Influence of a beta2-agonist on physical performance at low temperature in elite athletes.

Beta2-agonists are frequently used by elite cross-country skiers, a group of athletes with a high prevalence of asthma. It has been claimed that beta2-agonists have a positive effect on physical performance. The aim of the present study was to investigate whether inhalation of a beta2-agonist increases physical performance at low temperature in healthy, nonasthmatic athletes with normal bronchial responsiveness. Twenty elite male athletes (cyclists, cross-country skiers, middle and long distance runners) with no history of allergy or airway disease and who had normal spirometry and methacholine bronchial provocation tests performed a maximal exercise test on a treadmill in a climate chamber at approximately 10 degrees C on two subsequent days. Before exercise they inhaled terbutaline (3 mg from MDI) or placebo in a randomized, single blind manner. After 10-min warm-up on the treadmill, a submaximal work preceded a stepwise increase of the workload until exhaustion. Lung function, ventilation, oxygen uptake, and heart rate were determined and blood samples for lactate and potassium analyses were drawn before, during, and after exercise. Terbutaline induced a significant bronchodilatation; FEV1 increased from 4.8 (4.4-5.1) L to 5.0 (4.6-5.4) L, mean (95% CI). There were no significant differences between the two treatments with regard to exercise time, 25.1 (24.3-25.8) min vs 24.9 (24.1-25.6) min, oxygen uptake and ventilation during exercise, or heart rate at maximal workload. Terbutaline induced an increase in serum lactate concentration but did not influence the lactate response to exercise. The serum potassium increase was attenuated at low workload but not at maximal work. The postexercise decrease in serum potassium concentration was significantly greater after terbutaline (-0.52 (-0.29 to -0.76) mmol x L-1) than after placebo (-0.13 (0.06 to -0.32) mmol x L-1 (P < 0.001). We conclude that inhalation of a beta2-agonist (terbutaline) in a dose that yields significant bronchodilatation does not influence physical performance at low temperature in healthy athletes. Acute inhalation of the beta2-agonist amplified the postexercise hypokalemia, a finding of unclear significance. Although there is a slight bronchodilatation and potential negative airways effect of cold air inhalation, a beta2-agonist does not increase physical performance in top athletes.

High prevalence of asthma in cross country skiers.

OBJECTIVES: To study the prevalence of asthma (asthma symptoms and bronchial hyperresponsiveness) in Swedish cross country skiers compared with non-skiers and monitor changes in symptoms and bronchial hyperresponsiveness during the year. DESIGN: Cross sectional study during the winter ski season and in the summer. SETTING: Six ski clubs for élite skiers (total 47) in two different areas of Sweden. SUBJECTS: 42 élite cross country skiers and 29 non-skiing referents. MAIN OUTCOME MEASURES: Bronchial responsiveness, asthma symptoms, and lung function. RESULTS: Bronchial responsiveness was significantly greater and asthma symptoms more prevalent in the skiers than in the referents. There was no difference in bronchial responsiveness within either group between winter and summer. 15 of the 42 skiers used antiasthmatic drugs regularly and 23 had a combination of asthma symptoms and hyperresponsive airways or physician diagnosed asthma, or both. Altogether 33 skiers had symptoms of asthma or bronchial hyperresponsiveness. One of the referents had symptoms of asthma and bronchial hyperresponsiveness, and none used antiasthmatic drugs regularly. CONCLUSIONS: Asthma, asthma-like symptoms, and bronchial hyperresponsiveness are much more common in cross country skiers than in the general population and non-skiers. Strenuous exercise at low temperatures entailing breathing large volumes of cold air is the most probable explanation of persistent asthma in skiers.

Extrapancreatic effects of a sulphonylurea. Decrease in xylose absorption by glipizide in type II diabetics.

The effects of glipizide on the absorption of glucose and d-xylose were studied in six type II diabetics on diet treatment alone. Glipizide was given intravenously (12 micrograms/kg at 0 min) or orally (5 mg at -30 min). Oral glucose (15 g) and xylose (25 g) loads were given at zero time. Glipizide stimulated insulin secretion and reduced glucose and xylose levels significantly with both routes of administration. The suppression of xylose levels lasted longer after oral than after intravenous administration of the drug. It is suggested that part of the influence of glipizide on postprandial glucose levels may represent interference with absorptive mechanisms.

Plasma cortisol following injection of 1-39 or 1-18 ACTH.

Forty units of 1-39 ACTH of animal origin or 0.4 mg of synthetic 1-18 ACTH administered at 8 A.M. via either the intramuscular route to 10 subjects with intact adrenocortical function produced comparable increases in plasma cortisol at 1, 2, and 6 hours. The increase in plasma cortisol lasted at least 6 hours but less than 12 hours after intravenous crystalline 1-39 ACTH and at least 16 hours but less than 24 hours after the same dose of 1-39 ACTH administered as a depot gel via the intramuscular route. However, neither intravenous nor the intramuscular injection of 1-39 ACTH produced increases that were still evident at 24 hours. Following either the intramuscular or intravenous injection of 0.4 mg of the synthetic 1-18 ACTH, the plasma cortisol increase was still evident at the 24th hour. Our findings indicate that the plasma cortisol responses to either 40 units of exogenous 1-39 ACTH of animal origin or to 0.4 mg of a synthetic 1-18 ACTH are most consistent in the first 6 hours following either intravenous or intramuscular injection.

Discrepancies between glycosuria and home estimates of blood glucose in insulin-treated diabetes mellitus.

Glycosuria can be a misleading indicator of blood or plasma glucose levels. Thus glycosuria may be present when blood glucose levels are within the normal fasting or postprandial range, and it may be absent when the blood glucose is distinctly above normal. In such patients the blood glucose must be measured, preferably by the patient, as a guide to insulin and other therapy. However, urine glucose tests are valid indicators in a minority of patients and are essential in all patients for the detection of acetone.

Parameters of good control in diabetes mellitus.

Optimal control of diabetes should achieve not only euglycemia and normal levels of glycosylated hemoglobin but also absence of the reversible concomitants of diabetes such as red cell rigidity, hyperlipidemia, increased capillary permeability, enlargement of the kidneys, proteinuria, etc. Unfortunately, in most patients consistent euglycemia cannot be assured even with two daily injections of insulin. However, self-measurement of blood glucose as a guide to insulin taken before each meal and at bedtime can, in selected patients, increase the frequency of normal glucose levels without undue hypoglycemia.

Diabetic complications and their prevention or reversal.

Patients with Type I, i.e., insulin-deficient diabetes, Type II or non-insulin-deficient diabetes, and impaired glucose tolerance or so-called chemical diabetes are variably predisposed to develop macroangiopathy, i.e., atherosclerosis, microangiopathy or basement membrane thickening, and neuropathy. Once these morphologic changes appear, they in all probability will remain irreversible even when precise regulation is attained. Hence prevention is the only realistic goal.