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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Diabetologia 7 (1971), S. 223-226 
    ISSN: 1432-0428
    Keywords: Guinea-pig anti-insulin serum ; insulin secretion in vivo ; stress ; exercise ; swimming ; phentolamine ; catecholamines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé Des rats reçoivent une injection d'antisérum anti-insulinique et d'albumine humaine marquée à l'iode131. Le débit sécrétoire d'insuline endogène est déduit de la réduction progressive du pool d'anticorps circulants non neutralisés. Le débit sécrétoire est nettement moindre chez les rats obligés à nager que chez les animaux témoins. Cet effet inhibiteur de l'exercice musculaire est levé par injection préalable de phentolamine. Ces données suggèrent que l'effet inhibiteur de l'effort sur la sécrétion d'insuline est secondaire à une libération de catécholamines.
    Abstract: Zusammenfassung Bei Ratten wurden Injektionen von Antiinsulin-Serum des Meerschweinchens und von menschlichem Albumin, das mit 131 J gekennzeichnet war, vorgenommen. Die Menge des endogen sezernierten Insulins wurde durch die progressive Abnahme im Pool der zirkulierenden, nicht neutralisierten Antikörper bestimmt. Zwang man die Tiere zu schwimmen, so erfolgte die Insulinsekretion auf einem sehr viel niedrigerem Niveau, als bei den Kontrollratten. Vorherige Injektionen von Phentolamin hob die durch die Arbeit bedingte Hemmung der Insulinabgabe auf. Diese Befunde unterstützten die Annahme, daß eine solche Hemmung durch die endogenen sezernierten Katecholamine zustande kommt.
    Notes: Summary Rats were injected with guinea-pig antiinsulin serum and131I-labelled human albumin. The amount of endogenously secreted insulin was estimated from the progressive reduction in the pool of circulating unneutralized antibodies. In animals compelled to swim, insulin secretion occured at a much lower rate than in control rats. Prior injection of phentolamine abolished the exercise-induced inhibition of insulin release. These findings support the concept that such inhibition is dure to endogenously released catecholamines.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1254
    Keywords: Cold wind ; Exertion ; Lactate ; Work-load
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geography , Physics
    Notes: Abstract Physiological and metabolic output responses to facial cooling during a graded maximal exercise and a prolonged submaximal exercise lasting 30 min at 65% $$\dot VO_2$$ max were investigated in five male subjects. Pedalling on a cycle ergometer was performed both with and without facial cooling (10°C, 4.6 m s−1). Facial cooling at the end of graded maximal exercise apparently had no effect on plasma lactate (LA), maximal oxygen consumption ( $$\dot VO_2$$ max), maximal heart rate (HR max), rectal temperature (T re), work-load, lactate threshold (LT), ventilatory threshold (VT) and onset of blood lactate accumulation (OBLA). However, the response to facial cooling after prolonged submaximal exercise is significantly different for heart rate and work-load. The results suggest that facial wind stimulation during maximal exercise does not produce a stress high enough to alter the metabolic and physiological responses.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-1254
    Keywords: Exercise ; Cold ; Lactate ; Catecholamines ; Workload
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geography , Physics
    Notes: Abstract This study was designed to clarify the effects of cold air exposure on metabolic and hormonal responses during progressive incremental exercise. Eight healthy males volunteered for the study. Informed consent was obtained from every participant. The following protocol was administered to each subject on three occasions in a climatic chamber in which the temperature was 20°, 0° or −20°C with relative humidity at 60%±1%. Exercise tests were conducted on an electrically braked ergocycle, and consisted of a propressive incremental maximal exercise. Respiratory parameters were continuously monitored by an automated open-circuit sampling system Exercise blood lactate (LA), free fatty acids (FFA), glucose levels, bicarbonate concentration (HCO 3 − ), acidbase balance, plasma epinephrine (E) and norepinephrine (NE) were determined from venous blood samples obtained through an indwelling brachial catheter. Maximal oxygen uptake was significantly different between conditions: 72.0±5.4 ml kg−1 min−1 at 20°C; 68.9±5.1 ml kg−1 min−1 at 0°C and 68.5±4.6 ml kg−1 min−1 at −20°C. Workload, time to exhaustion, glucose levels and rectal Catecholamines and lactate values were not significantly altered by thermal conditions after maximal exercise but the catecholamines were decreased during rest. Bicarbonate, respiratory quotient, lactate and ventilatory thresholds increased significantly at −20°C. The data support the contention that metabolic and hormonal responses following progressive incremental exercise are altered by cold exposure and they indicate a marked decrease in maximal oxygen uptake, time to exhaustion and workload.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1439-6327
    Keywords: Lactate threshold ; Onset on blood lactate accumulation ; Dietary modifications
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary This study was designed to clarify the effects of dietary modifications on the lactate threshold (LT) and on the onset of blood lactate accumulation (OBLA) during progressive incremental exercise. Six healthy males volunteered for the study. Informed consent was obtained from every participant. The following protocol was administered to each subject on three occasions: a 48-h period of mixed dieting (53% carbohydrates, 30% lipids, 17% proteins) preceding the first exercise test, immediately followed by a 48-h period of either a carbohydrate-rich (68% CHO, 23% lipids, 9% proteins) or a fat-rich (19% CHO, 57% lipids, 26% proteins) iso-caloric diet leading to the second exercise and separated from the third test by a 12-days period. Exercise tests were conducted on an electrically-braked ergocycle, and consisted of a progressive incremental maximal exercise. Respiratory parameters were continuously monitored by an automated open circuit sampling system. Exercise blood lactate (LA), free fatty acids (FFA), glucose levels and acid-base balance were determined from venous blood samples obtained through an indwelling brachial catheter. Peak lactate values, workload and performance time were not significantly altered by imposed diets. Furthermore, dietary modifications had no significant effect on LT, OBLA fixed at 4 mmol and ventilatory threshold. Increased pH and FFA mobilization were observed with fat-rich diet, while CHO-rich diet markedly increased the respiratory exchange ratio (R). It is concluded that LT and OBLA are not significantly altered by fat or CHO enrichment of diets.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1439-6327
    Keywords: Isotopic composition of food ; Isotopic composition of breath ; Stable isotope ; Metabolic response to exercise ; Respiratory exchange ratio
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The purpose of this study was to test the hypothesis that the well-documented changes in background 13C enrichment of expired CO2 observed in response to exercise and carbohydrate ingestion, in subjects living on a North American diet, are not present in subjects living on a Western European diet. The experimental protocol used by Pirnay et al. in 1977 and by Krzentowski et al. in 1984 in subjects living on a Western European diet (4 h of exercise on a treadmill at ∼50% VO2max with ingestion of 100 g of glucose in 400 ml of water) was duplicated as closely as possible in six subjects living on a North American diet. The actual amounts of exogenous glucose oxidized, computed with a high artificial 13C enrichment of glucose (+189.7‰ δ 13C PDB-1) which allows one to neglect the 1–2‰ δ changes in 13C background, were [mean (SEM)] 54.7 (5.4) and 84.2 (3.4) g over 2 h and 4 h of exercise, respectively. These values compare well with data computed by Pirnay et al. [56.6 (13.1) and 94.9 (4.2) g] and by Krzentowski et al. [55.0 (6.2) and 88.0 (4.5) g] using a natural enrichment of glucose (−11.21 and −10.63‰ δ 13C PDB-1, respectively) assuming no change in 13C background in their Western European subjects. Under the same assumption and using a natural enrichment of glucose (−11.30‰ δ 13C PDB-1) the oxidation of exogenous glucose was overestimated by 30–40% in our North American subjects. This result indicates that because of a lower input of 13C in their diet, the difference between the isotopic composition of carbohydrate and fat stores are smaller, and changes in 13C background are small or absent in response to moderate workload in Western European subjects, when compared to their North American counterparts.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1439-6327
    Keywords: Supramaximal exercise ; Diet ; Blood glucose ; Insulin ; Catecholamines
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The effects of supramaximal exercise on blood glucose, insulin, and catecholamine responses were examined in 7 healthy male physical education students (mean±SD: age=21±1.2 years; $$\dot V_{{\text{O}}_{{\text{2 max}}} } $$ =54±6 ml · kg−1 · min−1) in response to the following three dietary conditions: 1) a normal mixed diet (N); 2) a 24-h low carbohydrate (CHO) diet intended to reduce liver glycogen content (D1); and 3) a 24-h low CHO diet preceded by a leg muscle CHO overloading protocol intended to reduce hepatic glycogen content with increased muscle glycogen store (D2). Exercise was performed on a bicycle ergometer at an exercise intensity of 130% $$\dot V_{{\text{O}}_{{\text{2 max}}} } $$ for 90 s. Irrespective of the dietary manipulation, supramaximal exercise was associated with a similar significant (p〈0.01) increase in the exercise and recovery plasma glucose values. The increase in blood glucose levels was accompanied by a similar increase in insulin concentrations in all three groups despite lower resting insulin levels in conditions D1 and D2. Lactate concentrations were higher during the early phase of the recovery period in the D2 as compared to the N condition. At cessation of exercise, epinephrine and norepinephrine were greatly elevated in all three conditions. These results indicate that the increase in plasma glucose and insulin associated with very high intensity exercise, persists in spite of dietary manipulations intended to reduce liver glycogen content or increase muscle glycogen store. These data suggest that the blood glucose increase following supramaximal exercise is most likely related to hepatic glycogenolysis in spite of a substantial decrease in liver glycogen content.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    European journal of applied physiology 66 (1993), S. 552-552 
    ISSN: 1439-6327
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    European journal of applied physiology 66 (1993), S. 547-551 
    ISSN: 1439-6327
    Keywords: Sweat measurement ; Electrolyte ; Exercise ; Sweat gland
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The purpose of this study was to modify a previously described local sweat collector to facilitate the investigation of sweat rate and composition in a warm (30°C) and humid (relative humidity 80%) environment. The adherence of the collector to the skin was improved and a pouch was appended at the lower end of the collector. The limitations of the closed collector were examined by comparing the local sweat rate and the quantity of electrolyte excreted in sweat with those obtained using a second collector with a wide opening (to permit free evaporation) and by changes in the body mass. Eight subjects performed exercise on a cycle ergometer consisting of four equal periods of 15 min each, at 60% maximal oxygen consumption, with a rest of 5 min between each period. The sweat produced on a local skin area (85 cm2, upper posterior thorax region) was collected at the end of each period, before measuring the body mass on a sensitive (±1 g) platform balance. The mean local sweat rate [2.61 (SEM 0.19) Mg-CM−2. min-1] was 2.4 times greater than the pro-rated whole body mass loss but the two were strongly correlated (r=0.82,P〈0.01). Compared to the open collector, the greater quantity of electrolyte excreted into the closed collector would suggest that the conditions which prevailed in the closed collector, such as a higher local skin temperature, may have affected the function of the sweat gland. This method enabled the efficiency of local sweat evaporation to be assessed by measuring the difference between sweat volume collected in the open and in the closed collectors. Recovery of water volumes at rest indicated that no contamination and no apparent leakage occurred. This improved sweat collector is suitable for obtaining clean local sweat samples of up to 6 ml, and for measuring the sweat composition and also sweat rate during exercise in warm and humid conditions.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1439-6327
    Keywords: Somatotropin ; Insulin-like growth factor I (IGF I) ; Exercise ; Hypoxia ; Glucose metabolism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The response of plasma insulin-like growth factor I (IGF I) to exercise-induced increase of total human growth hormone concentration [hGHtot] and of its molecular species [hGH20kD] was investigated up to 48 h after an 1-h ergometer exercise at 60% of maximal capacity during normoxia (N) and hypoxia (H) (inspiratory partial pressure of oxygen = 92 mmHg (12.7 kPa);n = 8). Lactate and glucose concentrations were differently affected during both conditions showing higher levels under H. Despite similar maximal concentrations, the increase of human growth hormone (hGH) was faster during exercise during H than during N[hGHtot after 30 min: 8.6 (SD 11.4) ng · ml−1 (N); 16.2 (SD 11.6) ng · ml−1 (H);P 〈 0.05]. The variations in plasma [hGH20kD] were closely correlated to those of [hGHtot], but its absolute concentration did not exceed 3% of the [hGHtot]. Plasma IGF I concentration was significantly decreased 24 h after both experimental conditions [N from 319 (SD 71) ng · ml-1 to 228 (SD 72) ng · ml−1,P 〈 0.05; H from 253 (SD 47) to 200 (SD 47) ng · ml−1,P 〈 0.01], and was still lower than basal levels 48 h after exercise during H [204 (SD 44) ng · ml−1,P 〈 0.01]. Linear regression analysis yielded no significant correlation between increase in plasma [hGHtot] or [hGH20kD] during exercise and the plasma IGF I concentration after exercise. It was concluded that the exercise-associated elevated plasma [hGH] did not increase the hepatic IGF I production. From our study it would seem that the high energy demand during and after the long-lasting intensive exercise may have overridden an existing hGH stimulus on plasma IGH I, which was most obvious during hypoxia.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    European journal of applied physiology 58 (1989), S. 699-704 
    ISSN: 1439-6327
    Keywords: Testosterone ; Δ4-androstenedione ; DHEA ; DHEA-SO4 ; LH ; FSH ; Anxiety ; Exertion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary This study evaluates the relationship between trait anxiety and both androgen and gonadotrophic hormone levels at rest and during severe physical exercise. Twelve volunteers were selected among 160 untrained male collegial students and classified as anxious (N=6) or non-anxious (N=6) subjects according to their scores on three trait-anxiety tests (STAI, IPAT, 16 PF). Serum Δ4-androgen (testosterone and Δ4-androstenedione), Δ4-androgen (DHEA and DHEA-SO4) and gonadotrophin (LH and FSH) concentrations were measured by radioimmunoassay before, during and after 20 minutes of intensive bicycle exercise (80% of maximal heart rate). Results indicate significantly lower serum Δ4-androgens in anxious subjects before exercise. However, for each subject and irrespective of his anxiety level, all measured serum androgen concentrations increased significantly during exercise, although Δ4-androstene-dione remained lower in anxious subjects than in non-anxious ones. Serum LH concentrations (but not FSH) were signicantly higher in anxious subjects throughout the observation periods. However, exercise induced in each subject a significant decrease in the serum level of both gonadotrophic hormones. The results suggest that trait anxiety level may constitute an important factor that affects both pre-exercise and exercise serum androgen concentrations in untrained subjects.
    Type of Medium: Electronic Resource
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