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Biomedical subjects

D A Cunningham

Publications and source records attributed to D A Cunningham.

At least 163 records · Page 9Linked to original sources
PubMed1981

Krypton 81m ventilation scanning in chronic obstructive airways disease.

Ventilation and perfusion scans using 81Krm and 99Tcm-labelled macroaggregates have been studied in 60 patients with established chronic obstructive airways disease. Matched defects were found in all patients distributed throughout the lungs. Patients scanned during acute exacerbation frequently showed basal mismatched defects of ventilation (21 out of 30) and in a few follow-up scans showed resolution on treatment. Other patients also scanned in acute exacerbation showed unmatched defects of perfusion thought to represent pulmonary emboli. Poor correlation was found between scan defects assessed on a semiquantitative basis and conventional lung function tests.

Humans↗
PubMed1981

Reasons for dropout from exercise programs in post-coronary patients.

The dropout rate in the 7-yr Ontario Exercise Heart Collaborative Study of post-coronary men engaged in exercise programs was examined in order to determine possible contributing factors. A questionnaire pertaining to psychosocial and program-related variables was distributed to 728 subjects who were previously assigned randomly on the basis of four prognostic risk factors (occupation, personality, hypertension, and angina) into exercise groups: low intensity exercise (LIE), and high intensity exercise (HIE). Comparisons of answers by the 639 respondents (266 dropouts; 373 compliers) were made initially by chi-square analysis to determine significant categories of questions and, subsequently, by a logistic transform to determine the specific questions which related significantly to the dropout rate. It was found that three main categories were associated with a high dropout rate: convenience aspects of the exercise center, perceptions of the exercise program, and family/lifestyle factors. These three main categories should be carefully considered when designing and implementing potential compliance-improving strategies for secondary prevention exercise programs entailing long-term adherence.

Angina Pectoris↗
PubMed1981

Effect of interval training and detraining on anaerobic fitness in women.

Seventeen female volunteers (x age = 23.9 yr) participated in a 6 week investigation of the effect of high intensity interval training on anaerobic fitness. The subjects were randomly assigned to a treatment (exercise n = 9) or a control (no exercise n = 8) group. The training program consisted of 10 one minute work periods on the bicycle ergometer separated by one minute rest periods. This was done 3 days per week. The training intensity progressed from 110% of the experimental group's initial mean maximal oxygen intake (VO2 max) at week 1 to 15% of same group's initial mean VO2 max week 6. Improvements in the exercise group were significantly in VO2 max (+7.7%), peak post exercise blood lactate (-62.0%), maximum oxygen debt (+19.8%), and time of bicycle ride to exhaustion (+47.5%). The control group did not change significantly on any of the selected parameters. After 2 weeks of detraining oxygen debt decreased significantly to its pretraining value. The retention of increases in post exercise peak blood lactate and time of bicycle ride to exhaustion was 40% and 38% respectively. Twenty-four % of the increase in VO2 max induced by the training regime was retained.

Adult↗
PubMed1981

Daily energy expenditure of young boys as related to maximal aerobic power.

Daily energy expenditure, and participation in regular physical activity over one year, were determined in 28 boys (age 12.3 years) by (1) heart rate (fh) recorded on an oxford Medilog tape recorder and used to approximate energy expenditure using individual fh-VO2 relationships established from a standard step test; total daily average energy expenditure, time spent, and energy expended in activity above a defined threshold, training fh = (.6 (fh max - fh rest) + fh rest) and, (2) a questionnaire designed to determine involvement in regular physical activities over the preceeding year. Maximal oxygen uptake (2.47 +/- 0.36 l-min-1) was measured on a treadmill test. A step-wise multiple regression analysis was used to describe the association between maximal aerobic power and the measures of body size (wt. - 43.8 kg, ht. - 152.2 cm), fatness (sum of skinfolds -67.4 mm), daily energy expenditure (11.66 MJ), and participation in regular physical activity. Body mass and fatness made the only significant contributions to the variance (R2 = 0.77). The relationship was VO2 (l.min-1) = 0.47 (body mass- kg) -0.04 (sum of 6 skinfolds) + 0.71. Measures of daily energy expenditure, the time the heart rate was above a training threshold, and the number of regular physical activities, added little to the measured variance (R2 = 0.78) above that accounted for by body mass amd fatness.

Adolescent↗
PubMed1980

Gas transport capacity and echocardiographically determined cardiac size in children.

One hundred and seventeen boys (10, 12, and 14 yr of age) were studied to determine the relation between maximal gas transport capacity (VO2 max) and cardiac size and the interaction of growth and physical activity on this relation. VO2 max was measured during treadmill exercise and heart size was obtained during supine rest by M-mode echocardiography. Left ventricular end-diastolic diameter (LVIDd), resting stroke volume (SV), and calculated left ventricular mass (LVM) were highly correlated (0.75 < r < 0.84) with VO2 max within all age categories. Subjects with high VO2 max had significantly (P < 0.05) larger LVIDd, end-diastolic volumes, resting SV, calculated LVM, and, with the exception of the 12 yr olds, larger left ventricular end-systolic diameters and volumes than subjects with lower VO2 max. Multiple linear regression analysis revealed that fat-free weight accounted for most of the variance in VO2 max and that cardiac dimensions were only of minimal importance in determining maximal gas transport capacity in this study. The seemingly good relationship between cardiac dimensions and VO2 max was mainly attributable to the shared influence of body size on both these factors.

Adolescent↗
PubMed1980

Eating habits and caloric intake of physically active young boys, ages 10 to 14 years.

Eating habits of 104 male participants (ages 10 to 14 years) in organized ice hockey were compared across age groups and levels of competition. The boys were members of either a highly skilled and intensively active competitive league group (CL) or a less skilled, moderately active house league group (HL). Eating habits were recorded during a school day from a 24 hour recall questionnaire administered by a trained interviewer. The types and amounts of foods eaten were recorded and caloric intake was calculated. The total caloric intakes were not significantly different by age or competitive group. The boys had higher caloric intakes by age (200 kcal day-1) than reported by other studies but the caloric intake by kilogram of body weight was similar. There was a trend towards larger caloric intake by the CL boys (ages 10 and 11 years), however when divided by body weight the differences were not significant suggesting that this trend was due to a greater body weight of the CL boys and not a significantly increased caloric expenditure. The types of foods eaten (fruit, vegetables, dairy, meat, bread or "empty calories") were similar for the two activity groups and across ages 10 to 14 years. The caloric intakes of dairy and meat products of both groups were significantly higher than for the other food groups.

Adolescent↗
PubMed1980

The value of combining noninvasive techniques in exercise testing.

A 3-stage cycle ergometer exercise test which combines the noninvasive measurement of systolic time intervals (STI's), stroke volume (SV), mean systolic ejection rate (MSER) and blood pressure was administered to 2 groups of middle-aged men. Group 1 included 15 healthy men. Group 2 consisted of 20 men with coronary artery disease (CAD), confirmed by a proven myocardial infarction. The groups were matched for age, weight and height. Over the range of heart rates (HR's) encountered (70--173 beats min-1) the STI's described an inversely linear relationship with HT. At all exercise HR's, group 2 displayed higher values for total electromechanical systole (QS2), left ventricular ejection time (LVET) and the pre-ejection period (PEP), and lower values for SV and MSER. Statistical comparison of all variables at a common HR of 100 beats min-1 indicated that QS2 and MSER best discriminated between the groups. It was concluded that this test is sufficiently sensitive to detect differences in cardiac performance in groups of subjects, but not for the diagnosis of CAD in individual patients.

Adult↗
PubMed1979

Cardiovascular response to interval and continuous training in women.

Three groups of five women (age = 18--25 years) participated in a 12-week training program. Cardiovascular responses up to 85% VO2 max to interval (ITG) and continuous (CTG) training were studied in two groups, before training and after 4, 8, and 12 weeks of training four times per week. A control group was assessed before and after 6 and 12 weeks. Both exercise groups demonstrated significant increases in Cao2--Cvo2 after 8 weeks with only slight further increases after 12 weeks (CTG = 8.9%, ITG = 20.0% at 85% VO2 max). No significant changes were noted in either group in SV (+ 5 ml ITG, + 9 ml CTG) or in their Qc. These results indicated that, in response to high intensity training, women may demonstrate similar cardiovascular adaptations to training as have been observed for men.

Adolescent↗
PubMed1979

Effects of endurance training on left ventricular dimensions in healthy men.

Echocardiography was employed to measure the serial effects of jogging on resting left ventricular dimensions and function. Twelve men were exercised (mean age 36.8 yr) and 10 served as controls (mean age 34.8 yr). Increases of 14 and 18% were observed for predicted aerobic capacity in the training group (TG) after 3 and 6 mo of training, respectively; the control group (CG) displayed a small detraining effect. Echocardiographic findings included a significant (P less than 0.05) reduction in resting heart rate and a moderate increase in stroke volume (SV) in the TG compared to the CG. The increased SV appeared to be due to increased end-diastolic dimensions (LVIDd, LVEDV), secondary to greater ventricular filling rather than a more vigorous ventricular contraction. Posterior wall thickness, septal thickness, and calculated left ventricular muscle mass were not significantly increased in the TG compared to CG after either 3 or 6 mo training. It was concluded that left ventricular structure and resting contractile status are not altered by 6 mo of jogging training in healthy, previously sedentary men.

Heart↗
PubMed1979

Exercise and human collateralization: an angiographic and scintigraphic assessment.

The effect of exercise on the development of intercoronary collaterals and on left ventricular function is controversial. Twenty male patients (mean age 48 years, range 36-54 years) who had suffered an acute myocardial infarction were randomly allocated to an exercise group (10 patients) and a control group (10 patients). Both groups underwent coronary angiography, left ventricular function studies and myocardial perfusion studies with labeled microspheres, before and after the 7-month experimental period. Both groups had similar extent of disease as measured angiographically and both had mild progression of disease. Neither group showed changes in extent of callateralization, myocardial perfusion or left ventricular function. The exercise group had a significant increase in anginal threshold and a significant (p less than 0.01) decrease in heart rate at a given work load. Exercise, therefore, does not appear to affect progression of disease, myocardial perfusion, extent of collateralization, or left ventricular function in patients with coronary artery disease.

Adult↗
PubMed1979

Urinary cyclic AMP and cyclic GMP in normal and asthmatic subjects during exercise.

The purpose of this study was to compare exercise-induced changes in urinary cyclic AMP and cyclic GMP of normal and asthmatic subjects. All subjects were exercised to 80% of predicted maximum heart rate for 15 minutes on a bicycle ergometer. FEV1 was measured before and after exercise to determine the degree of bronchoconstriction due to exercise. Five urine specimens were collected by voluntary voiding at 20 minute intervals (one specimen before exercise and four after exercise). Before exercise, the asthmatic subjects excreted less cyclic GMP (p less than 0.05) but the same cyclic AMP as the normal subjects. Creatinine excretion in nine asthmatic subjects decreased by 24% (p less than 0.01) during exercise. In sixteen normal subjects (post-exercise bronchoconstriction less than 10%) cyclic AMP excretion increased by 19% (p less than 0.05) within 20 minutes after exercise, while cyclic GMP excretion did not change significantly. In thirteen asthmatic subjects (post-exercise bronchoconstriction greater than 20%) cyclic AMP excretion did not change significantly, while cyclic GMP excretion increased by 23% (p less than 0.05) within 20 minutes after exercise. This study has shown that exercise affects the excretion of cyclic AMP, cyclic GMP, and creatinine in normal and asthmatic subjects. The response of normal and asthmatic groups to exercise was the same for creatinine but different for cyclic AMP and cyclic GMP.

Adolescent↗
PubMed1979

Characteristics of the elite minor hockey player.

Few studies have been reported which evaluate the cardiorespiratory responses of young athletes and fewer still which are concerned with the young elite hockey player. The problems of measurement were outlined and described. These included the selection of appropriate samples for study, the identification of those variables to be measured which will yield the most important factors and the appropriate methods for use with these subjects. Comparisons between young athletes and normative data on less active boys were described. In the athletic population the maximal aerobic power increased across ages 10 to 14, whereas, the values for the less active norms decreased with age. Values for age related changes in blood lactate were also reported.

Adolescent↗
PubMed1978

Relationship between maximal oxygen uptake and left ventricular function in exercise.

Left ventricular systolic time intervals (STI's), cardiac output, and arterial blood pressures were measured during bicycle ergometer work in three groups of 10 young men (aged 20-33 yr) who represented average (VO2max = 42-45 ml.kg-1.min-1), moderate (VO2max = 50-56 ml.kg-1.min-1), and high (VO2max = 59-72 ml.kg-1.min-1) levels of cardiovascular fitness. The subjects were studied using noninvasive procedures at steady-state heart rate of approximately 110, 130, and 150 beats.min-1. At all exercise levels, the fitter subjects displayed slightly shorter values for the preejection period (PEP) compared with less fit groups. Significantly (P less than 0.05) larger stroke volumes, longer left ventricular ejection times (LVET), faster mean systolic ejection rates and lower PEP/LVET ratios were found in the group with the highest aerobic capacity. Although these observations appear to indicate a superior mean level of left ventricular performance in groups who represent high levels of cardiovascular fitness, it was concluded that the use of STI values by themselves to describe the cardiovascular fitness of an individual would not be warranted.

Adult↗
PubMed1978

Reliability of noninvlasive methods for measuring cardiac function in exercise.

Externally recorded systolic time intervals (STI's), indirect (CO2 re-breathing) cardiac output, and auscultatory blood pressures were measured during upright bicycle ergometer work in 20 healthy men, aged 24-56 yr. The subjects were studied on 2 separate days at steady-state work loads chosen to represent light (mean heart rate (HR) = 96 beats.min-1), moderate (HR = 118 beats.min-1) and heavy (HR = 147 beats.min-1) exercise. In addition to determinations of cardiac output, systolic time intervals, and blood pressure, the individual's mean systolic ejection rate (stroke volume/left ventricular ejection time) was calculated as a measure of left ventricular function. In general, heart-rate-corrected STI's were found to be reliable and reproducible. Reliability coefficients for total electromechanical systole and left ventricular ejection time ranged from 0.93 to 0.96 while those for the preejection period and its subcomponents were between 0.63 and 0.88. The reliability of cardiac output, stroke volume, mean systolic ejection rate, and systolic blood pressure was also considered to be acceptable but tended to be higher during moderate and heavy work (r = 0.85-0.95) compared to light exercise (r = 0.60-0.83).

Blood Pressure Determination↗
PubMed1978

Urinary catecholamine excretion during competition in 11 to 23 year old hockey players.

Stress experienced by young athletes (ages 11 to 23 years) during competition was studied by comparing urinary epinephrine (E) and norepinephrine (NE) excretion at rest, during bicycle exercise (55% max) and during a hockey game. Athletes were divided into four groups: 11, 12, 16, and 23 years olds with four subjects in each group. Urinary production rates were similar between experimental conditions and age groups. Both resting E and NE levels were constant across all ages. Game E levels were significantly higher (P less than 0.05) than resting and bicycle levels in both the 16 and 23 year old groups. Epinephrine excretion during hockey was also significantly higher (P less than 0.05) in the 23 year old athletes than in the 11 and 12 year olds and in the 16 year olds compared to the 11 year olds. Game NE was significantly elevated (P less than 0.05) above resting levels in the 16 and 23 year olds. Submaximal NE excretion was not significantly different from resting levels in any of the age groups (P greater than 0.05). Physical stress as reflected by NE excretion was constant across all ages within each experimental condition. Generally, sympathetic stimulation and NE excretion appeared to be related to intensity of physical activity, being greater during hockey than during submaximal exercise. Significant adrenal medullary activation and E excretion was evident only during hockey and then, only in the older athletes.

Adolescent↗
PubMed1977

Reliability and reproducibility of maximal oxygen uptake measurement in children.

Maximal aerobic capacity of 66 ten year old ice hockey players was measured on a treadmill twice over a 4 to 5 month period. This time approximated mid (T1) to post (T2) competitive season. The results of these VO2 max tests were grouped according to the presence or absence of a plateau in the oxygen uptake (less than 2.1 ml/kg-min) during the last work loads before fatigue. The mean values for T1 and T2 were not significantly different for any of the measurements made; the reproducibility was considered to be high. The reliability of the measures varied with the presence or absence of a plateau at maximum, for example; VO2 max, plateau r = 0.74, no plateau r = 0.27; heart rate, plateau r = 0.92, no plateau r = 0.40. The differences between the mean values for the "double plateau" group when compared to the "no plateau" group were not significant for VO2 max, HR or VE. The differences were significant for the post-exercise blood lactate and respiratory exchange values at T2 only; the "double plateau" group reached higher values in each case (R = 1.00 vs 0.92; blood lactate 6.5 vs 5.4 mM/1).

Child↗