The effect of exercise training on cognitive function in older adults with mild cognitive impairment: a meta-analysis of randomized controlled trials

OBJECTIVES

Investigations of exercise and cognition have primarily focused on healthy or demented older adults, and results have been equivocal in individuals with mild cognitive impairment (MCI). Our aim was to evaluate efficacy of exercise on cognition in older adults with MCI.

DESIGN

We conducted a meta-analysis of random controlled trials (RCTs) of exercise effects on cognitive outcomes in adults with MCI. Searches were conducted in Medline, EMBASE, CINAHL, PEDro, SPORTSDICUS, PsychInfo, and PubMed.

PARTICIPANTS

Adults aged over 65 years with MCI or Mini-Mental State Exam mean score 24-28 inclusive.

MEASUREMENTS

Study quality was assessed using the PEDro scale; data on participant and intervention characteristics and outcomes were extracted, followed by meta-analysis.

RESULTS

Fourteen RCTs (1,695 participants; age 65-95 years) met inclusion criteria. Quality was modest and under-powering for small effects prevalent. Overall, 42% of effect sizes (ESs) were potentially clinically relevant (ES >0.20) with only 8% of cognitive outcomes statistically significant. Meta-analysis revealed negligible but significant effects of exercise on verbal fluency (ES: 0.17 [0.04, 0.30]). No significant benefit was found for additional executive measures, memory, or information processing. Overall results were inconsistent with benefits varying across exercise types and cognitive domains.

CONCLUSIONS

There is very limited evidence that exercise improves cognitive function in individuals with MCI, although published research is of moderate quality and inconclusive due to low statistical power. Questions remain regarding the magnitude, generalization, persistence, and mechanisms of benefits. Large-scale, high-quality RCTs are required to determine if exercise improves cognition or reduces dementia incidence in those with MCI.

Changes in insulin resistance and HbA1c are related to exercise-mediated changes in body composition in older adults with type 2 diabetes: interim outcomes from the GREAT2DO trial

OBJECTIVE

To investigate changes in body composition after 12 months of high-intensity progressive resistance training (PRT) in relation to changes in insulin resistance (IR) or glucose homeostasis in older adults with type 2 diabetes.

RESEARCH DESIGN AND METHODS

One-hundred three participants were randomized to receive either PRT or sham exercise 3 days per week for 12 months. Homeostasis model assessment 2 of insulin resistance (HOMA2-IR) and glycosylated hemoglobin (HbA1c) were used as indices of IR and glucose homeostasis. Skeletal muscle mass (SkMM) and total fat mass were assessed using bioelectrical impedance. Visceral adipose tissue, mid-thigh cross-sectional area, and mid-thigh muscle attenuation were quantified using computed tomography.

RESULTS

Within the PRT group, changes in HOMA2-IR were associated with changes in SkMM (r = -0.38; P = 0.04) and fat mass (r = 0.42; P = 0.02). Changes in visceral adipose tissue tended to be related to changes in HOMA2-IR (r = 0.35; P = 0.07). Changes in HbA1c were related to changes in mid-thigh muscle attenuation (r = 0.52; P = 0.001). None of these relationships were present in the sham group (P > 0.05). Using ANCOVA models, participants in the PRT group who had increased SkMM had decreased HOMA2-IR (P = 0.05) and HbA1c (P = 0.09) compared with those in the PRT group who lost SkMM. Increases in SkMM in the PRT group decreased HOMA2-IR (P = 0.07) and HbA1c (P < 0.05) compared with those who had increased SkMM in the sham group.

CONCLUSIONS

Improvements in metabolic health in older adults with type 2 diabetes were mediated through improvements in body composition only if they were achieved through high-intensity PRT.

The effect of whole body vibration exposure on muscle function in children with cystic fibrosis: a pilot efficacy trial

Background

To examine the effects of whole body vibration (WBV) exposure on muscle function in children with Cystic Fibrosis (CF). Non-randomised controlled cross-over trial.

Methods

The setting was home-based WBV exposure. The participants were children (8 - 15 years) with CF (n = 7). Intervention: participants served as their own controls for the first four weeks (usual care), then underwent four weeks of parentally-supervised home-based WBV exposure followed by four weeks washout (usual care). The WBV exposure consisted of 20 - 30 minutes of intermittent (1 min vibration:1 min rest) exposure on a Galileo platform (20 - 22Hz, 1 mm amplitude) 3 days/week. The primary outcome measures of absolute and relative lower body (leg extension (LE), leg press (LP)), upper body (chess press (CP)) strength and power, and power were measured at baseline, and weeks 4, 8 and 12. Secondary exploratory outcomes were cardiorespiratory fitness, pulmonary function and health-related quality of life.

Results

Six participants completed the training without adverse events. Muscle function changes following WBV exposure were not statistically significant. However, moderate-to-large relative effect sizes (ES) favouring WBV were evident for leg extension strength (ES = 0.66 (-0.50, 1.82)), LP relative strength (ES = 0.92 (-0.27, 2.11)), leg press peak power (ES = 0.78 (-0.50, 2.07)) and CMJ height (ES = 0.60 (-0.56 to 1.76)).

Conclusions

The results from this first controlled trial indicate that WBV may be a potentially effective exercise modality to safely increase leg strength and explosive power in children with CF. Potentially clinically relevant changes support continued investigation of the efficacy, mechanism and feasibility of this intervention in future large-scale studies.

Integration of balance and strength training into daily life activity to reduce rate of falls in older people (the LiFE study): randomised parallel trial

OBJECTIVES

To determine whether a lifestyle integrated approach to balance and strength training is effective in reducing the rate of falls in older, high risk people living at home.

DESIGN

Three arm, randomised parallel trial; assessments at baseline and after six and 12 months. Randomisation done by computer generated random blocks, stratified by sex and fall history and concealed by an independent secure website.

SETTING

Residents in metropolitan Sydney, Australia.

PARTICIPANTS

Participants aged 70 years or older who had two or more falls or one injurious fall in past 12 months, recruited from Veteran's Affairs databases and general practice databases. Exclusion criteria were moderate to severe cognitive problems, inability to ambulate independently, neurological conditions that severely influenced gait and mobility, resident in a nursing home or hostel, or any unstable or terminal illness that would affect ability to do exercises.

INTERVENTIONS

Three home based interventions: Lifestyle integrated Functional Exercise (LiFE) approach (n=107; taught principles of balance and strength training and integrated selected activities into everyday routines), structured programme (n=105; exercises for balance and lower limb strength, done three times a week), sham control programme (n=105; gentle exercise). LiFE and structured groups received five sessions with two booster visits and two phone calls; controls received three home visits and six phone calls. Assessments made at baseline and after six and 12 months.

MAIN OUTCOME MEASURES

Primary measure: rate of falls over 12 months, collected by self report. Secondary measures: static and dynamic balance; ankle, knee and hip strength; balance self efficacy; daily living activities; participation; habitual physical activity; quality of life; energy expenditure; body mass index; and fat free mass.

RESULTS

After 12 months' follow-up, we recorded 172, 193, and 224 falls in the LiFE, structured exercise, and control groups, respectively. The overall incidence of falls in the LiFE programme was 1.66 per person years, compared with 1.90 in the structured programme and 2.28 in the control group. We saw a significant reduction of 31% in the rate of falls for the LiFE programme compared with controls (incidence rate ratio 0.69 (95% confidence interval 0.48 to 0.99)); the corresponding difference between the structured group and controls was non-significant (0.81 (0.56 to 1.17)). Static balance on an eight level hierarchy scale, ankle strength, function, and participation were significantly better in the LiFE group than in controls. LiFE and structured groups had a significant and moderate improvement in dynamic balance, compared with controls.

CONCLUSIONS

The LiFE programme provides an alternative to traditional exercise to consider for fall prevention. Functional based exercise should be a focus for interventions to protect older, high risk people from falling and to improve and maintain functional capacity.

TRIAL REGISTRATION

Australia and New Zealand Clinical Trials Registry 12606000025538.

Cognitive and memory training in adults at risk of dementia: a systematic review

BACKGROUND

Effective non-pharmacological cognitive interventions to prevent Alzheimer's dementia or slow its progression are an urgent international priority. The aim of this review was to evaluate cognitive training trials in individuals with mild cognitive impairment (MCI), and evaluate the efficacy of training in memory strategies or cognitive exercises to determine if cognitive training could benefit individuals at risk of developing dementia.

METHODS

A systematic review of eligible trials was undertaken, followed by effect size analysis. Cognitive training was differentiated from other cognitive interventions not meeting generally accepted definitions, and included both cognitive exercises and memory strategies.

RESULTS

Ten studies enrolling a total of 305 subjects met criteria for cognitive training in MCI. Only five of the studies were randomized controlled trials. Meta-analysis was not considered appropriate due to the heterogeneity of interventions. Moderate effects on memory outcomes were identified in seven trials. Cognitive exercises (relative effect sizes ranged from .10 to 1.21) may lead to greater benefits than memory strategies (.88 to -1.18) on memory.

CONCLUSIONS

Previous conclusions of a lack of efficacy for cognitive training in MCI may have been influenced by not clearly defining the intervention. Our systematic review found that cognitive exercises can produce moderate-to-large beneficial effects on memory-related outcomes. However, the number of high quality RCTs remains low, and so further trials must be a priority. Several suggestions for the better design of cognitive training trials are provided.

Effects of high-intensity progressive resistance training and targeted multidisciplinary treatment of frailty on mortality and nursing home admissions after hip fracture: a randomized controlled trial

RATIONALE

Excess mortality and residual disability are common after hip fracture.

HYPOTHESIS

Twelve months of high-intensity weight-lifting exercise and targeted multidisciplinary interventions will result in lower mortality, nursing home admissions, and disability compared with usual care after hip fracture.

DESIGN

Randomized, controlled, parallel-group superiority study.

SETTING

Outpatient clinic

PARTICIPANTS

Patients (n = 124) admitted to public hospital for surgical repair of hip fracture between 2003 and 2007.

INTERVENTION

Twelve months of geriatrician-supervised high-intensity weight-lifting exercise and targeted treatment of balance, osteoporosis, nutrition, vitamin D/calcium, depression, cognition, vision, home safety, polypharmacy, hip protectors, self-efficacy, and social support.

OUTCOMES

Functional independence: mortality, nursing home admissions, basic and instrumental activities of daily living (ADLs/IADLs), and assistive device utilization.

RESULTS

Risk of death was reduced by 81% (age-adjusted OR [95% CI] = 0.19 [0.04-0.91]; P < .04) in the HIPFIT group (n = 4) compared with usual care controls (n = 8). Nursing home admissions were reduced by 84% (age-adjusted OR [95% CI] = 0.16 [0.04-0.64]; P < .01) in the experimental group (n = 5) compared with controls (n = 12). Basic ADLs declined less (P < .0001) and assistive device use was significantly lower at 12 months (P = .02) in the intervention group compared with controls. The targeted improvements in upper body strength, nutrition, depressive symptoms, vision, balance, cognition, self-efficacy, and habitual activity level were all related to ADL improvements (P < .0001-.02), and improvements in basic ADLs, vision, and walking endurance were associated with reduced nursing home use (P < .0001-.05).

CONCLUSION

The HIPFIT intervention reduced mortality, nursing home admissions, and ADL dependency compared with usual care.

A randomized controlled trial of whole body vibration exposure on markers of bone turnover in postmenopausal women

Purpose. To examine the effects of two doses of low-frequency (12 Hz), low-magnitude (0.3 g), whole body vibration on markers of bone formation and resorption in postmenopausal women. Methods. Women were recruited and randomized into a sham vibration control group, one time per week vibration group (1×/week), or three times per week vibration group (3×/week). Vibration exposure consisted of 20 minutes of intermittent vibration for the 1×/week and 3×/week groups, and sham vibration (<0.1 g) for the control group for eight weeks. Double-blinded primary outcome measures were urine markers of bone resorption: N-telopeptide X normalised to creatinine (NTx/Cr) and bone formation: bone-specific alkaline phosphatase (ALP). Results. Forty-six women (59.8 ± 6.2 years, median 7.3 years since menopause) were enrolled. NTx/Cr was significantly reduced (34.6%) in the 3×/wk vibration group but not in the 1×/wk vibration group compared with sham control (P < .01) group. No effect of time or group allocation was observed on the bone formation marker ALP (P = .27). Conclusion. We have shown for the first time that low-frequency, low-magnitude vibration 3×/week for eight weeks in postmenopausal women results in a significant reduction in NTx/Cr, a marker of bone resorption, when compared with sham vibration exposure.

Exercise prescription for patients with type 2 diabetes and pre-diabetes: a position statement from Exercise and Sport Science Australia

Type 2 diabetes mellitus (T2DM) and pre-diabetic conditions such as impaired fasting glucose (IFG) and/or impaired glucose tolerance (IGT) are rapidly increasing in prevalence. There is compelling evidence that T2DM is more likely to develop in individuals who are insufficiently active. Exercise training, often in combination with other lifestyle strategies, has beneficial effects on preventing the onset of T2DM and improving glycaemic control in those with pre-diabetes. In addition, exercise training improves cardiovascular risk profile, body composition and cardiorespiratory fitness, all strongly related to better health outcomes. Based on the evidence, it is recommended that patients with T2DM or pre-diabetes accumulate a minimum of 210 min per week of moderate-intensity exercise or 125 min per week of vigorous intensity exercise with no more than two consecutive days without training. Vigorous intensity exercise is more time efficient and may also result in greater benefits in appropriate individuals with consideration of complications and contraindications. It is further recommended that two or more resistance training sessions per week (2-4 sets of 8-10 repetitions) should be included in the total 210 or 125 min of moderate or vigorous exercise, respectively. It is also recommended that, due to the high prevalence and incidence of comorbid conditions in patients with T2DM, exercise training programs should be written and delivered by individuals with appropriate qualifications and experience to recognise and accommodate comorbidities and complications.

Study of Mental Activity and Regular Training (SMART) in at risk individuals: a randomised double blind, sham controlled, longitudinal trial

Background

The extent to which mental and physical exercise may slow cognitive decline in adults with early signs of cognitive impairment is unknown. This article provides the rationale and methodology of the first trial to investigate the isolated and combined effects of cognitive training (CT) and progressive resistance training (PRT) on general cognitive function and functional independence in older adults with early cognitive impairment: Study of Mental and Regular Training (SMART). Our secondary aim is to quantify the differential adaptations to these interventions in terms of brain morphology and function, cardiovascular and metabolic function, exercise capacity, psychological state and body composition, to identify the potential mechanisms of benefit and broader health status effects.

Methods

SMART is a double-blind randomized, double sham-controlled trial. One hundred and thirty-two community-dwelling volunteers will be recruited. Primary inclusion criteria are: at risk for cognitive decline as defined by neuropsychology assessment, low physical activity levels, stable disease, and age over 55 years. The two active interventions are computerized CT and whole body, high intensity PRT. The two sham interventions are educational videos and seated calisthenics. Participants are randomized into 1 of 4 supervised training groups (2 d/wk × 6 mo) in a fully factorial design. Primary outcomes measured at baseline, 6, and 18 months are the Alzheimer's Disease Assessment Scale (ADAS-Cog), neuropsychological test scores, and Bayer Informant Instrumental Activities of Daily Living (B-IADLs). Secondary outcomes are psychological well-being, quality of life, cardiovascular and musculoskeletal function, body composition, insulin resistance, systemic inflammation and anabolic/neurotrophic hormones, and brain morphology and function via Magnetic Resonance Imaging (MRI) and Spectroscopy (fMRS).

Discussion

SMART will provide a novel evaluation of the immediate and long term benefits of CT, PRT, and combined CT and PRT on global cognitive function and brain morphology, as well as potential underlying mechanisms of adaptation in older adults at risk of further cognitive decline.

Trial Registration

Australia and New Zealand Clinical Trials Register (ANZCTR): ANZCTRN12608000489392

Lower limb muscle strengthening does not change frontal plane moments in women with knee osteoarthritis: A randomized controlled trial

BACKGROUND

Osteoarthritis is a common musculo-skeletal problem accompanied with muscle weakness. Muscle weakness may be readily improved by resistance training. Greater muscle strength has been associated with a lower knee joint loading rate.

METHODS

We conducted a single-blind randomized controlled trial of 54 female patients with osteoarthritis in at least one knee, according to the American College of Rheumatology clinical criteria. Patients were randomized into a 6-month high intensity progressive resistance training or a sham-exercise program. The primary outcomes were first peak knee and hip adduction moment measured using three-dimensional gait analysis at self-selected habitual and maximal speeds. Secondary outcomes were sagittal plane knee and hip moments, peak muscle strength, gait speed, and self-reported knee osteoarthritis symptoms measured by the Western Ontario and McMaster Osteoarthritis Index (WOMAC).

FINDINGS

Six months of high intensity resistance training did not change the first peak knee or hip adduction moment at either habitual or maximum walking speeds (P>0.413) compared to the sham-exercise. However, the second peak hip adduction moment (P=0.025) and WOMAC pain score (P<0.001) were reduced significantly in both groups over time, but there was no group effect. The changes in the second peak hip adduction moment were inversely related to the changes in the WOMAC pain score (r=-0.394, P=0.009).

INTERPRETATIONS

Muscle strength training in women with osteoarthritis, while effective for reducing osteoarthritis symptoms, appeared to operate through mechanisms other than improved knee or hip joint loading, as paradoxically, improved symptoms were related to decreases of hip adduction moment in late stance.

Progressive resistance training and dynamic alignment in osteoarthritis: A single-blind randomised controlled trial

BACKGROUND

we hypothesised that high intensity progressive resistance training would improve lower limb dynamic alignment and function (lower knee adduction moment, increased muscle strength, and fewer knee osteoarthritis symptoms).

METHODS

women (n=54) with osteoarthritis in at least one knee were randomised into a 6-month resistance training or a sham-exercise program. The primary outcomes were dynamic shank and knee adduction angles and knee adduction moment of the most symptomatic knee measured with quantitative gait analysis. Secondary outcomes were muscle strength, gait speed, and osteoarthritis symptoms.

FINDINGS

dynamic alignment and knee adduction moment did not change over time or between groups. Muscle strength improved in both groups over time, but significantly more in the resistance training group (P=0.002). By contrast, gait velocity and pain improved over time (P ≤ 0.009) in both groups. Improvements in shank adduction angle were related to improvements in self-reported disability (r=0.381, P=0.015), but not to changes in muscle strength, gait velocity, or pain (all P>0.05).

INTERPRETATIONS

although muscle strength improved significantly more in the PRT group, the hypothesised reduction in knee adduction moment, shank and knee adduction angles were not evident after either exercise modality. However, improvements in disability and shank adduction angle were significantly directly related. Initial alignment should be used to stratify this population into separate groups when designing future trials and alternative modes of training investigated to potentially enhance beneficial alterations in knee alignment.

Behavioral strategies in diabetes prevention programs: a systematic review of randomized controlled trials

The worldwide epidemic of type 2 diabetes (T2D) emphasizes the need for guidelines regarding community implementation of lifestyle modification prevention programs. An understanding of effective behavioral strategies is needed if evidence translation is to be realized. The aim of this paper is to systematically review the behavioral change strategies for lifestyle T2D prevention programs.

METHODS

randomized controlled trials (RCTs) of lifestyle interventions for the prevention of T2D were reviewed with a systematic literature search. Data relating to the behavioral strategies and trial outcomes were extracted.

RESULTS

overall, lifestyle interventions were successful in reducing the incidence of T2D. The behavioral strategies utilized in these interventions were drawn from a variety of theoretical backgrounds. All RCTs utilized intensive modes of delivery and were associated with low dropout rates of 5.5-13.4%.

CONCLUSIONS

the available evidence shows that a robust behavioral change strategy is an essential part of an effective lifestyle modification program, as the absence of intensive individualized advice or "information only" more closely resembles the control group interventions used in these RCTs.

Effect of standing posture during whole body vibration training on muscle morphology and function in older adults: a randomised controlled trial

BACKGROUND

Whole body vibration (WBV) is a novel modality of exercise shown to improve musculoskeletal function. This study aims to examine the effects of standing posture during low magnitude WBV training on muscle function and muscle morphology in older adults.

METHODS

Nineteen men and women (50-80 years) were recruited to a three month randomised controlled trial and allocated to one of three groups: WBV with flexed knees (FK), WBV with locked knees (LK), or sham WBV with flexed knees (CON). Exposure was intermittent (1 min WBV:1 min rest) for 20 min, three times per week for 13 weeks. Measurements were taken at baseline and at three months. Primary outcomes included upper and lower body muscle function (strength, power and velocity). Secondary outcomes were muscle morphology, balance, habitual and maximal gait velocity, stair climb power, and chair stand performance.

RESULTS

Sixteen subjects completed the study. Relative (%) upper body contraction velocity improved significantly after WBV with FK compared to LK (FK 16.0%, LK -7.6%, CON 4.7, p = 0.01). Relative upper body strength (LK 15.1%, p = 0.02; FK 12.1%, p = 0.04; CON 4.7%) increased significantly following WBV compared to control. Absolute (p = 0.05) and relative (p = 0.03) lower leg strength significantly improved with both standing postures (LK 14.4%; FK 10.7%; CON 1.3%). Only the LK group differed significantly from CON in relative leg strength gains (p = 0.02). Potentially clinically meaningful but statistically non-significant improvements in lower leg muscle cross-sectional area (LK 3.7 cm², FK 2.4 cm², CON 2.2 cm² p = 0.13) were observed after WBV with LK compared to the other groups. No significant effects of WBV on any functional performance tests were observed.

CONCLUSIONS

Our results suggest that WBV may improve muscle strength and contraction velocity in some muscle groups in older adults. However, hypothesised differential adaptation to standing posture (FK > LK) was observed only for upper body contraction velocity, making recommendations regarding this prescriptive element inconclusive. The efficacy, mechanism of action and long term feasibility of WBV for musculoskeletal health in older adults warrants continued investigation in robustly designed, sufficiently powered future studies.

TRIAL REGISTRATION

ACTRN12609000353291.

The effect of exercise on haemodynamics in intermittent claudication: a systematic review of randomized controlled trials

Changes in lower limb haemodynamics such as arterial pressure and/or flow have often been, and continue to be, cited as possible mechanisms for the improvement in walking performance that occurs with exercise training in individuals with peripheral arterial disease (PAD), but data are conflicting in this regard. There are a small number of literature reviews examining the effects of exercise on PAD, however, there has been insufficient analysis synthesizing possible mechanisms of effect, overall benefits and limitations of these trials. Our objective was therefore to systematically review the evidence for the effect of exercise on lower limb haemodynamic measures of resting and post-exercise ankle brachial index (ABI), resting toe pressure, and resting and reactive hyperaemic calf blood flow in PAD. A systematic search of studies published between 1934 and March 2010 was conducted using MEDLINE, EMBASE, AMED, SportDiscus, CINAHL, PEDro, Premedline, Google Scholar and Web of Knowledge databases. Eligible studies included randomized controlled trials using an exercise intervention for the treatment of intermittent claudication with haemodynamic measures of disease severity as outcomes. Relative effect sizes (ESs) and 95% confidence intervals were calculated for outcomes. Correlation and regression analyses were performed to establish relationships between symptoms and haemodynamic outcomes. Thirty-three trials including 1237 subjects with mild to moderate claudication met the eligibility criteria. Exercise did not significantly change lower extremity haemodynamics in most trials; nor were clinical improvements related to changes in resting ABI (mean ES 0.09 +/- 0.26; r = 0.02; p = 0.94), post-exercise ABI (mean ES 0.18 +/- 0.3; r = -0.33; p = 0.52) or reactive hyperaemic calf blood flow (mean ES 0.38 +/- 0.67; r = 0.35; p = 0.26). A relationship may exist between a change in symptoms and changes in resting toe pressure (mean ES 0.22 +/- 0.22; r = 0.75; p = 0.25) and resting calf blood flow (mean ES 0.09 +/- 0.16; r = 0.59; p = 0.22). Changes in resting and post-exercise ABI and reactive hyperaemic calf blood flow do not appear to explain the clinical benefits of exercise in PAD. More study is required in the areas of resting toe pressure and resting calf blood flow.

The effect of whole body vibration exposure on muscle or bone morphology and function in older adults: a systematic review of the literature

CONTEXT AND OBJECTIVE

The aim of this study was to examine the effect of whole body vibration (WBV), a novel exercise modality, on muscle or bone morphology and function in older adults.

METHODS

A literature search of published randomised controlled trials (RCTs) was conducted using multiple databases and hand searching for study designs reporting the effects of WBV in older adults on any outcomes related to muscle function, or muscle or bone morphology. Concomitant exercise was only included if the control group performed the same exercise as the active WBV group, but without vibration.

RESULTS

Six RCTs met the inclusion criteria of this review, three reporting measures of muscle only, two assessing bone measures only and one detailing measures of both bone and muscle. Study design varied greatly across the six trials and only six of 35 musculoskeletal outcomes analysed were statistically significant. All statistically significant improvements were of muscle function.

CONCLUSIONS

The published literature to date provides only weak support for the efficacy of WBV exposure for muscle function, muscle morphology, or bone architecture in older adults. Irregularities in study design and WBV protocols across the literature and poor quality trials contribute to this inconsistency, revealing the need for more uniformity in future trials. Future research should be more robust in design, include larger cohorts, longer interventions and standardisation of protocols. They should also investigate the optimal dose-response relationships and variation in vibration characteristics, to determine the true efficacy, clinical relevance, and underlying mechanisms of muscle and bone adaptations.

Glucose Tranporter-4 expression in monocytes: a systematic review

OBJECTIVE

The purpose of this review was to systematically assess the extent of current knowledge of Glucose Tranporter-4 (GLUT-4) expression in monocytes in humans to address its potential use as a non-invasive and reliable model to investigate the relationships between insulin signalling, GLUT-4 expression and insulin action in vivo.

METHOD

Electronic database searches were performed with the keywords 'monocyte', 'leukocyte' and 'white blood cells', and the terms 'GLUT', 'glucose transporter' and 'SLC2A4' (solute carrier family 2 member 4). Studies were examined for robustness of design and outcomes by consensus of three reviewers.

RESULTS

Six cross-sectional or observational studies met the criteria for review. Insulin-stimulated GLUT-4 expression in monocytes from subjects likely to have impaired insulin sensitivity appeared blunted relative to healthy subjects.

CONCLUSION

The available results provide evidence that monocyte GLUT-4 translocation does occur in response to acute insulin exposure, and may be sensitive to the relative state of insulin resistance of the individual. However, due to the limited quantity and robustness of published data, the ultimate utility of monocyte GLUT-4 expression as an index of whole body insulin responsiveness and the clinical relevance of this methodology is unresolved at this time.

Resistive Exercise for Arthritic Cartilage Health (REACH): a randomized double-blind, sham-exercise controlled trial

Background

This article provides the rationale and methodology, of the first randomised controlled trial to our knowledge designed to assess the efficacy of progressive resistance training on cartilage morphology in women with knee osteoarthritis.

Development and progression of osteoarthritis is multifactorial, with obesity, quadriceps weakness, joint malalignment, and abnormal mechanical joint forces particularly relevant to this study. Progressive resistance training has been reported to improve pain and disability in osteoarthritic cohorts. However, the disease-modifying potential of progressive resistance training for the articular cartilage degeneration characteristic of osteoarthritis is unknown. Our aim was to investigate the effect of high intensity progressive resistance training on articular cartilage degeneration in women with knee osteoarthritis.

Methods

Our cohort consisted of women over 40 years of age with primary knee osteoarthritis, according to the American College of Rheumatology clinical criteria. Primary outcome was blinded measurement of cartilage morphology via magnetic resonance imaging scan of the tibiofemoral joint. Secondary outcomes included walking endurance, balance, muscle strength, endurance, power, and velocity, body composition, pain, disability, depressive symptoms, and quality of life.

Participants were randomized into a supervised progressive resistance training or sham-exercise group. The progressive resistance training group trained muscles around the hip and knee at 80% of their peak strength and progressed 3% per session, 3 days per week for 6 months. The sham-exercise group completed all exercises except hip adduction, but without added resistance or progression. Outcomes were repeated at 3 and 6 months, except for the magnetic resonance imaging scan, which was only repeated at 6 months.

Discussion

Our results will provide an evaluation of the disease-modifying potential of progressive resistance training for osteoarthritis.

Trial Registration

ANZCTR Reference No. 12605000116628

Adaptations to exercise training within skeletal muscle in adults with type 2 diabetes or impaired glucose tolerance: a systematic review

The aim of this investigation was to review morphological and metabolic adaptations within skeletal muscle to exercise training in adults with type 2 diabetes mellitus (T2DM) or impaired glucose tolerance (IGT). A comprehensive, systematic database search for manuscripts was performed from 1966 to March 2008 using computerized databases, including Medline, Premedline, CINAHL, AMED, EMBASE and SportDiscus. Three reviewers independently assessed studies for potential inclusion (exposure to exercise training, T2DM or IGT, muscle biopsy performed). A total of 18 exercise training studies were reviewed. All morphological and metabolic outcomes from muscle biopsies were collected. The metabolic outcomes were divided into six domains: glycogen, glucose facilitated transporter 4 (GLUT4) and insulin signalling, enzymes, markers of inflammation, lipids metabolism and so on. Beneficial adaptations to exercise were seen primarily in muscle fiber area and capillary density, glycogen, glycogen synthase and GLUT4 protein expressions. Few randomized controlled trials including muscle biopsy data existed, with a small number of subjects involved. More trials, especially robustly designed exercise training studies, are needed in this field. Future research should focus on the insulin signalling pathway to better understand the mechanism of the improvements in insulin sensitivity and glucose homeostasis in response to various modalities and doses of exercise in this cohort.

Effects of exercise on adiponectin: a systematic review

Secreted from white adipose tissue, circulating concentrations of adiponectin are reduced in the presence of metabolic and cardiovascular disease such as obesity and type 2 diabetes. The aim of this systematic review is to assess the body of evidence critically for the effects of exercise on adiponectin levels. Literature searches using the Medline, CINAHL, Cochrane Controlled Trials registry, EMBASE, and SportDiscus databases were conducted from 1966 to September 2006 using keywords pertaining to "adiponectin" and "exercise." Thirty-three trials met the inclusion criteria. Study designs consisted of 5 cross-sectional studies, 7 trials of acute exercise, 11 uncontrolled trials, 2 non-randomized controlled trials, and 8 randomized controlled trials (RCTs). Exercise of varying prescription has been shown to increase serum adiponectin in 38% of RCTs, demonstrating small-to-moderate effect sizes (ESs). One study reported a dose-response effect of resistance training intensity and the augmentation of adiponectin. Inconsistent support in the literature exists for increasing adiponectin levels after short-term exposure to robust aerobic or resistance training of moderate-to-high intensities. Particular attention should be directed toward high-risk cohorts, in whom augmentation of the anti-inflammatory cytokine adiponectin may assume critical importance.

Muscular strength and cardiorespiratory fitness is associated with higher insulin sensitivity in children and adolescents

OBJECTIVE

To investigate the relationship of muscular strength and cardiorespiratory fitness (CRF) to insulin resistance.

METHODS

In a cross sectional study of 126 volunteers (10-15 years) we measured insulin, glucose, lipids, body mass, height, waist circumference (WC), strength and CRF. Linear and logistic regression models assessed the relationships between these factors and estimated insulin resistance (Homeostasis Assessment Model2; HOMA2-IR).

RESULTS

Greater insulin resistance was associated with greater adiposity, lower CRF, and strength. Upper body strength and WC were the only independent predictors of insulin resistance, accounting for 39% of the variance (p < 0.001). Children in the highest and middle tertiles of absolute upper body strength were 98% less likely to have high insulin resistance than those with the lowest strength, adjusted for maturation and central adiposity, body mass (OR = 0.019; p = 0.003). Similar trends were present for high vs. low CRF.

CONCLUSION

Muscular strength has been identified for the first time as an independent and powerful predictor of better insulin sensitivity in children. Lower strength, CRF and higher central adiposity are highly predictive of higher levels of insulin resistance in this cohort, and should be considered potential targets for interventions designed to enhance metabolic fitness in children and adolescents.

Estimation of thigh muscle cross-sectional area by dual-energy X-ray absorptiometry in frail elderly patients

BACKGROUND

Thigh muscle mass and cross-sectional area (CSA) are useful indexes of sarcopenia and the response to treatment in older patients. Current criterion methods are computed tomography (CT) and magnetic resonance imaging.

OBJECTIVE

The objective was to compare thigh muscle mass estimated by dual-energy X-ray absorptiometry (DXA), a less expensive and more accessible method, with thigh muscle CSA determined by CT in a group of elderly patients recovering from hip fracture.

DESIGN

Midthigh muscle CSA (in cm(2)) was assessed from a 1-mm CT slice and midthigh muscle mass (g) from a 1.3-cm DXA slice in 30 patients (24 women) aged 81 +/- 8 y during 12 mo of follow-up. Fat-to-lean soft tissue ratios were calculated with each technique to permit direct comparison of a variable in the same units.

RESULTS

Baseline midthigh muscle CSA was highly correlated with midthigh muscle mass (r = 0.86, P < 0.001) such that DXA predicted CT-determined CSA with an SEE of 10 cm(2) (an error of approximately 12% of the mean CSA value). CT- and DXA-determined ratios of midthigh fat to lean mass were similarly related (intraclass correlation coefficient = 0.87, P < 0.001). When data were expressed as the changes from baseline to follow-up, CT and DXA changes were weakly correlated (intraclass correlation coefficient = 0.51, P = 0.019).

CONCLUSIONS

Assessment of sarcopenia by DXA midthigh slice is a potential low-radiation, accessible alternative to CT scanning of older patients. The errors inherent in this technique indicate, however, that it should be applied to groups of patients rather than to individuals or to evaluate the response to interventions.

Progressive resistance training in breast cancer: a systematic review of clinical trials

BACKGROUND

Progressive resistance training (PRT) may be effective for targeting the sequelae of breast cancer and its treatment given the unique anabolic nature of this exercise modality. Therefore, our objectives were: (1) to systematically review studies that have prescribed PRT after breast cancer surgery, (2) to summarize the efficacy of PRT in this cohort, and (3) to delineate areas for future investigations.

METHOD

A systematic review using computerized databases was performed.

RESULTS

The systematic review located 10 trials: Four uncontrolled trials, one controlled trial and five randomized controlled trials (RCTs). PRT was prescribed with aerobic training in 8/10 trials reviewed, and in isolation in 2/10 trials reviewed. Upper body PRT was prescribed in 7/10 trials, including 4/5 RCTs. No exacerbation of objectively measured or subjectively reported lymphedema symptoms was reported in any of these trials. Adverse events were rare, generally musculoskeletal in nature, and were managed effectively by conservative means. Overall, the studies we reviewed suggest that women surgically treated for breast cancer can derive health-related and clinical benefits by performing PRT after breast cancer surgery. Further research may be required to stimulate greater advocacy for PRT among oncologists, and in community care settings.

CONCLUSIONS

Robustly designed RCTs prescribing targeted PRT regimens throughout various phases of breast cancer treatment are warranted. RCTs with thorough, standardized reporting of interventions and adverse events are required to establish the efficacy of this intervention for the post-treatment management of breast cancer patients and survivors as a means to improve health status and quality of life.

Multi-modal exercise programs for older adults

BACKGROUND

Various modalities of exercise have been demonstrated to improve physical function and quality of life in older adults. Current guidelines stress the importance of multi-modal exercise for this cohort, including strengthening exercises, cardiovascular, flexibility and balance training. There is a lack of evidence, however, that simultaneously prescribed doses and intensities of strength, aerobic, and balance training in older adults are both feasible and capable of eliciting changes in physical function and quality of life.

METHODS

A comprehensive, systematic database search for manuscripts was performed. Two reviewers independently assessed studies for potential inclusion. Physical and functional performance outcomes were extracted. The relative effect sizes (ES) were calculated with 95% confidence intervals.

RESULTS

Fifteen studies were included totalling 2,149 subjects; the mean cohort age ranging from 67 +/- 8 to 84 +/- 3 years. A low mean relative ES for strength was seen across the reviewed studies. Only six of the eleven studies that included balance measurements found a significant improvement in balance compared to controls. Aerobic fitness was seldom measured or reported. Five out of the six studies investigating fall rates showed a significant reduction. Functional and quality of life measures generally did not improve with exercise.

CONCLUSION

Multi-modal exercise has a positive effect on falls prevention. The limited data available suggests that multi-modal exercise has a small effect on physical, functional and quality of life outcomes. Future research should include robustly designed trials that involve multi-modal exercise at individually prescribed intensities based on doses found to be effective in single-modality studies.

A rationale and method for high-intensity progressive resistance training with children and adolescents

BACKGROUND

The rising prevalence of obesity in children and adolescents is implicated in the metabolic abnormalities that track into adulthood. The associated increased incidence of insulin resistance, metabolic syndrome and type 2 diabetes being identified in younger cohorts has given rise to a critical global health issue. Muscular strength is a vital component of metabolic fitness that provides protection from insulin resistance in adults, and we have recently shown this to be true in children as well. Targeting muscular strength deficiencies at an early age may be an effective preventative strategy for metabolic syndrome and type 2 diabetes.

PURPOSE

There is limited evidence-based best practice for progressive resistance training (PRT), adiposity and metabolic fitness in children and adolescents. The purpose of this paper is to describe the methodology we utilized for implementing a PRT program to avoid publication bias, enable replication of the study and share a novel program that we have found safe and suitable for use with youth.

METHODS

We conducted the first randomized controlled trial (RCT) prescribing high-intensity PRT to children and adolescents (10-15 years) as a community-based primary prevention program to address adiposity and metabolic health. Participants were instructed to complete 2 sets of 8 repetitions of 11 exercises targeting all the major muscle groups twice a week at an RPE of 15-18 for 8 weeks.

RESULTS

Primary outcome was waist circumference; secondary outcomes included insulin resistance, lipid levels, muscle strength, cardiorespiratory fitness, body composition, self-efficacy, self-concept, habitual physical activity, nutritional and sedentary behavior patterns.

CONCLUSION

The supervised PRT program that we used with children and adolescents has been described in detail. The efficacy of this modality of exercise for metabolic fitness and other health outcomes is now under investigation.

Rotator cuff tear in an elderly woman performing progressive resistance training: case report from a randomized controlled trial

The purpose of this article is to document a rotator cuff tear sustained by an elderly woman performing progressive resistance training (PRT) in a recent randomized controlled clinical trial. The patient was a sedentary 73-y-old Caucasian woman. Investigation revealed an acute, full-thickness tear of the right supraspinatus secondary to performing a shoulder press exercise. Further investigation via MRI revealed degenerative disease of the acromioclavicular joint including lateral downsloping of the acromion and an anteroinferior acromial spur, which would presdispose to impingement. Conservative management was implemented in this case for over 6 months with minimal success. The patient remained functionally limited in virtually all activities of daily living. Given the medical history, health status, physical condition, and age of our patient, it is probable that degenerative changes predisposed the patient to the injury. To our knowledge this is the first published report of an older adult sustaining a rotator cuff tear during PRT.

Progressive resistance training and nutrition in renal failure

Nutrition and exercise are an integral part of the medical management of many chronic and complex conditions. They are interrelated and share many common metabolic pathways that may affect disease processes and their management. In nephrology, nutritional interventions have been relatively well studied and are recommended in many evidence-based clinical practice guidelines for managing people with chronic kidney disease (CKD). Over the past 20 years, growing evidence has suggested that aerobic exercise interventions are efficacious, and that the rationale for progressive resistance training (PRT) is strong, particularly in this population, despite a more limited evidence base to date. In the small number of clinical trials that have included patients with CKD, PRT programs have proved safe, feasible to administer, and efficacious. They have been shown to improve clinical, physical, and functional outcomes.

Efficacy and Feasibility of a Novel Tri-Modal Robust Exercise Prescription in a Retirement Community: A Randomized, Controlled Trial

OBJECTIVES

To test the feasibility and efficacy of current guidelines for multimodal exercise programs in older adults.

DESIGN

Randomized, controlled trial.

SETTING

Retirement village.

PARTICIPANTS

Thirty-eight subjects (14 men and 24 women) aged 76.6 +/- 6.1.

INTERVENTION

A wait list control or 10 weeks of supervised exercise consisting of high-intensity (80% of one-repetition maximum (1RM)) progressive resistance training (PRT) 3 days per week, moderate-intensity (rating of perceived exertion 11 to 14/20) aerobic training 2 days per week, and progressive balance training 1 day per week.

MEASUREMENTS

Blinded assessments of dynamic muscle strength (1RM), balance, 6-minute walk, gait velocity, chair stand, stair climb, depressive symptoms, self-efficacy, and habitual physical activity level.

RESULTS

Higher baseline strength and psychological well-being were associated with better functional performance. Strength gains over 10 weeks averaged 39+/-31% in exercise, versus 21+/-24% in controls (P=.10), with greater improvements in hip flexion (P=.01), hip abduction (P=.02), and chest press (P=.04) in the exercise group. Strength adaptations were greatest in exercises in which the intended continuous progressive overload was achieved. Stair climb power (12.3+/-15%, P=.002) and chair stand time (-7.1+/-15%, P=.006) improved significantly and similarly in both groups. Reduction in depressive symptoms was significantly related to compliance (attendance rate r=-0.568, P=.009, PRT progression in loading r=-0.587, P=.02, and total volume of aerobic training r=-0.541, P=.01), as well as improvements in muscle strength (r=-0.498, P=.002).

CONCLUSION

Robust physical and psychological adaptations to exercise are linked, although volumes and intensities of multiple exercise modalities sufficient to cause significant adaptation appear difficult to prescribe and adhere to simultaneously in older adults.

Worksite intervention effects on sleep quality: A randomized controlled trial

Employees with sleep disturbance are at increased risk of disease. Exercise is believed to be effective for improving sleep quality, but few studies have been conducted. This study investigated the effects of a 24-week worksite exercise/behavioral intervention on self-rated sleep quality, via the Pittsburgh Sleep Quality Index (PSQI), in 73 employees. Greater post-test improvements in the PSQI (-2.0 +/- 2.6 vs. -1.3 +/- 2.7 points, p = .006, and -16 +/- 61 vs. -1 +/- 76%, p = .02) were found in treatment versus controls, and in women versus men (by -2.7 points [-5.0 to -0.3 points, p = .03], and by -72% [-142 to -2%, p = .04]). Similar results were found in the shift worker subgroup. Changes in sleep scores were not significantly related to baseline characteristics, changes in psychological health or quality-of-life scores, or level of exercise compliance.

Progressive resistance training during hemodialysis: Rationale and method of a randomized-controlled trial

Skeletal muscle wasting in patients receiving maintenance hemodialysis (HD) has been well documented. The rationale for prescribing progressive resistance training (PRT) in this cohort in an attempt to reverse this catabolism and induce a wide spectrum of physiological, functional, and psychological health-related adaptations is extremely strong. Unfortunately, the barriers to exercise adoption in this cohort are many, which may explain the persisting sedentariness of this population and the lack of widespread clinical programs such as are now commonplace in cardiac rehabilitation and pulmonary rehabilitation units. Current health care practices for HD patients do not address the negative health issues of inactivity and muscle wasting. Therefore, we conducted the first randomized-controlled trial to prescribe PRT during maintenance HD treatment. The purpose of this paper is to present the rationale and methodology that we utilized for implementing intradialytic PRT in a conventional outpatient HD clinic. Potential areas for modification of PRT regimens in this setting are also presented.

Worksite intervention effects on physical health: a randomized controlled trial

Overweight and physical inactivity are risk factors for increased disease burden and health care expenditure. Well-designed studies are still needed to determine the treatment efficacy of worksite interventions targeting such risk factors. This randomized controlled trial was conducted at one of Australia's casinos in 2002-2003, to investigate the effects of a comprehensive exercise and lifestyle intervention on physical fitness. Only 6.4% of the workforce expressed interest in being study participants. Seventy-three employees (aged 32 +/- 8 years, 51% overweight/obese, 73% shift workers and 52% women) were recruited and randomized to treatment or wait-list control groups for 24 weeks, 44 of whom completed the intervention. Components of the intervention include supervised moderate-to-high intensity exercise including combined aerobic (at least 20 min duration 3 days/week) and weight-training (for an estimated 30 min completed 2-3 days/week), and dietary/health education (delivered via group seminars, one-on-one counselling and literature through the provision of a worksite manual). ANCOVA, by intention-to-treat and of study completers, found significant between-group differences in the mean waist circumference and predicted maximal oxygen uptake (VO2max), favouring the intervention, but effects were concentrated in one subject. For study completers, between-group differences in the mean waist circumference (82.3 +/- 9.2 versus 90.5 +/- 17.8 cm, p = 0.01) and predicted VO2max (47 versus 41 ml/kg/min, p < 0.001) remained significant without the outlier, favouring the intervention. Higher intervention compliance predicted greater improvements in physical fitness. No significant effects on body mass or body mass index were found. This worksite intervention significantly improved waist circumference and aerobic fitness in healthy but sedentary employees, most of whom were shift workers. Worksite interventions have the potential to counter the increasing burden of overweight and obesity, particularly visceral adiposity, as well as physical inactivity; however, substantial barriers to adoption/adherence need to be overcome for greater feasibility and impact on employee physical health.

Strategies, time, and costs associated with the recruitment and enrollment of nursing home residents for a micronutrient supplementation clinical trial

BACKGROUND

Concomitant with the substantial growth of the elderly population in the last decade, there has been a steady rise in the number of nursing home residents aged 65 years and older. Well designed, rigorously conducted clinical intervention trials provide an important source of data for evidence-based improvements in the medical care of nursing home residents. The information available on strategies for the recruitment and screening of participants for such studies in long-term care facilities, as well as the financial and time costs for carrying out these investigations, is limited.

METHODS

This report describes our experience in recruiting 617 nursing home residents for a multisite, double-blind, randomized, placebo-controlled trial designed to determine the efficacy of a 1-year period of vitamin E supplementation in preventing respiratory tract infections. Comparisons of the projected staffing costs and actual costs incurred are presented, using a retrospective method for the determination of unit costs.

RESULTS

Initially, 874 consents were obtained from 2815 potential participants, of which only 617 were enrolled. Each successful enrollment required an average of 15 hours of staff time at a combined personnel and supply cost of $515 per participant and a total study cost of $317,661. Several obstacles were encountered during the recruitment and enrollment process: resistance on the part of family or primary care provider; transfer out of facility; and changes in the medical condition of the patient, including death.

DISCUSSION

The results of this report should prove useful to investigators developing budgets for nursing home-based clinical trials by providing a more accurate determination of the personnel needed and the costs associated with recruitment and enrollment of participants.

Force Steadiness in the Lower Extremities as an Independent Predictor of Functional Performance in Older Women

The relationship between isometric force control and functional performance is unknown. Submaximal steadiness and accuracy were measured during a constant force-matching task at 50% of maximal isometric voluntary contraction (MVC) of the knee extensors in 19 older women (70–89 years). Other variables included MVC, rate of torque development, and EMG activity. Functional performance was assessed during maximal performance of walking endurance, chair rising, and stair climbing. Isometric steadiness (but not accuracy) was found to independently predict chair-rise time and stair-climbing power and explained more variance in these tasks than any other variable. Walking endurance was related to muscle strength but not steadiness. These results suggest that steadiness is an independent predictor of brief, stressful functional-performance tasks in older women with mild functional impairment. Thus, improving steadiness might help reduce functional limitations or disability in older adults.

A randomized controlled trial of high versus low intensity weight training versus general practitioner care for clinical depression in older adults

BACKGROUND

Although exercise has been shown to relieve depression, little is known about its mechanism or dose-response characteristics. We hypothesized that high intensity progressive resistance training (PRT) would be more effective than either low intensity PRT or standard care by a general practitioner (GP) in depressed elderly persons, and that high intensity PRT would provide superior benefits in quality of life, sleep quality, and self-efficacy.

METHODS

Sixty community-dwelling adults >60 years with major or minor depression were randomized to supervised high intensity PRT (80% maximum load) or low intensity PRT (20% maximum load) 3 days per week for 8 weeks, or GP care.

RESULTS

A 50% reduction in the Hamilton Rating Scale of Depression score was achieved in 61% of the high intensity, 29% of the low intensity, and 21% of the GP care group (p =.03). Strength gain was directly associated with reduction in depressive symptoms (r = 0.40, p =.004), as was baseline social support network type (F = 3.52, p =.015), whereas personality type, self-efficacy, and locus of control were unrelated to the antidepressant effect. Vitality quality-of-life scale improved more in the high intensity group than in the others (p =.04). Sleep quality improved significantly in all participants (p <.0001), with the greatest relative change in high intensity PRT (p =.05).

CONCLUSIONS

High intensity PRT is more effective than is low intensity PRT or GP care for the treatment of older depressed patients.

Exercise training in patients receiving maintenance hemodialysis: a systematic review of clinical trials

BACKGROUND

Exercise is not routinely advocated in patients with end-stage renal disease (ESRD) receiving maintenance hemodialysis (HD), compared to best practice in other chronically diseased cohorts. Lack of widespread awareness of the exercise in HD literature may be contributing to these shortcomings of clinical practice. Therefore, our objectives are: (1) to systematically review trials of exercise training involving adult HD patients; (2) to provide empirical evidence that exercise can elicit health-related adaptations in this cohort, and (3) to provide recommendations for future investigations.

METHOD

A systematic review of the literature using computerized databases was performed.

RESULTS

According to the 29 trials reviewed, HD patients can safely derive a myriad of health-related adaptations from engaging in appropriately structured exercise regimens involving aerobic and/or resistance training. However, methodological limitations within this body of literature may be partially responsible for minimal advocacy for exercise in this cohort.

CONCLUSIONS

Robustly designed RCTs with thorough, standardized reporting are required if clinical practice and quality of life of this cohort is to be enhanced through the integration of exercise training and mainstream medical practice. Future trials should demonstrate the clinical importance, and long-term feasibility and applicability of exercise training for this vulnerable patient population.

Exercise training effects on skeletal muscle plasticity and IGF-1 receptors in frail elders

Age-related sarcopenia inhibits mobility, increasing the risk for developing many diseases, including diabetes, arthritis, osteoporosis, and heart disease. Tissue plasticity, or the ability to regenerate following stress, has been a subject of question in aging humans. We assessed the impact of 10-weeks of resistance training on markers of skeletal muscle plasticity and insulin growth factor-1 (IGF-1) receptor density in a sub sample of subjects who, in an earlier study, demonstrated enhanced immunohistochemical labeling of IGF following resistance training. Muscle biopsies from the vastus lateralis of five elderly men and women were taken prior to and following 10 weeks of resistance training (N = 3) or a control period (N = 2). Immunogold labeling and quantitative electron microscopy techniques were used to analyze markers of IGF-1 receptor density and tissue plasticity. The experimental subjects showed a 161 ± 93.7% increase in Z band damage following resistance training. Myofibrillar central nuclei increased 296 ± 120% (P = 0. 029) in the experimental subjects. Changes in the percent of damaged Z bands were associated with alterations in the presence of central nuclei (r = 0.668; P = 0.0347). Post hoc analysis revealed that the relative pre/post percent changes in myofibrillar Z band damage and central nuclei were not statistically different between the control and exercise groups. Exercise training increased myofibrillar IGF-1 receptor densities in the exercise subjects (P = 0.008), with a non-significant increase in the control group. Labeling patterns suggested enhanced receptor density around the Z bands, sarcolemma, and mitochondrial and nuclear membranes. Findings from this study suggest that the age-related downregulation of the skeletal muscle IGF-1 system may be reversed to some extent with progressive resistance training. Furthermore, skeletal muscle tissue plasticity in the frail elderly is maintained at least to some extent as exemplified by the enhancement of IGF-1 receptor density and markers of tissue regeneration.

Optimal Load for Increasing Muscle Power During Explosive Resistance Training in Older Adults

BACKGROUND

Muscle power (force x velocity) recedes at a faster rate than strength with age and may also be a stronger predictor of fall risk and functional decline. The optimal training paradigm for improving muscle power in older adults is not known, although some literature suggests high velocity, low load training is optimal in young adults.

METHODS

One hundred twelve healthy older adults (69 +/- 6 years) were randomly assigned to either explosive resistance training at 20% (G20), 50% (G50), or 80% (G80) one repetition maximum (1RM) for 8-12 weeks or to a nontraining control group (CON). Participants trained twice per week (five exercises; three sets of eight rapidly concentric and slow eccentric repetitions) using pneumatic resistance machines. Repeated-measures analysis of variance and covariance (ANOVA and ANCOVA) were used to determine the effects of training.

RESULTS

Average peak power increased significantly and similarly in G80 (14 +/- 8%), G50 (15 +/- 9%), and G20 (14 +/- 6%) compared to CON (3 +/- 6%) (p < .0001). By contrast, a positive dose-response relationship with training intensity was observed for relative changes in average strength (r = .40, p = .0009) and endurance (r = .43, p = .0005). Average strength increased in G80 (20 +/- 7%), G50 (16 +/- 7%), and G20 (13 +/- 7%) compared to CON (4 +/- 4%) (p < .0001). Average muscle endurance increased in G80 (185 +/- 126%, p < .0001), G50 (103 +/- 75%, p = .0004), and G20 (82 +/- 57%, p = .0078) compared to CON (28 +/- 29%).

CONCLUSION

Peak muscle power may be improved similarly using light, moderate, or heavy resistances, whereas there is a dose-response relationship between training intensity and muscle strength and endurance changes. Therefore, using heavy loads during explosive resistance training may be the most effective strategy to achieve simultaneous improvements in muscle strength, power, and endurance in older adults.

A Rationale for Intradialytic Exercise Training as Standard Clinical Practice in ESRD

The purpose of this article is to present a rationale for intradialytic exercise training in patients with end-stage renal disease based on the empirical evidence to date and determine whether this evidence has translated into enhanced renal rehabilitation practices throughout the world. According to the published literature, intradialytic exercise improves exercise adoption and adherence in this cohort, is performed safely, and is feasible to administer. Moreover, intradialytic exercise can improve solute removal, dialysis adequacy, intradialytic protein synthesis, muscular strength, peak oxygen consumption, nutritional status, and quality of life. Despite these findings, there currently are no policies or position stands regarding exercise prescription for hemodialysis patients in Australia. According to a telephone survey we conducted, intradialytic exercise programs are essentially nonexistent in this country. However, such programs are being implemented successfully as standard clinical practice in dialysis units in Germany, and there is reason to believe that this practice can be expanded throughout the world. At present, additional research is indicated. There is a lack of large-scale, robustly designed, randomized, controlled trials of intradialytic exercise training. Such research is needed to conclusively show the clinical importance of intradialytic exercise for hemodialysis patients, which may influence current standard clinical practice among nephrologists and, as such, improve the health and quality of life of this vulnerable cohort.

Physiological and functional responses to low-moderate versus high-intensity progressive resistance training in frail elders

BACKGROUND

The purpose of this efficacy study was to measure the dose-response effect of a free weight-based resistance training program by comparing the effects of two training intensities (low-moderate and high) of the knee extensor (KE) muscles on muscle function, functional limitations, and self-reported disability.

METHODS

The authors conducted a single-blinded, randomized, placebo-controlled trial. Twenty-two institutionalized elders (mean age, 81.5 years) were assigned to either high-intensity strength training (HI; n = 8), low-moderate intensity strength training (LI; n = 6), or weight-free placebo-control training (PC; n = 8). The HI group trained at 80% of their 1-repetition maximum and the LI group trained at 40%. All groups performed 3 sets of 8 repetitions, 3 times per week for 10 weeks. Outcome measures included KE maximal strength, KE endurance, and functional performance as assessed by 6-minute walking, chair-rising, and stair-climbing tests, and by self-reported disability.

RESULTS

KE strength and endurance, stair-climbing power, and chair-rising time improved significantly in the HI and LI groups compared with the PC group. Six-minute walking distance improved significantly in the HI group but not in the LI group compared with the PC group. Changes observed in HI were significantly different from those observed in the LI group for KE strength and endurance and the 6-minute walking test, with a trend in the same direction for chair-rising and stair-climbing. Changes in strength were significantly related to changes in functional outcomes, explaining 37% to 61% of the variance.

CONCLUSIONS

These results show strong dose-response relationships between resistance training intensity and strength gains, and between strength gains and functional improvements after resistance training. Low-moderate intensity resistance training of the KE muscles may not be sufficiently robust from a physiologic perspective to achieve optimal improvement of functional performance. Supervised HI, free weight-based training for frail elders appears to be as safe as lower intensity training but is more effective physiologically and functionally.

Anthropometric assessment of 10-y changes in body composition in the elderly

BACKGROUND

An increased central distribution of fat with advancing age is associated with chronic metabolic and cardiovascular abnormalities. Little is known about the magnitude or pattern of fat distribution and its association with healthy aging.

OBJECTIVE

This study describes approximately 10-y changes in body composition at 11 anthropometric sites in elderly persons and the metabolic and physical activity factors associated with these changes.

DESIGN

Skinfold thicknesses, girths, body fat by hydrodensitometry, physical activity by questionnaire, and metabolic variables were examined twice, 9.4 +/- 1.4 y apart, in 54 men and 75 women aged 60.4 +/- 7.8 y at baseline.

RESULTS

Subcutaneous fat declined (-17.2%; P < 0.001), whereas total fat mass increased (7.2%; P < 0.05). Waist and hip circumference changes were the best anthropometric predictors of total fat mass change (r(2) = 0.40-0.65, P < 0.0001). Thigh girth change was more strongly associated with fat-free mass change (r(2) = 0.22, P < 0.01) than with fat mass change (r(2) = 0.07, P < 0.05) in women. An increase in physical activity was associated with an attenuation of thigh girth decline in men and women (F ratio = 5.13, P < 0.007). Traditional metabolic markers of visceral adiposity (triacylglycerol, glucose, and total cholesterol) were not significantly related to the change in waist circumference.

CONCLUSIONS

Skinfold thicknesses cannot be used to assess changes in body fat mass because of age-related fat redistribution. Higher levels of physical activity can attenuate the decline in appendicular lean tissue expected over 10 y. Waist and thigh girths, rather than skinfold thicknesses, should be considered for use in longitudinal studies in the elderly because the changes in these girths capture increased abdominal adiposity and sarcopenia, respectively.

The effects of multidimensional home-based exercise on functional performance in elderly people

BACKGROUND

This study tested the hypothesis that a home-based exercise program would improve functional performance in elderly people.

METHODS

We conducted a 6-month, single-blinded, randomized controlled trial. 72 community dwelling men and women (aged >/=70 years) with self-reported and laboratory-based functional impairment were recruited for the study. Participants were randomly assigned to either a home-based progressive strength, balance, and general physical activity intervention or an attention-control group that received home-based nutrition education. Functional performance was measured in the laboratory using the Physical Performance Test (PPT) and the Established Populations for Epidemiologic Studies of the Elderly (EPESE) short physical performance battery. Physiologic capacity was measured by strength (one repetition maximum), dynamic balance (tandem walk), gait speed (2-meter walk), and cardiovascular endurance (6-minute walk).

RESULTS

70 participants (97%) completed the 6-month trial. Compliance with study interventions within each group ranged from 75% in controls to 82% in exercisers. PPT increased by 6.1 +/- 13.4% in exercisers and decreased by 2.8 +/- 13.6% in controls (p =.02). EPESE improved by 26.2 +/- 37.5% in exercisers and decreased by 1.2 +/- 22.1% in controls (p =.001). Dynamic balance improved by 33.8 +/- 14.4% in exercisers versus 11.5 +/- 23.7% in controls (p =.0002). There were no differences between groups in the change in strength, gait speed, or cardiovascular endurance.

CONCLUSIONS

Minimally supervised exercise is safe and can improve functional performance in elderly individuals. The improvements in functional performance occurred along with improvements in balance but without a significant change in muscle strength or endurance.