Exercise, ethanol and arachidonic acid metabolism in healthy men.
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Biomedical subjects
Publications and source records attributed to R Rauramaa.
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The effects of a beta 1-selective (metoprolol, 150 mg per day) and a non-selective beta-blocking agent (propranolol, 120 mg per day) on metabolic and hormonal responses to physical exercise (a 30 min bicycle ergometer test) were investigated against placebo in seven healthy male volunteers with a double blind cross-over design. The blood glucose level remained unchanged during placebo, it tended to increase during metoprolol, whereas it decreased during propranolol. Both metoprolol and propranolol counteracted the exercise-induced increase in plasma free fatty acids and caused a slight decrease in muscle glycogenolysis. The increase in blood lactate concentration during exercise was not influenced by beta-blockade. The secretion of glucagon and cortisol was not modified significantly by beta-blockade, whereas the growth hormone response to exercise was promoted equally by both beta-blocking agents. It has been assumed previously that, during treatment with beta-blocking agents, diminished hepatic gluconeogenesis, caused by the lack of lactate or free fatty acids, may result in a decline in blood glucose levels. The present results indicate that an inhibition of beta 2-mediated hepatic glycogenolysis by propranolol may also influence blood glucose homeostasis during exercise.
The aim of the present study was to analyse to what extent serum lipoproteins are determined by overweight and physical fitness. Fifty-eight middle-aged males were divided into lean, overweight and obese subgroups according to their body mass indices, which characterization was also well in accordance with two skinfold thicknesses. Maximal oxygen consumption per body weight was lowest in the obese. HDL cholesterol was decreased in the obese compared to the lean. HDL cholesterol correlated separately significantly with maximal oxygen consumption and body mass index when all the three groups were combined. Physical fitness was a less dominant determinant of HDL cholesterol than body mass index. The importance of physical fitness as a determinant of HDL cholesterol was less marked in the obese than in the lean and overweight suggesting a need for certain level of physical activity before it can influence serum lipoprotein levels.
The effect of acute physical exercise on skeletal muscle glycogen content and on lipoprotein lipase activity of muscle, adipose and lung tissues was studied in streptozotocin diabetic and control rats. Rats were accustomed to treadmill running for two weeks after streptozotocin treatment. For an exercise bout of moderate intensity rats were randomly divided into two groups: one was sacrificed immediately after exercise and the other 24 hours afterwards. In addition there was a nonexercised sedentary group. No depletion of glycogen was observed after exercise in the vastus lateralis muscle of control (nondiabetic) rats. No difference in glycogen utilization was found in soleus muscle between diabetic and control rats. In diabetic rats a slight decrease occurred in the lipoprotein lipase activity in adipose tissue immediately after exercise, while in control rats there was a significant decline 24 hours after exercise. In soleus muscle a slight but significant increase of lipoprotein lipase activity occurred 24 hours after exercise in diabetic rats but not in control rats. The results suggest that nonketotic streptozotocin diabetes of short duration does not influence muscle glycogen in the resting state, but glycogen utilization is disturbed in white muscle during moderate treadmill running in untrained diabetic rats. The increase in lipoprotein lipase activity after physical exercise in red muscle of diabetic rats occurs during the recovery phase.
Beta-blockade is known to induce muscle fatigue and tendency to hypoglycaemia during prolonged exercise. In addition, beta-blocking agents influence the secretion of many hormones, which regulate glucose. We have investigated the effects of a beta 1-selective (metoprolol) and a non-selective (propranolol) beta-blocking agent on muscle glycogenolysis, blood glucose and lactate levels, plasma levels of free fatty acids and on secretion of insulin, growth hormone, glucagon and cortisol during physical exercise in a double blind cross-over study in seven healthy male volunteers. They participated in three bicycle ergometer tests each lasting for 30 minutes under treatment of placebo (C), metoprolol (M) or propranolol (P). A biopsy was obtained from the vastus lateralis muscle before and immediately after the exercise for muscle glycogen assay. The glycogen concentration after exercise tended to be lower in C than in M or P experiment. The blood glucose level decreased during P and at 30 min there was a significant difference between P and C. The blood lactate was significantly lower before exercise during P than C or M. The increase of blood lactate during exercise, however, was not inhibited by P. Both beta-blocking agents counteracted the increase of FFA during exercise. There was a marked increase of growth hormone secretion during beta-blockade. The secretion of glucagon and cortisol were slightly increased by P and M, but the plasma insulin level was not affected by beta-blockade.
The aim of this study was to find out how individually prescribed moderate physical training influences aerobic power and body weight in obese middle-aged men and women. 210 persons with poor physical fitness and body mass index (BMI) over 25 kg/m2 were accepted. Of these 169 persons were without regular medication and in this group 95 persons trained actively for the complete follow-up period of 17 months while 74 persons dropped out during the study. Maximal oxygen consumption was estimated indirectly before training and after 2, 5, 11 and 17 months of training. The exercise physiologist prescribed an individual training program, which was checked every six weeks. The most popular sports were walking and skiing. Initial aerobic power was poor in both sexes (3.1 +/- 0.1 l/min in men and 2.3 +/- 0.1 l/min in women, mean +/- SE). In the actively training group it increased significantly after two months and remained on this improved level for the rest of the observation period (total increase 14% in men and 11% in women). Initial BMI was 29.8 +/- 0.5 kg/m2 in men and 29.1 +/- 0.4 kg/m2 in women. The greatest change in body weight in the actively training group also took place during the first months. The mean decrease of body weight was 4.8 +/- 0.8 kg in men and 3.3 +/- 0.6 kg in women after 17 months. In conclusion, obese middle-aged men and women initially in poor physical condition can benefit from an individually prescribed training program resulting in significantly increased aerobic power and a minor loss of overweight.
The aim of the study was to clarify the feasibility of physical training for middle-aged borderline-hypertensive males. Blood pressure of 59 subjects was followed for nine months, whereafter 25 persons were classified as borderline-hypertensive and 34 persons as normotensive. Both groups were randomly allocated into training and control groups. Training lasted for four months, of which the first two included supervised bicycle ergometer exercise. During the last two months training was unsupervised. After training estimated maximal oxygen consumption increased significantly both in borderline-hypertensive and normotensive men. After training resting diastolic blood pressure decreased significantly both in training and control groups. This finding supports the importance of sufficiently long follow-up of blood pressure before eventual drug therapy when blood pressure is mildly elevated. Diastolic blood pressure during 50-minute ergometer exercise was decreased after four months of training in borderline-hypertensives and did not any longer differ from that of normotensives. Individually prescribed physical training is worth regarding as one treatment modality for middle-aged borderline-hypertensive patients.
Lipoprotein lipase (LPL) activity was studied in adipose, muscle and lung tissues of post-weanling rats 48 and 96 hours after experimentally induced diabetes by streptozotocin administration. Weight gain was reduced, and blood glucose level increased about 3-4 fold above the control level as an indication of the diabetic state. LPL activity in brown and white adipose tissues decreased in diabetic rats to 10-30% of the control level. In soleus muscle the LPL activity was slightly enhanced 96 hours after the streptozotocin injection. In cardiac muscle the LPL activity was markedly increased already 48 hours after the administration of streptozotocin and the increase remained significant until 96 hours. There was in the pulmonary tissue also an increase of LPL activity of diabetic rats, although this was significant only 96 hours after streptozotocin treatment. The results suggest marked tissue specific variation in the LPL activity. Moreover, tissue responses to experimentally induced diabetes vary. In adipose tissue the decrease in the LPL activity suggests that lipid transport to adipocytes is decreased while an increase in skeletal and cardiac muscles and in lung tissue proposes that their lipid utilization is enhanced.
A controlled trial is reported on the effects of mild-to-moderate physical activity on serum lipoproteins. After two baseline examinations 100 asymptomatic middle-aged men were randomly assigned to exercise and control groups. The exercise group participated in a 4-month exercise program that consisted of 3-4 weekly sessions. The control group was advised to maintain their previous exercise habits. The success of the program was corroborated by the increase in VO2 in the training group, but not in the control group. Serum triglycerides decreased from 1.54 +/- 0.10 to 1.27 +/- 0.08 mmol/1 (p less than 0.001) and high-density lipoprotein (HDL) cholesterol increased from 1.27 +/- 0.04 to 1.41 +/- 0.04 mmol/1 (p less than 0.01) in the exercise group during the trial. No change was seen in the control group. As the concentration of apolipoprotein AI stayed constant in both groups, the ratio HDL cholesterol/apolipoprotein AI increased only in the exercise group. The level of low-density lipoprotein (LDL) cholesterol and apolipoprotein AII decreased in both groups during the trial. The alterations in serum triglycerides and HDL cholesterol in the exercise group were not dependent on weight reduction; similar changes were also seen in subjects with constant body weight during the intervention.
Monozygous twin pairs (two female and four male) were used in a strength training study so that one member of each pair served as training subject (TS) and the other members as nonexercising controls (CS). TS trained four times a week for 12 weeks with maximal isometric knee extensions of the right leg. The parameters studied included muscle strength, endurance time, electromyographic activity, and activities of several key enzymes in nonoxidative an oxidative muscle metabolism. The results disclosed that in addition to a 20% increase in isometric knee extension strength in the trained leg of TS, an average increase of 11% was observed in strength of TS untrained leg. CS did not demonstrate any change in muscle strength. Training also included an improvement in the maintenance of a static load of 60% of the pretraining maximum. Increase in the maximum integrated electromyographic activity (IEMG) of the rectus femoris muscle occurred concomitantly with the knee extension strength. Traning also caused reduction in the IEMG/tension ratio at submaximal loads indicating a more econimical usage of the rectus femoris muscles. Muscle biopsies taken from the vastus lateralis muscle showed that the enzyme activities of MDH, SDH, and HK were higher, and LDH and CPK lower in the trained leg as compared to the nontrained control leg of TS or to the values of the untrained member of the twin pair. It is concluded that isometric strength training as used in the present study can cause increased recruitment of the availabel motor unit pool, improved efficiency at submaximal loads, and surprisingly also enchancement of the oxidative metabolism in the muscle.
We investigated the prevalence of carotid atherosclerosis and its association with serum lipoprotein cholesterol fractions in 412 Eastern Finnish men ages 42, 48, 54, or 60 years who were examined between February and December 1987 in the Kuopio Ischaemic Heart Disease Risk Factor Study. Carotid atherosclerosis was assessed with high-resolution B-mode ultrasonography. Of the participants, 37% had thickening of the intimal or medial layer of the arterial wall, 10% had plaques, 2% had stenosis in the right or left common carotid artery or in the carotid bifurcation, and only 51% were free of any detectable carotid atherosclerosis. The prevalence of atherosclerosis was 14.1%, 32.0%, 67.7%, and 81.9% in the four age groups, respectively. The mean age-adjusted serum low density lipoprotein (LDL) cholesterol concentration was 3.67 mmol/l (142 mg/dl) in men free of carotid atherosclerosis and 4.02 mmol/l (155 mg/dl) in those with at least intimal thickening (p = 0.003 for difference). The mean age-adjusted serum cholesterol concentration in the high density lipoprotein (HDL) fraction was 1.34 mmol/l (52 mg/dl) in the atherosclerosis-free and 1.27 mmol/l (49 mg/dl) in the atherosclerotic men (p = 0.029 for difference). There was a similar difference in both the serum HDL2 and the HDL3 cholesterol levels. Serum LDL and HDL (inverse) cholesterol were significant determinants of severity of carotid atherosclerosis in a multivariate regression model adjusting for age, obesity, plasma fibrinogen, cigarette-years, and duration of hypertension. Our data reveal the high prevalence of atherosclerosis in middle-aged Eastern Finnish men and provide further evidence of the roles of LDL and HDL cholesterol in atherosclerosis.