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Biomedical subjects

R J Maughan

Publications and source records attributed to R J Maughan.

156 records · Page 9Linked to original sources
PubMed1983

Incidence of training-related injuries among marathon runners.

A questionnaire was sent to all 960 entrants in a major city marathon race to obtain information on training-related injuries. A total of 497 replies were received; of these 287 (58%) had incurred some form of injury during preparation for the race. Seventy-one of these individuals reported more than one injury. Almost all injuries affected the lower limb, with 113 cases (32%) involving pain or disability in the knee. More than half the injured runners (158, 55%) sought no professional advice; approximately half (146, 51%) received no treatment other than rest, which was not generally considered a form of therapy. Only 18 runners (6%) reported no improvement in their condition, while 143 individuals (51%) reported a full recovery. Injury incurred during training was thought by 98 runners (35%) to have had an adverse effect on their racing performance. These results suggest that runners preparing to compete in marathon races can expect their training to be interrupted by injury.

Adult↗
PubMed1982

A simple, rapid method for the determination of glucose, lactate, pyruvate, alanine, 3-hydroxybutyrate and acetoacetate on a single 20-mul blood sample.

Existing methods for the estimation of glucose, lactate, pyruvate, alanine, 3-hydroxybutyrate and acetoacetate normally require relatively large volumes of blood. In addition spectrophotometric methods are tedious and time-consuming. A series of simple methods for the measurement of these metabolites whereby all can be measured on a single 20-microl blood sample is described here. All methods, with the exception of that for glucose, which is measured spectrophotometrically, depend on the use of fluorimetry to determine the concentration of the reduced co-enzyme NADH. As far as is possible, the methods have been standardised for the sake of simplicity and convenience. In routine use they have proved to be both rapid and reliable.

3-Hydroxybutyric Acid↗
PubMed1982

Muscle citrate content and the regulation of metabolism in fed and fasted human skeletal muscle.

Blood and muscle metabolite levels were measured in seven healthy young adult male subjects in a fed state and again following a 24-hour fast. Skeletal muscle samples were obtained under local anaesthesia from m.vastus lateralis using a needle biopsy technique. The blood glucose concentration fell during fasting; the blood lactate concentration remained unchanged. Plasma free fatty acid concentrations rose, as did 3-hydroxybutyrate and acetoacetate levels. There was no change in the amount of carbohydrate stored as glycogen in the muscle in response to fasting. The muscle content of phosphagens (adenosine triphosphate and phosphocreatine), glycolytic intermediates (glucose-6-phosphate, fructose-6-phosphate, fructose-1,6-diphosphate, triose phosphates and lactate) and citrate was also not affected by fasting. There was a significant increase in the muscle content of 3-hydroxybutyrate. These results give no indication as to the mechanisms by which a decreased rate of carbohydrate degradation might occur in muscle in the fasted state. It is clear, however, that an intracellular accumulation of citrate and a consequent inhibition of glycolysis at the level of phosphofructokinase does not take place in fasting human skeletal muscle.

Adult↗
PubMed1982

Effects of pollen extract upon adolescent swimmers.

Many competitive sportsmen in this country regularly use pollen extract as a dietary supplement in the belief that it can lead to an improvement in performance. We have investigated the effects of a six-week course of pollen extract administration on a variety of physiological parameters in a group (n = 20) of adolescent swimmers. At the time of the study, all subjects were training on a daily basis. During the course of the study, maximum oxygen uptake increased in both the treatment group and the placebo group, no difference between the response of the two groups being observed. Vital capacity showed a significant increase in the treatment group, but not in the placebo group. The results indicate that no positive benefit was obtained from the use of pollen supplementation. However, the number of training days missed due to upper respiratory tract infections was much less in the pollen treatment group (4 days) than in the placebo group (27 days). In a study of longer duration, this difference could lead to an improved performance by the pollen treatment group due to fewer interruptions to training.

Adolescent↗
PubMed1981

The effects of a glycogen-loading regimen on the capacity to perform anaerobic exercise.

The effect of a pattern of exercise and dietary modifications, which was designed to produce alterations in the muscle glycogen content, on the capacity to perform anaerobic exercise was investigated. Six young male subjects worked to exhaustion on a bicycle ergometer at a supramaximal work load equivalent to 104 +/- 5% of VO2max after a normal diet, after a carbohydrate (CHO)-free diet following prolonged exhausting exercise, and after a high-CHO diet. This regimen has previously been shown to cause changes in the glycogen content of the working muscle. Mean work time for subjects on the first test was 4.87 +/- 1.07 min (mean +/- SD). After the low-CHO diet, the time for which work could be maintained was reduced in an increase to 3.32 +/- 0.93 min, whereas administration of the high-CHO diet resulted in an increase to 6.65 +/- 1.39 min. The resting blood lactate concentration was lower than normal following the low-CHO diet and higher than normal following the high-CHO diet. Post exercise blood lactate concentrations reached a peak between 2 and 6 min after exhaustion and again were lower (8.60 +/- 1.58 mmol/l) after the low-CHO diet and higher (12.86 +/- 1.42 mmol/l) after the high-CHO diet than after performing the same intensity of work to exhaustion on a normal diet (11.66 +/- 1.16 mmol/l). The rate of lactate accumulation appeared to be approximately the same during exercise under all three dietary conditions. If this is the case, it suggests that the alterations in endurance capacity do not result from changes in the rate of anaerobic glycolytic energy production, but possibly from a change in the total capacity of the system.

Adult↗
PubMed1978

Fat and carbohydrate metabolism during low intensity exercise: effects of the availability of muscle glycogen.

Four subjects were studied during exercise at 50% of maximum oxygen uptake after a normal diet, after a low carbohydrate (CHO) diet following exercise-induced glycogen depletion, and after a high CHO diet. This regime has previously been shown to cause changes in the amount of glycogen stored in the exercising muscles. Metabolic and respiratory parameters were measured during the exercise. The respiratory exchange ratio, blood lactate, blood pyruvate, blood glucose and plasma triglycerides were lower than normal following the low CHO diet and higher than normal following the high CHO diet. Plasma free fatty acids and plasma glycerol were higher than normal after the low CHO diet and lower than normal after the high CHO diet. The contribution of CHO to metabolism was less than normal after the low CHO diet and greater than normal after the high CHO diet. The altered availability of FFA does not appear to be a result of the variations in the blood lactate content.

Adult↗
PubMedDate not supplied

Serum creatine kinase activity after isometric exercise in premenopausal and postmenopausal women.

The study was designed to examine the response of women of different ages to exercise-induced muscle damage. Twenty-four women were placed into 3 groups: a postmenopausal group (POST) of 6 women aged 52.8 (2.1) years [mean (SD)] who were at least 2 years without menses; a premenopausal group (PRE) of 10 women aged 43.6 (2.2) years with regular menstrual cycles of 27 (2) days; and a young (YNG) group of 8 women aged 24.6 (3.5) years with regular cycles of 31 (4) days. Serum 17 beta-estradiol measures were taken to confirm menopausal status. Three-month diaries were used to determine regular cycles. Subjects performed 40 maximal isometric knee extensions with a work:rest ratio of 10:20 seconds. Serum creatine kinase activity (CK), muscle soreness (MS), and maximal isometric strength (MVC) were assessed 24 hours prior to, immediately prior to, and 6, 24, 48, and 72 hours after exercise. Subjects experienced significant (p less than .01) increases in CK and MS, and significant decrements in MVC, with peak changes at 24 or 48 hours. Thus, isometric exercise caused slight muscle damage and muscle weakness. No significant differences among the groups were found for any measure (p greater than .05). Thus, estrogen does not seem to serve as a factor in protecting the muscle from damage due to moderate isometric exercise.

Adult↗