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Biomedical subjects

T Janson

Publications and source records attributed to T Janson.

6 recordsLinked to original sources
PubMed2003

Effects of sodium citrate ingestion before exercise on endurance performance in well trained college runners.

OBJECTIVE: To test the hypothesis that sodium citrate administered two hours before exercise improves performance in a 5 km running time trial. METHODS: A total of 17 male well trained college runners (mean (SD) O(2)MAX 61.3 (4.9) ml/kg/min) performed a 5 km treadmill run with and without sodium citrate ingestion in a random, double blind, crossover design. In the citrate trial, subjects consumed 1 litre of solution containing 0.5 g of sodium citrate/kg body mass two hours before the run. In the placebo trial, the same amount of flavoured mineral water was consumed. RESULTS: The time required to complete the run was faster in the citrate trial than the placebo trial (1153.2 (74.1) and 1183.8 (91.4) seconds respectively; p = 0.01). Lower packed cell volume and haemoglobin levels were found in venous blood samples taken before and after the run in the citrate compared with the placebo trial. Lactate concentration in the blood sample taken after the run was higher in the citrate than the placebo trial (11.9 (3.0) v 9.8 (2.8) mmol/l; p<0.001), and glucose concentration was lower (8.3 (1.9) v 8.8 (1.7) mmol/l; p = 0.02). CONCLUSION: The ingestion of 0.5 g of sodium citrate/kg body mass shortly before a 5 km running time trial improves performance in well trained college runners.

Adult↗
PubMed2001

Influence of prolonged continuous exercise on hormone responses to subsequent exercise in humans.

This study examined the possibility that fatigue may modify the hormone responses to exercise. A group of 12 endurance trained athletes ran for 2 h (blood lactate concentrations of approximately 2 mmol x l(-1)) in order to induce fatigue. The subjects exercised for 10 min at 70% maximal oxygen uptake before (1st test) and after (2nd test) the 2 h run to assess hormone responsiveness. A 1 min anaerobic power test was performed to assess muscle power. Cortisol, growth hormone, testosterone and insulin concentrations were determined before and after the 1st and 2nd tests. The 1st test resulted in increases in concentrations (P < 0.05) of cortisol and growth hormone, a decrease in insulin concentration (P<0.01) and no change in testosterone concentration. The 2 h run caused decreases of insulin, increases of growth hormone concentration and variable responses in the concentrations of cortisol and testosterone. The 2nd test decreased insulin concentration further (P < 0.05), but responses of the concentrations of testosterone, growth hormone and cortisol were variable. In 6 subjects (group A) cortisol displayed an increase [mean (SD)] from baseline concentrations [+ 304.0 (60.0) nmol x l(-1)], while in the other 6 subjects (group B) a decrease or no change was seen [+ 3.1 (5.3) nmol x l(-1), between groups, P<0.05]. Growth hormone concentration was substantially higher in group A [+ 14.7 (4.8) ng x ml(-1)] than group B [+ 6.0 (2.9) ng x ml(-1)] following the 2nd test. In group A anaerobic muscle power was higher, while in group B it was lower, after the 2 h run than before the 2 h run (P < 0.05). The findings suggest that fatigue from prolonged endurance activity may introduce a resetting in the pituitary-adrenocortical component of the endocrine system, expressed either by intensified or by suppressed endocrine functions.

Adult↗
PubMed1981

The value of clinical lip strength measurements.

The strength of the lips was measured with a dynamometer in fifty children, aged 7 to 13 years, with varying types of malocclusion. The lip strength was related to the electromyographically recorded activity of the lips during the lip strength measurements and to bite and facial morphology. The morphology was recorded on dental casts and profile radiographs. The lip strength measurements were found, in duplicate determinations, to have limited reproducibility. There was no correlation between lip strength and the EMG activity of the lips during the recordings. Lip strength was not correlated to dentoalveolar cephalometric variables, including relationship and inclination of the incisors. Nor was there any correlation between lip strength and lip morphology. The value of lip strength measurements seems to be limited, due either to difficulties in recording lip strength or to a small influence of lip muscle forces on the dentition.

Adolescent↗
PubMed1978

Sensitivity and precision of activated partial thromboplastin time (APTT) methods. A multicenter study.

The Activated Partial Thromboplastin Time (APTT) test, Cephotest, was compared to other APTT methods in current use in 4 specialized coagulation laboratories. In 3 of 4 laboratories, the sensitivity of Cephotest was superior (P less than 0.001) to that of the local APTT method. There was no statistically significant difference between the APTT methods with regard to precision of repetitive testing. In each laboratory, the normal range of Cephotest was estimated on freshly collected plasma samples from healthy subjects. A mean value between 28.8 and 35.8 s, with a standard deviation of 1.1-3.3 s, was obtained. It is concluded that the composition of the APTT method if of importance for the sensitivity of this test, but does not influence the precision of repetitive testing to a significant degree. The use of a standardized reagent facilitates comparison of the results obtained with the APTT method from one laboratory to another.

Blood Coagulation Tests↗