European journal of applied physiology and occupational physiology
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Eur J Appl Physiol Occup Physiol · Jan 1990
Comparative StudyComparison of arterial, end-tidal and transcutaneous PCO2 during moderate exercise and external CO2 loading in humans.
Static relationships between arterial, transcutaneous and end-tidal PCO2 (PaCO2, PtcCO2, PetCO2) as well as the dynamic relationship between PetCO2 and PtcCO2 were studied during moderate bicycle ergometer exercise with and without external CO2 loading. The exercise pattern consisted of 5-min intervals of constant power at 40 W and 100 W and 900 s of randomised changes between these two power levels. The external CO2 loading was achieved by means of controlled variations of inspiratory gas compositions aimed at a constant PetCO2 of 6.5 kPa (49 mm Hg). ⋯ The dynamic relationship between both parameters was found to be independent of whether internal or external CO2 loadings were applied. It is concluded that the combination of PetCO2 and PtcCO2 measurements allows an improved non-invasive assessment of PaCO2. While PetCO2 better reflects the transients, PtcCO2 can be employed to determine slow changes of the absolute PaCO2.
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Eur J Appl Physiol Occup Physiol · Jan 1990
Beta-endorphin, adrenocorticotropic hormone, cortisol and catecholamines during aerobic and anaerobic exercise.
Twelve non-specifically trained volunteers (aged 26.5 years, SD 3.6) performed exhausting incremental graded exercise (ST) and 1-min anaerobic cycle ergometer exercise (AnT) at 2-h intervals for the purpose of investigating beta-endorphin (beta-E) behaviour dependent on exercise intensity and anaerobic metabolism. In order to determine [beta-E], adrenocorticotropic hormone [ACTH], cortisol [C], adrenaline [A] and noradrenaline [NA] concentrations, venous blood samples were collected prior and subsequent to exercise until the 20th min of the recovery period, as well as in ST before and after exceeding the individual anaerobic threshold (THan,i). Before, during and after ST, lactate concentration, heart rate and perceived degree of exertion were also determined; after AnT maximum lactate concentration was measured. ⋯ In AnT the increases of [beta-E] and [A] demonstrated a correlation (r = 0.65; P less than 0.05). Both in AnT and ST there was a relationship between the maximum concentrations of beta-E and lactate (r = 0.63 and 0.71; each P less than 0.05). We therefore conclude that physical exercise with increasing or mostly anaerobic components leads to an increase in [beta-E], the extent correlating with the degree of lactate concentration.(ABSTRACT TRUNCATED AT 250 WORDS)
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Eur J Appl Physiol Occup Physiol · Jan 1990
Cardiac responses to the Valsalva manoeuvre in different body positions.
A standardized Valsalva manoeuvre (VM) with a 15-s straining period was repeated in each of four postures by six male subjects. The postures were supine (SUP), sitting leaning back (LB), sitting leaning forward (LF) and standing (ST). During straining, the increase in heart rate (fc) was different between LB and LF (+50% and +23%, respectively P less than 0.05). ⋯ Consequently, this posture would appear to be superior to other postures during unavoidable VM (weight lifting and defaecation). To perform tests on autonomic function LB would appear to be superior to the other postures because of the large autonomic responses, combined with minimum risk for the subject. The impedance method provided simple and reproducible determinations of SV changes during VM.
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Eur J Appl Physiol Occup Physiol · Jan 1988
Intramuscular pressure and muscle blood flow in supraspinatus.
Intramuscular pressure and muscle blood flow was measured in the supraspinatus muscle in 6 healthy subjects. The recordings were performed at rest, during isometric exercise, during an isometric muscle contraction of 5.6 kPa (42 mm Hg) and 10.4 kPa (78 mm Hg) and at rest after the contraction. ⋯ A muscle contraction pressure of 5.6 kPa (42 mm Hg), which is 16% of maximal voluntary contraction, reduces local muscle blood flow significantly. It is concluded that the high intramuscular pressures found in supraspinatus during work with the arms elevated impedes local muscle blood flow.
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Eur J Appl Physiol Occup Physiol · Jan 1987
Enhanced brain protection during passive hyperthermia in humans.
Selective brain cooling during hyperthermia by emissary venous pathways from the skin of the head to the brain has been reported both in animals and humans. Heat protection of the brain extends tolerance to high deep body temperature in animals, and may be enhanced in humans if the head is cooled. ⋯ Face-fanning maintained tympanic temperature 0.57 degrees C lower than esophageal temperature, and improved comfort. External head cooling techniques enhancing physiological brain cooling can therefore be useful for the protection of the human brain during heat stress or passive therapeutic hyperthermia.