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Volume 45 Number 7, 2008
   Pages 1091 — 1102

Abstract - Effects of acute leg ischemia during cycling on oxygen and carbon dioxide stores

Jack A. Loeppky, PhD;1* Burke Gurney, PhD;2 Milton V. Icenogle, MD3

1Research Service, Department of Veterans Affairs Medical Center (VAMC), Albuquerque, NM; 2Department of
Orthopaedics and Division of Physical Therapy, University of New Mexico Health Sciences Center, Albuquerque, NM; 3Cardiology Section, VAMC, Albuquerque, NM

Abstract — This study estimated changes in whole body oxygen stores (O2s) and carbon dioxide stores (CO2s) during steady state exercise with leg ischemia induced by leg cuff inflation. Six physically fit subjects performed 75 W steady state exercise for 15 min on a cycle ergometer. After 5 min of exercise, cuffs on the upper and lower legs were inflated to 140 mmHg. Cuffs were deflated after 5 min and exercise continued for another 5 min. O2 uptake symbol for vo2 uptake and CO2 output symbol for co2 output significantly increased during the first 30 s after inflation, significantly decreased between 60 and 90 s, and then rose linearly until deflation. O2 uptake and CO2 output significantly increased further after cuff deflation, peaking between 30 and 60 s and then returned to near baseline exercise levels. Model-estimated changes in total O2s and CO2s were compared with time-integrated store changes from O2 uptake and CO2 output. During 5 min after cuff deflation, O2 uptake and  CO2 output exceeded the model-estimated change in stores by 273 and 697 mL, respectively. These results reflect the O2 cost repayment of the anaerobic component and lactate buffering to neutralize circulating metabolites caused by the preceding ischemia.

Key words: anaerobic exercise, bicarbonate buffering, carbon dioxide stores, ergoreflex, ischemia, lactate, oxygen deficit, oxygen stores, rehabilitation, ventilation/perfusion ratio, ventilation response.


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