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Biomedical subjects

R J Shephard

Publications and source records attributed to R J Shephard.

At least 343 records · Page 19Linked to original sources
PubMed1980

Post-coronary rehabilitation and risk factors, with special reference to diet.

Volunteers were randomly allocated to high intensity exercise (HIE, n = 17, added energy expenditure, 254 progressing to 761 kJ . day-1) and light intensity exercise (LIE, n = 13, < 76 kJ . day-1) programs for a period of one year, commencing 3-12 months after myocardial infarction. Dietary behaviour (7-day records), activity levels (diary records of prescribed activity) and body composition (skinfold readings) were noted at the beginning and end of the study. Both subject groups initially had a low level of energy expenditure (approximately 9.4 MJ . day-1) and a diet relatively low in animal fat. The HIE group showed no significant changes of energy intake, body composition, or blood lipids over the year of observation. In contrast, the LIE group reported a decrease in both energy intake (1.45 MJ . day-1, P < 0.05) and the intake of most individual dietary constituents. It also showed a decrease of triglyceride (P < 0.05), but a suggestion of an increase of subcutaneous fat (triceps, P < 0.05). The HIE program does not confer any necessary advantage of body composition or serum lipid levels, but it does allow a larger food intake. It may thus be of particular value for patients who find adherence to low energy or low cholesterol diets irksome.

Body Composition↗
PubMed1979

Influence of running pace upon performance: effects upon treadmill endurance time and oxygen cost.

Three possible patterns of pacing (type 1, fast/slow; type 2, slow/fast; and type 3, steady rate) were compared over a 1400 m, 4 min run. The subsequent running time to exhaustion at 370 m . min-1 was significantly longer with a type 1 than with a type 2 protocol (P less than 0.05). The steady rate pattern gave results intermediate between type 1 and type 2 pacing. Data for oxygen debt and recovery heart rate confirmed the superiority of type 1 pacing. Possible explanations included (1) a reduction of inefficient anaerobic work, and (2) a greater mechanical efficiency associated with the better matching of required effort to a tapering physiological power. Runners should aim at a steady physiological rather than a steady physical load.

Adult↗
PubMed1979

Attitudes of health science students towards teaching practices, examinations, and other related issues.

A brief multiple choice questionnaire explored the attitudes of students enrolled in several health science faculties (medicine, pharmacy, nursing, and physical and health education). A substantial proportion indicated a wish for more challenging lectures. On the other hand, the majority of students devoted less than one hour of personal study per week to required 'courses', interest in health-related 'courses' being particularly weak. Small textbooks with minimal references were desired, and relatively little use was made of free lecture handouts. Financial constraints had little influence on personal study, but affected textbook purchase. The demand for 'handouts' would have been reduced by a charge. Frequent term examinations as a stimulus to learning were favoured by all groups, as were full or challenging presentations by instructors. Team teaching, although favoured generally, was not equally appealing to all groups.

Adult↗
PubMed1979

Determinations of performance and mechanical efficiency in nordic skiing.

Determinants of performance and mechanical efficiency of effort have been made on a group of ten male nordic skiers, all participants in the University of Toronto ski-team. The oxygen intake at the maximum attainable speed of skiing on a level course averaged 89.6 percent of the maximum oxygen intake observed during uphill treadmill running; the latter (average 63.9 ml.kg-1 min-1) may be compared with values greater than 80 ml.kg1 min-1 for international competitors. Maximum heart rates and respiratory gas exchange ratios were generally lower during skiing than running, and it is suggested that the maximum oxygen intake attained during skiing is limited by the individual's skill. In support of this the more experienced skiers were able to reach close to 100 percent of the treadmill maximum oxygen intake during level skiing. A multiple regression analysis indicated that the skiing speed sustained over a one-hour period was related to experience of skiing, maximum oxygen intake, and the percentage of body fat. Assuming a dynamic friction coefficient of 0.075, a drag area of 0.7 m2 and a drag coefficient of 1.0, the gross mechanical efficiency of the university-class skier averaged a little under 20 percent, with a net efficiency of 21.3 percent.

Biomechanical Phenomena↗
PubMed1979

Recurrence of myocardial infarction in an exercising population.

The Ontario Multi-Centre Exercise-Heart trial is making a prospective study of 751 male subjects following well-documented episodes of myocardial infarction. Comparison is here made between the 50 participants who sustained a recurrence of their myocardial infarction, and the 701 participants who did not. Reinfarction was a little more likely with a history of multiple previous infarctions, but was unrelated to such indicators of infarct severity as symptoms, electrocardiographic abnormalities, enzyme changes, cardiac arrest, arrhythmia, or minimum systolic blood pressure. Features noted on admission to the trial, which may have an adverse effect, include smoking history and related symptoms, residual disability, shortness of breath, and angina of effort. The main physiological warning sign was a low and decreasing cardiac output at a submaximal work load, with a compensatory widening of arteriovenous oxygen difference. With the possible exception of exercise non-compliance, none of the adverse findings is sufficiently consistent to be of value when advising individual patients.

Heart↗
PubMed1979

Effects of physical training on cardiovascular function following myocardial infarction.

Three to twelve (7.1 +/- 3.2) months after myocardial infarction, subjects under 54 (45.0 +/- 4.7) yr were assigned randomly to high-intensity (HIE, n = 37) or low-intensity (LIE, n = 42) exercise programs. Cardiac outputs (Q) during graded bicycle ergometer exercise were measured by a CO2-rebreathing method on entry and after 6 and 12 mo of training. The initial exercise Q was low in relation to work load, due to a low stroke volume (SV). Over the year of training, the predicted maximal O2 intake of the HIE group increased significantly (from 26.0 to 30.3 ml.kg-1.min-1), while that of the LIE group showed no significant alteration. During the first 6 mo, the heart rate of the HIE group was significantly reduced at each work level. There was an associated widening of arteriovenous oxygen difference, but SV was unchanged. These findings were attributed to extracardiac factors, including a redistribution of blood flow, biochemical changes in the trained muscle, and a secondary reduction of sympathetic drive. Over the second 6 mo, the SV of the HIE group increased 10%; this may reflect an increase of intrinsic myocardial contractility that develops if high-intensity training is sustained. The LIE group showed no major changes of cardiovascular function over the year of observation.

Adult↗
PubMed1979

A head-out exercise body plethysmograph.

A head-out exercise body plethysmograph has been developed to facilitate investigations of the extrathoracic airways. An airtight seal around the neck is provided by a pliable sheet of dental dam braced by a tubular bean bag. A set of bicycle pedals is connected by a chain drive, axle, and wall-mounted sealed ball bearing to an external ergometer. The box is air-conditioned to allow exercise up to work loads of 200 W with a temperature increase of less than 1 degree C above ambient laboratory readings. Nose, mouth, and extrathoracic airways are easily accessible for airflow and pressure measurements. O2, CO2, and humidity levels of respired air are not disturbed, verbal communication with the subject is possible, and the subject is unlikely to feel claustrophobic. The plethysmograph has a flat frequency response to 4.2 Hz; it thus functions accurately in both resting and exercise measurements of respiratory minute ventilation. The plethysmograph can also be used for determinations of nasal and oral airflow and pressure, and the study of breathing patterns.

Humans↗
PubMed1979

[Bone maturity and physical performance].

We have examined the relation between physical performance (as measured with the CAHPER tests), bone age (Greulich and Pyl's wrist evaluation) and dental age (Garn's method). Our study included 164 boys and 149 girls aged from 7 to 11. In spite of interesting significant simple correlation between most of the CAHPER tests and bone age measurements for the pre-pubescent period, the latter remains of negligible value in predicting physical performance in the studied children when variables like chronological age, body height and body weight are already included in the prediction equation.

Age Determination by Skeleton↗