Sedentary behaviour and bone health in older adults: a systematic review.

Older adults spend more than 8 h/day in sedentary behaviours. Detrimental effects of sedentary behaviour (SB) on health are established, yet little is known about SB and bone health (bone mineral density; BMD) in older adults. The purpose of this review is to examine associations of SB with BMD in older adults. Five electronic databases were searched: Web of Science (Core Collection); PubMed; EMBASE; Sports Medicine and Education and PsycInfo. Inclusion criteria were healthy older adults mean age ≥ 65 years; measured SB and measured BMD using dual-energy X-ray absorptiometry. Quality was assessed using National Institute of Health Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies. After excluding duplicates 17813 papers were assessed; 17757 were excluded on title/abstract, 49 at full text, resulting in two prospective and five cross-sectional observational studies reviewed. Four were rated 'good' and three were rated 'fair' using the quality assessment criteria. Findings varied across the studies and differed by gender. In women, four studies reported significant positive associations of SB with BMD at different sites, and two found significant negative associations. Five studies which examined both men and women, men reported negative or no associations of SB with femoral neck, pelvic, whole body, spine or leg BMD. Whilst these findings suggest differences between men and women in the associations of SB with BMD, they may be due to the varying anatomical sections examined for BMD, the different methods used to measure SB, the varied quality of the studies included and the limited number of published findings.

Characteristics of a protocol to collect objective physical activity/sedentary behaviour data in a large study: Seniors USP (understanding sedentary patterns).

The Seniors USP study measured sedentary behaviour (activPAL3, 9 day wear) in older adults. The measurement protocol had three key characteristics: enabling 24-hour wear (monitor location, waterproofing); minimising data loss (reducing monitor failure, staff training, communication); and quality assurance (removal by researcher, confidence about wear). Two monitors were not returned; 91% (n=700) of returned monitors had 7 valid days of data. Sources of data loss included monitor failure (n=11), exclusion after quality assurance (n=5), early removal for skin irritation (n=8) or procedural errors (n=10). Objective measurement of physical activity and sedentary behaviour in large studies requires decisional trade-offs between data quantity (collecting representative data) and utility (derived outcomes that reflect actual behaviour).

Systematic comparative validation of self-report measures of sedentary time against an objective measure of postural sitting (activPAL).

BACKGROUND: Sedentary behaviour is a public health concern that requires surveillance and epidemiological research. For such large scale studies, self-report tools are a pragmatic measurement solution. A large number of self-report tools are currently in use, but few have been validated against an objective measure of sedentary time and there is no comparative information between tools to guide choice or to enable comparison between studies. The aim of this study was to provide a systematic comparison, generalisable to all tools, of the validity of self-report measures of sedentary time against a gold standard sedentary time objective monitor. METHODS: Cross sectional data from three cohorts (N = 700) were used in this validation study. Eighteen self-report measures of sedentary time, based on the TAxonomy of Self-report SB Tools (TASST) framework, were compared against an objective measure of postural sitting (activPAL) to provide information, generalizable to all existing tools, on agreement and precision using Bland-Altman statistics, on criterion validity using Pearson correlation, and on data loss. RESULTS: All self-report measures showed poor accuracy compared with the objective measure of sedentary time, with very wide limits of agreement and poor precision (random error > 2.5 h). Most tools under-reported total sedentary time and demonstrated low correlations with objective data. The type of assessment used by the tool, whether direct, proxy, or a composite measure, influenced the measurement characteristics. Proxy measures (TV time) and single item direct measures using a visual analogue scale to assess the proportion of the day spent sitting, showed the best combination of precision and data loss. The recall period (e.g. previous week) had little influence on measurement characteristics. CONCLUSION: Self-report measures of sedentary time result in large bias, poor precision and low correlation with an objective measure of sedentary time. Choice of tool depends on the research context, design and question. Choice can be guided by this systematic comparative validation and, in the case of population surveillance, it recommends to use a visual analog scale and a 7 day recall period. Comparison between studies and improving population estimates of average sedentary time, is possible with the comparative correction factors provided.

Quantitative data analysis of perceived barriers and motivators to physical activity in stroke survivors.

BACKGROUND: Levels of physical activity after stroke are low, despite multiple health benefits. We explored stroke survivors' perceived barriers, motivators, self-efficacy and intention to physical activity. METHODS: Fifty independently mobile stroke survivors were recruited prior to hospital discharge. Participants rated nine possible motivators and four possible barriers based on the Mutrie Scale, as having 'no influence', 'some influence' or 'a major influence' on physical activity. Participants also rated their self-efficacy and intention to increasing walking. RESULTS: The most common motivator was 'physical activity is good for health' [34 (68%)]. The most common barrier was 'feeling too tired' [24 (48%)]. Intention and self-efficacy were high. Self-efficacy was graded as either 4 or 5 (highly confident) on a five-point scale by [34 (68%)] participants, while 42 (84%) 'strongly agreed' or 'agreed' that they intended to increase their walking. CONCLUSION: Participants felt capable of increasing physical activity but fatigue was often perceived as a barrier to physical activity. This needs to be considered when encouraging stroke survivors to be more active.

Phase I/II trial of formoterol fumarate combined with megestrol acetate in cachectic patients with advanced malignancy.

PURPOSE: The aim of this study was to test the safety, tolerability and efficacy of a novel combination of an anabolic ß2-agonist and an appetite stimulant in patients with cancer cachexia. METHODS: Thirteen patients (M/F 5:8) with advanced malignancy and involuntary weight loss received oral formoterol (80 µg/day) and megestrol acetate (480 mg/day) for up to 8 weeks. Quadriceps size (MRI), quadriceps and hand-grip strength, lower limb extensor power, physical activity and quality of life were measured at baseline and at 8 weeks. Response criteria were specified pre-trial, with a major response defined as an increase in muscle size ≥ 4 % or function ≥ 10 %. RESULTS: Six patients withdrew before 8 weeks, reflecting the frail, comorbid population. In contrast, six out of seven (86 %) patients completing the course achieved a major response for muscle size and/or function. In the six responders, mean quadriceps volume increased significantly (left 0.99 vs. 1.05 L, p=0.012; right 1.02 vs. 1.06 L, p=0.004). There was a trend towards an increase in quadriceps and handgrip strength (p>0.05). The lack of appetite symptom score declined markedly (76.2 vs. 23.8; p=0.005), indicating improvement. Adverse reactions were few, the commonest being tremor (eight reports), peripheral oedema (three), tachycardia (two) and dyspepsia (two). CONCLUSIONS: In this frail cohort with advanced cancer cachexia, an 8-week course of megestrol and formoterol in combination was safe and well tolerated. Muscle mass and/or function were improved to a clinically significant extent in most patients completing the course. This combination regimen warrants further investigation in larger, randomized trials.

Responsiveness of muscle size and strength to physical training in very elderly people: a systematic review.

The purpose of this review was to determine whether very elderly muscle (>75 years) hypertrophies in response to physical training. The databases MEDLINE; EMBASE; CINAHL Plus and SPORTDiscus were systematically literature searched with reference lists of all included studies and relevant reviews. Controlled trials (inactive elderly control group) involving healthy elderly participants over 75 years participating in an intervention complying with an established definition of physical training were included. Data extraction and quality assessment were performed using the PEDro scale. Data analysis was performed on muscle size and strength using RevMan (software version 5.1). Four studies were included of which four of four measured changes in gross muscle size. Training induced increases in muscle size from 1.5%-15.6% were reported in three of four studies, and one of four studies reported a decrease in muscle size (3%). The greatest gain in muscle mass was observed in a study of whole body vibration training. Meta-analysis of three studies found an increase of thigh muscle cross-sectional area (mean difference 2.31 cm(2) or 0.2%, 95% confidence interval (CI): 0.62 to 4.00; P = 0.008) and muscle strength (standardized mean difference 1.04, 95% CI: 0.65 to 1.43; P < 0.001). Physical training when delivered as resistance training has the ability to elicit hypertrophy and increase muscle strength in very elderly muscle.

A novel oral tracer procedure for measurement of habitual myofibrillar protein synthesis.

RATIONALE: Conventionally, myofibrillar protein synthesis is measured over time periods of hours. In clinical studies, interventions occur over weeks. Functional measures over such periods may be more representative. We aimed to develop a novel method to determine myofibrillar protein fractional synthetic rate (FSR) to estimate habitual rates, while avoiding intravenous tracer infusions. METHODS: Four healthy males were given 100 g water enriched to 70 Atom % with (2)H2O as a single oral bolus. Vastus-lateralis needle biopsies were performed and plasma samples collected, 3-13 days post-dose. (2)H enrichment in body water was measured in plasma using continuous flow isotope ratio mass spectrometry (IRMS). Myofibrillar protein was isolated from muscle biopsies and acid hydrolysed. (2)H enrichment of protein-bound and plasma-free alanine was measured by gas chromatography (GC)/pyrolysis/IRMS. Myofibrillar protein FSR was calculated (% day(-1)). RESULTS: The tracer bolus raised the initial enrichment of body water to 1514 ppm (2)H excess. Water elimination followed a simple exponential. The average elimination half-time was 8.3 days. Plasma alanine, labelled during de novo synthesis, followed the same elimination kinetics as water. The weighted average myofibrillar protein FSR from the four subjects was 1.38 % day(-1) (range, 1.0-1.9 % day(-1) ). CONCLUSIONS: Myofibrillar protein FSR was measured in free-living healthy individuals over 3-13 days. Using a single oral (2)H2O bolus, endogenous labelling of alanine occurred in a predictable manner giving estimates of synthesis comparable with published values. Furthermore, the protocol does not compromise the ability to measure other important metabolic processes such as total energy expenditure.

Blunting of adaptive responses to resistance exercise training in women over 75y.

BACKGROUND: It is unclear how aging affects adaptive responses to resistance exercise training (RET), especially in women. We hypothesized that (i) increases in muscle mass and function after RET would be blunted in older women, and (ii) reduced 'pro-anabolic' changes in gene expression after a single bout of RE may underlie the blunting. METHODS: Muscle biopsies were obtained from 9 older (76-82y) and 16 younger (19-30y) women at rest and 2.5h after RE (6×20 quadriceps maximal voluntary contractions (MVCs)) for measurement of select anabolic (e.g. IGFs, MyoD) and catabolic (e.g. MAFBx, MuRF-1) transcripts by RT-PCR. Thereafter participants undertook a supervised program of RET (4×15 MVCs 3× wk/12wk). We measured knee extensor muscle volume, fatty infiltration, and mechanical muscle quality before and after RET. RESULTS: Before RET, older women were ~30% weaker (MVC 208 vs. 297N) and had ~40% less quadriceps muscle (0.97 vs. 1.54L) with greater fatty infiltration (14% vs. 10%). The most notable difference in mRNA expression after RE was for regulated in development and DNA damage response 1 (REDD1) (an endogenous suppressor of mammalian target of rapamycin (mTOR) signaling), which was depressed (-80%), but only in young women. Moreover, adaptive responses to RET were blunted in older women with respect to increases in muscle volume (+2.5% (old) vs. +6.2% (young)) and strength (+16% (old) vs. +27% (young)). CONCLUSIONS: Adaptations to RET are markedly blunted in older women, perhaps in-part due to the inability to downregulate REDD1 and thus upregulate mTOR signaling after RE.

Serum concentrations of myostatin and myostatin-interacting proteins do not differ between young and sarcopenic elderly men.

Sarcopenia is the loss of muscle size and function during ageing. The aim of this study was to test whether serum concentrations of myostatin and interacting proteins (GASP-1, FLRG, and follistatin) differed between young and elderly sarcopenic men. Isometric knee extensor maximal voluntary contraction and quadriceps cross-sectional area (magnetic resonance imaging measurement) were significantly higher in young (22 ± 2 years; 266 ± 54 N/m; 8,686 ± 1,154 mm(2)) than in mildly sarcopenic (69 ± 3 years; 183 ± 17 N/m; 6,621±718 mm(2)) and severely sarcopenic men (76 ± 6 years; 127 ± 23 N/m; 5,846 ± 591 mm(2)), respectively (p ≤ .01 for all comparisons). There was a trend (p = .06) toward higher FLRG in young (20 ± 8 ng/mL) than in mildly (15 ± 6 ng/mL) and severely sarcopenic men (17 ± 8 ng/mL). Myostatin, follistatin, GASP-1, tumor necrosis factor α, and interleukin-6 did not differ significantly. Insulin-like growth factor-1 and free testosterone were both significantly lower in sarcopenic men (p < .001). This suggests that altered serum concentrations of myostatin and myostatin-interacting proteins are not contributing to sarcopenia with the possible exception of FLRG.

Physical fitness training for stroke patients.

BACKGROUND: Stroke patients have impaired physical fitness and this may exacerbate their disability. It is not known whether improving physical fitness after stroke reduces disability. OBJECTIVES: The primary aims of the review were to establish whether physical fitness training reduces death, dependence and disability after stroke. The secondary aims of the review included an investigation of the effects of fitness training on secondary outcome measures (including, physical fitness, mobility, physical function, health and quality of life, mood and the incidence of adverse events). SEARCH STRATEGY: We searched the Cochrane Stroke Group Trials Register (June 2003). In addition, the following electronic databases were searched: Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, 2002 Issue 4), MEDLINE (1966 to December 2002), EMBASE (1980 to December 2002), CINAHL (1982 to December 2002), SPORTDiscus (1949 to December 2002), Science Citation Index Expanded (1981 to December 2002), Web of Science Proceedings (1982 to December 2002), Physiotherapy Evidence Database (December 2002), REHABDATA (1956 to December 2002) and Index to UK Theses (1970 to December 2002). We hand searched relevant journals and conference proceedings and screened reference lists. To identify unpublished and ongoing trials we searched trials directories and contacted experts in the field. SELECTION CRITERIA: Randomised controlled trials were included when an intervention represented a clear attempt to improve either muscle strength and/or cardiorespiratory fitness, and whose control groups comprised either usual care or a non-exercise intervention. DATA COLLECTION AND ANALYSIS: Data from eligible studies were independently extracted by two reviewers. The primary outcome measures were death, disability and dependence. The lack of common outcome measures prevented some of the intended analysis. MAIN RESULTS: A total of twelve trials were included in the review. No trials reported death and dependence data. Two small trials reporting disability showed no evidence of benefit. The remaining available secondary outcome data suggest that cardiorespiratory training improves walking ability (mobility). Observed benefits appear to be associated with specific or 'task-related' training. REVIEWER'S CONCLUSIONS: There are few data available to guide clinical practice at present with regard to fitness training interventions after stroke. More general research is needed to explore the efficacy and feasibility of training, particularly soon after stroke. In addition more specific studies are required to explore the effect of content and type of training. Further research will require careful planning to address a number of issues peculiar to this type of intervention.

Muscle function of women aged 65-89 years meeting two sets of health criteria.

This study compared the isometric strength, leg extensor power, and some potentially related functional abilities of elderly women selected for exercise studies according to two sets of readily applicable exclusion criteria. The health status criteria ("healthy" and "medically stable") differed principally in respect to duration of freedom from diagnosed or symptomatic disease, medication taken and Body Mass Index. Fifty "healthy" women and fifty "medically stable" women, aged 65 to 89 and evenly distributed over the age range, were recruited through local and national newspapers. There was no significant difference between the two health groups in strength or power. However, the women in the "medically stable" group were heavier and had more difficulty in rising from a chair. The strength of the relationships between strength, power and kneel rise time were very dependent on body weight for the "medically stable" women but not for the "healthy" women. The health criteria used to classify elderly subjects must be clearly specified so that there may be easier interpretation of results from future studies. This is especially true in studies where body weight might be important.

Effects of resistance training on strength, power, and selected functional abilities of women aged 75 and older.

OBJECTIVE: To determine the effects of 12 weeks of progressive resistance strength training on the isometric strength, explosive power, and selected functional abilities of healthy women aged 75 and over. DESIGN: Subjects were matched for age and habitual physical activity and then randomly assigned into either a control or an exercise group. SETTING: The Muscle Function Laboratory, Royal Free Hospital School of Medicine, London. PARTICIPANTS: Fifty-two healthy women were recruited through local and national newspapers. Five dropped out before and seven (4 exercisers and 3 controls) during the study. Pre- and posttraining measurements were obtained from 20 exercisers (median age 79.5, range 76 to 93 years) and 20 controls (median age 79.5, range 75 to 90 years). INTERVENTIONS: Training comprised one supervised session (1 hour) at the Medical School and two unsupervised home sessions (supported by an exercise tape and booklet) per week for 12 weeks. The training stimulus was three sets of four to eight repetitions of each exercise, using rice bags (1-1.5 kg) or elastic tubing for resistance. The exercises were intended specifically to strengthen the muscles considered relevant for the functional tasks, but were not to mimic the functional measurements. No intervention was prescribed for the controls. MEASUREMENTS: Pre- and posttraining measurements were made for isometric knee extensor strength (IKES), isometric elbow flexor strength (IEFS), handgrip strength (HGS), leg extensor power (LEP), and anthropometric indices (Body impedance analysis, arm muscle circumference, and body weight). Functional ability tests were chair rise, kneel rise, rise from lying on the floor, 118-m self-paced corridor walk, stair climbing, functional reach, stepping up, stepping down, and lifting weights onto a shelf. Pre- and posttraining comparisons were made using analysis of variance or analysis of covariance (using weight as a covariate) for normally distributed continuous data and one-sided Fishers exact test (2 x 2 table) for discontinuous data. RESULTS: Improvements in IKES (mean change 27%, P = .03), IEFS (22%, P = .05), HGS (4%, P = .05), LEP/kg (18%, P = .05) were associated with training, but the improvement in LEP (18%, P = .11) did not reach statistical significance. There was an association between training and a reduction in normal pace kneel rise time (median change 21%, P = .02) and a small improvement in step up height (median 5%, P = .005). The other functional tests did not improve. CONCLUSIONS: Progressive resistance exercise can produce substantial increases in muscle strength and in power standardized for body weight in healthy, very old women. However, isolated increases in strength and LEP/kg may confer only limited functional benefit in healthy, independent, very old women.

Strength, power and related functional ability of healthy people aged 65-89 years.

This cross-sectional study was designed to examine the effects of healthy ageing on muscle strength, power, and potentially related functional ability. Subjects were recruited through local and national newspapers and inclusion was based on strict health criteria, by questionnaire. Isometric knee extensor, isometric elbow flexor and handgrip strength, leg extensor power, timed rise from a low chair, lifting a weighted bag on to a surface, and stepping unaided on to boxes of different heights were measured in 50 men and 50 women, evenly distributed over the age range 65-89 years. The differences in isometric strength and leg extensor power over the age range were equivalent to 'losses' of 1-2% per annum and approximately 3 1/2% per annum, respectively. The decline of explosive power was faster than the decline of knee extensor strength in men (p = 0.0001), but not significantly so in women (p = 0.08). Power standardized for body weight influenced chair rise time and step height. Isometric knee extensor strength standardized for body weight influenced chair rise time.

Exercise studies with elderly volunteers.

The practicalities of conducting exercise studies with elderly and very elderly people have not been well described. In order to help others plan and perform such studies we describe our experience of recruiting volunteers, applying selection criteria, measuring strength, power, cardiorespiratory responses, and potentially related functional abilities. Exclusion criteria are offered, for safety and to characterize subjects as free of disease which might alter their exercise performance. International agreement on these, or similar, criteria would be valuable. The budget must be adequate for prolonged recruitment before a study and for the liberal use of taxis during it. With healthy subjects in their seventies, the coefficients of variation (CV) for repeated measurements of strength and power were: handgrip 3%, isometric knee extension 6%, isometric elbow flexion 6%, and lower limb extensor power 9%. CV for isometric knee extension by healthy subjects in their eighties was 4%. Treadmill ergometry is more time-consuming than with younger subjects. During progressive treadmill tests, the heart rate interpolated to oxygen consumptions of 10 and 15 ml.kg-1.min-1 had CV = 4% and 7%, respectively.

The quadriceps strength of healthy elderly people remeasured after eight years.

Isometric quadriceps strength was remeasured in 14 healthy survivors of a group of elderly people first studied 8 years previously. There were 4 men (median age 81 years, range 79 to 84) and 10 women (82 years, range 79 to 89). They were selected for their health, not their levels of physical activity. Nevertheless, they were active when first studied and, with 1 exception, had maintained or increased their levels of physical activity. Isometric quadriceps strength was well preserved; the median change in the strength of the stronger quadriceps was only -0.3% per annum (95% confidence interval = -1.4 to +0.8).

Short-stepping gait in severe heart failure.

BACKGROUND: Patients with severe chronic heart failure seem to take shorter steps than healthy controls when walking on a treadmill and when walking freely along a corridor. In healthy individuals the pattern of walking affects the oxygen cost of exercise, and so this observation might be relevant to the limitation of exercise in heart failure. METHOD: Length of stride was analysed as stride/stature index in 15 controls, 10 patients with moderate heart failure, 10 patients with severe heart failure, and 10 patients with angina, walking at a constant speed/stature index. RESULTS: The stride/stature index was 0.64 in the controls in patients with New York Heart Association (NYHA) class II heart failure, and in patients with angina. It was 0.49 in patients with NYHA class III heart failure. In the patients with heart failure the stride/stature index correlated with exercise capacity determined as peak oxygen consumption VO2max (R = +0.62, p < 0.005). When healthy controls walked in time to a metronome adjusted to decrease their stride/stature index to approximately that seen in severe heart failure steady-state oxygen consumption increased by a mean of 15%. CONCLUSIONS: The length of stride is reduced in severe heart failure, and when healthy controls adopt this gait the oxygen cost of walking is increased. A short-stepping gait may contribute to the limitation of exercise capacity in heart failure.

Within-breath changes of airway calibre in patients with airflow obstruction by continuous measurement of respiratory impedance.

We bench-tested a commercially available instrument for measuring respiratory impedance (Siregnost FD5: Siemens) and found that resistance (R) and phase changes were accurately recorded in models. In a single human subject, total respiratory resistance (R(l)) was closely comparable to resistance measured by the Mead-Whittenberger technique. The derived continuous variable (R(os)) was similar to R at less than 4 cmH2O . litres-1 . sec, but underestimated R at higher values. Ros was highly correlated with airways resistance by body plethysmography (R(aw)), but with a low slope and high intercept (R(os) = 1.38 + 0.59 R(aw): r = 0.89). Because of turbulence, both in model larynxes and in normal subjects, R(os) tends to rise with increases in flow in either direction. R(os) also tends to fall as lung volume rises, and vice versa, reflecting cyclic changes in airway calibre. We devised indices of expiratory narrowing of airways from the maximum flow-volume loop, and the plethysmographic alveolar pressure-flow loop, and compared them with the slope of the relation between R(os) and lung volume during tidal breathing, in nine normal subjects and 16 patients with airflow obstruction. Twelve of the 16 patients, all with abnormal flow-volume loops, had high R(os)-volume slopes, demonstrating excessive expiratory narrowing even during tidal breathing. We found no patients with normal inspiratory R(os) together with an abnormal R(os)-volume slope. Thus unstressed inspiratory calibre was never dissociated from airways narrowing on expiration.

Strength training and power output: transference effects in the human quadriceps muscle.

The effects of strength training of the quadriceps on peak power output during isokinetic cycling has been investigated in group of 17 young healthy volunteers. Subjects trained by lifting near-maximal loads on a leg extension machine for 12 weeks. Measurements of maximal voluntary isometric force were made at 2-3 week intervals and a continual record was kept of the weights lifted in training. Peak power output was measured at 110 rev min-1 and at either 70 or 80 rev min-1 before and after the 12 week training period. Measurements of maximum oxygen uptake (VO2max) were made on 12 subjects before and after training. The greatest change was in the weights lifted in training which increased by 160-200%. This was accompanied by a much smaller increase in maximum isometric force (3-20%). There was no significant change in peak power output at either speed. The VO2max remained unchanged with training. The role of task specificity in training is discussed in relation to training regimes for power athletes and for rehabilitation of patients with muscle weakness.