Abstract 13331: Novel Near-Infrared Spectroscopy-Guided Treadmill Exercise Training Associated with Improvements in Claudication Among Subjects with Peripheral Arterial Disease
Introduction: Supervised exercise treadmill is a recommended therapy for claudication in peripheral arterial disease (PAD). While repetitive claudication during exercise improves symptoms, the mechanisms of benefit are not well understood and the technique is poorly tolerated. Near infrared spectroscopy (NIRS) allows for real-time assessment of skeletal muscle blood flow during exercise and can be used as measure of tissue hypoxia. Moreover, in health and in PAD, NIRS-derived post-exercise recovery of muscle oxygen consumption fit to a mono-exponential curve yields a time constant (Tc) that is an index of mitochondrial capacity.
Methods and Results: We devised a novel supervised treadmill exercise training program wherein subjects with claudication from PAD trained thrice weekly for hour-long sessions over a 12 week period. Exercise intensity was determined by 15% reduction in resting skeletal muscle oxygenation by NIRS rather than by symptoms of pain. We randomly assigned subjects to NIRS-guided training (n=6, age 68.5±8.5, 33% female) versus traditional pain-based training (n=7, age 71.2±9.1 years, 29% female). Training cohorts were similar in baseline ankle-brachial index (0.8±0.2 vs. 0.8±0.3, p=NS) and baseline symptom-free walking time on a Gardner graded treadmill test (3.5±1.8 vs. 1.7±0.9 min, p=NS). At the completion of 36 training sessions, NIRS-trained subjects demonstrated similar improvements in symptom-free walking time (mean 7.3±3.3 vs 6.3±3.5 min at 12 week follow up, p<0.01 for change from baseline and p=NS between cohorts) as the traditional pain-based cohort. The NIRS-guided cohort reported lower claudication pain scores during training than controls (mean 2.0±1.5 vs 3.7±2.5 out of 10, p=0.06). In both NIRS-guided and pain-guided cohorts, measure of ABI was unchanged while mitochondrial oxidative capacity (Tc) improved (96.1±.0 to 50.0±8.8 sec, 75.2±43.0 to 59±21.0 sec, respectively; p<0.01 compared to baseline).
Conclusions: NIRS-guided treadmill exercise training leads to improvements in claudication comparable to that seen with traditional pain-based training regimens. Adaptations in mitochondrial oxidative capacity rather than improved tissue perfusion may account for improved walking times.
Author Disclosures: J. Murrow: None. J. Brizendine: None. B. Djire: None. H. Young: None. K.K. McCully: None.
This research has received full or partial funding support from the American Heart Association
- © 2014 by American Heart Association, Inc.