906 resultados para Muscle Strength.


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Objectives: To assess the effectiveness of a multivitamin (MV) tablet on nutritional status, quantitative heel ultrasound (QUS), mobility, muscle strength and falls. The design comprised two groups matched on mobility levels, randomized to receive a daily MV or placebo (P) tablet for 6 months. The setting was an Australian residential care facility.

Subjects: A total of 92 aged care residents. Serum micronutrients, body weight, QUS, rate of falls, hand grip strength, and the timed up and go test were assessed at baseline and 6 months.

Results: A total of 49 participants consumed a MV and 43, a matched P for 6 months. There was a greater increase in the MV vs P group for serum 25(OH)D (mean differencestandard error, 33.42.6 nmol l-1), folate (13.42.8 nmol l-1), and vitamin B12 (178.040.3 pmol l-1) (all P<0.001). Adequate 25(OH)D concentrations (50 nmol l-1) were found among 77% of participants in the MV group vs 10% taking P (P<0.001). Adjusting for baseline levels, the increase in QUS was greater in the MV vs P group (3.02.0 dB MHz-1 vs -2.92.1 dB MHz-1, respectively, P=0.041). There was a trend towards a 63% lower mean number of falls in the MV vs P group (0.30.1 falls vs 0.80.3 falls, P=0.078).

Conclusions: MV supplementation raised serum vitamin B12 and folate concentrations and increased serum 25(OH)D, which was accompanied by an apparent positive effect on bone density. We also found a trend towards a reduction in falls and this could contribute to a reduction in fractures.

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Elite athletes require a greater dietary protein intake than recreationally active people to maintain optimal muscular function. The timing of protein ingestion relative to exercise is critical to maximizing its physiological impact on skeletal muscles. Sports protein supplements provide a convenient means of supplying athletes with an adequate and timely source of quality dietary protein. There is now strong evidence that not all dietary proteins are equipotent in their effects on various aspects of athletic performance and specific protein isolates can provide benefits to athletes beyond simple supply of nutritional amino acids. Thus, there is an opportunity to develop new functional protein supplements to maximize athletic performance. This paper outlines the clinical evidence for the benefits of dairy proteins in sports performance and describes the development of new dairy protein supplements to build muscle strength, and to expedite recovery of strength following muscle-damaging eccentric exercise.

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In residential care, inadequate calcium and folate intakes and low serum vitamin D (25(OH)D) concentrations are common. We assessed whether daily provision of calcium, folate, and vitamin D3-fortified milk for 6 months improved nutritional status (serum micronutrients), bone quality (heel ultrasound), bone turnover markers (parathyroid hormone, C-terminal collagen I telopeptide, terminal propeptide of type I procollagen), and/or muscle strength and mobility in a group of Australian aged care residents. One hundred and seven residents completed the study (mean (SD) age: 79.9 (10.1) years; body weight: 68.4 (15.4) kg). The median (inter-quartile range) volume of fortified milk consumed was 160 (149) ml/day. At the end of the study, the median daily vitamin D intake increased to 10.4 (8.7) μg (P < .001), which is 70% of the adequate intake (15 μg); and calcium density (mg/MJ) was higher over the study period compared with baseline (161 ± 5 mg/MJ vs. 142 ± 4 mg/MJ, P < .001). Serum 25(OH)D concentrations increased by 23 ± 2 nmol/L (83 (107)%, P < .001), yet remained in the insufficient range (mean 45 ± 2 nmol/L). Consumption of greater than the median intake of milk (160 ml/day) (n = 54, 50%) increased serum 25(OH)D levels into the adequate range (53 ± 2 nmol/L) and reduced serum parathyroid hormone by 24% (P = .045). There was no effect on bone quality, bone turnover markers, muscle strength, or mobility. Consumption of fortified milk increased dietary vitamin D intake and raised serum 25(OH)D concentrations, but not to the level thought to reduce fracture risk. If calcium-fortified milk also was used in cooking and milk drinks, this approach could allow residents to achieve a dietary calcium intake close to recommended levels. A vitamin D supplement would be recommended to ensure adequate vitamin D status for all residents.

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OBJECTIVE—There are limited data on the effects of resistance training on the capacity to perform activities of daily living (ADLs) and quality of life (QoL) for individuals with a high number of metabolic risk factors (HiMF). In this study, we examined the effect of resistance training on the capacity to perform ADLs and QoL in individuals with HiMF and compared any benefits with individuals with a low number of metabolic risk factors (LoMF).

RESEARCH DESIGN AND METHODS—Fifty-five untrained individuals, aged 50.8 ± 6.5 years, were randomized to four groups: HiMF training (HiMFT), HiMF control, LoMF training (LoMFT), and LoMF control. At baseline and after 10 weeks of resistance training, participants underwent anthropometric measurements and assessments of aerobic power (Vo2peak), muscle strength, capacity to perform ADLs, and a self-perceived QoL questionnaire. A repeated-measures ANOVA was used to examine the effect of training over time among groups.

RESULTS—
Training increased lean body mass in both HiMFT (P = 0.03) and LoMFT (P = 0.03) groups. Total fat content and Vo2peak improved in the LoMFT group only. Muscle strength improved in both training groups (P < 0.01). Time to complete ADLs was reduced by 8.8% in the LoMFT group (P < 0.01) and 9.7% in the HiMF group (P < 0.01). Only the HiMFT group reported improvement in QoL.

CONCLUSIONS— Resistance training improved muscle strength and the capacity to perform ADLs in individuals with HiMF and LoMF. Resistance training improved QoL for the HiMF group, and this result was independent of changes in body fat content or aerobic power. Longer training regimens may be needed to improve QoL in individuals with LoMF.

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The purpose of the study was to investigate the psychological response to the very first session of resistance exercise on positive well-being (PWB), psychological distress (PD), and perception of fatigue in untrained men and women who are obese. Forty-five (male = 22, female = 23) untrained, middle-aged volunteers (mean ± SEM, 51.0 ± 1.0; range, 40-69 years) participated in the study. Participants were divided into 4 groups according to sex and obesity level (i.e., men who are obese, men who are nonobese, women who are obese, women who are nonobese). The threshold for obesity was defined as waist circumference ≥94 cm for men and 80 cm for women. Measures included body composition, aerobic power, muscle strength, and quality of life (Short Form 36, SF-36). Before and after resistance exercise, participants completed the Subjective Exercise Experience Scale (SEES). Paired sample t-tests were used to assess changes in SEES scores within group pre- and post-exercise and repeated-measures analysis of variance were used to assess changes in SEES scores between groups. Exercise increased the perception of PWB in both women who are obese and nonobese, without changes in PD or fatigue. In women, the change in PWB after exercise was negatively correlated with most scales of the SF-36, particularly with the mental health dimension (r = -0.55, p < 0.01). No significant changes in PWB, PD, or fatigue were found in men who are obese. Acute resistance exercise improved PWB in women who are obese and nonobese and those with lower self-perceived quality of life scores at the start improved the most. In addition, resistance exercise did not increase feelings of distress in either women or men who are obese.

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Introduction and Purpose: Brain-derived neurotrophic factor (BDNF) and physical inactivity contribute to the development of the metabolic syndrome (MetS). There appears to be an association between BDNF and risk factors for MetS, and the effects of resistance training (RT) on BDNF and metabolic risk in middle-aged individuals with high and low numbers of metabolic risk factors (HiMF and LoMF, respectively) are unclear and are the focus of this research.

Methods: Forty-nine men (N = 25) and women (N = 24) aged 50.9 ± 6.2 yr were randomized to four groups, HiMF training (HiMFT), HiMF control (HiMFC), LoMF training (LoMFT), and LoMF control (LoMFC). Before and after 10 wk of RT, participants underwent tests for muscle strength and anthropometry, and a fasting blood sample was taken. Data were analyzed using Spearman correlations and repeated-measures ANOVA.

Results: BDNF was positively correlated with plasma triglycerides, glucose, HbA1C, and insulin resistance. BDNF was elevated in HiMF compared with LoMF (904.9 ± 270.6 vs 709.6 ± 239.8 respectively, P = 0.01). Training increased muscle strength and lean body mass but had no effect on BDNF levels or any examined risk factors.

Conclusion: BDNF levels correlated with risk factors for MetS and were elevated in individuals with HiMF. RT had no effect on BDNF levels or other risk factors for MetS. As RT has an effect on muscle strength and lean body mass, it should be added to other nonpharmacological interventions for middle-aged individuals with HiMF such as aerobic and/or diet.

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Background : The Angiotensin Converting Enzyme (ACE) gene may influence the risk of heart disease and the response to various forms of exercise training may be at least partly dependent on the ACE genotype. We aimed to determine the effect of ACE genotype on the response to moderate intensity circuit resistance training in chronic heart failure (CHF) patients.

Methods :
The relationship between ACE genotype and the response to 11 weeks of resistance exercise training was determined in 37 CHF patients (New York Heart Association Functional Class = 2.3 ± 0.5; left ventricular ejection fraction 28 ± 7%; age 64 ± 12 years; 32:5 male:female) who were randomised to either resistance exercise (n = 19) or inactive control group (n = 18). Outcome measures included VO2peak power output and muscle strength and endurance. ACE genotype was determined using standard methods.

Results :
At baseline, patients who were homozygous for the I allele had higher VO2peak (p = 0.02) and peak power (p = 0.003) compared to patients who were homozygous for the D allele. Patients with the D allele, who were randomised to resistance training, compared to non-exercising controls, had greater peak power increases (ID p < 0.001; DD p < 0.001) when compared with patients homozygous for the I allele, who did not improve. No significant genotype-dependent changes were observed in VO2peak, muscle strength, muscle endurance or lactate threshold.

Conclusion :
ACE genotype may have a role in exercise tolerance in CHF and could also influence the effectiveness of resistance training in this condition.

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The database contains the following clinical, questionnaire and socio-demographic data suitable for cross-sectional and longitudinal analyses:
-Body composition: dual-energy x-ray absorptiometry (DXA) measures of the lumbar spine (posterior-anterior projection), proximal femur, whole body and forearm (ultradistal forearm and distal 33%)
-Other clinical assessments: body weight, height, arm span, waist and hip circumferences, blood pressure, visual acuity, muscle strength, functional reach test and timed ‘up-&-go’ test.
-Mental health: Major axis psychiatric disorders diagnosed using a Structured Clinical Interview.
-Blood and urine collections: blood and urine collected after an overnight fast.
-Questionnaires: exposure to disease, use of medications and supplements, diet, mobility, physical activity, sleep, sun exposure, falls and fractures, alcohol and tobacco use, reproductive history, family history of fractures and disease, quality of life, pain, anxiety and depression.
-Socio-demographics: Country of birth, ethnicity, marital status, education, housing and employment status, occupation, socioeconomic Index for Areas (SEIFA) scores.

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Background : Osteoporosis affects over 220 million people worldwide, and currently there is no 'cure' for the disease. Thus, there is a need to develop evidence-based, safe and acceptable prevention strategies at the population level that target multiple risk factors for fragility fractures to reduce the health and economic burden of the condition.

Methods :
The 'Osteo-cise: Strong Bones for Life' study will investigate the effectiveness and feasibility of a multi-component targeted exercise, osteoporosis education/awareness and behavioural change program for improving bone health and muscle function, and reducing falls risk in community-dwelling older adults at an increased risk of fracture. Men and women aged 60 years or above will participate in an 18-month randomised controlled trial comprising a 12-month structured and supervised community-based program and a 6-month 'research to practise' translational phase. Participants will be randomly assigned to either the 'Osteo-cise' intervention or a self-management control group. The intervention will comprise a multi-modal exercise program incorporating high velocity progressive resistance training, moderate impact weight-bearing exercise and high challenging balance exercises performed three times weekly at local community-based fitness centres. A behavioural change program will be used to enhance exercise adoption and adherence to the program. Community-based osteoporosis education seminars will be conducted to improve participant knowledge and understanding of the risk factors and preventative measures for osteoporosis, falls and fractures. The primary outcomes measures, to be collected at baseline, 6, 12, and 18 months, will include DXA-derived hip and spine bone mineral density measurements and functional muscle power (timed stair-climb test). Secondary outcomes measures include: MRI-assessed distal femur and proximal tibia trabecular bone micro-architecture, lower limb and back maximal muscle strength, balance and function (four square step test, functional reach test, timed up-and-go test and 30-second sit-to-stand), falls incidence and health-related quality of life. Cost-effectiveness will also be assessed.

Discussion :
The findings from the Osteo-cise: Strong Bones for Life study will provide new information on the efficacy of a targeted multi-modal community-based exercise program incorporating high velocity resistance training, together with an osteoporosis education and behavioural change program for improving multiple risk factors for falls and fracture in older adults at risk of fragility fracture. Trial Registration: Australian New Zealand Clinical Trials Registry reference ACTRN12609000100291

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 Light-load exercise training with blood flow restriction (BFR) increases muscle strength and size. However, the hemodynamics of BFR exercise appear elevated compared with non-BFR exercise. This questions the suitability of BFR in special/clinical populations. Nevertheless, hemodynamics of standard prescription protocols for BFR and traditional heavy-load exercise have not been compared. We investigated the hemodynamics of two common BFR exercise methods and two traditional resistance exercises. Twelve young males completed four unilateral elbow flexion exercise trials in a balanced, randomized crossover design: (a) heavy load [HL; 80% one-repetition maximum (1-RM)]; (b) light load (LL; 20% 1-RM); and two other light-load trials with BFR applied (c) continuously at 80% resting systolic blood pressure (BFR-C) or (d) intermittently at 130% resting systolic blood pressure (BFR-I). Hemodynamics were measured at baseline, during exercise, and for 60-min post-exercise. Exercising heart rate, blood pressure, cardiac output, and rate–pressure product were significantly greater for HL and BFR-I compared with LL. The magnitude of hemodynamic stress for BFR-C was between that of HL and LL. These data show reduced hemodynamics for continuous low-pressure BFR exercise compared with intermittent high-pressure BFR in young healthy populations. BFR remains a potentially viable method to improve muscle mass and strength in special/clinical populations.

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Summary - Vitamin D can improve muscle function and reduce falls, but whether it can strengthen neural connections within the brain and nervous system is not known. This 10-week randomised controlled trial indicates that treatment with 2,000 IU/day vitamin D3 does not significantly alter neuroplasticity relative to placebo in older adults.
Introduction - The purpose of this study was to examine the effects of vitamin D supplementation on neuroplasticity, serum brain-derived neurotrophic factor (BDNF) and muscle strength and function in older adults.
Methods - This was a 10-week double-blinded, placebo-controlled randomised trial in which 26 older adults with 25-hydroxyvitamin D [25OHD] concentrations 25–60 nmol/L were randomised to 2,000 IU/day vitamin D3 or matched placebo. Single- and paired-pulse transcranial magnetic stimulation applied over the motor cortex was used to assess changes in motor-evoked potentials (MEPs) and short-interval intracortical inhibition (SICI), as measures of corticospinal excitability and inhibition respectively, by recording electromyography (EMG) responses to stimulation from the wrist extensors. Changes in muscle strength, stair climbing power, gait (timed-up-and-go), dynamic balance (four square step test), serum 25(OH)D and BDNF concentrations were also measured.
Results - After 10 weeks, mean 25(OH)D levels increased from 46 to 81 nmol/L in the vitamin D group with no change in the placebo group. The vitamin D group experienced a significant 8–11 % increase in muscle strength and a reduction in cortical excitability (MEP amplitude) and SICI relative to baseline (all P < 0.05), but these changes were not significantly different from placebo. There was no effect of vitamin D on muscle power, function or BDNF.
Conclusions - Daily supplementation with 2,000 IU vitamin D3 for 10 weeks had no significant effect on neuroplasticity compared to placebo, but the finding that vitamin D treatment alone was associated with a decrease in corticospinal excitability and intracortical inhibition warrants further investigation as this suggests that it may improve the efficacy of neural transmission within the corticospinal pathway.

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While physical activity, energy restriction and weight loss are the cornerstone of type 2 diabetes management, less emphasis is placed on optimizing skeletal muscle mass. As muscle is the largest mass of insulin-sensitive tissue and the predominant reservoir for glucose disposal, there is a need to develop safe and effective evidence-based, lifestyle management strategies that optimize muscle mass as well as improve glycaemic control and cardiometabolic risk factors in people with this disease, particularly older adults who experience accelerated muscle loss.

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The musculoskeletal benefits of calcium and vitamin-D3 supplementation and exercise have been extensively studied, but the effect on metabolism remains contentious. Urine samples were analyzed by (1)H-NMR spectroscopy from participants recruited for an 18-month, randomized controlled trial of a multi-component exercise program and calcium and vitamin-D3 fortified milk consumption. It was shown previously that no increase in musculoskeletal composition was observed for participants assigned to the calcium and vitamin-D3 intervention, but exercise resulted in increased bone mineral density, total lean body mass, and muscle strength. Retrospective metabolomics analysis of urine samples from patients involved in this study revealed no distinct changes in the urinary metabolome in response to the calcium and vitamin-D3 intervention, but significant changes followed the exercise intervention, notably a reduction in creatinine and an increase in choline, guanidinoacetate, and hypoxanthine (p < 0.001, fold change > 1.5). These metabolites are intrinsically involved in anaerobic ATP synthesis, intracellular buffering, and methyl-balance regulation. The exercise intervention had a marked effect on the urine metabolome and markers of muscle turnover but none of these metabolites were obvious markers of bone turnover. Measurement of specific urinary exercise biomarkers may provide a basis for monitoring performance and metabolic response to exercise regimes.