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Biomedical subjects

R A Wiswell

Publications and source records attributed to R A Wiswell.

29 records · Page 2Linked to original sources
PubMed1989

Exercise prescription in pregnancy: weight-bearing versus non-weight-bearing exercise.

Bicycle ergometry (non-weight-bearing exercise) and treadmill (weight-bearing exercise) were compared to assess physiologic responses to similar work loads. A total of 22 subjects at 29.3 +/- 1.6 (+/- SEM) weeks' gestation who performed non-weight-bearing exercise were compared with 15 similarly fit subjects at 26.1 +/- 2.3 weeks' gestation who performed weight-bearing exercise at three submaximal levels. Measurements by indirect calorimetry indicate preferential carbohydrate use during non-weight-bearing exercise at submaximal levels.

Adult↗
PubMed1986

Fetal heart rate responses to maternal exercise.

The fetal heart rate responses to mild, moderate, and strenuous maternal exercise were studied in 45 healthy subjects. In the majority of cases, the fetal heart rate increased during and after maternal exercise. Fetal bradycardia was recorded in five fetuses; this appears to be a sporadic event. There was no correlation between the individual fetal heart responses, gestational age, exercise intensity, and maternal circulating catecholamines.

Blood Glucose↗
PubMed1985

Changes with age in monosynaptic reflexes elicited by mechanical and electrical stimulation.

Absence of the achilles tendon reflex (T) has been reported to increase with age. Other investigators have reported no age relationship. Age changes in the Hoffmann reflex (H) have been examined in only one recent investigation. It was our purpose to compare the T and H reflexes of healthy, active old (n = 20) against young (n = 20) subjects using methods which provide stimulus-response data for both T and H. We also compared the age differences of H against T to estimate fusimotor involvement in age changes. No significant age difference were found in the response:stimulus ratio for T. Amplitude of H responses were 32.7 percent smaller in the old (P less than 0.04) and M waves were smaller by 24 percent (P less than 0.025). No significant age difference was found between mechanically and electrically elicited reflexes; and, therefore, our data do not support fusimotor involvement in the age changes of monosynaptic reflexes.

Achilles Tendon↗
PubMed1983

The effect of NH4Cl induced chronic metabolic acidosis on work capacity in man.

Eleven male and female subjects were randomly assigned to two treatment groups. One experimental ammonium chloride (NH4Cl) group (n = 6) and one calcium carbonate (CaCO3) placebo control group (n = 5) received treatment lasting 10 days. No significant changes were observed in several ventilatory parameters (VE, VE/V2, VE/VO2) during submaximal or maximal exercise. Heart rates and performance times were similarly unaltered. Changes were observed in oxygen consumption (VO2) and plasma lactates (HLa) during submaximal exercise at 40% maximal power output (approximately 48% VO2max). VO2 decreased from 1.12 l X min-1 to 1.04 l X min-1 (t = 2.87, p less than 0.05) and HLa were depressed from 2.3 to 1.9 mM X 1(-1) (t = 3.92, p less than 0.02). HLa and VO2max were not changed during an incremental VO2max test. The evidence suggests that under conditions of experimental renalcompensated, chronic metabolic acidoses (CMA), there are no significant changes in most cardiopulmonary parameters measured during maximal and submaximal exercise. It appears that the decrements in performance reported by previous investigators may be due to pH changes of acidosis rather than accompanying compensatory changes of acid-base control.

Acidosis↗
PubMed1982

Comparison of oxygen kinetics in young and old subjects.

Five older men (aged 60-69 yr) and five young men (aged 21-29 yr) with approximately equal levels of age-corrected VO2 max were compared with respect to oxygen kinetics at equal absolute workloads (100 watts) and at equal relative workloads (45% VO2 max) on a cycle ergometer. At 45% VO2 max, half times for VO2 response to instantaneous transition from unloaded pedalling were 30.0 s and 27.4 s for old and young respectively (t = 0.260, p less than 0.80). No significant differences were found in the VE response and by inference none existed in O2 extraction. Mean half times for heart rate responses at a workload of 100 W were 24.2 s and 20.6 s for old and young groups respectively (t = 0.722, p less than 0.49). Mechanical efficiency estimated from steady state data at 100 W was 19.8% and 20.5% for old and young groups respectively (t = 0.574). The close similarity in responses to submaximal work in old and young subjects of equivalent fitness suggests caution in the interpretation of agewise decrements observed in physiological variables which may be sensitive to physical fitness status.

Age Factors↗
PubMed1979

Time course of O2-pulse during various tests of aerobic power.

The purpose of this study was to test the hypothesis that oxygen pulse typically reaches a maximum before maximal oxygen consumption by observing the time course of oxygen pulse throughout exercise to maximal stress and to discern those physiologic variables which might predispose an individual to reach a peak in oxygen pulse before achieving maximal oxygen consumption. Thirty male volunteers ranging in age from 18-25 (X = 20.5) years were recruited for this study. Maximal oxygen uptake was assessed on both bicycle ergometer and treadmill. Based upon the results of the exercise tests, subjects were classified into subgroups as a consequence of whether or not a maximal oxygen pulse or a plateau in oxygen pulse was demonstrated during submaximal exercise. The results indicate that submaximal peaking or at least the achieving of plateau values of oxygen pulse does in fact occur in some but not all indivuals. It was observed that this phenomenon occurs at a relatively high percentage of maximal heart rate and maximal oxygen consumption. It appeared that individuals who demonstrate low heart rates at low-work intensities, high maximal heart rates, and a disproportionate increase in R for a given ventilation are most likely to reach a submaximal peak in oxygen pulse. Oxygen pulse during submaximal exercise appears to provide a good indication of cardiorespiratory fitness.

Adolescent↗
PubMed1977

Effects of water immersion on lung volumes: implications for body composition analysis.

Lung volumes of 20 healthy young men were measured before and after water immersion to the neck level. Immersion resulted in significant decreases (P less than 0.01) in forced vital capacity (FVC) (8.9%), expiratory reserve volume (ERV) (61%), total lung capacity (TLC) (5.6%), and functional residual capacity (FRC) (2.9%). Significant increases were observed in inspiratory capacity (IC) (10%) and residual volume (RV) (6.7%). The increase in RV was attributed to a possible "stiffness" of the lung tissue caused by pulmonary vascular engorgement. Densitometric analysis was made on each subject using hydrostatic weighing techniques. Subsequent calculation of body density and per-cent body fat indicated significant (P less than 0.01) differences when using RV measured on land and in water. Body fat was 14.0% using the land RV in the computation of density and decreased to 13.4% using the RV measured in water. It was concluded that when obtaining body density values. RV should be measured concurrently while the subject is in the water.

Adult↗