THE EFFECTS OF ACTIVITY AND BED REST ON TISSUE OXYGEN-TENSION, PERFUSION, AND PLASMA-VOLUME

An experimental study with a crossover design was used to compare the effects of activity and bed rest on subcutaneous oxygen (PscO2), perfu sion (BFsc), and plasma volume, and to explore the relationship of car diovascular fitness to these variables. Fifteen healthy males were ran domized to bed rest or activity and later completed the remaining prot ocol. Exercise prescription for the activity protocol and cardiovascul ar fitness were based on a treadmill performance test. Repeated measur ements were made of subcutaneous oxygen and temperature using an optod e in upper arm subcutaneous tonometers. Perfusion and PscO2 were great er during bed rest (p < .05). Post boc analysis revealed a trend towar d higher heart rates and diastolic blood pressure during the activity protocol. Change in plasma volume did not differ between protocols, an d cardiovascular fitness was unrelated to PscO2 or BFsc. Findings sugg est that in uninjured individuals, higher levels of activity intensity reduce oxygen levels and blood flow in peripheral tissues.