Relationship Between Muscle Oxygen Saturation and Exercise Load in Patients with Malignant Hematopoietic Disease

Our previous research confirmed that patients with malignant hematopoietic disease already had a low hemoglobin level before allogeneic hematopoietic stem cell transplantation (allo-HSCT). However, no study has determined whether a correlation exists between exercise load, hemoglobin level, and muscle oxygen saturation (SmO₂), during exercise. Therefore, the purpose of this study was to investigate whether near-infrared spectroscopy (NIRS)-derived SmO₂ is associated with exercise load, as determined by a dynamometer, before allo-HSCT. This study included 19 male patients who received allo-HSCT in Hyogo College of Medicine Hospital (Japan) between November 2009 and October 2012. Patients performed isometric repeated dorsiflexion at 50% maximum voluntary contraction for 180 s to determine exercise load, and SmO₂ was evaluated during exercise at the same time using NIRS (BOM-L1TRW, Omega Wave, Inc., Japan). The hemoglobin level was also evaluated before allo-HSCT. Patients with hematopoietic disease before allo-HSCT already had a low hemoglobin level. There was a significant correlation between exercise load and ∆SmO₂; however, the hemoglobin level was not correlated with exercise load. In these patients, exercise load might be affected by muscle oxygen consumption rather than by the hemoglobin level. This finding shows that NIRS can used to assess fatigue in patients with malignant hematopoietic disease.