ABSTRACT
The study was designed to find out (1) whether the effect of 3-day bed rest on blood glucose (BG) and plasma insulin (IRI) responses to glucose ingestion depends on preceding physical activity and (2) whether plasma adrenaline (A), noradrenaline (NA) and cardiovascular changes following a glucose load are modified by bed rest. Eleven sedentary students (22.5+/-0.3 yrs), 8 long distance runners (18.6+/-0.3 yrs) and 10 strength trained athletes (21.2+/-2.1 yrs) were examined before and after bed rest. Plasma IRI, BG, NA, A, heart rate (HR), and blood pressure (BP) were measured during 2 hrs following glucose (75 g) ingestion. The responses of BG and IRI to glucose load were calculated as incremental areas under the curves (auc). Both in athletes and untrained subjects bed rest markedly increased IRIauc, while BGauc was elevated only in sedentary subjects (p<0.05). The greatest increases in IRIauc and IRI/BG ratios were found in the endurance athletes. The data from all subjects (n = 29) revealed that the initial plasma NA and glucose-induced increases in NA and A were lowered after bed rest (p < 0.01). These effects were most pronounced in the endurance athletes. Bed rest did not influence HR or BP in any group. It is concluded that (1) the athletes have more adequate compensation for the bed-rest-induced decrement in insulin sensitivity than sedentary men; (2) three-day bed rest diminishes basal sympathetic activity and attenuates sympathoadrenal response to oral glucose; (3) endurance athletes have greater sympathetic inhibition than strength athletes or sedentary men.
Subject(s)
Bed Rest , Blood Circulation/drug effects , Hormones/blood , Metabolism/drug effects , Physical Education and Training , Physical Endurance/physiology , Administration, Oral , Adolescent , Adult , Blood Glucose/analysis , Blood Pressure/drug effects , Glucose/administration & dosage , Glucose/pharmacology , Glucose Tolerance Test , Heart Rate/drug effects , Humans , Insulin/blood , Reference Values , Time FactorsABSTRACT
NASA: Circulatory and hormonal parameters were measured in endurance-trained athletes and control subjects during orthostatic tolerance tests conducted prior to and after three days of bed rest. Heart rate and blood pressure changes due to bed rest appeared to be the same in both groups. Hormonal changes, however, were different between the two groups, with the athletes having decreased sympathoadrenal activity and increased plasma renin activity. Untrained subjects had changes in cortisol secretion only.^ieng
Subject(s)
Bed Rest/adverse effects , Hormones/blood , Hypotension, Orthostatic/physiopathology , Physical Endurance/physiology , Physical Fitness/physiology , Adolescent , Adult , Blood Pressure/physiology , Catecholamines/blood , Catecholamines/metabolism , Epinephrine/blood , Epinephrine/metabolism , Heart Rate/physiology , Hormones/metabolism , Humans , Hydrocortisone/blood , Hydrocortisone/metabolism , Hypotension, Orthostatic/etiology , Male , Norepinephrine/blood , Norepinephrine/metabolism , Renin/blood , Renin/metabolism , Running/physiologyABSTRACT
NASA: Endurance trained long distance runners and untrained individuals underwent three days of bed rest and oral glucose loading. Before and after bed rest, individuals were given glucose tolerance tests, and their heart rates, blood pressure, blood glucose levels, insulin levels, and catecholamine interactions were measured. Results indicated that glucose tolerance is more affected by bed rest-induced deconditioning in untrained individuals than in trained individuals.^ieng
