The effects of exercise training on muscle oxygenation of patients with intermittent claudication

Abstract Funding Acknowledgements Type of funding sources: None. Background. Intermittent claudication (IC) is characterized by a cramp-like pain during walking caused by insufficient blood flow to the lower limbs during exercise. The walking impairment caused by IC can lead to a vicious cycle of physical inactivity, decreased quality of life and progression of cardiovascular risk factors. Although current evidence supports the benefits of walking training to increase walking capacity, little is known about its effect on muscle oxygenation in this population. Purpose. The aim of this study was to investigate the effects of a hybrid 12-week walking program (combined center- and home-based walking) on muscle oxygenation of IC patients. Methods. Thirty-seven patients with IC were enrolled of which 33 completed follow-up measurements (age 71 ± 9 yrs, body mass index 26 ± 4 kg/m2, ankle brachial index (ABI) 0.7 ± 0.2) after the 12-week intervention. Outcome measures were pain-free walking capacity (PFWC), maximal walking capacity (MWC) and calf muscle oxygenation, respectively evaluated using a submaximal treadmill test, a Gardner treadmill test and near-infrared spectroscopy (NIRS). Results. After the 12-week intervention, significantly higher values (reported as median and interquartiles) for PFWC (162 m [122, 217] to 272 m [150, 401]; p < 0.001) and MWC (458 m [260, 638] to 611 m [333, 840]; p < 0.001) were observed. As shown in Table 1, NIRS data measured during the submaximal walking test showed an increased availability of oxygenated hemoglobin (p = 0.048) and decreased deoxyhemoglobin (p = 0.013), while total hemoglobin remained unchanged after the 12-week intervention. During the Gardner test, time to reach minimum tissue saturation index (TSI%) increased (p < 0.001), yet no change was noted on minimum TSI during exercise, despite increased MWC. Despite a trend towards faster recovery times, no significant changes were observed after the 12-week intervention. Conclusion. Hybrid walking exercise therapy improves deoxygenation kinetics and walking capacity in IC patients. Increased availability of oxygenated hemoglobin might underly the improvement in walking capacity.