Biomedical subjects

L Hermansen

Publications and source records attributed to L Hermansen.

At least 37 records · Page 2Linked to original sources

PubMed1977

Capillary supply of skeletal muscle fibers in untrained and endurance-trained men.

Muscle fiber diameters and numbers of capillaries per fiber, per square millimeter, and around each fiber were determined in needle biopsies from the lateral part of the quadriceps muscle of 23 young men. Twelve subjects were untrained (UT) and eleven were endurance-trained (ET) athletes. Average values for maximal oxygen uptake were 51.3 (UT) and 72.0 ml/kg-min (ET). Mean fiber diameters were not significantly different in the two groups (48.8 and 49.1 micron). The capillaries per fiber ratios were 1.77+/-0.10 and 2.49+/-0.08 (mean+/-SE) in the UT and ET groups, respectively. The numbers of capillaries around each fiber were 4.43+/-0.19 (UT) and 5.87+/-0.18 (ET). The numbers of capillaries per mm2 were 585+/-40 (UT) and 821+/-28 (ET). Fiber diameters were 28% smaller in ultrathin than in fresh-frozen sections from the same biopsies. After correction for this difference, the numbers of capillaries per mm2 were 305 and 425 in the UT and ET, respectively. The capillaries per fiber ratio increased with increasing fiber diameter, but not sufficiently to maintain the number of capillaries per mm2. Fibers containing many mitochondria are surrounded by more capillaries than fibers with few mitochondria.

Adolescent↗

PubMed1977

Altered control of skin blood flow during exercise at high internal temperatures.

We have investigated further the behavior of skin blood flow (SkBF) as internal temperature (measured as esophageal temperature (Tes)) rises in a heated exercising man. A previous study showed that when skin temperature (Tsk) is driven up in exercising men, the increase in SkBF is less than that found for the same Tes and Tsk in a resting man. In this study, we extended our observations into the range of higher Tes to see if SkBF (measured plethysmographically as changes in forearm blood flow) could be driven to higher levels despite competition with skeletal muscle for cardiac output. After Tsk was elevated to 38 degrees C by means of water-perfused suits, subjects exercised at 525-900 kp.m/min (86-147 W) for 17-30 min while Tsk was held at 38 degrees C. We found that SkBF increase per unit increase in Tes is attenuated at higher Tes. In seven men, the average slope obtained from linear regression of FBF on Tes below 38 degrees C was 7.6 flow units/degrees C. Above 38 degrees C, the average was 2.12 flow units/degrees C. In some subjects, the FBF response appeared virtually saturated at a plateau despite a steady rate of increase in Tes with time. Clearly, SkBF does not increase in direct proportion to Tes without bound. Other stimuli (presumably related to blood pressure regulation) interact either to reduce the rate of SkBF increase or to prevent any further increase after Tes exceeds 38 degrees C.

Adult↗

PubMed1977

Synthesis of muscle glycogen during recovery after prolonged severe exercise in diabetic and non-diabetic subjects.

Glycogen synthesis rate in skeletal muscle studied in six juvenile diabetic and six non-diabetic males ingesting a carbohydrate rich diet during 12 h of resting recovery after exhaustive bicycle exercise. The diabetic subjects took their regular insulin. Blood samples and muscle biopsies were obtained at rest prior to exercise, immediately after cessation of exercise and after 2,4,6.9 and 12 h of recovery. A marked decrease in muscle glycogn content was observed in response to exercise in both groups of subjects. Mean glycogen utilization rate was the same in the two groups. Glycogen synthesis rate during the first 4 h or recovery was 6.4 +/- 0.6 mmol glucosyl units/kg w.w./h in the diabetic subjects and 7.2 +/- 0.7 mmol glycosyl units/kg w.w./h in the non-diabetic subjects. During the next 8 h glycogen synthesis rate was approximately 1/3 of that being 2.0 +/- 0.3 and 2.4 +/- 0.5 mmol glucosyl units/kg w.w./h in the two groups respectively. Glycogen synthetase I-activity increased markedly in response to exercise in both groups of subjects. However, no differences were observed between the groups. No significant differences in muscle glucose 6-phosphate concentrations were observed between the two groups. Plasma glucose levels were significantly higher in the diabetic than in the non-diabetic subjects. It is concluded that glycogen synthesis during recovery following prolonged severe exercise can proceed at the same rate in diabetic subjects taking their regular insulin as in non-diabetic subjects.

Adolescent↗

PubMed1976

Human cardiovascular and respiratory responses to graded muscle ischemia.

Responses of heart rate (HR), mean arterial blood pressure (MAP) ventilation (VE), and forearm blood flow (FBF) to different degrees of leg muscle ischemia were measured in eight subjects in a four-part experiment. Part I. Total circulatory occlusion (OCCL) of resting legs for 15 min had little or no effect on HR, MAP, VE, or FBF. Part II. OCCL of the legs for 3 min immediately after exercise at 50-250 W did not affect HR or end-tidal CO2; it lowered VO2 and VE and prevented recovery of MAP. Part III. OCCL beginning at end and 10, 20, 30 s before end of 7-min exercise (100-150 W) and continuing 3 min into recovery period produced sustained and graded increments (5-10 mmHg) in MAP, only small changes in HR, and accelerated recovery of VE while end-tidal CO2 remained constant. Part IV. OCCL at end and 30 s before end of exercise increased FBF 2.5-3.5 times; both skin and muscle vasodilated. Thus muscle ischemia preceded by exercise can raise MAP without affecting VE, whereas baroreflexes may lower HR and raise FBF. The results suggest the presence of muscle chemoreceptors whose major effect is on MAP.

Adult↗

PubMed1975

Alcoholism and the hyperactive child syndrome.

Comparisons were made between alcoholics and nonalcoholics in a sample of Danish adoptees (mean age 30) and it was found that the alcoholics, as children, were more often hyperactive, truant, antisocial, shy, aggressive, disobedient, and friendless. The literature suggesting a relationship between the hyperactive child syndrome and subsequent alcoholism is reviewed, as well as a possible relationship between these disorders and antisocial behavior. The adoptive parent of the two groups did not differ with regard to socioeconomic class, psychopathology, or drinking histories. However, 10 of the 14 alcoholics had biological parents who were alcoholic, with no known alcoholism among the biological parents of the nonalcoholics. As adults, the alcoholics differed from the nonalcoholics only with regard to drinking history, use of drugs, and overt expression of anger.

Adoption↗

PubMed1974