To examine the relationship between handgrip strength and leg extension power, walking speed, and intermittent claudication for lumbar spinal stenosis (LSS) using computed tomography. We examined patients who underwent laminectomy for LSS from June 2015 through March 2018. Before spine surgery, we evaluated walking distance, handgrip strength, leg extension power (LEP), 10-m walk test (time and steps), psoas muscle index (PMI), and the area of both total and multifidus muscle using plain computed tomography imaging at the third lumbar level. Handgrip strength was compared with comorbidities including anemia, diabetes, hypertension, marital status, etc. RESULTS: There were 183 patients (55 female, 128 male) with a mean age of 70.5 years. Handgrip strength significantly correlated with LEP (P < 0.001, r = 0.723), walking speed (P < 0.001, r = - 0.269), 10-m walking test (steps) (P < 0.001, r = - 0.352), area of skeletal muscle at L3 level (P < 0.001, r = 0.469), area of psoas muscle (P < 0.001, r = 0.380), PMI (P < 0.001, r = 0.253), and intermittent claudication. Age, height, and weight were correlated with handgrip strength, but BMI was not correlated. Handgrip strength was significantly reduced by anemia, hypertension, and single marital status. The more handgrip strength patients with LSS have, the more LEP, the faster walking speed, the greater area of psoas and skeletal muscle, the fewer steps for a 10-m walk they have, and the longer walking distance. Age, height, and weight were associated with handgrip strength, but BMI has no association. Low handgrip strength was related to comorbidities including anemia, hypertension, and marital status.