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Biomedical subjects

J M Patrick

Publications and source records attributed to J M Patrick.

At least 37 records · Page 2Linked to original sources
PubMed1983

The rising ventilatory cost of bicycle exercise in the seventh decade: a longitudinal study of nine healthy men.

Submaximal bicycle exercise tests have been performed in nine healthy men on seven annual occasions between the ages of 64 and 70 years. Ten younger men (average age 33 years) have also been studied once for comparison. The ventilatory cost of submaximal work at VO2 = 1 litre/min rises significantly from 24.3 +/- 0.8 litres/min at age 64 years to 31.8 +/- 1.8 litres/min at age 70 years; the latter value differs significantly from that of the young men (25.6 +/- 0.9 litres/min). Similar changes are seen in the ventilation at 75 W and at VCO2 = 1 litre/min. The rate of change, between 3% and 5% per year, is considerably greater than that found for the change with age in cross-sectional studies of younger men. There is also a rise in the respiratory quotient, consistent with the hyperventilation found. The cardiac frequency at 1 litre/min also rose with age in the older men, and rough estimates of the decline in their aerobic capacity suggest that progressive anaerobiosis could account for at least some of this increase in ventilation seen during submaximal work.

Adult↗
PubMed1983

Effect of age, sex and illness on salt taste detection thresholds.

Salt taste detection thresholds have been measured by a forced-choice, up-down sip method in 146 healthy subjects aged 10-95 years, and in 43 ill elderly patients. Thresholds are shown to increase log linearly with age after the age of 20 years. Thresholds are higher in smokers than non-smokers and the lower thresholds of women are accounted for by their lower prevalence of smoking. Ill patients have higher thresholds than healthy subjects of the same age and this is not specifically associated with any diagnosis. The methodology of taste threshold measurement and earlier studies of taste thresholds are reviewed.

Adult↗
PubMed1982

Factors affecting the heart rate during self-paced walking.

The results of 277 self-paced walking tests have been analysed for the effects of body composition, sex and age using step-up multiple regression analysis. Equations are given for the influence of the significant factors on chosen walking speeds and on heart rate (fc) (standardised at 4.8 km . h-1 by interpolation from points recorded at three walking speeds). The basic equations are: Normal speed (km . h-1) = 1.72 + 2.13 stature (m) - 0.008 age (years) Fast speed (km . h-1) = 0.54 + 3.69 stature (m) - 0.016 age (years) For men: fc4.8 (beat . min-1) = 161 - 50.7 stature (m) + 0.223 body weight (kg) For women: fc4.8 (beat . min-1) = 161 - 50.7 stature (m) + 0.223 body weight (kg) + 4.43 The significant factors affecting freely chosen walking speeds are stature and age. When estimates of body composition are available, percentage fat is found to be the most influential single factor affecting fc, while sex no longer has a significant effect, and age now has a negative influence. When allowance is made for these factors the effects of customary physical activity can be seen more clearly.

Adult↗
PubMed1982

Changes in body fat and muscle in manual workers at and after retirement.

The changes in body fat and muscle in 73 men retiring from manual work have been measured in a longitudinal anthropometric study. Body fat increased by about 3% and body muscle decreased by about 1% between measurements made just before retirement and again 1 year later. The decline in muscle was even greater in a subgroup of 22 men who reported that their activity was less after retirement: but a subgroup of 11 whose activity was said to have been greater after retirement showed an increase in body muscle. A sub-sample of 26 men were measured on five further annual occasions (Fig. 1). The initial increase in body fat was reversed, and fat measurements fell back significantly to or below the pre-retirement values. Body muscle, however, continued to decline steadily at the initial rate, and the ratio of thigh muscle area to body mass fell significantly in retirement in the group as a whole. The possible contributions of ageing and of changes in energy balance and physical activity to these findings are discussed.

Adipose Tissue↗
PubMed1981

The limitation of exercise ventilation during speech.

Ventilation in steady-state treadmill exercise at five different speeds has been measured in six subjects using an inductance plethysmograph whose calibration is described. A printed passage of 100 words was read aloud during the fifth minute of each exercise period:this took about 30 sec. At each exercise level ventilation was reduced during speech to about 55% of the control value: at the highest level the reduction was 38 1. min-1 from a control ventilation of 78 1. min-1. Respiratory frequency was reduced but tidal volume was not affected. Twenty-four per cent of the ventilation during the speech period at the heaviest exercise was accounted for by non-phonated (silent) expirations. Immediately after the speech period, ventilation overshot by about 14% and then returned to the control value within 30 sec. The results are interpreted in terms of the precedence taken by the speech requirement for restricted expiratory airflow rates over the ventilatory requirement for gas exchange.

Humans↗
PubMed1981

Ventilatory function in Nigerian coal miners.

Ventilatory capacity has been measured in 675 Nigerian colliery employees classified in three groups according to occupation: coalface workers, other underground workers with low exposure to dust, and surface workers in administrative and clerical jobs. Men with current respiratory symptoms were excluded, as were ex-miners. The faceworkers were a slightly older group who smoked less, and they were presumed to be more active. Faceworkers had a highest forced vital capacities (adjusted for age and stature) but the lowest values for indices reflecting maximal expiratory airflows, (FEV1/FVC, PFR FEF, and FMF). Apparently coalface work is associated with an 8% impairment of maximum expiratory airflow, probably due to dust exposure, but also with a modest enhancement in FVC, possibly due to training of the respiratory muscles. Regression coefficients on age for the airflow indices are significantly more negative in faceworkers than in the other groups. Smoking and duration of service did not significantly affect the pattern of results. FEV1 does not vary among the occupational groups in the colliery, and the mean value is close to that predicted on the basis of reference equations previously obtained for non-miners in Nigeria.

Adolescent↗
PubMed1979

Ventilatory pattern following diazepam and lorazepam.

The effect of intravenous diazepam (10 mg) or lorazepam (2 mg) on the ventilatory pattern has been studied in two groups of ten patients prior to elective surgery. Injection of lorazepam was followed by a periodic pattern of ventilation in nine patients.

Adult↗
PubMed1979

The effect of beta-adrenoceptor blockade on factors affecting exercise tolerance in normal man.

1 We have studied the effects of single oral doses of 80 mg propranolol and 100 mg metoprolol on the cardiovascular and respiratory responses to progressive exercise in nine healthy men in double-blind, placebo-controlled experiment. As judged by their effects on exercise heart rate and cardiac output the doses of the two drugs used were equivalent. 2 Beta-adrenoceptor blockade reduced oxygen consumption by 3.5% over the whole work range with an increase in the respiratory exchange ratio of 0.056 units. Carbon dioxide production and exercise ventilation were unchanged. The two drugs had similar effects. Possible mechanisms for these observations are discussed. 3 Perceived exertion during exercise was increased by both the beta-adrenoceptor blocking drugs and this may be of relevance to the symptom of fatigue reported by patients on these drugs. Endurance, assessed as either total work done or maximal work achieved, was reduced by 15%.

Adrenergic beta-Antagonists↗
PubMed1978

Propranolol and the ventilatory response to hypoxia and hypercapnia in normal man.

1. The effect on respiration of a single dose of propranolol has been studied in normal subjects. 2. The degree of beta-adrenoreceptor blockade was assessed in terms of the impaired heart-rate response to progressive exercise and the plasma propranolol concentration. 3. No effect of propranolol was demonstrated on either the ventilatory response to rebreathing CO2 in hyperoxia, or the response to progressive isocapnic hypoxia. Simple indices of maximal expiratory flow (FEV 1.0% and PEFR) were also unchanged. 4. The absence of any effect of propranolol on the chemical control of breathing in man is discussed in relation to the conflicting literature.

Adult↗
PubMed1978

Cardiac output during submaximal exercise in New Guineans: the relation with body size and habitat.

Cardiac performance in moderate bicycle exercise has been measured in five groups of New Guineans (N = 161). Men and women in both coastal and highland (2000 m) locations were studied, as well as a group of highland men after migration to the coast. The results have all been standardized to an oxygen consumption of 1 1.min(-1). Cardiac output values are similar to those previously quoted for Europeans; a significant positive correlation with body size is found, and resident highlanders appear to have slightly larger cardiac outputs (+4%) and larger stroke volumes (+10%) after adjustment for body size, but this is not because they have larger hearts. The highland migrants at sea-level share none of the 'altitude' characteristics of the highland residents and, after size-adjustment, correspond with the lowlanders. The cardiac frequencies of the lowland women are higher than the other groups (+15 beats.min(-1)) after adjustment for differences in body size. Their values are close to those found previously for moderately active Europeans, while all the other New Guinean subjects have lower cardiac frequencies probably because of their greater habitual activity.

Adaptation, Physiological↗