PURPOSE This study aimed to investigate the effects of an 8-week unstable surface Pilates training on physical fitness, abdominal muscle thickness, lumbar isokinetic muscle function, and pain in women aged 30–40 who are living a sedentary lifestyle and experiencing nonspecific low back pain. METHODS The training group (TR, n = 15) performed Pilates using small apparatuses on an unstable surface for 50 min/session, three sessions per week for 8 weeks, whereas the control group (n = 13) maintained their usual living pattern during the same intervention period. RESULTS 1) The body weight, body mass index, percent body fat, and fat mass decreased significantly in the TR, 2) whereas the hand grip strength, trunk extension, sit-andreach, and modified Schober test scores improved significantly. 3) The thickness of the external oblique, internal oblique, and transversus abdominis increased significantly in the TR. 4) Lumbar isokinetic flexor strength per body weight increased significantly in the TR. The endurance and endurance per body weight of the lumbar isokinetic extensor and lumbar isokinetic flexor also significantly increased in the TR. 5) The Korean Oswestry disability index (KODI) and the visual analog scale (VAS) score decreased significantly in the TR. 6) Significant negative correlations were found between the change rates in the KODI and nondominant hand grip strength, external oblique thickness, transversus abdominis thickness, and lumbar isokinetic extensor endurance. A significant negative correlation was found between the change rates in the VAS score and external oblique thickness. CONCLUSIONS The results revealed that the 8-week unstable surface Pilates training was beneficial in improving physical fitness, abdominal muscle thickness, lumbar isokinetic muscle function, disabilityindex, and pain levels in women aged 30–40 years who were having a sedentary lifestyle and experiencing nonspecific low back pain.
