Showing papers by "Roy J. Shephard published in 1996"

Quality of life and cardiorespiratory function in chronic heart failure: effects of 12 months' aerobic training.

Abstract: OBJECTIVE: To examine the long-term benefits and safety of aerobic training in patients with chronic heart failure. DESIGN: Non-randomised control trial with 52 weeks follow up. SETTING: Outpatient cardiac rehabilitation referral centre. PATIENTS: Patients with compensated chronic heart failure (mean (SD) age 62 (6) years, New York Heart Association stage III, initial resting ejection fraction 22 (7)%). Experimental group of 17 men, 4 women; control group 8 men, 1 woman. INTERVENTIONS: Experimental group: progressive, supervised aerobic walking programme for 52 weeks. Control group: standard medical treatment. MAIN OUTCOME MEASURES: Six-minute walk distance, progressive cycle ergometer test to subjective exhaustion, disease-specific quality of life questionnaire, and standard gamble test, all measured at entry, 4, 8, 12, 16, 26, and 52 weeks. RESULTS: Control data showed no changes except a small trend to improved emotional function (P = 0.02 at 12 weeks only). Fifteen of the 21 patients completed all 52 weeks of aerobic training; two withdrew for non-cardiac reasons (16, 52 weeks). Three were withdrawn because of worsening cardiac failure unrelated to their exercise participation (4, 4, 8 weeks), and one had a non-fatal cardiac arrest while shopping (16 weeks). Gains of cardiorespiratory function plateaued at 16-26 weeks, with 10-15% improvement in six-minute walk, peak power output, and peak oxygen intake linked to gains in oxygen pulse and ventilatory threshold and reductions in resting heart rate. Marked improvements in quality of life followed a parallel course. CONCLUSIONS: Aerobic training is safe and beneficial in compensated chronic heart failure. Gains in aerobic function and quality of life persisted over a programme lasting 52 weeks.

Worksite fitness and exercise programs: a review of methodology and health impact.

Abstract: Purpose. To examine the methodology of worksite fitness and exercise programs and to assess their effect on health-related fitness, cardiac risk factors, life satisfaction and well-being, and illness and injury. Search methods. The 52 studies reviewed cover English-language literature for the period from 1972 to 1994, as identified by a search of the Cumulative Index Medicus, Medline, the Canadian Sport Documentation Centre's “Sport Discus,” computerized bibliography, and my own files. Reports were divided into five controlled experimental studies, 14 quasi-experimental studies with matched controls (one reported in abstract), and 33 other interventions of varied quality. Summary. Methodologic problems include difficulty in allowing for Hawthorne effects, substantial sample attrition, and poor definition of the intervention (exercise or broad-based health promotion). Findings are analyzed by specific fitness and health outcomes. Program participants show small but favorable changes in body mass, ...

The health consequences of "modernization" : evidence from circumpolar peoples

Abstract: Preface 1. The circumpolar habitat and its peoples - traditional lifestyle and early research findings 2. Concept of the International Biological Programme Human Adaptability Project and IBP studies of circumpolar peoples 3. Changes in social structure and behaviour 4. Secular trends in diet, metabolism and body composition 5. Secular trends in physical fitness and cold tolerance 6. Secular trends in lung function and respiratory disease 7. Secular trends in growth and development 8. Current health status 9. Lessons from the Arctic Bibliography Index.

Endurance exercise with and without a thermal clamp: effects on leukocytes and leukocyte subsets

Abstract: To test how leukocyte responses to endurance exercise were modified by clamping body temperature, nine men (27.3 +/- 6.0 yr) completed four 80-min immersions to midchest at water temperatures of 23...

Development of public policy and physical activity initiatives internationally.

Abstract: Epidemiological, pathological, clinical, and experimental studies over the past 40 years convincingly show that physical inactivity and low physical fitness contribute substantially to the major chronic diseases prevalent in industrialised societies. Several industrialised countries around the world report increases in physical activity participation among adults in recent years, but the prevalence of inactivity remains high. These increases in voluntary exercise are at least partially offset by decreasing daily energy demands due to increased mechanisation at home, at work and during leisure-time. In developing countries, physical inactivity is becoming a prevalent lifestyle due to rapid social and economic changes. Clinical interventions and mass appeals to be more physically active are limited in effectiveness against the background of increasingly sedentary lifestyles. Exercise scientists and public health officials need to turn attention to public policy and legislative initiatives to restructure physical and social environments to encourage more physical activity and discourage sedentary habits.

Effects of moderate endurance exercise and training on in vitro lymphocyte proliferation, interleukin-2 (IL-2) production, and IL-2 receptor expression

Abstract: This study was designed to examine immunological responses to an acute bout of cycle ergometry exercise before and after moderate endurance training. Previously sedentary males were randomly assigned to matched training (n=9) or control (n=6) groups. Training comprised 12 weeks during which supervised cycle ergometer exercise took place [30 min at 65–70% of maximal oxygen intake\((\dot VO_{2max} )\), 4–5 days · week−1]. An acute bout of exercise (60 min; 60%\(\dot VO_{2max} \) was performed initially and after the 12-week interval. Samples of peripheral venous blood were taken at rest, after 30 and 60 min of exercise, and at 30 and 120 min post-exercise. Training improved\(\dot VO_{2max} \) by an average of 20% (40.6 to 49.2 ml · kg−1 · min−1). Relative to baseline and control measures, the resting concentration of (CD3-CD16+/CD56+) natural killer (NK) cells increased by 22% (P<0.05). The resting count of total CD25+ [interleukin-2 receptor (IL-2R) α chain] lymphocytes did not change following training, but dual staining analysis showed a 100% increase in the fraction of CD16+ CD25+ NK cells (P < 0.05). Likewise the resting CD122+ (IL-2Rβ chain) lymphocyte count increased 35% after training, the greatest increases (44%) being in CD16+ CD122+ NK cells (P<0.05). Soluble IL-2R levels also increased 33% (P< 0.05) after training. Following acute exercise at the same relative intensity; trained individuals exhibited a larger increase in the NK cell count, reduced lymphocytopenia, and attenuation of exercise-induced suppression of lymphocyte proliferation and IL-2 production (P<0.05). In addition, smaller increases in CD4 and CD8 counts during exercise were noted, but with faster recovery post-exercise (P<0.05). Addition of recombinant IL-2 (rIL-2) to phytohemagglutinin-stimulated peripheral blood mononuclear cell cultures did not reverse exercise-induced suppression of cell proliferation, either before or after training. However, rIL-2 did augment the spontaneous blastogenesis of exercise and post-training samples relative to baseline (P < 0.05). We conclude that moderate endurance training is associated with sustained alterations in immune function, both at rest and when exercising. Further investigations are necessary to determine the impact on overall health and susceptibility to disease.

Habitual Physical Activity and Quality of Life

Abstract: (1996). Habitual Physical Activity and Quality of Life. Quest: Vol. 48, No. 3, pp. 354-365.

Effects of heat and intermittent exercise on leukocyte and sub-population cell counts

Abstract: This study examined the combined effects of heat stress and intermittent exercise on circulating leukocyte and sub-population cell counts. Using a randomized-block design, 11 healthy male subjects [mean (SD) age = 29.1 (3.0) years maximal oxygen consumption (\(\dot V{\text{O}}_{{\text{2max}}}\)) = 47.6 (6.1) ml/(kg-min)] were assigned to four conditions. Each subject exercised on a cycle ergometer at 50% \(\dot V{\text{O}}_{{\text{2max}}}\) (two 30-min bouts, with 45 min rest between), or acted as his own control by sitting at 23°C, or at 40°C, 30% relative humidity, for 3 h. Blood samples taken prior to, during, and after each rest and exercise bout, and at corresponding times when sitting were used for Coulter cell counter and flow cytometric analysis. Sitting conditions did not produce any significant immunological changes. Intermittent exercise induced a biphasic response of granulocytosis, monocytosis and lymphocytosis, with a return to baseline between exercise bouts. One hour following the second exercise bout, samples showed a consistent granulocytosis, monocytosis and lymphocytosis (CD3+, CD4+, CD8+ and CD19+ cell counts). The second exercise bout produced a larger response than the first, further exacerbated when exercising at 40°C. We conclude there is a synergism between heat and exercise exposure. An increase in core temperature and exercise stress recruit leukocytes into the peripheral circulation, with potentiation of the response during a second bout of exercise. However, while the increase of core temperature remains moderate, the disturbance of immune function does not appear to have great clinical significance.

The athlete's heart: is big beautiful?

Abstract: Development of the concept of "athlete's heart" is traced through early clinical and radiographic studies to modern echocardiography and magnetic resonance imaging. It is noted that the lower limits of criteria for the diagnosis of a "pathological" enlargement of the heart have frequently been revised in an upward direction, as the prevalence of large hearts has been recognised in both endurance and power sports competitors who are in good health. Belief that hypertrophic cardiomyopathy is the commonest cause of sports related death in young adults is traced to weak diagnostic criteria and frequent republication of a very small group of cases. Although the existence of a congenital myocardial dystrophy is now well established, this condition is extremely rare, and has no particular predilection for athletes. Genetically based screening tests may become available in the future, but the exclusion of young adults from sports participation on echocardiographic criteria appears costly and ineffective. For most people, the development of a large heart is not a pathological sign--rather, it is a desirable outcome that will enhance performance on the sports field, and will allow longer independence in old age.

Impact of heat exposure and moderate, intermittent exercise on cytolytic cells.

Abstract: This study examined the impact of heat exposure and moderate, intermittent exercise on the CD16+ and CD56+ cell counts and cytolytic activity. Eleven healthy male subjects [mean (SD): age = 27.1(3.0) years, peak oxygen intake, VO2maxO2 peak = 47.6 (6.2) ml · kg−1 · min−1] were assigned to each of four different experimental conditions according to a randomized-block design. While in a climatic chamber maintained at a comfortable temperature (23°C) or heated (40°C, 30% relative humidity, r.h.), subjects performed either two 30-min bouts of cycle-ergometer exercise at ≈50% VO2maxO2 peak (separated by a 45-min recovery interval), or remained seated for 3 h. Blood samples were analyzed for CD16+ and CD56+ cell counts, cytolytic activity and the concentrations of various exercise stress hormones (norepinephrine, epinephrine and cortisol). Heat exposure alone had no significant effect on cytolytic cells. The (CD16+ and CD56+) cell count increased significantly (P < 0.0001) during each exercise bout under both environmental conditions, but returned to baseline levels 15–45 min following each exercise bout. Total cytolytic activity (determined by a standard 51Cr release assay using K562 cells) followed a similar pattern, but cytolytic activity per CD16+ or CD56+ cell was not significantly modified by exercise. Our findings show a strong association between hemodynamic factors and recruitment of cytolytic cells into the peripheral circulation. Alterations in cytolytic activity of the whole blood during and following moderate exercise seem to be the result of changes in CD16+ and CD56+ cell counts.

Associations between health behaviours and health related fitness.

Abstract: OBJECTIVE: To examine relations between health behaviours and health related fitness. METHODS: Subjects were a convenience sample of 350 healthy adults (172 men, 178 women). Covariance analysis adjusted data for significant influences of age and socioeconomic status. Obesity was assessed by anthropometry and body density. Cardiovascular fitness was assessed and various metabolic measurements were made. Questionnaires on physical activity and health related behaviours were completed. RESULTS: Cigarette abstinence was associated with a small abdominal circumference (men) and a low trunk/extremity skinfold ratio (women). Obesity indices (body mass index, total skinfolds, percent fat, and abdominal circumference) were negatively associated with perceived fitness. Leisure activity and exercise frequency were also negatively linked to some obesity indices. Blood glucose, cholesterol, HDL-cholesterol, and triglycerides were favourably influenced by perceived activity, exercise frequency, and perceived fitness, but not by exercise intensity. Abstinence from coffee was associated with a low cholesterol/HDL ratio (men only). Principal component, discriminant, and multiple logistic regression analyses showed only weak clustering of habitual physical activity with other positive health behaviours. CONCLUSIONS: Although multiphasic health promotion programmes are economical, favourable interactions between individual programme elements seem likely to be quite limited.

The place of perceived exertion ratings in exercise prescription for cardiac transplant patients before and after training.

Abstract: OBJECTIVE: Heart rate provides a poor guide to exercise prescription after cardiac transplantation. This study explores whether the rating of perceived exertion (RPE) provides useful alternative information. METHODS: Borg's original categoric scale was applied to 36 male patients [T, age 47(SD 9 years] as they performed a progressive cycle ergometer test an average of seven months (range two to 23 months) after cardiac transplantation. The test was repeated after 16(7) months of progressive exercise centred rehabilitation. Sedentary but healthy controls [C, n = 45, age 45(7) years] performed a similar progressive cycle test. RESULTS: Initially, 13 RPE units corresponded to 66(12)% of peak VO2 in T and 50(11)% in C. Rehabilitation augmented peak VO2 (by 19%) and estimated lean body mass (by 3.5%) in the cardiac transplant patients. The increase of heart rate (HR) at 13 RPE units [delta HR = 10(17) beats.min-1] showed moderate correlations with gains of lean mass (r = 0.72) and gains of peak VO2 (r = 0.58). The relative oxygen intake at 13 RPE units remained unchanged at 68(12)% of peak VO2. CONCLUSIONS: Large inter-individual variations of RPE at a given VO2 limit the value of perceived exertion in exercise prescription. Ratings seem best restricted to fine tuning fixed distance/fixed speed exercise prescriptions in patients undergoing rehabilitation after cardiac transplantation.

The Health Consequences of 'Modernisation': Evidence from Circumpolar Peoples

Abstract: What are the health consequences of a transition from an active 'hunter-gatherer' lifestyle to that of sedentary modern living? In this book, the impact of 'modernization' is assessed in various populations in the circumpolar regions. The hazards of living in polar regions, and the adaptations shown culturally, behaviourally and physically by the indigenous peoples are examined and the effect of changes in habitual activity, diet, and general lifestyle due to more urban living patterns on the body composition, pulmonary function and susceptibility to disease discussed. The implications of this switch are important not only for all those concerned about the survival of indigenous communities around the world, but for all of us living in an increasingly sedentary, urban environment. Anthropologists, physiologists and those interested in population fitness will find this a comprehensive and valuable volume.

Determination of body heat storage: how to select the weighting of rectal and skin temperatures for clothed subjects.

Abstract: Two methods of estimating body heat storage were compared under differing conditions of clothing and acclimation to heat. Sixteen male subjects underwent 6 consecutive days or two 6-day periods, separated by a 1-day rest period of heat acclimation, exercising 60 min.day-1 at 45%-55% of maximal aerobic power in a hot, dry environment (dry bulb temperature 40 degrees C; relative humidity 30%; and wind speed 0.3 m.s-1). Before and after acclimation, the subjects entered the same environment, wearing either normal light combat clothing or clothing protective against nuclear, biological, and chemical agents; they walked on a treadmill at 1.34 m.s-1, 0% slope continuously (n = 11 for normal clothing) or as repeated 15-min bouts of exercise followed by 15-min sitting rest (n = 5 for normal clothing and n = 16 for protective clothing). Average exposure times were 147 min (preacclimation) and 150 min (postacclimation) for continuous exercise and 150 min (both pre- and postacclimation) for intermittent exercise while wearing normal clothing, and 103 min (preacclimation) and 116 min (postacclimation) for intermittent exercise while wearing protective clothing. Heat storage was determined calorimetrically (from heat gains and heat losses) and thermometrically [using various weightings of rectal temperature (Tre) and mean skin temperature (Tsk)]. There were only minor (<5%) differences in estimated heat storage, whether calculations used a single specific heat (3.47 kJ.kg-1.degree C-1) or a value computed according to the subject's body composition. When wearing normal clothing, a formula with an invariant relative weighting for Tre to Tsk of 4:1 provided the best thermometric estimate of heat storage. When wearing protective clothing, the invariant relative weighting of 4:1 underestimated heat storage by 2%-12%; underestimation was attenuated by using respective relative weightings for a thermoneutral and hot environment of 2:1 and 2:1 or 4:1 and 9:1 before acclimation and 4:1 and 9:1 after acclimation. We conclude that the accuracy of thermometric estimates of heat storage can be improved by modifying the weighting factors according to environment, acclimation, and type of clothing.

Nutritional, immunologic and psychological responses to a 7250 km run.

Abstract: OBJECTIVE Health, nutritional status, aerobic power, mood state and immune function were studied over 112 days of aerobic activity (a 7250 km cross-Canada run). TYPE OF STUDY CASE REPORT a healthy nulliparous 43 yr old woman ran 65 km/day for 112 days at a 7.9 km/h pace. MEASURES Food intake, Profile of Mood State and Beck Depression Inventory were monitored weekly. Resting lymphocyte subsets and cytokines were determined before the run, at 3324, 5700 and 7250 km, and after recovery. Clinical data, ventilatory threshold, maximal oxygen intake and immune responses to maximal exercise were obtained before and after the run. OBJECTIVE Health, nutritional status, aerobic power, mood state and immune function were studied over 112 days of aerobic activity (a 7250 km cross-Canada run). TYPE OF STUDY CASE REPORT a healthy nulliparous 43 yr old woman ran 65 km/day for 112 days at a 7.9 km/h pace. MEASURES Food intake, Profile of Mood State and Beck Depression Inventory were monitored weekly. Resting lymphocyte subsets and cytokines were determined before the run, at 3324, 5700 and 7250 km, and after recovery. Clinical data, ventilatory threshold, maximal oxygen intake and immune responses to maximal exercise were obtained before and after the run. RESULTS Early muscle pain was treated with Ibuprofen. A mild paronychia responded to saline soaks, and exercise-induced asthma necessitated inhalation of fenoterol hydrobromide, beclomethasone diproprionate and ipatropium bromide. Food intake, (16.7 MJ/day), was 4.3 MJ/day less than expenditure, covered by metabolizing 16.7 kg of tissue (81.4% fat, 18.6% lean tissue). Ventilatory threshold and aerobic power showed little change. Initial psychological data showed tension and lack of confidence. Depression increased when crossing the Rockies, and there was anger and lack of vigor after the event. The CD8 count was low throughout; the CD25 count increased, but the CD16/56 count, IL-6 and TNF-alpha decreased over the run. Three weeks later, IL-6 had increased, but TNF-alpha remained low. CONCLUSIONS Given substantial fat reserves, an exercise-induced energy deficit of 4.3 MJ/day can be sustained for 112 days without significant adverse consequences for immune function.

Asphyxial death of a young skier.

Abstract: OBJECTIVE: Review of the cause of death in fatal downhill skiing accidents is important to prevention: this report concerns a boy found dead with his head buried in powder snow. EXPERIMENTAL DESIGN: Case history of an 11-year-old boy who was found dead 4 hours following descent of a steep ski slope. SETTING: Treatment by mountain rescue team and hospital emergency room. PATIENT: A boy who was discovered immersed head first in one meter of powder snow, with no sign of an avalanche or struggling, and no vital signs. The differential diagnosis included concussion + asphyxia, cervical injury, loss of consciousness from other causes, and hypothermia. INTERVENTIONS: Standard cardio-pulmonary resuscitation, rewarming by bladder irrigation and extracorporeal circulation. RESULTS: The rectal temperature, initially 29.4 degrees C, fell further to 23.3 degrees C during evacuation in a heated ambulance. On hospital admission, a blood sample showed creatine kinase 5306 units, K+ 16 mM, pH 6.38, PaCO2 223 Torr, and PaO2 67 Torr. There was no ECG rhythm, and radiography revealed pulmonary edema but no cervical malignment. Emergency measures normalized blood gases, but did not restore cardiac action. CONCLUSIONS: Death was caused by asphyxia, secondary to mild concussion. The public needs education on the dangers of deep powder snow. Adventurous skiers should wear helmets, and should not ski alone on steep mountainsides. Language: en