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Biomedical subjects

R J Shephard

Publications and source records attributed to R J Shephard.

At least 379 records · Page 21Linked to original sources
PubMed1978

Relationship between heart rate and relative oxygen intake in male subjects aged 10 to 27 years.

Regression equations relating heart rate (fh) to relative oxygen intake (% VO2max) have been calculated for bicycle ergometer exercise. The five groups of subjects were boys aged 10--11, 13--14 and 16--17 years, average young adults aged 23--27 years, and middle and long distance runners aged 20--25 years. The heart rate at a given % of VO2max was higher for younger than for older boys; however, the heart rate discrepancy between groups diminished at increasing intensities of exercise. The results are discussed in relation to the use of heart rates in training and exercise prescription. At high work loads, graphs of % maximum heart rate against % VO2max are relatively independent of age, but at the lower levels of activity common in everyday life, the % VO2max of adolescents must be predicted for age-specific regression lines.

Adolescent↗
PubMed1977

Loss of body weight and fat during exercise in a cold chamber.

Ten men spent one week in a cold climatic facility performing a simulated arctic military exercise demanding an energy expenditure of 13-16 MJ-day-1. Although the ration pack was adequate, extensive plate wastage led to a negative energy balance of 2.2 MJ-day-1. Fluid intake was also insufficient, with a 3.25% decrease of body weight, and a 9.7% decrease in skin thickness over the cold exposure. Extensive fat mobilization was indicated by a decrease of skinfold thicknesses, an increase of body density, and associated ketonuria and glycosuria. The fat breakdown far exceeded the calculated energy deficit, and it is postulated that much of the "surplus" energy was required for synthesis of additional muscle protein. In the arctic environment, both energy and fluid balances are better maintained because there are few distraction from the simple pleasure of preparing and eating meals.

Adipose Tissue↗
PubMed1977

Treatment of obesity by exercise in the cold.

Six obese men aged 25 to 46 years exercised vigorously for 3 1/2 hours in a cold chamber (-34 degrees C) on 10 successive days. There was an early water loss of about 1 kg, probably due to mobilization of glycogen stores, and a subsequent fat loss of about 4 kg (as estimated from readings of skinfold thickness and confirmed by underwater weighing). The total fat loss was much greater than the calculated external energy deficit (as estimated from dietary records, an activity diary and use of a Kofranyi-Michaelis respirometer). Although some energy was "wasted" through ketosis, much of the additional energy was apparently used for synthesis of additional muscle protein. Both readings of skinfold thickness and underwater weighing indicated that the loss of adipose tissue was well sustained in the first 2 months after the exercise program. Further experiments are recommended to determine whether cold exposure makes a specific contribution to the observed weight loss, and whether this approach would be equally effective in a larger and less selected sample of obese patients.

Adult↗
PubMed1977

Sexual activity after myocardial infarction.

Questionnaires on sexual activity were completed by 161 patients attending an exercise-centred rehabilitation program an average of some 3 years after a myocardial infarction. In almost half the group, sexual activity was unchanged or increased compared with the period before the infarction. In the remainder it was reduced; this group included 29 men who had adopted a more passive sexual role and 26 who were now having angina or ventricular premature beats during intercourse. Although the patients with diminished activity could not be distinguished by means of formal personality test, questionnaires completed by their wives suggested that they were less willing to assume responsibility, had increased difficulty in adjusting to life at home and at work and were more neurotic and depressed than those with normal or increased activity. Furthermore, those with decreased sexual activity had a poorer response to training in terms of attendance, final average jogging distance and gains in physiologic status. Since the frequency of angina and ventricular premature beats was less during intercourse than during standard laboratory exercise, it was concluded that normal sexual relations carry no special risk for the average postcoronary patient; indeed, by enhancing self-esteem and encouraging effective participation in an exercise programm, acceptance of normal sexual activity may improve the prognosis.

Blood Pressure↗
PubMed1977

Endurance training and body compostition of the elderly.

Body composition was studied in subjects from the seventh decade of life (13 M, 25F), observations being made on recruitment and at selected points over a 1-year program of endurance training. As at younger ages, the women initially had more subcultaneous fat than the men, particularly over the limbs. In both sexes, excess weights (9.3 kg. M; 8.1 kg, F) and average skinfold radings (16.2 mm, M; 21.1mm, F) were greater than in younger adults. Edurance training (1 hr of supervised exercise, 150-200 kcal persession, nominal four sessions per week) progressively reduced skinfold readings, by an average of 1.6 mm at 7 weeks, by 2.4 dependent upon the intensity and the frequency of exercise undertaken by the individual. Total body potassium (40K determinations) agreed well with previous studies of older subjects. Body fat estimated form 40K showed a fair correlation with skinfold estimates of body fat (r=0.69, M; 0.93, F), but absolute precentages were higher by 40K(36.6%, M; 48.7%, F) than by subcutaneous fat measurements (20%, M;32% F). Body potassium increased by 4% over the year of training, 70% of this change, occurring between the 14th and the 52nd week of conditioning. Small gains were also recorded in arm circumference, grip strenght (R but not L) and knee extension force. Neutron activation data showed that both sexes had lower initial bone calcium counts than sedentary middle-aged adults. The sample as a whole showed no calcium loss over the year of training, but the group taking the least exercise did show a significant loss (P less than 0.05). Modest endurance training of an elderly population seems not only to correct loss of cardiorespiratory condition, but also to induce favorable changes in body fat and lean mass.

Aged↗
PubMed1977

Activity patterns of elderly men and women.

The activity patterns of elderly men and women (greater than 60 years) were examined by diaries, ECG taperecorders, and electro-chemical integrators. Although the subjects thought that they were active relative to others of their age, both activity measurements and initial assessments of fitness indicated an inactive life style. At different periods of the day, the heart rate averaged 70-90 beats per minute, and the physical training threshold was rarely approached. During the week, the women engaged in 90 min. more physical activity than the men. However, at the weekend the men added an average of 100 min. of physical activity, whereas the women carried out 30 min. less physical work. Introduction of a 1-hour physical activity class four times per week increased the average daily energy expenditure by 150-200 kCal, to 2500 kCal in the men and 2200 kCal in the women. The added activity was sufficient to augment aerobic power, to induce favorable changes in body composition and to initiate change in other areas of life style, including a diminished use of the car.

Activities of Daily Living↗
PubMed1977

Depression following myocardial infarction: the effects of distance running.

A proportion of postcoronary patients seen 16 to 18 months after infarction are seriously depressed (high D score on Minnesota Multiphasic Personality Inventory). A follow-up of 44 such depressed patients showed a significant (p less than 0.001) decrease of standardized D scores, from 80 to 72 units over 4 years of exercise-based rehabilitation. There were associated decreases in scores for hysteria, hypochondriasis, and psychasthenia. A decrease of D score was associated with exercise compliance. An increase of D score was associated with a significant (p less than 0.05) worsening of ST segmental sagging, suggesting that progression of the disease process had contributed to the increase of depression. All of the patients had high (feminine) scores on the masculinity/femininity scale of the MMPI test. This finding was unrelated to the daily running distance or medication; it could represent a "feminine" personality, or be a typical response in a well-educated white collar group. Evidence of successful group interaction may be indicated by reduction in scores for social introversion and schizophrenic traits.

Adult↗
PubMed1977

On the choice of fluid for the hydration of middle-aged marathon runners.

Nine subjects (five well-trained post-coronary patients and four other middle-aged joggers) paticipated in a 42 km "Marathon" race. The course was covered in an average of 212 minutes under pleasantly warm conditions (Maximum 21.7 degree C, 69% relative humidity). Subjects were given initial hyperhydration and repeated subsequent doses of water, "Erg" (Na+ 19mE/l K+ 10.7mE/l, glucose 5.3g/100 ml) or a "Special Solution" (during the race Na+ 21mE/1 glucose 4.1g/100 ml; after the race Na+ 20 mE/l, K+ 4.7mE/l., glucose 4.1 g/100 ml). Weight loss averaged 2.2 kg and sweat production 3.3l taking account of water liberated from the hydration of glycogen and the oxidation of food stuffs, it was estimated that most subjects suffered relatively little dehydration over the race (0.4--0.8l). This was confirmed by a sustained urine production of greater than 100ml/hr. Nevertheless, rectal temperatures showed substantial elevation over the race (final readings 38.3 - 40.2 degree C). In terms of fluid balance and stability of plasma mineral composition, the runners drinking water performed slightly better than those receiving the other two solutions. Nevertheless, there may be merit in giving potassium solutions during recovery from vigorous effort.

Adult↗
PubMed1977

LaTulippe--a case study of a one hundred and sixty kilometre runner.

A 55 year old runner covered 160 km within a 20 hour period. His speed averaged 8.16 km/h, at an estimated 59.1% of maximum oxygen intake. After the first four hours of running, one of five fluids was taken in rotation every twelve minutes. Volumes ingested whe heart rate for the final four hours (125/min) was not increased relative to oxygen consumption for this portion of the run. Constancy of heart rate, continued urine production and formal fluid balance calculations all indicate that hydration was well maintained over the run. Caloric intake averaged 480 kcal/h (2.01 MJH), being greatest fro the ice-creas/syrup mixture; the energy deficit (56/KA/H, 235 kJ/h) was small during that part of the run in which food was provided.

Blood Pressure↗
PubMed1977

Responses to sustained use of anabolic steroid.

Description is given of six body-builders who had been taking Methandrostenolone (up to 20 mg/day in intermittent courses for a year or more). At the time of examination there was no subjective disturbance of sexual function, but testosterone levels were low relative to laboratory standards and luteinizing hormone levels were also reduced - particularly in relation to testosterone concentrations. Abnormal liver function tests were seen in three of the six subjects, and one had mild diabetes with high serum cholesterol, triglycerides and uric acid. The weight gain of the group was not outstanding, and the only possible finding was a high haemoglobin and haematocrit in one of the six subjects.

Adult↗
PubMed1977

Training and electrocardiographic abnormalities in the elderly.

Electrocardiograms (CM5 lead, where one lead is attached in the V5 position and one at the manubrium sterni, with the neutral lead on the back of the neck) have been recorded from 14 men and 25 women aged 60 to 75 years, at rest, during progressive bicycle ergometer exercise to 75 to 85 per cent maximum oxygen intake, and during the subsequent recovery phase. Earlier studies showing a high frequency of ischaemic electrocardiographic abnormalities in women are confirmed; it is suggested that this may reflect a high work load per unit mass of myocardium. Training induces an elevation of the ST segment at rest and during recovery, with a reduction in ST depression during work at a given heart rate, the exercise changes being related to the intensity and frequency of training selected by the subject. Possible explanations of the response to regular exercise include not only the development of the collateral circulation, but also a lessening of the hyperkalaemia of effort and a reduction in the work load per unit mass of myocardium secondary to hypertrophy or a change in the average dimensions of the heart.

Aged↗
PubMed1977

Loss of body fat during an arctic winter expedition.

Fifty-five soldiers have been observed over a vigorous 10-day sledging patrol in the Canadian arctic and subarctic. Initial observations showed a low level of physical fitness (26% body fat, aerobic power 41.9 +/- 7.8 ml kg-1 min-1, handgrip force 43.7 +/- 7.2 kg). Over 2-week northern sojourn, energy expenditures as measured by a Kofranyi-Michaelis respirometer and diary observation averaged 3248 kcal (13.6 MJ) day-1, with a small (152 kcal (633 kJ)) positive daily energy balance. A weight loss of 1 kg, presumably water, was made good within 1 week of return to the south. A fat loss of some 3.9 kg was probably attributable largely to the demands of lean tissue synthesis. The lean mass was increased by 3.9 kg over the trial, with parallel gains of muscle force and aerobic power. The rapid mobilization of depot fat led to marked ketonuria.

Adipose Tissue↗
PubMed1977

Perception of exertion in the elderly, effects of aging, mode of exercise and physical training.

Ratings of perceived exertion by the Borg psychophysical scale have been made on 26 men and 30 women aged 60 to 70 yr. All were volercise lines relating the ratings of exertion to heart rate were closely similar in men and women, scores at all heart rates being 2 or 3 units higher than in young adults. A brief progressive exercise protocol on the treadmill yielded somewhat lower ratings than bicycle ergometer work, the discrepancy being marked in women. At any given oxygen intake, ratings were higher for females than malesy nd higher for old than young subjects. However, when oxygen intake was expressed as a percentage of the directly measured maximum oxygen intake, scores became independent of sex and age. A 35-wk. period of conditioning substantially reduced heart rates but had little effect on the perception of effort at a given work load. This unexpected result may reflect a closer approximation of core and skin temperatures with reduction of sub-cutaneous fat.

Age Factors↗
PubMed1977

Longevity and causes of death of athletes.

Since Morgan, many research workers have attempted to answer the question whether intensive training and athletic competition can alter life span. A review of the literature yields few clear conclusions. The difficulty seems that the human life span is affected by a multiplicity of factors including physical characteristics (sex, age and body type), lifestyle (factors such as habitual activity, smoking and drinking habits and diet), environmental variables (air and water quality, exposure to sunlight, noise etc.), physiological factors, personality and inheritance. Relative to these confounding factors, athletic competition usually occupies too short a portion of the life span to have a significant effect on longevity. The important question may well be not the kind of sport pursued or the intensity of the required training, but whether the activity is continued to an advanced age.

Humans↗