title: Chronobiology of exercise: the influence of scheduling upon glycemic responses of control and of subjects with diabetes mellitus.
abstract: Exercise programs contribute significantly to: a) improve cardiovascular fitness; b) lower blood pressure in hypertension; and c) facilitate glycemic control in subjects with Diabetes Mellitus (DM). The mechanisms involved in promoting the above responses remain undetermined. Circadian phases at which exercise is applied could play a major role in optimizing the individual's physiological responses to exercise. In a pilot study, controls and a subject with Insulin Dependent Diabetes Mellitus (IDDM) were exercised at 0800 and 2000 hours: pedaling on an exercycle for 30 minutes at rates that maintained tachycardia at 70% of maximum reserve heart rates (Karvomen et al., 1957). All subjects were on "standard" rest-activity schedules (rest 2300-2400 to 0600-0700) and were allowed a single 360 ml Sustacal meal either at 2400 hours or at 1200 hours; i.e., 8 hours preceding the exercise program. Blood samples were obtained for determinations of glucose (finger tip) just before exercise (0 time) and at 10, 20, 30, 40 and 60 minutes of exercise/post exercise periods. The results suggest that non-diabetics experience a rapid decrease in blood glucose levels which does not recover during the 60 minute sampling time when exercise was in the morning. However, when these individuals exercised during the evening, glucose levels did not fall as much on a percentage basis and full recovery was obtained within 40-60 minutes. In the case of the diabetic patient, after morning exercise, glucose levels did not decline and after 40 minutes had risen above resting glucose levels.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Univ. of Tennessee, Memphis.
authors.forename: S S
authors.initials: SS
authors.lastname: Cardoso
authors.forename: R J
authors.initials: RJ
authors.lastname: Feuers
authors.forename: T H
authors.initials: TH
authors.lastname: Tsai
authors.forename: J D
authors.initials: JD
authors.lastname: Hunter
authors.forename: L E
authors.initials: LE
authors.lastname: Scheving
mesh_terms: D001786:Blood Glucose / Q000378:metabolism*; D002940:Circadian Rhythm / Q000502:physiology*; D003922:Diabetes Mellitus, Type 1 / Q000097:blood* / Q000188:drug therapy / Q000628:therapy; D004334:Drug Administration Schedule; D015444:Exercise / Q000502:physiology*; D005081:Exercise Therapy; D006801:Humans; D007328:Insulin / Q000008:administration & dosage
chemical_list: D001786:Blood Glucose; D007328:Insulin