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), perfusion (BFsc), and plasma volume, and to explore the relationship of cardiovascular fitness to these variables. Fifteen healthy males were randomized to bed rest or activity and later completed the remaining protocol. Exercise prescription for the activity protocol and cardiovascular fitness were based on a treadmill performance test. Repeated measurements were made of subcutaneous oxygen and temperature using an optode in upper arm subcutaneous tonometers. Perfusion and PscO2 were greater during bed rest (p < .05). Post hoc analysis revealed a trend toward higher heart rates and diastolic blood pressure during the activity protocol. Change in plasma volume did not differ between protocols, and cardiovascular fitness was unrelated to PscO2 or BFsc. Findings suggest that in uninjured individuals, higher levels of activity intensity reduce oxygen levels and blood flow in peripheral tissues.