Association of low back pain with muscle weakness, decreased mobility function, and malnutrition in older women: A cross-sectional study

Background Low back pain (LBP) and decreased mobility function are common problem among older people. Muscle weakness has been reported as a risk factor for these conditions, and exercise therapy can improve them. We created a novel exercise device that also measures abdominal trunk muscle strength. Malnutrition has also emerged as a major problem among older people. Muscle is a direct key linking decreased mobility function and malnutrition. This study aimed to examine the associations of LBP with not only decreased physical function and muscle weakness but also nutritional status of older people. Methods We examined the associations of LBP with muscle weakness, decreased mobility function (locomotive syndrome [LS]), and malnutrition among older women. The study included 101 female patients aged 60 years or older scheduled to undergo surgery for degenerative lower extremity diseases. Preoperatively, physical tests including abdominal trunk muscle strength assessment using the device and laboratory tests were conducted. Subjects with LBP (numerical rating scale >= 2; range, 0-4) during the preceding month were allocated to the LBP group (n = 36). Other subjects were allocated to the non-LBP group (n = 65). Results The LBP group had lower abdominal trunk and knee extensor muscle strength, lower serum albumin, and hemoglobin levels as blood biomarkers associated with malnutrition risk, and higher LS test scores than the non-LBP group. A multivariate analysis showed that abdominal trunk muscle weakness and advanced LS were associated with LBP. LBP intensity was negatively correlated with abdominal trunk and knee extensor muscle strength and positively correlated with the LS test score. The serum hemoglobin level was negatively correlated with the LS test score. Conclusion Abdominal trunk muscle weakness and decreased mobility function were associated with LBP among older women.