Different weekly frequencies of Pilates did not accelerate pain improvement in patients with chronic low back pain.

• Different weekly frequencies of Pilates did not accelerate pain improvement. • Most patients reduced pain in 30% and 50% after the first week of treatment. • Most patients reported complete pain improvement after the last week of treatment. Recent evidence recommends Pilates for the treatment of chronic low back pain. However, it is still unknown if different weekly frequencies of Pilates can accelerate the improvement of symptoms in patients with chronic low back pain verified by a daily pain assessment. To analyze whether different weekly frequencies of Pilates can accelerate pain reduction by 30%, 50%, and 100% in patients with non-specific chronic low back pain and the necessary number of weeks to reach these improvements. Two hundred and twenty-two patients were randomized into three groups: Pilates group 1 received treatment once a week, Pilates group 2 received treatment twice a week, and Pilates group 3 received treatment three times a week. All groups received Pilates for six weeks. Pain intensity was measured daily before and after each intervention session using the Pain Numerical Rating Scale. The assessor was not blind. The survival analysis showed that all Pilates groups had a pain reduction of 30%, 50%, and 100% at the same speed during treatment. There was no difference between the different weekly frequencies of Pilates for any of the comparisons (p > 0.05). After the first week of treatment, 44.6% of the patients in Pilates group 3 showed complete pain improvement, followed by 37.8% of the patients in Pilates group 2 and 29.7% in Pilates group 1. After the last week, 71.6% (Pilates group 1), 77% (Pilates group 2), and 78.4% (Pilates group 3) of the patients reported complete improvement of symptoms. Different weekly frequencies of Pilates did not accelerate pain improvement in patients with non-specific chronic low back pain. Registered in Clinical Trials Registry: NCT02241538 (https://clinicaltrials.gov/ct2/show/NCT02241538).