Physical activity and body composition: what do the national surveys reveal?

Measures of height, body weight, waist and hip girths are available from the Allied Dunbar National Fitness Survey and have been used to explore differences between respondents reporting differing levels of habitual physical activity. Body mass index (BMI), waist-to-hip ratio (WHR) and waist-to-height ratio were derived. Physical activity was estimated from a structured interview. The questionnaire permitted a separate estimate of levels of participation in vigorous and moderate intensity activity, as well as total energy expenditure. Each index of body composition was regressed against the measures of physical activity and other lifestyle factors. Relationships between activity and body composition measures were weak with different patterns emerging for men and women. These data suggest that it is doubtful whether changes in body composition brought about by interventions to increase population levels of physical activity will be revealed by measuring BMI. However WHR and waist-to-height ratio indices reflecting the bulk of the intra-abdominal fat stores may prove more informative.

Modelling the associations of BMI physical activity and diet with arterial blood pressure: some results from the Allied Dunbar National Fitness Survey.

In order to identify risk factors (e.g. physical inactivity, dietary composition) associated with blood pressure within a given population, it is necessary to adjust for differences in known associations (e.g. age, body weight) using a method such as the analysis of covariance. However, the blood pressure results from the Allied Dunbar National Fitness Survey (ADNFS) were found to be non-linear with age, positively skewed (with heteroscedastic errors) and therefore non-normally distributed. Hence, before valid inferences can be drawn from such data, there is a clear need to formulate an appropriate model for blood pressure that will overcome these undesirable characteristics. A multiplicative model (with allometric body size components) was proposed and fitted to the ADNFS blood pressure results. After a logarithmic transformation the parsimonious solution was able to confirm the association with BMI, the non-linear changes with age, and overcome the heteroscedastic and positively skewed errors, i.e. the residuals from the fitted log-linear models for both systolic and diastolic blood pressure were symmetric and normally distributed. Other factors were found to make a significant additional contribution to the prediction of blood pressure. Cyclists, participants in vigorous physical activity and those subjects who consumed more fresh fruit, rice or pasta, and wine were found to have significantly lower mean levels of blood pressure. Indeed, the gap in blood pressure between participants and non-participants in vigorous physical activity increased further with age. However, subjects who drank more beer tended to have significantly higher mean levels of blood pressure. Thus by developing an appropriate model for arterial blood pressure, some well known, and some less well known, associations with arterial blood pressure have been identified. The results suggest that physical activity and other lifestyle factors may protect against hypertension.

Physical activity among persons with disabilities--a public health perspective.

Regular physical activity, sports participation, and active recreation are essential behaviors for the prevention of disease, promotion of health, and maintenance of functional independence. This health behavior is essential for persons with and without disabilities. Population-based surveys have consistently demonstrated that persons with disabilities are less likely to be physically active, compared to persons without such limitations. However, these observations are based on relatively few surveys and are dependent on physical activity assessment methods that may not be sensitive and specific enough for persons with disabilities. Studies clearly demonstrate that many persons, representing a variety of selected disabilities, can adapt to increased levels of physical activity, as evidenced by alterations in various components of physical fitness. More importantly, other studies consistently provide evidence that participation in regular physical activity among persons with selected impairments and disabilities results in improved functional status and quality of life. Further efforts are critically needed in the area of the development of physical activity assessment methodology for persons with disabilities. Methods need to be developed that will provide survey researchers and those in public health the capacity to measure and monitor activity patterns of persons with disabilities. This information is important not only for public health officials but also health policy analysts, service providers, and disability advocacy groups. Further understanding of the role of physical activity in the maintenance of function and independence among persons with disabilities is needed. The understanding of environmental and social barriers to physical activity among persons with disabilities needs further exploration. Finally, physical activity determinants research among persons with disabilities, including the role of assistive technology as well as maximizing the intrinsic capacity of functional anatomy and physiology, needs to be addressed.

Lack of variation in muscle strength with menstrual status in healthy women aged 45-54 years: data from a national survey.

Isometric handgrip, quadriceps muscle strength and leg extensor power were assessed as part of a large representative survey of adult men and women in England. The gender ratios for these muscle strength measurements did not differ across age groups, which ranged from 25 to 65 years. Data from a subsample of women who were aged between 45 and 54 years and free of major health problems or current gynaecological problems (n = 299) and were analysed to see if there were differences in the muscle measurements according to reported menstrual status. Analysis of variance was used to compare four subgroups of women as follows: those who were still menstruating regularly (n = 89), those who had stopped altogether (n = 92), those who were irregular (n = 33) and those on hormone replacement therapy (n = 15). No significant differences were found between these subgroups in any of the three muscle measurements, body mass, fat-free mass (derived from four skinfolds), body mass index, or customary activity levels. There was a significant age difference of 2 years between two subgroups. After having controlled for this, using analysis of covariance, the outcome was not changed. These women were also compared with men in the same age range; the women had about 60% of the strength of the men and a highly significant difference remained after controlling for fat-free mass in all subgroups. No evidence was found for an ergogenic effect of the high oestrogen status conferred by natural menstruation or hormone replacement therapy.

Effect of 'antiembolism' compression hosiery on leg blood volume.

Blood volume in the legs of healthy volunteers and the ability of graduated compression hosiery to reduce that volume were investigated with gamma scintigraphy. Changing posture from supine to upright, or pneumatic thigh cuffs inflated to either 20 or 40 mmHg with the subject supine, significantly increased leg blood volumes; the mean increase was: upright 126 ml, 20 mmHg cuff 44 ml, and 40 mmHg cuff 113 ml. A significant trend in reducing these volumes was noted in three brands of commercially available stockings, with the subject supine and without thigh cuffs (Page's L trend 132.5, P < 0.01) and when cuffs were applied at 20 mmHg (Page's L trend 128, P = 0.05). Few of the commercially available stockings delivered the 'standard' compression profile of 18 mmHg at the ankle, 14 mmHg at the calf and 8 mmHg at the upper thigh. The effects of other compression profiles were assessed, using custom-made stockings, and pneumatic cuffs inflated to 20 mmHg applied to the upper thighs to impede venous return. There was no consistent reduction of blood volume in the popliteal region, although decreases were seen in the upper and lower calf. The major determinant of performance was compression at the calf; the ankle to calf compression gradient was not important. Stockings with a profile of 16.8 mmHg at the ankle, 14.5 mmHg at the calf and 6.4 mmHg at the upper thigh performed best.

Local research ethics committees. Widely differing responses to a national survey protocol.

The diversity in responses of local research ethics committees (LRECs) is illustrated with reference to consideration of the protocols for a national survey of physical activity, fitness and health in healthy volunteers. The survey included a questionnaire administered in the home, followed by a physical appraisal carried out in a mobile laboratory. The study was eventually approved by the 30 local committees to which it was submitted, but there was marked variation in the type of enquiries received and the special arrangements requested. At one extreme, some committees approved the study before seeing the detailed ethical submission; at the other extreme, suggested expensive and time-consuming alterations to the standard procedures. Our experience reveals a lack of uniformity in the operation of LRECs, serious enough to delay and even inhibit useful research, and a failure of some committees to adhere to guidelines suggested by the Royal College of Physicians and the Department of Health.

Exercise in prevention of disease.

Measures to increase individual participation in adequate amounts of physical exercise have a key place among the strategies to improve health and prevent disease. The scientific justification is based on a variety of evidence drawn from numerous epidemiological, clinical and physiological studies and is accepted as sound. The prevalence of physical disability is high. Disability attributable to age or chronic disease is helped by exercise. Inactivity compounds the effects of disability--an effect which deserves recognition because it is reversible and not inevitable. The association between a high level of habitual physical activity and a reduction in the individual risk for coronary vessel disease (CVD) is real and appears to be causal. Regular vigorous aerobic exercise is certainly effective in maintenance of health. Weight-bearing exercise has been shown to prevent osteoporosis at any age. The links between many of the functional adaptations which occur with exercise and improvements in health have been demonstrated. The exercise programmes which are effective have been defined.

Falls by elderly people at home: prevalence and associated factors.

Of 1042 individuals aged 65 years and over who were successfully interviewed in a community survey of health and physical activity, 35% (n = 356) reported one or more falls in the preceding year. Although the overall ratio of female fallers to male fallers was 2.7:1, this ratio approached unity with advancing age. Mobility was significantly impaired in those reporting falls. Asked to provide a reason for their falls, 53% reported tripping, 8% dizziness and 6% reported blackouts. A further 19% were unable to give a reason. There was no association between falls and the use of diuretics, antihypertensives or tranquilizers, but a significant association between falls and the use of hypnotics and antidepressants was found. Discriminant analysis of selected medical and anthropometric variables indicated that handgrip strength in the dominant hand and reported symptoms of arthritis, giddiness and foot difficulties were most influential in predicting reports of recent falls.

Levels of customary physical activity among the old and the very old living at home.

With an activity inventory designed specifically for use among elderly people, detailed profiles of customary physical activity were obtained from 507 old (aged 65-74 years) and 535 very old (aged 75 years and over) individuals randomly sampled from the community. Participation in four categories of activity was assessed: outdoor productive activities; indoor productive activities; leisure activities; and walking. Customary engagement in many activities was found to be low, age (old versus very old) and sex being among the most important determinants of participation. The method of assessment is described, and activity profiles normative for older age groups are presented.

Prevalence, frequency, and duration of hypnotic drug use among the elderly living at home.

Details of consumption of hypnotic drugs derived from a nationally representative sample of elderly people were analysed in terms of the prevalence, duration, and likely frequency of use. Of 1020 randomly selected subjects aged 65 and over 16% (166) reported using (mainly benzodiazepine) hypnotic drugs, and of these 89% reported having taken such a drug the night before the interview. Most of these users (73%) had been taking hypnotic drugs for more than one year, with 25% reporting drug use for more than 10 years. These results suggest that for most elderly users of hypnotic drugs, patterns of consumption encourage the development of cumulative effects and benzodiazepine dependence.

Characteristics of subjective insomnia in the elderly living at home.

Profiles of sleeping habits, subjective sleep quality, and mental and physical well-being were obtained from 1023 elderly individuals randomly sampled from the Nottinghamshire Family Practitioner Committee's records. Subjective insomnia at least 'sometimes' was reported by 37.9% of the sample. Discriminant analysis of selected health and demographic variables indicated that symptoms of anxiety, sex and self-ratings of health were the factors most influential in predicting reports of problem sleep. Thus, respondents classified as subjective insomniacs tended to have significantly higher anxiety scores, to be women, and to rate their health as below average. Relative to the non-insomniac respondents, those complaining of sleep problems also perceived their sleep latency as longer, and their total sleep as shorter. These results emphasize that, in addition to apparently 'normal' age-related changes in the structure of sleep, subjective insomnia in old age may often be mediated by the physical and psychological disorders which can accompany ageing.

Human orthostatic reflexes after taking temazepam at night.

1. Cardiovascular orthostatic reflexes have been studied at night in 12 healthy male subjects who were given two soft gelatin capsules each containing 0 or 10 mg temazepam at 21.30 h. 2. The changes in heart rate, blood pressure and forearm blood flow on consecutive 5 min exposures to lower body negative pressure (suction) at 30, 40 and 50 mm Hg were measured before and then 1.5 and 9.5 h after giving doses of 10 or 20 mg temazepam in a placebo-controlled double-blind cross-over study. 3. Pre-suction resting values were not affected by temazepam, but 1.5 h after giving the capsules there were significant differences in the responses to suction between the placebo and 20 mg temazepam experiments: the tachycardia after 20 mg temazepam was about one-third greater and the forearm vasoconstriction was about 50% less. The effect of the 10 mg dose was equivocal. No residual effects were detected the next morning. 4. These alterations in orthostatic reflexes soon after the administration of temazepam at night did not impair the maintenance of arterial blood pressure in these healthy subjects.

Validation of a simple mechanical accelerometer (pedometer) for the estimation of walking activity.

A small (28 g) mechanical accelerometer has been tested by subjecting it to controlled bench tests consisting of repetitive vertical oscillations on two designs of test rig. The accelerometer's 3-digit display provided a cumulated score with a maximum of 99.9 units. This score was compared with an independent count of the imposed oscillations and found to be linear with time (r = 0.996) and reproducible on retest (coefficient of variation = +/- 1.5%). The sensitivity ranged from 6.2 to 7.4 units/10,000 oscillations. The response was related to the maximal applied acceleration (calculated from the amplitude and frequency of the oscillations on the assumption that they were sinusoidal) and independent of the amplitude and frequency used. The threshold maximal acceleration was less than 2 m s-2 and the response had reached a plateau at 4 m s-2. During field studies the accelerometer was firmly attached over the hip in a waistband where it responded to the vertical accelerations produced by walking. When compared with an independent count of footsteps from a heel-mounted resistance pad the accelerometer score (after calibration) was not significantly different. The mean difference was (0.29 +/- 0.67, S.D.) 10(3) "steps" in a younger group (n = 8, mean age 39 years) and (0.46 +/- 1.08, S.D.) 10(3) "steps" in an older group of women (n = 6, mean age 65 years). Scores of around 10 X 10(3) "steps" can be expected in a day in moderately active young subjects and 40 X 10(3) "steps" in a week in the elderly. Simultaneously recorded scores from both right and left hips wee not significantly different.(ABSTRACT TRUNCATED AT 250 WORDS)

The relationship of arrhythmias to walking activity during mobilization after myocardial infarction.

The extent to which everyday walking activity is responsible for ventricular arrhythmias in the first 6 weeks after suspected myocardial infarction has been studied by simultaneous 24-hour recordings of electrocardiogram and walking activity. Forty-eight recordings from 46 patients were identified which contained couplets, ventricular tachycardia or R-on-T extrasystoles. In 24 recordings (50%) all the arrhythmias occurred whilst the patient was at rest and in a further four recordings there were fewer arrhythmias during activity than would have been expected by chance. Nineteen recordings (40%) contained arrhythmias which may have been induced by activity but in only three of these was the relationship definite. Clear evidence of arrhythmias precipitated by walking was found in only a minority of patients mobilizing after suspected myocardial infarction.

Objective measurements of customary physical activity in elderly men and women before and after retirement.

An objective method for assessing customary physical activity has been described, based on heart rate and footfall signals recorded on magnetic tape using small body-borne recorders. Computer analyses were used to obtain indices of the intensity and duration of periods of physical activity using both biosignals. Threshold values were set for each individual at a heart rate related to a standard walking speed of 4.8 km . h-1 (3 miles per hour). Four activity indices were defined in terms of time spent above this threshold and the intensity of the heart rate elevation above it, applying criteria relating to the duration of periods of activity or the concurrent activation of the walking signal. The choice and validity of these indices are discussed, and results for several groups of subjects presented. Three groups of subjects aged over 60 years were studied before and after retirement: twenty-five were steel-workers and thirty-nine were factory-workers (men and women). Rather low levels of activity were recorded. After one year of retirement the female factory workers showed a significant decrease in activity. In men this was found only after several years of retirement had elapsed.

Methods of teaching medical ethics at the University of Nottingham.

Medical ethics has been described as a thread woven into the fabric of the Nottingham curriculum. There exist a wide variety of relevant learning experiences, occurring at intervals throughout each of the five years of the course. The introduction of the students to clinical method from the start creates the need for early consideration of ethical aspects of professional behaviour and this in turn stimulates spontaneous discussion and inquiry amongst the students. The school has chosen to rely on having a sufficient number of medical teachers from various disciplines willing to discuss in all the necessary detail their own clinical decisions.

KIE: The approach to teaching medical ethics at the University of Nottingham medical school is described. Physicians from various departments are involved in the effort. Over the course of five years, the medical students have a wide variety of relevant learning experiences, including informal observation of physician patient encounters, lectures on medical ethics, discussion sessions, role playing as research subjects and experimenters, and special projects.