The Influence of Muscle Flexibility Training on Chronic Pain in Older Adults: An Exploratory Systematic Review

Background/Objectives: This exploratory systematic review aims to analyze the influence of isolated muscle flexibility training on the reduction of chronic pain symptoms in older adults aged 65 years or more. Articles were selected from the Web of Science, PubMed, and Scopus databases, using the EndNote software for reference management. The selection process followed the PICOS framework and the PRISMA 2020 guidelines, and the review protocol was registered in the PROSPERO database. Methods: The inclusion criteria comprised randomized controlled trials with participants aged 65 or older, evaluating the effect of flexibility training as a standalone intervention on chronic pain, and published in English or Portuguese. Studies were excluded if they involved multimodal training, did not specify participants' ages, evaluated only acute or postoperative pain, or were not peer-reviewed articles. Results: From an initial pool of 1390 articles, only three met all criteria and were included in the final analysis. These studies-conducted in China (n = 2) and the United States (n = 1)-showed moderate methodological quality (PEDro score = 7/10). Two trials applied Proprioceptive Neuromuscular Facilitation (PNF) in participants with knee osteoarthritis, while the third compared a flexibility-based program to combined strength and aerobic training in a healthy elderly population. All studies reported significant reductions in chronic pain symptoms following flexibility training interventions. Conclusions: The reviewed evidence suggests that muscle flexibility training, particularly using techniques like PNF, may be a promising therapeutic strategy to mitigate specific chronic pain-related symptoms in older adults, particularly reductions in joint stiffness, movement discomfort, and pain intensity associated with osteoarthritis. However, the limited number of high-quality trials and heterogeneity in protocols and pain assessment tools highlight the need for further research.