT) on several metabolic syndrome variables. The metabolic consequences of reduced muscle mass, as a result of normal aging or decreased physical activity, lead to a high prevalence of metabolic disorders. The purpose of this review is: (i) to perform a meta-analysis of randomized controlled trials (RCTs) regarding the effect of RT on obesity-related impaired glucose tolerance and type 2 diabetes mellitus; and (ii) to investigate the existence of a dose-response relationship between intensity, duration and frequency of RT and the metabolic clustering. Thirteen RCTs were identified through a systematic literature search in MEDLINE ranging from January 1990 to September 2007. We included all RCTs comparing RT with a control group in patients with abnormal glucose regulation. For data analysis, we performed random effects meta-analyses to determine weighted mean differences (WMD) with 95% confidence intervals (CIs) for each endpoint. All data were analysed with the software package Review Manager 4.2.10 of the Cochrane Collaboration. In the 13 RCTs included in our analysis, RT reduced glycosylated haemoglobin (HbA(1c)) by 0.48% (95% CI -0.76, -0.21; p = 0.0005), fat mass by 2.33 kg (95% CI -4.71, 0.04; p = 0.05) and systolic blood pressure by 6.19 mmHg (95% CI 1.00, 11.38; p = 0.02). There was no statistically significant effect of RT on total cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triglyceride and diastolic blood pressure. Based on our meta-analysis, RT has a clinically and statistically significant effect on metabolic syndrome risk factors such as obesity, HbA(1c) levels and systolic blood pressure, and therefore should be recommended in the management of type 2 diabetes and metabolic disorders.

Efeito de 12 semanas de treinamento com pesos sobre a força muscular, composição corporal e triglicérides em homens sedentários

O objetivo do presente estudo foi verificar o efeito de 12 semanas de treinamento com pesos (TP) sobre a força muscular, composição corporal e triglicérides em homens sedentários. Para tanto, 14 homens saudáveis e sedentários foram separados aleatoriamente, de forma balanceada, em grupo experimental (GE = 29 ± 1 anos; 180,0 ± 3,0cm; 80,5 ± 1,8kg) e grupo controle (GC = 27 ± 1 anos; 170,0 ± 2,0cm; 76,2 ± 0,9kg). O GE foi submetido a um protocolo de TP durante 12 semanas, com frequência de três vezes por semana. O programa de TP foi composto por 10 exercícios executados em duas séries de 10-20 repetições. Medidas de massa corporal, estatura, espessura de dobras cutâneas e triglicérides foram realizadas antes e após o período de intervenção. Adicionalmente, o teste de uma repetição máxima (1RM) foi aplicado nos exercícios supino em banco horizontal e mesa extensora, nos período pré, após seis e 12 semanas de acompanhamento. Foram encontradas diferenças significativas (P < 0,05) após as 12 semanas de TP apenas no GE para o somatório das dobras cutâneas, ao passo que a massa corporal e os triglicérides não sofreram alterações nesse período. Com relação aos valores de força muscular, identificou-se aumento significativo (P < 0,05) no GE em ambos os exercícios entre o primeiro e o segundo teste de 1RM e entre o segundo e o terceiro. Conclui-se, portanto, que 12 semanas de TP foram suficientes para aumentar a força muscular e reduzir o somatório de dobras cutâneas sem, contudo, alterar os valores de triglicérides e massa corporal.

Exercise training, lipid regulation, and insulin action: a tangled web of cause and effect

Lipids are a strong mediator of coronary artery disease and cardiovascular risk. Although the effects of exercise to improve high-density lipoprotein (HDL) cholesterol and serum triglycerides (TGs) have been known for some time, the effects of different amounts and intensities of exercise on fasting and postprandial serum lipids are little understood. Normal lipid physiology is perturbed in insulin resistant states, where inhibition of lipolysis is impaired, particularly in the postprandial period when excursions in insulin and serum TGs are particularly high. In our STRRIDE (Studies of a Targeted Risk Reduction Intervention through Defined Exercise) study, three important metabolic cardiovascular risk-related variables were improved more by moderate intensity than vigorous-intensity exercise. Moderate-intensity exercise was significantly more effective at lowering TGs and improving insulin sensitivity than was vigorous exercise. Additionally, a composite score for metabolic syndrome improved significantly with low-amount/moderate, but did not with low-amount/vigorous-intensity exercise. That all three of these strong, independent, cardiovascular risk factors were significantly affected by moderate-intensity exercise suggests that regular walking exercise might be as effective, if not more so, than more vigorous exercise in favorably modifying cardiovascular risk. Despite the impressive effects of regular exercise on fasting lipids and atherogenic dyslipidemia, they are more impressive when compared with the trajectory of changes that occur in individuals that remain inactive, without regular exposure to regular exercise. A scientific priority for future investigations should be to study the independent and combined effects of exercise intensity and amount on exercise responses through a direct comparison between two groups matched on amount but differing in intensity.

The effect of strength and endurance training on insulin sensitivity and fat distribution in human immunodeficiency virus-infected patients with lipodystrophy

CONTEXT

Fat redistribution, insulin resistance, and low-grade inflammation characterize HIV-infected patients with lipodystrophy. Currently, no effective therapies exist for the combined treatment of fat redistribution and insulin resistance.

OBJECTIVE

Our objective was to evaluate the effects of strength and endurance training on insulin sensitivity and fat distribution in HIV-infected patients with lipodystrophy.

SUBJECTS AND METHODS

Twenty sedentary HIV-infected men with lipodystrophy were randomly assigned to supervised strength or endurance training three times a week for 16 wk. The primary endpoints were improved peripheral insulin sensitivity (euglycemic-hyperinsulinemic clamp combined with isotope-tracer infusion) and body fat composition (dual-energy x-ray absorptiometry scan). Secondary endpoints included fasting lipids and inflammatory markers.

RESULTS

Insulin-mediated glucose uptake increased with both endurance training (55.7 +/- 11 to 63.0 +/- 11 micromol glucose/kg lean mass.min, P = 0.02) and strength training (49.0 +/- 12 to 57.8 +/- 18 micromol glucose/kg lean mass.min, P = 0.005), irrespective of training modality (P = 0.24). Only strength training increased total lean mass 2.1 kg [95% confidence interval (CI), 0.8-3.3], decreased total fat 3.3 kg (95% CI, -4.6 to -2.0), trunk fat 2.5 kg (95% CI, -3.5 to -1.5), and limb fat 0.75 kg (95% CI, -1.1 to -0.4). Strength training significantly decreased total and limb fat mass to a larger extent than endurance training (P < 0.05). Endurance training reduced total cholesterol, low-density lipoprotein cholesterol, free fatty acids, high-sensitivity C-reactive protein, IL-6, IL-18, and TNF-alpha and increased high-density lipoprotein cholesterol, whereas strength training decreased triglycerides, free fatty acids, and IL-18 and increased high-density lipoprotein cholesterol (P < 0.05 for all measurements).

CONCLUSION

This study demonstrates that both strength and endurance training improve peripheral insulin sensitivity, whereas only strength training reduces total body fat in HIV-infected patients with lipodystrophy.

Type 2 diabetes mellitus, resistance training, and innate immunity: is there a common link?

Type 2 diabetes mellitus is a serious chronic disease that is very prevalent in the developed world. The etiology of this disease is not well understood. Recently, the role of the innate immune system in the pathogenesis of type 2 diabetes and its complications has received a great deal of attention. Cytokines, acute phase proteins, and phagocytes have been implicated in this model. Resistance training has known benefits in type 2 diabetic patients and older adults, such as improved insulin action, insulin sensitivity, fasting blood glucose and insulin, and glucose tolerance levels. Actions of pro-inflammatory mediators linked to dysregulated innate immune activity have been associated with type 2 diabetes. The immunomodulatory effects of exercise, and in particular approaches such as resistance training, may provide a strategy to counter these pro-inflammatory effectors. However, the effects of resistance training on innate immunity have not been studied extensively in adults with type 2 diabetes or in older adults who are at increased risk for development of type 2 diabetes. This review discusses the possibility that resistance training may have positive effects on innate immunity in this population and so may provide benefits in addition to improving strength and functional abilities. In particular, the potential of resistance training to modulate pro-inflammatory parameters associated with type 2 diabetes, as a strategy that could provide multiple beneficial health outcomes, is addressed.

Resistance exercise in individuals with and without cardiovascular disease: 2007 update: a scientific statement from the American Heart Association Council on Clinical Cardiology and Council on Nutrition, Physical Activity, and Metabolism

Prescribed and supervised resistance training (RT) enhances muscular strength and endurance, functional capacity and independence, and quality of life while reducing disability in persons with and without cardiovascular disease. These benefits have made RT an accepted component of programs for health and fitness. The American Heart Association recommendations describing the rationale for participation in and considerations for prescribing RT were published in 2000. This update provides current information regarding the (1) health benefits of RT, (2) impact of RT on the cardiovascular system structure and function, (3) role of RT in modifying cardiovascular disease risk factors, (4) benefits in selected populations, (5) process of medical evaluation for participation in RT, and (6) prescriptive methods. The purpose of this update is to provide clinicians with recommendations to facilitate the use of this valuable modality.