Physical activity and endogenous pain modulation in older people: a scoping review

This scoping review aimed to explore and summarize studies investigating the relationship between physical activity and endogenous pain modulation in older people, using conditioned pain modulation as an assessment tool.

Pain is a common problem in older adults and significantly affects their quality of life. While physical activity is widely recommended as a non-pharmacological strategy to mitigate pain, the mechanisms underlying its potential analgesic benefits are not completely understood. One possible mechanism may be related to the influence of physical activity on endogenous pain modulation. This review focused on i) the different types of physical activity in relation to endogenous pain modulation in older adults; ii) the protocols applied to assess this relationship, particularly those using conditioned pain modulation; and iii) existing knowledge gaps requiring further research or interventions adapted for older people with pain.

Studies were included if they examined people aged 60 years or older, investigating physical activity as an intervention and its relationship with pain modulation, and used conditioned pain modulation as an outcome measure. Studies that did not use this outcome, or studies that included younger populations without subgroup analysis, were excluded.

The review followed the JBI methodology for scoping reviews. A comprehensive search was conducted across MEDLINE (Ovid), CINAHL (EBSCOhost), Embase (Embase.com), Cochrane Database of Systematic Reviews, Web of Science, the JBI EBP Database (Ovid), PsycINFO (Ovid), and PEDro. Gray literature was also searched (ProQuest, OpenGrey, DART-Europe E-theses Portal, WHO International Clinical Trials Registry Platform, ClinicalTrials.gov, BASE). The searches covered studies published from 2000 to 2024 with no language or geographic restrictions. Two reviewers independently conducted eligibility screening and data extraction. The results were organized narratively and presented using summary tables and figures.

A total of 1717 articles was identified through database searches, and an additional 131 from gray literature sources. After screening titles and abstracts, and assessing full texts against the eligibility criteria, 6 studies were included in the review. Participants were older adults, generally between 60-75 years of age, and 4 of the studies focused specifically on people with knee osteoarthritis. The studies described a range of physical activity formats, including acute isometric or aerobic exercise protocols, longer-term exercise programs, and habitual physical activity measured through accelerometry. Conditioned pain modulation was investigated using varied methodological approaches, including different test and conditioning stimuli, anatomical application sites, sequences, and calculation strategies. Across the included literature, the conceptualization of physical activity and endogenous pain modulation differed substantially, as did reporting of intervention characteristics. Commonly reported limitations included small sample sizes, methodological heterogeneity, restricted study populations, and limited detail on how physical activity interventions were adapted for older participants.

The variability in methodologies across studies underscores the need to standardize pain modulation protocols before applying them more broadly to older adults, a population with added complexities and age-related factors that challenge result interpretation. Future research should aim to refine recommendations by developing tailored physical activity interventions for older adults, with particular attention to feasibility and adherence in this population.

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