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Biomedical subjects

J Persson

Publications and source records attributed to J Persson.

At least 109 records · Page 6Linked to original sources
PubMed1982

Leg blood flow during static exercise.

Leg blood flow was studied with the constant infusion dye technique during static exercise of the thigh muscles (quadriceps) and during hand-grips at 15 and 25-30% of MVC. Blood flow and oxygen uptake in the leg increased in quadriceps exercise and reached their highest values (around 1.21/min and 165 ml/min respectively) at 25-30% of MVC, whereas leg vascular resistance decreased. Regional circulatory adaptations and the oxygen uptake - leg blood flow relationship were in close agreement with the responses found in dynamic leg exercise. In view of the marked rise in intramuscular pressure previously observed during quadriceps contractions, a restriction of blood flow and an increased vascular resistance had been expected. Involuntary activation of leg muscles other than the quadriceps may explain the finding. Contractions of the contralateral quadriceps induced a slight increase in leg blood flow, whereas hand-grips had no influence on blood flow or vascular resistance in the leg. The distribution of the cardiac output during static contractions is discussed, and it is concluded that during hand-grips the increase in blood flow is predominantly distributed to the upper part of the body.

Humans↗
PubMed1981

Cardiovascular response to combined dynamic and static exercise.

The cardiovascular response to combined static handgrip at 20% MVC and dynamic leg exercise was studied in young male subjects. Cardiac output increased by 2.3 liters/min (30%) at isolated handgrip and by 1.0 liter/min (7%) when handgrip was added to dynamic exercise at 100 W. In spite of an increased arterial blood pressure, leg blood flow was unaffected by handgrip, both when it was performed isolated and in combination with dynamic exercise. Temperature measurements in mixed venous blood and subcutaneous tissue indicated an increased blood flow to peripheral circulatory areas. During combinations of handgrip and dynamic exercise at different levels of VO2, heart rate response to handgrip was progressively less marked as maximal oxygen uptake was approached. Therefore a vagal withdrawal seems to be the most important heart rate-increasing mechanism during combined exercise. Systolic blood pressure response to handgrip was still preserved at 25 and 45% of max VO2. At 95% of max VO2, the blood pressure response to handgrip was abolished, probably due to a competitive utilization of the same blood pressure-raising mechanism in dynamic and static exercise.

Blood Circulation↗
PubMed1978

A method for continuous electrocardiodynamic monitoring.

A new method is presented for the monitoring of cardiac time intervals, e.g. in clinical and industrial work investigation. The methods yields 'on-line' the electrocardiodynamic time profile during rest as well as effort, and has applications in health care, sports and occupational medicine. By means of analog processing of an electrocardiographic signal, ear densitogram and beat-by-beat display of the measured cardiac time intervals as amplitude-modulated pulses, an 'electrocardiodynamic time profile' is obtained. In order to estimate the accuracy and the limitations of the method, a comparison with computerized methods was performed. In an ergonomic experiment carried out by a Romanian-Swedish research team, analog and digital methods for the detection of cardiac time intervals showed good agreement.

Adolescent↗
PubMed1977

Feeding-induced hypocalcaemia. Preliminary studies in sheep.

The effect of feeding on calcium metabolism was studied in sheep. When crushed oats or pelleted concentrate was added to the diet of hay-fed sheep, there was a profound decrease in serum calcium. Serum calcium fell in spite of an increased daily intake of calcium.

Animal Feed↗