Effects of Exercise Training on Calf Tissue Oxygenation in Men With Intermittent Claudication

ObjectiveTo determine the effects of exercise training on calf tissue oxygenation in men with peripheral arterial disease and intermittent calf claudication.DesignThis pilot study was prospective and longitudinal and used a one-group, pretest-posttest design.SettingTertiary care medical center for veterans.ParticipantsFifteen male veterans (mean age 69 years) with Fontaine stage IIa peripheral arterial disease and classic intermittent claudication.Main Outcome MeasurementsBefore and after intervention, participants performed graded treadmill exercise tests while medial calf tissue oxygenation (StO2, % oxyhemoglobin saturation) was monitored continuously with near-infrared spectroscopy.InterventionThe intervention consisted of a 3-month exercise training program involving 3 sessions per week at the clinic (treadmill walking, calf ergometry) and 2 sessions per week at home (free walking, standing heel raises).ResultsAfter completion of the intervention, participants significantly increased their maximal treadmill exercise time from 7.19 to 11.27 minutes. Mean exercise StO2 decreased from 29% to 19% saturation, StO2 × time area increased from 421% · min to 730% · min StO2 nadir, and StO2 recovery time did not change significantly.ConclusionsAfter the exercise intervention, the improved treadmill walking performance was accompanied by greater calf tissue deoxygenation during exercise. Given the continued presence of ischemia, this finding may represent increased capillarization and diffusion-based enhancement of arteriovenous O2 extraction.