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Unformatted text preview: Kinesiology 314: Cardiovascular Deconditioning & Microgravity Detraining/Bedrest When trained: Decreased Max HR Increased BV and SV Increased CO Increased VO2 max Detraining? VO2 MaxBedrest vs detraining McGuire 2001 2030% 515% Detraining: Blood volume
Submax Exercise Max Exercise Detraining: Cardiac Output and SV Longer detraining Detraining: HR and AVO2 Diff Detraining: Muscle Shortterm detraining summary
Increased HR Decreased BV and SV Decreased CO Similar AV02 Diff Decreased VO2 max Increased HR Decreased BV and SV Decreased CO Decreased AV02 Diff Decreased aerobic enzymes/increased glycolytic enzymes Decreased VO2 max Difference between detraining and bedrest is RATE of change Spaceflight/Microgravity/Bedrest Bedrest Bedrest is severe detraining Headdown tilting is severe bedrest HDT leads to "cephalic fluid shift" Fluid shifts and vascular remodeling HLU: VO2 and HR HLU: Rat Muscle Atrophy21 days HLU: Muscle blood flow <10min Vascular control after HLU Less "metabolic vasodilation" in some skeletal muscles Vascular remodeling with HLU Endothelial function Protein changesNO synthase
Mechanisms?? Vasoconstrictor responses to microgravity: Recovery! HLU: Bone loss Microgravity: Orthostatic tolerance Summary Microgravity/Bedrest Maintained VO2 max while in space Decreased VO2 max on return 40% demonstrate orthostatic intolerance (ex?) Decreased BV/PV Decreased SV, CO Increased HR (submax) Vascular remodeling/dysfunction Stimulus for change (fluid shift/shear?) ...
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- Spring '08