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Biomedical subjects

R J Shephard

Publications and source records attributed to R J Shephard.

At least 145 records · Page 8Linked to original sources
PubMed1993

Relationship of premorbid mass and energy intake to increase of body mass during the treatment of anorexia nervosa.

Dietary intakes were compared in two groups of patients with anorexia nervosa, those who had earlier been "heavy" (n = 27, peak body mass = 65.0 +/- 7.5 kg) and those who had always been "light" (n = 25, peak body mass = 51.5 +/- 7.3 kg). Both groups were initially given a food intake of 7.5 MJ per day, and this was increased as needed to yield a controlled 1-2 kg per week increase of body mass. Body mass was restored most rapidly in the patients who reached the lowest weights, whether the classification was based upon the lowest body mass observed during the illness (gain in weeks 0-7, p < .002) or the body mass on admission to hospital (gain in weeks 0-14, p < .02, weeks 7-14, p < .01). Classifying patients in terms of their peak premorbid mass, the light group consumed food energy at a faster rate than the heavy group over the first 7 weeks of hospital treatment (p < .008), but nevertheless they did not gain more weight. Food intake reached a plateau in both groups between weeks 7 and 14 of treatment, although the light group was still consuming more energy than the heavy subjects (p < .005). Prospective observations on two light and two heavy patients confirmed both the time course of weight gain and the greater energy needed for a given increase of body mass in light patients. It is suggested that during the early stages of recovery from anorexia nervosa, energy utilization is more efficient in the heavier patients. However, it seems more difficult to sustain a high food intake in such patients, possibly because they fear a return to obesity.

Adolescent↗
PubMed1993

Relationship of impairment and functional ability to habitual activity and fitness following spinal cord injury.

Associations between a physically active leisure, physical fitness, impairment and disability have been tested in 123 volunteers (73 with paraplegia and 50 with quadriplegia). Active physical leisure was assessed by the questionnaire of Godin and Shephard (Canadian Journal of Sports Sciences 10, 141-6 1985). Fitness measures included body mass index, peak oxygen intake on a wheelchair ergometer, and tests of muscle strength and endurance (peak isokinetic torque, average muscle power and total muscle work for shoulder flexion, shoulder adduction and elbow flexion at movement speeds of 60 degrees and 180 degrees s-1). Primary impairment was assessed by the ISMGF scale, and secondary impairment was judged from reported pressure scores, spasticity, and urinary infections over the previous 12 months. Scores for self-care and mobility were obtained using a modified Barthel Index. Physically active leisure and fitness were unrelated to secondary impairment. However, functional ability for a given primary impairment was significantly correlated with peak oxygen intake and the three indices of muscle strength, particularly in individuals with high level lesions. Associations between physical activity and functional ability were weaker, but tended in the same direction. Although longitudinal studies are needed to prove the causality of these relationships, the findings point towards a significant influence of fitness status upon functional ability. Rehabilitation teams should thus give a stronger emphasis to systematic exercise conditioning programmes when planning overall treatment following SCI.

Activities of Daily Living↗
PubMed1993

A new approach to the interpretation of Canadian Home Fitness Test scores.

A modification of the Astrand (1960) nomogram procedure was applied to Canadian Home Fitness Test data obtained on 13,258 subjects, ages 15 to 69 years, during the 1981 Canada Fitness Survey. Norms were developed to allow an empirical five-level categorization of aerobic fitness, based on the attained rate of stepping and the recovery pulse count 5 to 15 s following exercise. Because of uncertainties regarding the net mechanical efficiency of stepping and the selective recruitment of fit older subjects, the apparent rate of aerobic fitness decrease with aging was no more than half of that seen in laboratory measurements, and the sex differential at any given age (about 25%) was larger than expected. The new approach thus does not claim a high level of accuracy for the predicted peak MET values. Nevertheless, it has an inherent advantage over the equation of Jetté et al. (1976) in that it takes more direct account of variations in pulse count when categorizing fitness. Moreover, there is no artificial ceiling that limits scores for very fit subjects. Tests are now needed to assess the accuracy of the proposed fitness categorizations relative to laboratory determinations of maximal oxygen intake.

Adolescent↗
PubMed1993

Vascular conductance and aerobic power in sedentary and active subjects and heart failure patients.

The relationship between peak aerobic power and a strain-gauge determination of local skeletal muscle vascular conductance 10-13 s after calf exercise to fatigue was examined in 21 middle-aged adults (age 38.1 +/- 2.5 yr): seven physically active men (A), seven sedentary men (S), and six men and one woman with compensated idiopathic heart failure (HF). The three subgroups were chosen as differing widely in peak O2 intake [48.2 +/- 1.2, 32.9 +/- 1.6, and 16.1 +/- 1.3 (SE) ml.kg-1 x min-1, respectively]. Calf vascular conductance showed a gradation with aerobic power: 64.8 +/- 3.8, 40.7 +/- 4.3, and 30.7 +/- 6.1 (SE) ml/min local flow per 10 liters of tissue per unit of blood pressure. There was a strong positive correlation between O2 intake and vascular conductance for the overall group (VO2 = 0.614 G + 3.5; r = 0.75, P < 0.001) and for the 14 normal subjects (VO2 = 0.377 G + 20.6; r = 0.74, P < 0.002). The mean conductance was smaller in HF (P < 0.001), with no significant slope in relation to O2 intake. There was no relationship between the resting cardiac ejection fraction [74.4 +/- 4.1% (SE) for A, 74.3 +/- 4.2% for S, and 25.8 +/- 5.2% for HF] and either peak aerobic power or calf vascular conductance. We conclude that peak aerobic power is strongly associated with local vascular conductance during peripherally limited exercise involving the calf muscles of one leg and that vascular conductance is particularly low in subjects with compensated idiopathic heart failure.

Adult↗
PubMed1993

Exercise in the prevention and treatment of cancer. An update.

Physical activity potentially encourages a healthy lifestyle and it could have a more direct preventive effect on certain forms of carcinogenesis (for instance, by speeding gastrointestinal transit, or by moderating sex hormone levels). However, there are also potential negative effects, particularly an excessive exposure to ultraviolet light in certain water sports. The many types of neoplasm and the equally varied sources of physical activity militate against finding any simple relationship between the risk of malignancy and the individual's physical activity history. Nevertheless, evidence that physical activity protects against certain forms of cancer can be deduced from studies of experimental animals, former athletes, people employed in active occupations, and those with an active recreational lifestyle. Many occupational surveys and a number of studies of recreational activity show an association between sedentary living and a risk of colon cancer, both in men and in women. Moreover, an application of Bradford Hill's criteria gives some support to the causal nature of the association. More limited data suggest that a history of active leisure is associated with a reduced risk of all-cause cancer and in women of breast and reproductive system cancers. The last observation must still be reconciled with an apparent increase in the risk of prostatic cancer in active men. Since moderate exercise elevates mood and helps to conserve lean tissue, it may finally be a helpful component of treatment after a neoplasm has been diagnosed.

Animals↗
PubMed1993

Metabolic adaptations to exercise in the cold. An update.

Metabolic adaptations to exercise in a cold environment include the liberation of heat by vigorous physical activity, shivering and various forms of nonshivering thermogenesis. During a single exposure to cold the main metabolic fuel is glycogen; however, repeated bouts of exercise in the cold also result in an increase in fat metabolism. Potential contributors to fat loss induced by exercise in the cold include: the energy cost of synthesising lean tissue; cold-induced excretion of ketones; stimulation of resting metabolism; and the high energy cost of movement in a cold environment (walking over snow, the weight of heavy boots, hobbling by winter clothing, and decreased mechanical efficiency of dehydrated muscles). Biochemical explanations of fat mobilisation include increased secretion of catecholamines, increased sensitivity of peripheral catecholamine receptors and a decrease in circulating insulin levels. Such fat loss may be helpful in treating moderate obesity, although the response seems less well developed in women than in men. Metabolic changes must be taken into consideration in preparing winter athletes for competition. Glycogen depletion has a negative effect on the performance of endurance competitors, but this can be countered by a combination of diet, training and cold acclimation.

Adaptation, Physiological↗
PubMed1993

Cardiac risk factors immediately following spinal injury.

Cardiac risk factors were evaluated in 48 persons (39 males, 9 females) with quadriplegia or paraplegia, resident in a specialized spinal injury hospital and seen 0.3 +/- 0.7 years after their spinal injury. The majority of the patients reported being extremely active physically prior to injury. Limited activity in the hospital involved the use of ergometers, pulleys, and weights; however, the majority of subjects expressed a wish for more exercise. Serum lipid profiles showed a relatively normal total cholesterol (mean 4.58 +/- 0.77 mmol/L), a very low high-density lipoprotein-cholesterol (0.91 +/- 0.27 mmol/L), a relatively normal low-density lipoprotein-cholesterol (2.86 +/- 0.68 mmol/L) and high triglycerides (1.89 +/- 0.88 mmol/L). Resting blood pressures were normal. The percentage of smokers (25%) was similar to the percentage of smokers in the general population, but many had quit smoking subsequent to hospitalization. Family histories and diet gave no evidence of increased cardiac risk. We conclude that individuals who sustain a spinal injury do not have a large inherent risk of cardiac events. In persons with paraplegia, cardiac problems develop mainly from the cumulative impact of reduced physical activity and a resulting adverse lipid profile. There may also be a reactive deterioration in other aspects of personal lifestyle, such as cigarette smoking after leaving the hospital. In high-level lesions, factors such as hypertension and a poor stroke volume with compensatory tachycardia may increase cardiac work rate during attempts at ambulation, further predisposing an individual to myocardial ischemia and cardiac arrest.

Adult↗
PubMed1993

Acculturation and loss of fitness in the Inuit: the preventive role of active leisure.

The association between active leisure pursuits and various indices of fitness has been examined in 165 males aged 13-39 years and 95 females aged 13-29 years, all Inuit residents of the community of Igloolik, NWT (69 degrees 40'N). The active individuals have largely conserved the high level of fitness that characterized the settlement in 1969/70, showing substantial advantages over their sedentary peers in terms of relative aerobic power (27.7%, males, 21.3%, females) and subcutaneous fat (18.3%, males, 5.9%, females), with a lesser trend to advantages of strength (handgrip force, 4.4%, males, 0.8% females; knee extension force, 8.3%, males, 2.0%, females). Much of their continued aerobic fitness can probably be attributed to physical activity although in the boys aged 13-16 years, a further factor is the selection of active leisure pursuits by tall, heavy and early maturing individuals. Both the lower body fat and the larger aerobic power are likely to have positive implications for future health. The current challenge is thus to increase the proportion of physically active villagers beyond the current 18.8% of males and 11.6% of females.

Acculturation↗
PubMed1993

Exercise and aging: extending independence in older adults.

Exercise plays an important role in enhancing the quality of life of the older patient, although studies have shown that regular physical activity does not significantly lengthen life expectancy. Improved physiologic and psychological function helps to maintain personal independence and reduces demands for acute and chronic care services. This has significant economic benefits, as the resultant cost savings will likely cover the costs of a well-designed exercise program. Primary care physicians can help older patients to realize these benefits by encouraging them to increase their physical activity and by prescribing appropriate exercise regimens.

Activities of Daily Living↗
PubMed1992

Return to work after spinal cord injury: the potential contribution of physical fitness.

The history, physical characteristics and fitness status of 60 persons who had sustained a spinal cord injury at least 3 years previously were considered in relation to current occupation. All subjects had completed their education, 39 being gainfully employed and 21 unemployed. The general characteristics of the sample, mainly beneficiaries of the Quebec Automobile Insurance Plan, were typical of spinal cord injured individuals in North America. The working group had a significantly higher current level of education than those who were unemployed (p less than .01). In terms of physical fitness, the workers were lighter, with a lower body mass index and a higher aerobic power (p less than .05). Isokinetic testing suggested a trend toward a higher peak torque in the workers. The total work performed (Nm.kg-1) during an isokinetic endurance test (25 biphasic contraction at 180 degrees.sec-1) was significantly higher in the workers, suggesting that such muscular endurance might be even more useful than greater peak isokinetic strength during vocational activities. However, the likelihood of employment was unrelated to habitual patterns of either aerobic exercise or overall physical activity. No significant differences of physical fitness or physical activity habits were found between workers holding sedentary versus physically demanding jobs. The results verified the positive relationship between physical fitness (body composition, aerobic power, muscular endurance) and the gainful employment of paraplegics, but failed to show any significant relationship between physical fitness and the acceptance of physically demanding work by such individuals.

Adolescent↗
PubMed1992

Acute exercise and immune function. Relationship between lymphocyte activity and changes in subset counts.

Twenty-one young male subjects exercised on a cycle ergometer for 60 min at 60% of VO2max. Blood samples collected every 30 min throughout exercise and continuing to 120 min recovery served for the immunological tests. Exercise induced biphasic changes in the various leucocyte subsets. There was a granulocytosis, lymphocytosis and monocytosis during exercise, and a further granulocytosis and a slight monocytosis, but a lymphocytopenia during recovery. All lymphocyte subsets (CD3+, CD19+, CD4+, CD8+, and CD16+ cells) increased in number during exercise, were decreased 30 min after exercise, and had not returned to baseline levels by 120 min of recovery. The apparent lymphocyte responsiveness to the mitogens phytohaemagglutinin (PHA) and pokeweed mitogen (PWM) declined significantly during exercise, returning to normal by 120 min of recovery. The natural killer (NK) activity rose markedly during exercise, but decreased to almost half the pre-exercise level at 30 and 60 min of recovery, returning to baseline levels after 120 min of recovery. Functional capability correlated well with the percentage of each major responder subset in the assay, suggesting that the in vitro lymphocyte PHA- and PWM-responsiveness and the NK activity did not change significantly on a per cell basis. The analysis of lymphocyte marker antigen density revealed that the CD3+, CD4+, CD8+ and CD19+ lymphocytes mobilized into the circulation during exercise did not express the respective CD3, CD4, CD8 and CD19 molecules as strongly as did the subsets circulating at rest, whereas the expression of the CD16 antigen on CD16+ lymphocytes remained unchanged.

Adult↗
PubMed1992

Cold, fitness and the exercise electrocardiogram. A 20 year longitudinal study of Canadian Inuit.

A 20 year longitudinal study has examined fitness, lung function and exercise electrocardiograms in the Inuit of Igloolik (NWT, 69 degrees 40' N). When first examined (1969/70), an energy expenditure of up to 16 MJ/day was estimated from Kofranyi-Michaelis respirometry. Step test predictions of maximal oxygen intake were also high initially, but values declined progressively with acculturation to a sedentary lifestyle. Throughout the 20 years, right-branch bundle block (RBBB) has been somewhat more prevalent than in southern Canada. The majority of those affected have shown no more than slight R-wave notching. In 1969/70, a few of the more marked cases of RBBB may have been attributable to chronic respiratory disease, but the majority of cases have shown high normal values for both lung function and maximal oxygen intake. We thus conclude that the major cause of RBBB in this community is a ventricular hypertrophy due to the vigorous physical demands of the traditional lifestyle.

Adolescent↗
PubMed1992

Assessment of quality of life before and after surgery for severe obesity.

Quality of life is poor in obese people because of poor physical health and mental well-being and impaired psychosocial functioning. Obese people perceive discrimination and prejudice against them as their heaviest burden. Reports of absence of psychopathology in obese people reflect adaptation to chronic disease or failure of assessment instruments to detect disturbances. We present information on the extraordinary suffering and perceived discrimination of obese people and discuss econometric assessment of quality of life. The Swedish national population study of obese subjects (SOS) is presented as well as studies of effects of surgical weight loss on quality of life. Most studies lack adequate controls and extrapolations from surgical populations are uncertain. Psychosocial factors are important predictors of outcome in terms of physical as well as mental health. Operated patients with significant weight loss after surgery demonstrate dramatic improvement in quality of life. This alone justifies treating severely obese patients surgically.

Humans↗
PubMed1992

Does exercise reduce all-cancer death rates?

A reanalysis is made of earlier data relating to initial physical fitness and the likelihood of death from all forms of cancer. It is argued that the original analysis may have been biased by an association between initial fitness and other health habits, particularly cigarette smoking. The association with fitness status remains after reanalysis of the data on the assumption that current smoking leads to a uniform doubling of the risk of cancer death, but the effect is weaker than previously reported. There remains some potential bias, in that the quantity of current smoking may have been linked to fitness status. Some 55% of deaths were untraced, but it is argued that any socioeconomic or other bias from this cause is likely to account for the association between cancer risk and low fitness status. Any reduction of cancer risk is associated with the change from an extremely sedentary to a moderately sedentary lifestyle. It thus cannot be explained in terms of the mechanisms previously invoked to explain low risks of colonic and reproductive cancers in endurance athletes.

Exercise↗
PubMed1992

Potential markers of heavy training in highly trained distance runners.

Markers of a heavy increase in training were examined in ten highly trained distance runners (mean(s.d.) age 29.8(1.7) years, maximal oxygen intake 65.3 ml kg-1 min-1, personal best 10-km time 31 min 4 s) who undertook a deliberate 38% increment of training over a 3-week period. Their running performance did not improve, and six of the ten subjects developed sustained fatigue, suggesting that training was excessive, although the full clinical picture of overtraining did not develop. The Profile of Mood States was the best single marker of disturbed function, indicating increased fatigue and decreased vigour. There were no useful changes of resting heart rate or perceived exertion during submaximal running, sleep was undisturbed, and there were no orthopaedic injuries. Two subjects developed rhinoviral infections following the heavy training, and a third complained of symptoms that were diagnosed 2 weeks later as exercise-induced asthma. The increase of serum cortisol normally induced by 30 min of submaximal exercise was no longer seen when the same acute exercise was performed after heavy training. Resting lymphocyte proliferation tended to increase in response to phytohaematoglutinin (PHA) and concanavalin A (Con A), the ratio of helper to suppressor cells (H/S) decreased, and pokeweed mitogen induced smaller increases in IgG and IgM synthesis. Whereas before heavy training, PHA-stimulated lymphocyte proliferation was unchanged by 30 min of acute submaximal exercise, after 3 weeks of heavy training the same bout of exercise caused an 18% suppression of proliferation. Likewise, heavy training brought about a decrease of T-lymphocytes in response to acute submaximal exercise, but an abolition of the acute exercise-induced decrease in the H/S ratio. The previously observed exercise-induced decrease of IgG synthesis did not occur when the same acute bout of exercise was performed after heavy training. We conclude that such minor and transient changes of immune function may possibly be a warning that training is becoming excessive, but they have only a limited significance for overall immune function.

Adult↗
PubMed1992

Immune responses and increased training of the elite athlete.

Ten elite male runners (age, 29.8 +/- 1.7 yr; maximum oxygen consumption, 65.3 +/- 4.9 ml.kg-1.min-1; 10-km times, 31 min 43 s +/- 1 min 46 s) deliberately increased training schedules by an average of 38% for 3 wk. Resting heart rate and maximal oxygen intake were unchanged, but the heart rate response to acute exercise was decreased. Following heavy training, blood samples taken at rest showed trends to a decreased helper/suppressor cell ratio, an increased phytohemagglutinin (PHA)- and concanavalin (ConA)-stimulated lymphocyte proliferation, and a decreased production of immunoglobulins IgG and IgM. Whereas PHA-stimulated lymphocyte proliferation was initially unchanged by acute exercise, after 3 wk of heavy training the same acute exercise caused an 18% suppression of proliferation. Acute exercise following heavy training did not alter pokeweed-stimulated IgG or IgM synthesis. There was no correlation between changes in lymphocyte subpopulations, helper/suppressor ratios, and mitogen-induced cellular proliferation. The immune system of endurance-trained athletes at rest seemed to tolerate the stress of heavy training, but superimposition of a bout of acute exercise on the chronic stress of heavy training resulted in immunosuppression, which was transient and most likely not of clinical significance.

Adult↗
PubMed1992

Effectiveness of training programmes for prepubescent children.

Early investigators suggested that endurance training had little influence upon the aerobic function of the prepubescent child. It is shown that the twin explanations of this supposed phenomenon (a high intrinsic level of physical activity and an immaturity of biochemical systems) have little foundation. Moreover, critical examination of the original experiments shows a number of problems of experimental design, often including an inadequate sample size, a lack of control group, an inappropriate pattern of training relative to the initial fitness of the child, and too short a period of observation. Recent, well-designed studies all show a response in prepubescent children. Comparison with adults is hampered by difficulties in matching training intensity, but there is no immediate evidence that the training response of the prepubescent child is less than in an older person. The main basis for the increase of oxygen transport seems an increase of cardiac stroke volume. Plainly, the development of athletic performance and the attack upon cardiac risk factors can be begun before puberty, although in the average prepubescent it may be more important for the school programmes to develop positive, lifelong attitudes, than to maximise aerobic function.

Age Factors↗