Effects of strength training on total and regional body composition in older men

Do sex or race differences influence strength training effects on muscle or fat?

PURPOSE

To examine the influence of sex and race on the effects of strength training (ST) on thigh muscle volume (MV), midthigh subcutaneous fat (SCF), and intermuscular fat (IMF).

METHODS

One hundred eighty-one previously inactive healthy Caucasian (N = 117) and African American (N = 54) men (N = 82) and women (N = 99), aged 50-85 yr, underwent about 10 wk of unilateral knee extension ST. Ten subjects were neither Caucasian nor African American and were, therefore, not included in the race analysis. Quadriceps MV and midthigh SCF and IMF cross-sectional area were measured with computed tomography before and after ST. Sex and race comparisons were made with a 2 x 2 (sex by race) analysis of covariance.

RESULTS

Training-induced increases in absolute MV were significantly greater (P < 0.001) in men than in women, though both sex groups increased MV significantly with ST (P < 0.001), and the relative (%) increases were similar. There were significant increases in MV within race groups (P < 0.001), but no significant differences between races. There were no significant changes in SCF or IMF, whether sex and racial groups were separated or combined. In addition, there was no sex by race interaction for changes in MV, SCF, or IMF with ST.

CONCLUSION

Strength training does not alter subcutaneous or intermuscular fat, regardless of sex or racial differences. Although men exhibit a greater muscle hypertrophic response to strength training than do women, the difference is small. Race does not influence this response.

Physical Activity: Physical Activity and the Metabolic Syndrome: A Review of the Evidence

Metabolic syndrome is a global public health problem identified as a seminal cause of cardiovascular disease and type 2 diabetes. The syndrome is characterized by the clustering of cardiovascular risk factors, including insulin resistance, central obesity, hypertension, and atherogenic dyslipidemia. Currently there are 5 working medical society definitions of metabolic syndrome. However, the majority of recent research focusing on metabolic syndrome has relied on the National Cholesterol Education Program (NCEP) definition because of its clinical utility. Studies of the association between physical activity and prevalence of metabolic syndrome using National Health And Nutrition Examination Survey (NHANES) data generally found the association to be reduced or attenuated by other lifestyle factors and is generally weaker in females. Other studies tracking physical activity over longer periods have generally found a stronger association between regular physical activity and lower prevalence or incidence of metabolic syndrome. Interventional studies are limited but suggest that regular exercise reduces the incidence of metabolic syndrome. The amount and intensity of physical activity required to prevent or reverse metabolic syndrome has yet to be definitely determined. Evidence suggests that regular, moderate-intensity physical activity may be preventive of metabolic syndrome and that activity of greater intensity may carry greater benefit. Greater cardiorespiratory fitness has demonstrated an even stronger negative association with metabolic syndrome. Strength training is recommended as an adjunct to regular aerobic exercise but is not the primary form of activity to prevent or manage metabolic syndrome.

Exercise alone reduces insulin resistance in obese children independently of changes in body composition

CONTEXT

The number of obese children with insulin resistance and type 2 diabetes is increasing, but the best management strategy is not clear.

OBJECTIVE

The objective of this study was to assess the effect of a structured 8-wk exercise training program on insulin resistance and changes in body composition in obese children.

DESIGN

The study was 8 wk of structured supervised exercise intervention with outcome measures before and after the exercise period.

SUBJECTS

Fourteen obese children (12.70 +/- 2.32 yr; eight male, six female) with high fasting insulin levels were enrolled into the study.

INTERVENTION

INTERVENTION consisted of 8 wk of supervised circuit-based exercise training, composed of three fully supervised 1-h sessions per week.

OUTCOME MEASURES

Outcome measures were assessed pretraining program and posttraining program and included insulin sensitivity (euglycemic-hyperinsulinemic clamp studies), fasting insulin and glucose levels, body composition using dual energy x-ray absorptiometry scan, lipid profile, and liver function tests.

RESULTS

Insulin sensitivity improved significantly after 8 wk of training (M(lbm) 8.20 +/- 3.44 to 10.03 +/- 4.33 mg/kg.min, P < 0.05). Submaximal exercise heart rate responses were significantly lower following the training (P < 0.05), indicating an improvement in cardiorespiratory fitness. Dual energy x-ray absorptiometry scans revealed no differences in lean body mass or abdominal fat mass.

CONCLUSION

An 8-wk exercise training program increases insulin sensitivity in obese children, and this improvement occurred in the presence of increased cardiorespiratory fitness but is independent of measurable changes in body composition.

Adrenergic receptor genotype influence on midthigh intermuscular fat response to strength training in middle-aged and older adults

BACKGROUND

There is little information regarding the effects of strength training on intermuscular fat (IMF). This study examines changes in IMF in response to strength training in carriers of the adrenergic receptor (ADR) beta2Glu27 polymorphism versus noncarriers and between carriers of ADRalpha2b Glu(9) polymorphism versus noncarriers.

METHODS

Midthigh IMF and muscle area were measured by computed tomography (CT) before and after 10 weeks of single-leg strength training in healthy, sedentary middle-aged and older (50-83 years) men (n = 46) and women (n = 52) in both their trained and untrained (control) legs.

RESULTS

The strength training program resulted in a substantial increase in one-repetition maximum strength (p <.001) and muscle area (p <.001), but no significant changes in IMF in the whole group. However, IMF was significantly reduced with strength training in participants carrying ADRbeta2 Glu27 (-2. 3 +/- 1.0 cm(2), p =.028), but no significant change was observed with ADRbeta2 Glu27 noncarriers. The decrease in IMF in ADRalpha2b Glu(9) carriers (-1.9 +/- 1.0 cm(2), p =.066) was significantly different (-2.9 +/- 1.5 cm(2), p =.043) from a nonsignificant increase in ADRalpha2b Glu(9) noncarriers. ADRbeta2 Glu27 carriers who also carried ADRalpha2b Glu(9) significantly lost IMF with strength training (-3.8 +/- 1.5 cm(2), p =.018).

CONCLUSION

ADR genotype influences IMF response to strength training.

Subcutaneous fat alterations resulting from an upper-body resistance training program

PURPOSE

It is believed spot reduction, the exercise-induced localized loss of subcutaneous fat, does not occur as a result of an exercise program; however, evidence as a whole has been inconsistent. To reexamine this concept, we compared subcutaneous fat measurements before and after resistance training among 104 subjects (45 men, 59 women).

METHODS

Subjects participated in 12 wk of supervised resistance training of their nondominant arm. Magnetic resonance imaging and skinfold calipers examined subcutaneous fat in the nondominant (trained) and dominant (untrained) arms before and after resistance training. Repeated-measures ANCOVA tested for subcutaneous fat differences within and between arms before, after, and from before to after resistance training by gender and measurement technique, with BMI and age as covariates. Simple linear regression compared subcutaneous fat changes before and after resistance training as assessed by MRI and skinfold.

RESULTS

Subcutaneous fat, measured by skinfold, decreased in the trained arm and not the untrained arm in the men (P < 0.01); it was similar in the total sample and in the women (P > 0.05). MRI determinations of subcutaneous fat changes were not different between arms in the total sample and by gender (P > 0.05).

CONCLUSION

Subcutaneous fat changes resulting from resistance training varied by gender and assessment technique. Skinfold findings indicate that spot reduction occurred in men but not in women. In contrast, MRI found a generalized subcutaneous fat loss independent of gender, supporting the notion that spot reduction does not occur as a result of resistance training. MRI, sensitive to changes along the entire upper arm, detected greater variation in resistance training responses, preventing significant differences between trained and untrained arms. Variation in upper-arm resistance training response was not evident from a single skinfold measurement at the belly of the muscle.

Alterations in IGF-I affect elderly: role of physical activity

The growth hormone–insulin-like growth factor I (IGF-I) axis is an important physiological regulator muscle for development. Although there is evidence that aging muscle retains the ability to synthesize IGF-I, there is also evidence that aging may be associated with attenuation of the ability of exercise to induce an isoform of IGF-I that promotes satellite cell proliferation. However, it is clear that overexpression of IGF-I in the muscle can protect against age-related sarcopenia. Strength training appears to be the intervention of choice for the prevention and treatment of sarcopenia. IGF-I has been implicated in the loss of the muscle with age, and IGF-I expression levels change as a consequence of strength training in older adults. However, it seems that advancing age, rather than declining serum levels of IGF-I, appears to be a major determinant of life-time changes in body composition in women and men. We concluded that resistive exercise is a significant determinant of muscle mass and function. Elevated levels of IGF-I have been found in physically active compared to sedentary individuals. Recent work suggests that IGF-I as a mediator plays an important role in muscle hypertrophy and angiogenesis, both of which characterize the anabolic adaptation of muscles to exercise.

Strength training and adiposity in premenopausal women: strong, healthy, and empowered study

BACKGROUND

American women aged 25-44 y gain 0.5-1 kg yearly, most of which is fat. Because few midlife women participate in strength training, this mode of activity may be a novel intervention for preventing age-associated fat increases in this population.

OBJECTIVES

The primary aim was to assess the efficacy of twice-weekly strength training to avoid increases in percentage body fat and intraabdominal fat.

DESIGN

A randomized controlled trial was conducted in an ethnically diverse sample of 164 overweight and obese [body mass index (in kg/m2): 25-35] women aged 25-44 y. The treatment group did twice-weekly strength training for 2 y. The standard care comparison group was given brochures recommending aerobic exercise. Assessments at baseline, 1, and 2 y included intraabdominal fat by computed tomography scan and body fat and fat-free mass by dual-energy X-ray absorptiometry.

RESULTS

During 2 y, percentage body fat changes were -3.68 +/- 0.99% for the treatment group and -0.14 +/- 1.04% for the control group, P = 0.01. Two-year intraabdominal fat changes were 7.05 +/- 5.07% for the treatment group and 21.36 +/- 5.34% for the control group, P = 0.05.

CONCLUSION

This study suggests that strength training is an efficacious intervention for preventing percentage body fat increases and attenuating intraabdominal fat increases in overweight and obese premenopausal women. This is relevant to public health efforts for obesity prevention because most weight gain can be assumed to be fat, including abdominal fat.

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.

Fat metabolism and acute resistance exercise in trained men

The purpose of this study was to investigate the effect of acute resistance exercise (RE) on lipolysis within adipose tissue and subsequent substrate oxidation to better understand how RE may contribute to improvements in body composition. Lipolysis and blood flow were measured in abdominal subcutaneous adipose tissue via microdialysis before, during, and for 5 h following whole body RE as well as on a nonexercise control day (C) in eight young (24 ± 0.7 yr), active (>3 RE session/wk for at least 2 yr) male participants. Fat oxidation was measured immediately before and after RE via indirect calorimetry for 45 min. Dialysate glycerol concentration (an index of lipolysis) was higher during (RE: 200.4 ± 38.6 vs. C: 112.4 ± 13.1 μmol/l, 78% difference; P = 0.02) and immediately following RE (RE: 184 ± 41 vs. C: 105 + 14.6 μmol/l, 75% difference; P = 0.03) compared with the same time period on the C day. Energy expenditure was elevated in the 45 min after RE compared with the same time period on the C day (RE: 104.4 ± 6.0 vs. C: 94.5 ± 4.0 kcal/h, 10.5% difference; P = 0.03). Respiratory exchange ratio was lower (RE: 0.71 ± 0.004 vs. C: 0.85 ± .03, 16.5% difference; P = 0.004) and fat oxidation was higher (RE: 10.2 ± 0.8 vs. C: 5.0 ± 1.0 g/h, 105% difference; P = 0.004) following RE compared with the same time period on the C day. Therefore, the mechanism behind RE contributing to improved body composition is in part due to enhanced abdominal subcutaneous adipose tissue lipolysis and improved whole body fat oxidation and energy expenditure in response to RE.

Musculoskeletal fitness and weight gain in Canada

BACKGROUND

Obesity is a growing health issue in Canada, and identifying the determinants of weight gain is important for the development of appropriate prevention strategies.

PURPOSE

To quantify the association between musculoskeletal fitness (MSF) and subsequent weight gain and development of obesity.

METHODS

The sample included 606 participants (20-69 yr; 291 men, 315 women) from the Physical Activity Longitudinal Study (PALS), a follow-up of participants from the 1981 Canadian Fitness Survey. Standardized assessments of height, weight, MSF (push-ups, sit-ups, grip strength, and trunk flexibility), and cardiorespiratory fitness were made at baseline (1981). Follow-up data on self-reported height and weight and body mass index (BMI) were collected by survey in 2002-2004. Logistic regression was used to predict obesity and weight gain of > or = 10 kg between 1981 and 2002-2004.

RESULTS

During the 20-yr follow-up, the prevalence of obesity (BMI > or = 30 kg.m(-2)) increased from 3.1 to 15.2%, reflecting a mean weight gain of 7.4 kg (men: 6.7 kg; women: 8.1 kg). Further, independent of age, sex, baseline BMI, physical activity, cardiorespiratory fitness, smoking, alcohol consumption, and income, low MSF was associated with significantly higher odds of having gained at least 10 kg during follow-up (OR: 1.78, 95% CI: 1.14-2.79).

CONCLUSIONS

The results indicate that MSF is a significant predictor of weight gain during a 20-yr period. Promoting participation in activities that enhance MSF may be beneficial in attenuating age-related weight gain and in preventing obesity among Canadians.

Influência de variáveis do treinamento contra-resistência sobre a força muscular de idosos: uma revisão sistemática com ênfase nas relações dose-resposta

A força muscular é considerada componente importante de programas de exercícios físicos. Os benefícios desse tipo de treinamento dependem da combinação do número de repetições, séries, sobrecarga, seqüência e intervalos entre as séries e exercícios. No entanto, não se tem ainda muito clara qual a melhor combinação dessas variáveis para uma ótima relação dose-resposta em pessoas idosas. O objetivo do estudo foi analisar as pesquisas sobre treinamento de força para idosos, por meio de revisão sistemática, com o propósito de identificar tendências comuns em termos de efeitos do treinamento provocados pela manipulação dessas variáveis. Após definição de critérios de inclusão, foram selecionados 22 estudos, agrupados por similaridade de tratamento (número de séries, freqüência semanal, intensidade, intervalos e ordem dos exercícios). Técnicas de estatística descritiva auxiliaram na determinação de possíveis tendências nas relações dose-resposta. Uma vez identificadas, essas tendências foram analisadas qualitativamente. De todas as variáveis revisadas, somente para a intensidade da sobrecarga foram encontradas evidências permitindo afirmar que cargas maiores seriam mais eficazes para induzir aumento de força nessa faixa etária. Quanto às demais variáveis, os resultados disponíveis na literatura não dão respaldo para inferências seguras quanto ao melhor delineamento de programas de treinamento que aliem, ao mesmo tempo, efetividade e segurança. Recomenda-se, então, que estudos sejam realizados para comparar experimentalmente os efeitos da manipulação dessas variáveis sobre a força muscular de idosos.

Skeletal muscle mass, fat mass, and hip bone mineral density in elderly women with hip fracture

Soft tissue body composition strongly affects bone health. Our aim was to investigate the relationship between both skeletal muscle mass (SMM) and fat mass (FM) and femoral bone mineral density (BMD) in a sample of elderly women with hip fracture. We assessed 293 of 325 hip fracture women admitted consecutively to a rehabilitation hospital. Soft tissue body composition and BMD were assessed by dual-energy X-ray absorptiometry (DXA), 23.2 +/- 7.7 (mean +/- SD) days after fracture occurrence. BMD was measured at four sites (neck, total femur, trochanter, intertrochanteric area) in the unfractured femur. Appendicular lean mass (aLM) was calculated as the sum of LM in arms and legs. We used two approaches to adjust aLM for body size: aLM divided by height squared (aLM/ht(2)), and aLM adjusted for height and FM (residuals). Both FM and aLM were significantly correlated with femoral BMD. However, the correlation coefficients for aLM were lower than for FM; they further decreased after adjustment for height squared, and were no longer significant after correction for both height and FM (residuals). When FM, aLM/ht(2), age, and time spent between fracture occurrence and DXA assessment were included together as the independent variables in a regression model, FM was the only independent variable significantly associated with BMD. The coefficients of partial correlation ranged from 0.414 to 0.647 depending on the femoral region of BMD assessment (P < 0.001). FM, but not SMM emerged as a pivotal determinant of BMD in our sample of hip fracture women.

Androgen deprivation therapy: monitoring and managing the complications

Because many patients who have biochemical relapse will live for many years,preventing additional morbidity in those who are treated with ADT is of the utmost importance. No standard therapy is currently available for men who have biochemical relapse, although data are beginning to show that earlierADT may result in improved survival, at least in patients who have somewhat more advanced disease or rapid PSA doubling times or velocities. Treatment with intermittent ADT may attenuate some of the morbidities, such as loss of bone mineral density. Not all patients will experience all or even many of these complications, but patients can be empowered by learning about these beforehand and under-standing what can be done to prevent, monitor, or treat the side effects. Table 2 summarizes recommendations for baseline evaluations of men prior to initiation of ADT, and Table 3 summarizes interventions for specific complications. Better markers to distinguish patients who will benefit from ADT are needed. Newer hormonal agents or supplements are being researched. In the meantime, patients and the health care team can work together to combat complications related to ADT.

Translational research in childhood obesity prevention

This article explores the state of translational research in childhood obesity prevention. Five phases of translational research and emerging findings from basic science that could be useful in the design of obesity prevention programs are described. Few intervention studies have been published, and these are dominated by Phase 3 trials (efficacy), conducted in school settings, with a limited number of studies finding significant effects on Body Mass Index or adiposity. Cost-benefit analyses are lacking. Research is needed to translate basic science findings into novel interventions (Phases 1 and 2) and to translate programs with known behavior change capability into dissemination trials (Phase 5). Translation can be facilitated by enhanced communication between basic science and prevention science researchers, the development of interventions for underused settings, using novel strategies, support by institutions and funding agencies for translation, and the design of interventions with translation in mind.

Effects of Aerobic and Resistive Exercise Training on Glucose Disposal and Skeletal Muscle Metabolism in Older Men

BACKGROUND

Aging is associated with insulin resistance, primarily as a result of physical inactivity and increased abdominal obesity. We hypothesized that aerobic (AEX) or resistive (RT) exercise training would result in comparable improvements in glucose disposal in older men, but that there would be different metabolic adaptations in skeletal muscle.

METHODS

Thirty-nine older (63+/-1 years, mean+/-standard error of the mean), overweight and obese (body mass index=30.3+/-0.4 kg/m2) men were assigned to AEX (treadmill walking and/or jogging, n=19) or RT (upper and lower body, n=20) programs 3 d/wk for 6 months, with 9 completing AEX and 13 completing RT. Testing before and after the exercise programs included body composition, euglycemic-hyperinsulinemic clamps, and vastus lateralis muscle biopsies.

RESULTS

Maximal oxygen consumption (VO2max) increased by 16% after AEX (p<.01), while leg and arm muscle strength increased by 45+/-5% and 27+/-5% after RT (p<.0001). Although participants were monitored to maintain their body weight during the exercise program, body weight decreased by 2% after AEX (p<.05), and increased by 2% after RT (p<.05). Whole-body glucose disposal, determined during the last 30 minutes of a 2-hour 480 pmol/m2/min euglycemic-hyperinsulinemic clamp, increased comparably by 20%-25% after AEX (51+/-5 to 61+/-5 microM/kgfat-free mass/min, p<.05) and RT (49+/-3 to 58+/-3 microM/kgfat-free mass/min, p<.05). The increase in vastus lateralis muscle glycogen synthase fractional activity in response to insulin stimulation was significantly higher after AEX compared to after RT (279+/-59% compared to 100+/-28% change, p<.05). Neither AEX nor RT altered muscle glycogen synthase total activity, glycogen content, or levels of phosphotidylinositol 3-kinase.

CONCLUSION

These results suggest that AEX and RT result in comparable improvements in glucose metabolism in older men, whereas an increase in insulin activation of glycogen synthase occurred only with AEX. These improvements in insulin sensitivity could reduce the risk of metabolic syndrome and type 2 diabetes and attenuate the development of cardiovascular disease.

The influence of physical activity on abdominal fat: a systematic review of the literature

The relationship between excess abdominal adipose tissue, metabolic and cardiovascular health risk has stimulated interest in the efficacy of physical activity in specifically perturbing this adipose depot. The evolution of imaging techniques has enabled more direct measurement of changes in abdominal and visceral fat. The purpose of this summary was to systematically review the relationship between physical activity and abdominal fat.

METHODS

Database searches were performed on MEDLINE, CINAHL, SPORT DISCUS and PUBMED, from 1985 to 2005 with keywords "exercise", "abdominal fat" and "visceral fat".

RESULTS

Nineteen randomized controlled trials (RCTs) and eight non-randomized controlled trials were selected. In RCTs using imaging techniques to measure change in abdominal fat in overweight or obese subjects, seven out of 10 studies (including three trials with type 2 diabetics) reported significant reductions compared with controls. Reductions in visceral and total abdominal fat may occur in the absence of changes in body mass and waist circumference. Waist-to-hip ratio is not a sensitive measure of change in regional adiposity in exercise studies. No studies fulfil the Consolidated Standards of Reporting Trials (CONSORT) statement's criteria for the highest quality of randomized trial; however, many studies were in progress or published before the opportunity to comply with these recommendations. Therefore, limited evidence from a number of studies suggests a beneficial influence of physical activity on reduction in abdominal and visceral fat in overweight and obese subjects when imaging techniques are used to quantify changes in abdominal adiposity. More rigorous studies are needed to confirm these observations.

Combined lower body endurance and upper body resistance training improves performance and health parameters in healthy active elderly

We investigated the effects of combined lower body (LB) endurance and upper body (UB) resistance training on endurance, strength, blood lipid profile and body composition in active older men. Ten healthy still active men (73+/-4 years, V(O2) peak: 36 (31-41) ml min-1 kg-1) were tested before and after 14 weeks of combined training (3 times week-1). Training consisted of 3x12 min of high intensity interval training on a bicycle for endurance interspersed by 3x12 min of UB resistance exercises. V(O2) peak during leg cycling and arm cranking, isokinetic torque of knee extensor and shoulder abductor and the cross-sectional area (CSA) of several muscles from UB and LB were measured. Sagittal abdominal diameter (SAD) and abdominal fat area were measured on MRI scans. Total body composition was assessed by hydrostatic weighing (HW) and dual-energy X-ray absorptiometry (DEXA). Blood lipid profile was assessed before and after training. By the end of the training period, V(O2) peak (l min-1) increased significantly by 9 and 16% in leg cycling and arm cranking tests, respectively. Maximal isokinetic torque increased both for the knee extensor and shoulder abductor muscle groups. CSA increased significantly in deltoid muscle. Percentage of body fat decreased by 1.3% (P<0.05) and abdominal fat and SAD decreased by 12 and 6%, respectively (P<0.01). There was also a significant decrease in total cholesterol and low-density lipoprotein. Thus, combined LB endurance and UB resistance training can improve endurance, strength, body composition and blood lipid profile even in healthy active elderly.

Efficacy of exercise for treating overweight in children and adolescents: a systematic review

BACKGROUND

Overweight prevalence among children/adolescents is increasing, while adult obesity may potentially cause a decline in life expectancy. More exercise is uniformly recommended, although treatment efficacy remains unclear.

OBJECTIVE

To determine the efficacy of exercise alone for treating overweight in children/adolescents.

DESIGN

A systematic review and meta-analysis of randomized trials published in English were completed following multiple database searches performed on December 10, 2004. Studies of isolated or adjunctive exercise/physical activity treatment in overweight/obese children or adolescents which reported any overweight outcome were included. Literature searches identified 645 papers which were manually searched, of which 45 were considered for inclusion, of which 13 papers which reported 14 studies were included (N=481 overweight boys and girls, aged approximately 12 years). Two reviewers independently identified relevant papers for potential inclusion and assessed methodological quality. Principal measures of effects included the mean difference (MD) (between treatment and control groups), the weighted MD (WMD), and the standardized MD (SMD).

RESULTS

Few studies were of robust design. The pooled SMD was -0.4 (-0.7, -0.1, P=0.006) for percent body fat, and -0.2 (-0.6, 0.1, P=0.07) for central obesity outcomes, whereas the pooled WMD was -2.7 kg (-6.1 kg, 0.8 kg, P=0.07) for body weight, all of which favored exercise. Pooled effects on body weight were significant and larger for studies of higher doses, whereas nonsignificant and smaller effects were seen for studies of lower doses of exercise (155-180 min/weeks vs 120-150 min/weeks).

CONCLUSIONS

Based on the small number of short-term randomized trials currently available, an aerobic exercise prescription of 155-180 min/weeks at moderate-to-high intensity is effective for reducing body fat in overweight children/adolescents, but effects on body weight and central obesity are inconclusive. Recommendations for future study designs are discussed.

Effects of progressive resistance training on body composition in frail older adults: results of a randomized, controlled trial

BACKGROUND

Progressive resistance exercise training (PRT) has been shown to increase muscle strength and fat-free mass (FFM) in elderly persons. Limited information is available regarding the effects of PRT on lean and fat mass in frail elderly persons.

METHODS

Ninety-one community-dwelling sedentary men and women, 78 years and older with physical frailty (defined using standardized objective criteria) were enrolled in a 9-month trial of exercise training (ET). Physical frailty was defined as having 2 of the 3 following criteria: modified Physical Performance Test score between 18 and 32, peak aerobic power between 10 and 18 ml/kg/min, or self-report of difficulty or assistance with two instrumental activities of daily living or one basic activity of daily living. Participants were randomly assigned to either a control (CTL) group that performed a low intensity home exercise program or a supervised ET group that performed 3 months of low intensity exercise and 3 months of PRT.

RESULTS

After completion of PRT, ET participants had greater improvements than did CTL participants in maximal voluntary force production for knee extension (mean Delta +5.3 +/- 13 ft/lb vs +1.1 +/- 11 ft/lb, p =.05), measured using isokinetic dynamometry. Total body FFM (measured using dual energy x-ray absorptiometry) increased in the ET group, but not in the CTL group (mean Delta +0.84 +/- 1.4 kg vs +0.01 +/- 1.5 kg, p =.005). Total, trunk, intra-abdominal, and subcutaneous fat mass (measured using dual energy x-ray absorptiometry and (1)H-magnetic resonance imaging) did not change in response to PRT.

CONCLUSIONS

Three months of supervised PRT induced improvements in maximal voluntary thigh muscle strength and whole body FFM in frail, community-dwelling elderly women and men. This supervised exercise program may not be sufficient to reduce whole-body or intra-abdominal fat area in this population.

Association of muscular strength with incidence of metabolic syndrome in men

PURPOSE

To examine the association between muscular strength and incidence of metabolic syndrome.

METHODS

Participants were 3233 men (20-80 yr) initially free of metabolic syndrome who had two or more clinical examinations between 1980 and 2003, including baseline muscular strength and cardiorespiratory fitness assessment. Metabolic syndrome was defined according to NCEP-ATP III criteria. Muscular strength was quantified by combining body weight-adjusted one-repetition maximal measures for leg and bench presses. Cardiorespiratory fitness was assessed by maximal treadmill test.

RESULTS

A total of 480 men developed metabolic syndrome during a mean follow-up period of 6.7 +/- 5.2 yr. In a Cox regression analysis adjusted for age, the hazard ratios (95% confidence intervals) of metabolic syndrome associated with the incremental categories of muscular strength were 1.00 (referent), 0.88 (0.69-1.12), 0.77 (0.60-0.98), and 0.54 (0.42-0.71), respectively (linear trend P < 0.0001). The inverse trend persisted after adjustment for smoking, alcohol intake, number of baseline metabolic syndrome risk factors, family history of diabetes, hypertension, and premature coronary disease (P = 0.004), but was attenuated (P = 0.06) when further adjusted for cardiorespiratory fitness. Compared with the lowest strength category, the highest strength category was associated with 44 and 39% lower risk (P < 0.05 each) of incident metabolic syndrome among normal weight body mass index (BMI < 25) and overweight or obese (BMI > or = 25) men, respectively. An inverse association of incident rates was also seen within stratum of age (20-39 yr, P < 0.001; 40-49 yr, P < 0.01; and 50+ yr, P < 0.05).

CONCLUSIONS

Muscular strength was inversely associated with metabolic syndrome incidence, independent of age and body size. Potential benefits of greater muscular strength presumably through resistance exercise training should be considered in primary prevention of metabolic syndrome.

Pediatric obesity and insulin resistance: chronic disease risk and implications for treatment and prevention beyond body weight modification

The study of childhood obesity has continued to grow exponentially in the past decade. This has been driven in part by the increasing prevalence of this problem and the widespread potential effects of increased obesity in childhood on lifelong chronic disease risk. The focus of this review is on recent findings regarding the link between obesity and disease risk during childhood and adolescence. We describe recent reports relating to type 2 diabetes in youth (2), prediabetes (69, 166), metabolic syndrome (33, 35), polycystic ovarian syndrome (77), and nonalcoholic fatty liver disease (58, 146), and the mediating role of insulin resistance in these conditions. In addition, we review the implications of this research for the design of more effective treatment and prevention strategies that focus more on the improvement of obesity-related metabolic abnormalities and chronic disease risk reduction than on the conventional energy balance approach that focuses on weight management.

Regional placement of bone mineral mass, fat mass, and lean soft tissue mass in young adult rugby union players

The purpose of the present study was to ascertain whether differences existed in the regional placement of bone mineral mass (BMM), fat mass (FM) and lean soft tissue mass (LSTM) between playing units in Rugby Union Football and between players and control subjects. Thirty young adult rugby players and 21 controls participated in the study. Players were assigned to groups as either forwards (n = 15) or backs (n = 15). Control subjects were matched (n = 15) to rugby players using the mean BMI of forwards and backs. BMM, FM and LSTM were measured using dual-energy X-ray absorptiometry. The digital image of each subject was partitioned into regional anatomical segments comprising the head, right and left arms, trunk, and right and left legs. Measurements were summed for the arms and legs respectively. One-way ANOVA was used to differentiate between- and within-groups; Tukey's post-hoc test was applied to identify pairwise differences. The alpha level was set throughout at p = 0.01. Principal components analysis was utilized to contrast the regional segments of each tissue in each of the groups. Forwards exhibited larger absolute (kg) amounts of BMM, FM and LSTM than backs or controls. In relative terms (%) there were no significant differences in BMM(%) between forwards, backs and controls in the arms and legs, but differences did occur between backs and controls at the trunk (2.9 vs. 2.5%). Backs had a significantly larger LSTM(%) than forwards at the arms (84.4 vs. 76.5%), legs (80.0 vs. 71.9%) and trunk (89.2 vs. 79.0%), whereas forwards had a greater FM(%) than backs at the arms (18.7 vs. 10.6%), legs (23.1 vs. 14.7%), and trunk (18.4 vs. 8.0%). The distribution of BMM showed a lower body-upper body contrast in forwards, a trunk-extremity contrast in backs and an arm-lower body contrast in controls. FM exhibited a trunk-extremity contrast in all three groups, while LSTM displayed an arm-lower body contrast in all three groups. It is concluded that there are significant regional tissue differences between forwards and backs, which may be related to playing function, and also differences between rugby players and controls.

Twice-weekly progressive resistance training decreases abdominal fat and improves insulin sensitivity in older men with type 2 diabetes

OBJECTIVE

To evaluate the influence of a twice-weekly progressive resistance training (PRT) program, without a concomitant weight loss diet, on abdominal fat and insulin sensitivity in older men with type 2 diabetes.

RESEARCH DESIGN AND METHODS

Nine older men (aged 66.6 +/- 3.1) with type 2 diabetes participated in a 16-week PRT supervised program (50-80% of the one repetition maximum), for all main muscle groups. Basal glycemia, HbA(1c), diet, habitual physical activity, body composition, and upper/lower maximal strength were measured. Insulin sensitivity was determined according to Bergman's minimal model procedure and abdominal fat was obtained by computed tomography. The measurements were taken 4 weeks before training (-4), immediately before training (0), and at 8-week intervals (i.e., weeks 8 and 16) during the 16-week training period.

RESULTS

No significant variation was observed in any of the above selected parameters during the 4-week control period. After PRT, both leg and arm maximal strength increased significantly by 17.1 and 18.2%, respectively. Visceral and subcutaneous abdominal fat decreased significantly by 10.3% (from 249.5 +/- 97.9 to 225.6 +/- 96.6 cm(3), P < 0.01) and by 11.2% (from 356.0 +/- 127.5 to 308.6 +/- 118.8 cm(3), P < 0.01), respectively, while no changes were observed in body mass. PRT significantly increased insulin sensitivity by 46.3% (from 2.0 +/- 1.2 to 2.8 +/- 1.6 . 10(4) . min(-1) . muU(-1) . ml(-1), P < 0.01), whereas it significantly decreased (-7.1%, P < 0.05) fasting blood glucose (from 146.6 +/- 28.3 to 135.0 +/- 29.3 mg/dl). Finally, a 15.5% increase in energy intake (from 2,287.1 +/- 354.7 to 2,619.0 +/- 472.1 kcal/day, P < 0.05) was observed.

CONCLUSIONS

Two sessions per week of PRT, without a concomitant weight loss diet, significantly improves insulin sensitivity and fasting glycemia and decreases abdominal fat in older men with type 2 diabetes.

Effect of Post-Exercise Supplement Consumption on Adaptations to Resistance Training

OBJECTIVE

Athletes are interested in nutritional manipulations that may enhance lean tissue gains stimulated by resistance training. Some research demonstrates that acute consumption of food containing protein causes superior muscle protein synthesis compared to isoenergetic foods without protein. This benefit has not been verified in longer-term training studies. We compared body composition and muscle function responses to resistance training in males who consumed a carbohydrate or a multi-macronutrient beverage following each training session.

METHODS

Nineteen, untrained men (18-25 years) consumed either a milk (MILK) or a carbohydrate-electrolyte (CHO) drink immediately following each workout during a 10 week resistance training program. Muscle strength (1RM for seven exercises), body composition (DXA scan), fasted, resting concentrations of serum total and free testosterone, cortisol, IGF-1, and resting energy expenditure (REE) were measured prior to and at the end of training.

RESULTS

Resistance training caused an increase (44 +/- 4%, p < 0.001) in muscular strength for all subjects. The training program reduced percent body fat (8%, p < 0.05, -0.9 +/- 0.5 kg) and increased fat-free soft tissue (FFST) mass (2%, 1.2 +/- 0.3 kg, p < 0.01). MILK tended to increase body weight and FFST mass (p = 0.10 and p = 0.13, respectively) compared to CHO. Resting total and free testosterone concentrations decreased from baseline values in all subjects (16.7%, 11%, respectively, p < 0.05). Significant changes in fasting IGF-1, cortisol, and REE across training were not observed for either group.

CONCLUSION

Post-resistance exercise consumption of MILK and CHO caused similar adaptations to resistance training. It is possible that a more prolonged training with supplementation period would expand the trend for greater FFST gains in MILK.

Associations of Muscle Strength and Fitness with Metabolic Syndrome in Men

PURPOSE

To examine the associations for muscular strength and cardiorespiratory fitness with the prevalence of metabolic syndrome among men.

METHODS

Participants were 8570 men (20-75 yr) for whom an age-specific muscular strength score was computed by combining the body weight adjusted one-repetition maximum measures for the leg press and the bench press. Cardiorespiratory fitness was quantified by age-specific maximal treadmill exercise test time.

RESULTS

Separate age and smoking adjusted logistic regression models revealed a graded inverse association for metabolic syndrome prevalence with muscular strength (beta = -0.37, P < 0.0001) and cardiorespiratory fitness (beta = -1.2, P < 0.0001). The association between strength and metabolic syndrome was attenuated (beta = -0.08, P < 0.01) when further adjusted for cardiorespiratory fitness. The association between cardiorespiratory fitness and metabolic syndrome was unchanged (beta = -1.2, P < 0.0001) after adjusting for strength. Muscular strength added to the protective effect of fitness among men with low (P trend = 0.0002) and moderate (P trend < 0.0001) fitness levels. Among normal weight (BMI < 25), overweight (BMI 25-30), and obese (BMI >or= 30) men, respectively, being strong and fit was associated with lower odds (73%, 69%, and 62% respectively, P < 0.0001) of having prevalent metabolic syndrome.

CONCLUSIONS

Muscular strength and cardiorespiratory fitness have independent and joint inverse associations with metabolic syndrome prevalence.

Recondicionamento muscular na DPOC: principais intervenções e novas tendências

Há algum tempo o condicionamento físico vem sendo parte obrigatória no tratamento de portadores de DPOC. Estes pacientes apresentam comumente intolerância ao exercício de intensidade variável e relacionada à disfunção muscular esquelética. Neste sentido, o exercício físico apresenta-se como ramo mais importante no processo de reabilitação pulmonar. O exercício aeróbio e o treino de força com pesos são fundamentais no incremento de capacidade física e qualidade de vida, principalmente naqueles indivíduos que apresentam as formas moderada ou grave da DPOC. Além disso, espera-se atualmente maior desenvolvimento nas pesquisas em relação à aplicação de estimulação elétrica neuromuscular (EENM) e ao uso criterioso de substâncias ergogênicas tais como esteróides anabolizantes e creatina oral. Tendo em vista as repercussões negativas da disfunção muscular e a importância da reabilitação pulmonar no tratamento da DPOC, esta revisão tem como objetivo reunir informações de estudos relevantes acerca das principais estratégias para o recondicionamento muscular esquelético nestes pacientes nos últimos 15 anos.

Regional bone mineral density after resistive training in young and older men and women

PURPOSE

The purpose of this study was to determine the effects of 6 months of whole-body resistive training (RT) on total and regional bone mineral density (BMD) and bone mineral content (BMC) by age and gender in young and older men and women.

METHODS

Younger men (n=10) and women (n=7) aged 20-29 years (25+/-1 years) and older men (n=10) and women (n=10) aged 65-74 years (69+/-1 years) participated in 6 months of progressive whole-body RT. Upper- and lower-body strength was assessed by the one repetition maximum (1RM) test, and total body fat, lean tissue mass, femoral neck BMD, Ward's triangle BMD, greater trochanter BMD, total-body BMD, and L2-L4 spine BMD were determined by dual-energy X-ray absorptiometry before and after 6 months of RT.

RESULTS

Percent body fat decreased only in the young men (P<0.05). Lean tissue mass increased after training in young men and women and older men (P<0.05) but did not change significantly in older women. Upper- and lower-body 1RM strength increased in all groups (P<0.01). Overall, there was a significant increase in BMD at the femoral neck, ward's triangle and greater trochanter BMD, as well as total body BMC and leg BMC (P<0.05). Total-body BMD and L2-L4 spine BMD did not change with RT. There were no gender differences in the training response between men and women for any of the BMD regions and no age differences in the training response, except for a trend between young and older subjects for femoral neck (P<0.08).

CONCLUSION

A 6-month RT program increases muscle mass and improves BMD of the femoral region in young and healthy older men and women as a group, with a trend for this to be greater in young subjects.

The Effects of High- and Moderate-Resistance Training on Muscle Function in the Elderly

The purpose of this study was to investigate the effects of a 12-week resistance-training program on muscle strength and mass in older adults. Thirty-three inactive participants (60-74 years old) were assigned to 1 of 3 groups: high-resistance training (HT), moderate-resistance training (MT), and control. After the training period, both HT and MT significantly increased 1-RM body strength, the peak torque of knee extensors and flexors, and the midthigh cross-sectional area of the total muscle. In addition, both HT and MT significantly decreased the abdominal circumference. HT was more effective in increasing 1-RM strength, muscle mass, and peak knee-flexor torque than was MT. These data suggest that muscle strength and mass can be improved in the elderly with both high- and moderate-intensity resistance training, but high-resistance training can lead to greater strength gains and hypertrophy than can moderate-resistance training.

[Strength training with elastic bands: measure of its effects in cardiac rehabilitation after coronary diseases]

OBJECTIVES

To compare high intensity strength training with weightlifting exercises or with elastic bands.

SETTING

Outpatient unit of cardiac rehabilitation. TYPE: Prospective randomised clinical trial.

POPULATION

Inclusion of coronary patients in phase II after medical or surgical treatment of a myocardiac infarction, without cardiac insufficiency; beta-blockers were accepted.

METHOD

Evaluation of coronary patients at beginning and at the end of a 4 week cardiac rehabilitation program. It included progressive aerobic training according to Karvonen method for all the patients, associated with weightlifting exercises (Koch press) in the control group, or use of elastic bands in the experimental group. Cardiac rate, oxygen consumption at rest and at maximum power were the main criteria with also muscle strength of quadriceps, hamstrings, biceps brachii, latissimus dorsi and triceps brachii, body mass indexes, quality of life with SF-36, anxiety (stay T test) and perceived exertion with the Borg 10-point category-ratio scale, myotendinous injuries (Shaw scale).

RESULTS

Twenty-six coronary patients, all male from 45 to 65 years old, all receiving beta-blockers, were included, 13 in each group. Control and experimental groups were initially similar. At the end of the 4 week program, all the two groups improved significantly their strength and power and there were no differences between the two groups. Perceived exertion was lower in the group using elastic bands and there were no myotendinous lesions.

CONCLUSION

Strength training with elastic bands is a low-cost, attractive, playful technique, proposed to a group of coronary patients, which appears as effective in cardiac rehabilitation as individual weightlifting training.

HIV Lipodystrophy Syndrome: A Primer

Treatment with highly active antiretroviral therapy (HAART) has been implicated in the development of anthropomorphic and metabolic abnormalities termed HIV lipodystrophy syndrome (or LDS). This primer offers a comprehensive overview of LDS including epidemiology, hypothesized etiologies, and clinical consequences. The evidence-based literature is reviewed for current treatment strategies including discontinuation of specific antiretrovirals, pharmacological management of dyslipidemia and insulin resistance, exercise training, facial augmentation, liposuction, and hormonal therapy. Patient education, counseling, and adherence are discussed.

Systematic Review of Progressive Resistance Strength Training in Older Adults

BACKGROUND

The aim of this systematic review was to quantify the effectiveness of progressive resistance strength training (PRT) to reduce physical disability in older people.

METHODS

Randomized controlled trials were identified from searches of relevant databases and study reference lists and contacts with researchers. Two reviewers independently screened the trials for eligibility, rated their quality, and extracted data. Only randomized controlled trials utilizing PRT as the primary intervention in participants, whose group mean age was 60 years or older, were included. Data were pooled using fixed or random effect models to produce weighted mean differences (WMD) and 95% confidence intervals (CI). Standardized mean differences (SMD) were calculated when different units of measurement were used for the outcome of interest.

RESULTS

62 trials (n = 3674) compared PRT with a control group. 14 trials had data available to allow pooling of disability outcomes. Most trials were of poor quality. PRT showed a strong positive effect on strength, although there was significant heterogeneity (41 trials [n = 1955], SMD 0.68; 95% confidence interval [CI] 0.52, 0.84). A modest effect was found on some measures of functional limitations such as gait speed (14 trials [n = 798], WMD 0.07 meters per second; 95% CI 0.04, 0.09). No evidence of an effect was found for physical disability (10 trials [n = 722], SMD 0.01; 95% CI -0.14, 0.16). Adverse events were poorly investigated, but occurred in most studies where they were defined and prospectively monitored.

CONCLUSIONS

PRT results in improvements to muscle strength and some aspects of functional limitation, such as gait speed, in older adults. However, based on current data, the effect of PRT on physical disability remains unclear. Further, due to the poor reporting of adverse events in trials, it is difficult to evaluate the risks associated with PRT.

Benefits of exercise and dietary measures to optimize shifts in body composition with age

Ageing is associated with changes in body composition, including an increase and redistribution of adipose tissue and a decrease in muscle and bone mass, beginning as early as the fourth decade of life. These changes have significant implications for the health and functioning of the individual because of their associations with chronic disease expression and severity, as well as geriatric syndromes such as mobility impairment, falls, frailty and functional decline. Therefore, understanding the preventive and therapeutic options for optimizing body composition in old age is central to the care of patients in mid-life and beyond. Pharmacological interventions are currently available for maintaining or improving bone mass, and much current interest is focused on anabolic agents that will preserve or restore muscle mass, as well as those that can potentially limit adipose tissue deposition. However, in this brief review, non-pharmacological modulation of body composition through appropriate dietary intake and physical activity patterns, will be discussed. There is sufficient evidence currently to suggest that a substantial portion of what have been considered 'age-related' changes in muscle, fat and bone are in fact related either to excess energy consumption, decreased energy expenditure in physical activity, or both factors in combination. In addition, selective underconsumption of certain macro- or micronutrients contributes to losses of muscle and bone mass. Each of the three compartments will be considered in turn, with recommendations for optimizing the size of these body tissue stores in early adulthood, and minimizing undesirable changes typically seen in middle and old age.

One- and two-year change in body composition as measured by DXA in a population-based cohort of older men and women

Changing body composition has been suggested as a pathway to explain age-related functional decline. No data are available on the expected changes in body composition as measured by dual-energy X-ray absorptiometry (DXA) in a population-based cohort of older persons. Body composition data at baseline, 1-yr follow-up, and 2-yr follow-up was measured by DXA in 2,040 well-functioning black and white men and women aged 70-79 yr, participants of the Health, Aging, and Body Composition Study. After 2 yr, a small decline in total body mass was observed (men: -0.3%, women: -0.4%). Among men, fat-free mass and appendicular lean soft tissue mass (ALST) decreased by -1.1 and -0.8%, respectively, which was masked by a simultaneous increase in total fat mass (+2.0%). Among women, a decline in fat-free mass was observed after 2 yr only (-0.6%) with no change in ALST and body fat mass. After 2 yr, the decline in ALST was greater in blacks than whites. Change in total body mass was associated with change in ALST (r = +0.58 to +0.70; P < 0.0001). Among participants who lost total body mass, men lost relatively more ALST than women, and blacks lost relatively more ALST than whites. In conclusion, the mean change in body composition after a 1- to 2-yr follow-up was 1-2% with a high interindividual variability. Loss of ALST was greater in men compared with women, and greater in blacks compared with whites, suggesting that men and blacks may be more prone to muscle loss.

Resistance exercise in men receiving androgen deprivation therapy for prostate cancer

PURPOSE

Androgen deprivation therapy is a common treatment in men with prostate cancer that may cause fatigue, functional decline, increased body fatness, and loss of lean body tissue. These physical changes can negatively affect health-related quality of life. Resistance exercise may help to counter some of these side effects by reducing fatigue, elevating mood, building muscle mass, and reducing body fat.

METHODS

In a two-site study, 155 men with prostate cancer who were scheduled to receive androgen deprivation therapy for at least 3 months after recruitment were randomly assigned to an intervention group that participated in a resistance exercise program three times per week for 12 weeks (82 men) or to a waiting list control group (73 men). The primary outcomes were fatigue and disease-specific quality of life as assessed by self-reported questionnaires after 12 weeks. Secondary outcomes were muscular fitness and body composition.

RESULTS

Men assigned to resistance exercise had less interference from fatigue on activities of daily living (P =.002) and higher quality of life (P =.001) than men in the control group. Men in the intervention group demonstrated higher levels of upper body (P =.009) and lower body (P <.001) muscular fitness than men in the control group. The 12-week resistance exercise intervention did not improve body composition as measured by changes in body weight, body mass index, waist circumference, or subcutaneous skinfolds.

CONCLUSION

Resistance exercise reduces fatigue and improves quality of life and muscular fitness in men with prostate cancer receiving androgen deprivation therapy. This form of exercise can be an important component of supportive care for these patients.

Effects of resistance versus aerobic training on coronary artery disease risk factors

Individuals exhibiting "the metabolic syndrome" have multiple coronary artery disease risk factors, including insulin resistance, hyperlipidemia, hypertension, and android obesity. We performed a randomized trial to compare the effects of aerobic and resistance training regimens on coronary risk factors. Twenty-six volunteers who exhibited android obesity and at least one other risk factor for coronary artery disease were randomized to aerobic or resistance training groups. Body mass index, waist-to-hip ratio, glucose, insulin, body composition, 24-hr urinary albumin, fibrinogen, blood pressure, and lipid profile were measured at baseline and after 10 weeks of exercise training. Both groups showed a significant reduction in waist-to-hip ratio and the resistance training group also showed a reduction in total body fat. There was no significant change in mean arterial blood pressure in either group. Fasting plasma glucose, insulin, total cholesterol, low-density lipoprotein (LDL) cholesterol, and triglycerides were unchanged in both groups. High-density lipoprotein (HDL) cholesterol increased (13%) with aerobic training only. Plasma fibrinogen was increased (28% and 34%, P < 0.02) in both groups and both groups showed a significant decrease (34% and 28%, P < 0.03) in microalbuminuria after their respective training regimen. In conclusion, resistance training was effective in improving body composition of middle-aged obese sedentary males. Only aerobic training was effective in raising HDL cholesterol. More studies are warranted to assess the effects of exercise on plasma fibrinogen and microalbuminuria.

A meta-analysis to determine the dose response for strength development

PURPOSE

The identification of a quantifiable dose-response relationship for strength training is important to the prescription of proper training programs. Although much research has been performed examining strength increases with training, taken individually, they provide little insight into the magnitude of strength gains along the continuum of training intensities, frequencies, and volumes. A meta-analysis of 140 studies with a total of 1433 effect sizes (ES) was carried out to identify the dose-response relationship.

METHODS

Studies employing a strength-training intervention and containing data necessary to calculate ES were included in the analysis.

RESULTS

ES demonstrated different responses based on the training status of the participants. Training with a mean intensity of 60% of one repetition maximum elicits maximal gains in untrained individuals, whereas 80% is most effective in those who are trained. Untrained participants experience maximal gains by training each muscle group 3 d.wk and trained individuals 2 d.wk. Four sets per muscle group elicited maximal gains in both trained and untrained individuals.

CONCLUSION

The dose-response trends identified in this analysis support the theory of progression in resistance program design and can be useful in the development of training programs designed to optimize the effort to benefit ratio.

Creatine supplementation enhances isometric strength and body composition improvements following strength exercise training in older adults

We sought to determine whether creatine monohydrate (CrM) supplementation would enhance the increases in strength and fat-free mass that develop during resistance exercise training in older adults. Twenty-eight healthy men and women over the age of 65 years participated in a whole-body resistance exercise program 3 days per week for 14 weeks. The study participants were randomly allocated, in a double-blind fashion, to receive either CrM (5 g/d + 2 g of dextrose; n = 14) or placebo (7 g of dextrose; n = 14). The primary outcome measurements included the following: total body mass, fat-free mass, one-repetition maximum strength for each body part, isometric knee extension, handgrip, and dorsiflexion strength, chair stand performance, 30-m walk test, 14-stair climb performance, muscle fiber type and area, and intramuscular total creatine. Fourteen weeks of resistance exercise training resulted in significant increases in all measurements of strength and functional tasks and muscle fiber area for both groups (p <.05). CrM supplementation resulted in significantly greater increases in fat-free mass and total body mass, as compared with placebo (p <.05). The CrM group also showed a greater increase in isometric knee extension strength in men and women, as compared with placebo (p <.05), and also greater gains in isometric dorsiflexion strength (p <.05), but in men only. There was a significant increase in intramuscular total creatine in the CrM group (p <.05). Finally, there were no significant side effects of treatment or exercise training. This study confirms that supervised heavy resistance exercise training can safely increase muscle strength and functional capacity in older adults. The addition of CrM supplementation to the exercise stimulus enhanced the increase in total and fat-free mass, and gains in several indices of isometric muscle strength.

Progressive resistance strength training for physical disability in older people

BACKGROUND

Muscle weakness in old age, is associated with physical disability and an increased risk of falls. Progressive resistance strength (PRT) training exercises (i.e. movements performed against a specific external force that is regularly increased during training) are designed to increase strength in older people.

OBJECTIVES

To assess the effect of PRT on measures of physical disability, functional limitation and impairment in older people, and identify adverse events.

SEARCH STRATEGY

We searched the Cochrane Musculoskeletal Injuries Group specialized register (to August 2002), CENTRAL/CCTR (The Cochrane Library Issue 2, 2002), MEDLINE (1966 to February 1, 2002), EMBASE (1980 to February 1, 2002), CINAHL (1982 to February 1, 2002), Sports Discus (1948 to February 1, 2002), PEDro - The Physiotherapy Evidence Database (accessed February 1, 2002) and Digital Dissertations (accessed February 1, 2002). We also searched reference lists of articles, reviewed conference abstracts and contacted authors.

SELECTION CRITERIA

Randomised trials of PRT alone for older people (i.e. mean age of 60 or over) were included.

DATA COLLECTION AND ANALYSIS

Two reviewers independently assessed trial quality and extracted data. Weighted mean differences (WMD) were obtained using fixed or random effect models as appropriate. When measures with different units were pooled, standardised mean differences (SMD) were calculated. Relative risks were calculated for dichotomous outcomes.

MAIN RESULTS

Sixty-six trials with 3783 participants were included. Most studies were small and of poor quality. PRT had a large positive effect on strength (41 trials, 1955 participants), but there was statistical heterogeneity that was not explained by differences in study quality, participant characteristics or the exercise program. Some functional limitation measures showed modest improvements (i.e. gait speed, 14 trials, 798 participants, WMD 0.07 m/s, 95% CI 0.04 to 0.09). However, there was no evidence that PRT had an effect on physical disability when activity measures or health related quality of life measures (HRQOL) were assessed (10 trials, 798 participants, SMD 0.01, 95% CI -0.14 to 0.16 ). Adverse events were poorly recorded, but musculoskeletal injuries were detected in most of the studies that prospectively defined and monitored these events.

REVIEWER'S CONCLUSIONS

PRT appears to be an effective intervention to increase strength in older people and has a positive effect on some functional limitations. However, the effect of this intervention on more substantive outcomes such as measures of disability or HRQOL remains unclear. It is difficult to determine the balance of risks and benefits of PRT because adverse events have generally been poorly collected and recorded.

Hemiparetic muscle atrophy and increased intramuscular fat in stroke patients

OBJECTIVE

To determine if skeletal muscle atrophy and greater fat deposition within the muscle are present in the hemiparetic limb of chronic (>6 mo) hemiparetic stroke patients.

DESIGN

Cross-sectional study.

SETTING

Hospital-based research center.

PARTICIPANTS

Sixty patients (47 men, 13 women; mean age +/- standard deviation, 65+/-9 y).

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

Patients underwent a total body scan by dual-energy x-ray absorptiometry to determine percentage of body fat, total lean mass, fat mass, and lean mass of the paretic and nonaffected legs, thighs, and arms. Thirty patients received computed tomography (CT) scans of their midthigh to determine muscle area, subcutaneous fat, and low-density lean tissue, as a measure of fat within the muscle area, of the paretic and nonaffected midthigh.

RESULTS

Patients were deconditioned (VO(2)peak: 1.2+/-0.3 L/min) with a percentage of body fat of 31.4%+/-9.8% and total lean mass of 51.4+/-9.1 kg. Lean mass of the paretic leg and thigh were 4% and 3% lower than the nonaffected leg (P<.001), but leg fat was not different. Arm lean mass of the paretic side was 7% lower than the nonaffected side, whereas arm fat was not different. CT studies showed that midthigh muscle area was 20% lower in the paretic limb than in the nonaffected leg (P<.001), midthigh subcutaneous fat was similar, and midthigh low-density lean tissue showed a trend to be 3% higher in the paretic leg (P=.06). The ratio of midthigh low-density lean tissue to muscle area was higher in the paretic leg (P<.001), which indicates a greater intramuscular fat relative to muscle area in the affected limb.

CONCLUSIONS

Our results show hemiparetic skeletal muscle atrophy and more fat within the muscle, factors that may contribute to functional disability and increased cardiovascular disease risk in chronic hemiparetic stroke patients.

Berger in retrospect: effect of varied weight training programmes on strength

The evidence that multiple sets of exercise are superior to a single set for maximal strength gains, as suggested by Berger in 1962, is reviewed. The validity and practical significance of Berger's strength training study are questioned. Well controlled, methodologically sound studies that minimise confounding variables are required to support the hypothesis that multiple sets of exercise elicit superior gains in strength.

High-intensity resistance training improves glycemic control in older patients with type 2 diabetes

OBJECTIVE

To examine the effect of high-intensity progressive resistance training combined with moderate weight loss on glycemic control and body composition in older patients with type 2 diabetes.

RESEARCH DESIGN AND METHODS

Sedentary, overweight men and women with type 2 diabetes, aged 60-80 years (n = 36), were randomized to high-intensity progressive resistance training plus moderate weight loss (RT & WL group) or moderate weight loss plus a control program (WL group). Clinical and laboratory measurements were assessed at 0, 3, and 6 months.

RESULTS

HbA(1c) fell significantly more in RT & WL than WL at 3 months (0.6 +/- 0.7 vs. 0.07 +/- 0.8%, P < 0.05) and 6 months (1.2 +/- 1.0 vs. 0.4 +/- 0.8%, P < 0.05). Similar reductions in body weight (RT & WL 2.5 +/- 2.9 vs. WL 3.1 +/- 2.1 kg) and fat mass (RT & WL 2.4 +/- 2.7 vs. WL 2.7 +/- 2.5 kg) were observed after 6 months. In contrast, lean body mass (LBM) increased in the RT & WL group (0.5 +/- 1.1 kg) and decreased in the WL group (0.4 +/- 1.0) after 6 months (P < 0.05). There were no between-group differences for fasting glucose, insulin, serum lipids and lipoproteins, or resting blood pressure.

CONCLUSIONS

High-intensity progressive resistance training, in combination with moderate weight loss, was effective in improving glycemic control in older patients with type 2 diabetes. Additional benefits of improved muscular strength and LBM identify high-intensity resistance training as a feasible and effective component in the management program for older patients with type 2 diabetes.

Segmentation of fat and muscle from MR images of the thigh by a possibilistic clustering algorithm

Physical training is proved to induce changes in physical capacity and body composition. We propose in this article a fast, unsupervised and fully three-dimensional automatic method to extract muscle and fat volumes from magnetic resonance images of thighs in order to assess these changes. The technique relies on the use of a fuzzy clustering algorithm and post-processings to accurately process the body composition of thighs. Results are compared on 11 healthy voluntary elderly people with those provided on the same data by a validated method already published, and its reliability is assessed on repeated measures on three subjects. The two methods statistically agree when computing muscle and fat volumes, and clinical implications of this fully automatic method are important for medicine, physical conditioning, weight-loss programs and predictions of optimal body weight.

Effect of long-term strength training on glucose metabolism. Implications for individual impact of high lean mass and high fat mass on relationship between BMI and insulin sensitivity

The aim of this study was to examine the independent effect of high lean mass on glucose metabolism, as well as its consequences on the classic relationship between BMI and insulin sensitivity (SI) in 3 groups: 1) 8 strength-trained males with BMI >27 kg/m2 (athletes); 2) 10 sedentary males with BMI >27 kg/m2 (obese); and 3) 12 sedentary males with BMI 22-25 kg/m2 (control). Body composition was measured with impedance analysis. Iv glucose tolerance test was performed at 09:00 h after overnight fast. Estimation of insulin sensitivity and glucose effectiveness by Minimal Model Approach. Plasma glucose and insulin determination by glucose-oxidase and RIA respectively. BMI and lean mass (LM) were greater in athletes than in controls, but there were no differences in fat mass (FM), basal glucose (Gb), basal insulin (Ib), glucose tolerance (Kg), SI, glucose effectiveness (Sg), acute insulin response to glucose (AIRG) and leptin. Obese showed greater FM, leptin, lb and AIRG than athletes, while SI was lower; BMI, LM, Gb, Kg and Sg were similar. BMI, FM, LM, Ib, AIRG and leptin were lower in controls than in obese, while SI index was greater; Gb, Sg and Kg were similar. We found that: 1) Resistance exercise does not modify glucose effectiveness, but can improve insulin sensitivity through FM reduction (LM augmentation alone has no effect on glucose metabolism); and 2) High BMI causes insulin resistance only if it depends on adipose tissue hypertrophy.

Prescription of resistance training for healthy populations

Although there are well documented protective health benefits conferred by regular physical activity, most individuals of all ages are not physically active at a level for sufficient maintenance of health. Consequently, a major public health goal is to improve the collective health and fitness levels of all individuals. The American College of Sports Medicine (ACSM) and other international organisations have established guidelines for comprehensive exercise programmes composed of aerobic, flexibility and resistance-exercise training. Resistance training is the most effective method available for maintaining and increasing lean body mass and improving muscular strength and endurance. Furthermore, there is an increasing amount of evidence suggesting that resistance training may significantly improve many health factors associated with the prevention of chronic diseases. These health benefits can be safely obtained by most segments of the population when prescribed appropriate resistance-exercise programmes. Resistance-training programmes should be tailored to meet the needs and goals of the individual and should incorporate a variety of exercises performed at a sufficient intensity to enhance the development and maintenance of muscular strength and endurance, and lean body mass. A minimum of 1 set of 8 to 10 exercises (multi-joint and single joint) that involve the major muscle groups should be performed 2 to 3 times a week for healthy participants of all ages. More technical and advanced training including periodised multiple set regimens and/or advanced exercises may be more appropriate for individuals whose goals include maximum gains in strength and lean body mass. However, the existing literature supports the guidelines as outlined in this paper for children and adults of all ages seeking the health and fitness benefits associated with resistance training.

Musculoskeletal fitness, health outcomes and quality of life

The health benefits and quality-of-life outcomes of a fit musculoskeletal system (musculoskeletal fitness) are reviewed in this article. The World Health Organization suggests health is a state of complete physical, mental or social well-being and not merely the absence of disease or infirmity. Physical health includes such characteristics as body size and shape, sensory acuity, susceptibility to disease and disorders, body functioning, recuperative ability and the ability to perform certain tasks. One aspect of physical health is the musculoskeletal system, which consists of 3 components; muscular strength, endurance and flexibility. Muscular strength (dynamic) is defined as the maximum force a muscle or muscle group can generate at a specific velocity. Muscular endurance is the ability of a muscle or muscle group to perform repeated contractions against a load for an extended period of time. Flexibility has 2 components, dynamic or static, where dynamic flexibility is the opposition or resistance of a joint to motion, that is, the forces opposing movement rather than the range of movement itself. Static flexibility is the range of motion about ajoint, typically measured as the degree of arc at the end of joint movement. If strength, endurance and flexibility are not maintained, musculoskeletal fitness is then compromised which can significantly impact physical health and well-being. Many health benefits are associated with musculoskeletal fitness, such as reduced coronary risk factors, increased bone mineral density (reduced risk of osteoporosis), increased flexibility, improved glucose tolerance, and greater success in completion of activities of daily living (ADL). With aging, the performance of daily tasks can become a challenge. Additionally, falls, bone fractures and the need for institutional care indicate a musculoskeletal weakness as we age. The earlier in life an individual becomes physically active the greater the increase in positive health benefits; however, becoming physically active at any age will benefit overall health. Improved musculoskeletal fitness (for example, through resistance training combined with stretching) is associated with an enhanced health status. Thus, maintaining musculoskeletal fitness can increase overall quality of life.

Body composition and food intake in elderly women subjected to resistance training

This study analyzed the effects of a 10-wk resistance training program on body composition in 11 elderly women (68.91 ± 5.43 yrs). A control group of 8 women (65.13 ± 4.09 yrs) served as inactive control. The body fat percentage (skinfold thickness and bioelectrical impedance), body-circumference measurements and sum of skinfolds were assessed before and after 10 weeks. Food intake was assessed immediately before week 0 and week 10, from 3-day diet records (energy, protein, carbohydrate and fat). After initial tests, the subjects began a training program consisting of eight exercises for the whole body. The training program only resulted in decrease in sum of skinfolds (p<=0.05). No significant changes in any variable were observed in the control group. In conclusion, the training program did not reduce body fat percentage, although it reduced sum of skinfolds.

Creatine supplementation combined with resistance training in older men

PURPOSE

To study the effect of creatine (Cr) supplementation combined with resistance training on muscular performance and body composition in older men.

METHODS

Thirty men were randomized to receive creatine supplementation (CRE, N = 16, age = 70.4 +/- 1.6 yr) or placebo (PLA, N = 14, age = 71.1 +/- 1.8 yr), using a double blind procedure. Cr supplementation consisted of 0.3-g Cr.kg(-1) body weight for the first 5 d (loading phase) and 0.07-g Cr.kg(-1) body weight thereafter. Both groups participated in resistance training (36 sessions, 3 times per week, 3 sets of 10 repetitions, 12 exercises). Muscular strength was assessed by 1-repetition maximum (1-RM) for leg press (LP), knee extension (KE), and bench press (BP). Muscular endurance was assessed by the maximum number of repetitions over 3 sets (separated by 1-min rest intervals) at an intensity corresponding to 70% baseline 1-RM for BP and 80% baseline 1-RM for the KE and LP. Average power (AP) was assessed using a Biodex isokinetic knee extension/flexion exercise (3 sets of 10 repetitions at 60 degrees.s(-1) separated by 1-min rest). Lean tissue (LTM) and fat mass were assessed using dual energy x-ray absorptiometry.

RESULTS

Compared with PLA, the CRE group had significantly greater increases in LTM (CRE, +3.3 kg; PLA, +1.3 kg), LP 1-RM (CRE, +50.1 kg; PLA +31.3 kg), KE 1-RM (CRE, +14.9 kg; PLA, +10.7 kg), LP endurance (CRE, +47 reps; PLA, +32 reps), KE endurance (CRE, +21 reps; PLA +14 reps), and AP (CRE, +26.7 W; PLA, +18 W). Changes in fat mass, fat percentage, BP 1-RM, and BP endurance were similar between groups.

CONCLUSION

Creatine supplementation, when combined with resistance training, increases lean tissue mass and improves leg strength, endurance, and average power in men of mean age 70 yr.