Does increasing steps per day predict improvement in physical function and pain interference in adults with fibromyalgia

Fibromyalgia (FM) is a complex multidimensional disorder characterized by chronic diffuse musculoskeletal pain, fatigue, disturbed sleep, and a reduced quality of life (1). The primary symptoms of FM are likely responsible for precipitating secondary indicators of the disease, including impaired functional ability (2), reduced physical activity participation (3), and below average exercise capacities (4). Medications are only beneficial in a minority of patients, often expensive, not available to everyone, and are sometimes not well tolerated (5). Consequently, an increasing amount of attention has been placed on self-management, non-pharmacological treatment strategies designed to help patients with FM achieve and maintain long-term symptom relief (6, 7). Physical activity and exercise are strongly recommended adjunct components in the overall medical management of FM (8–10). However, in order to sufficiently elucidate the relationship between increased physical activity and the subsequent improvement in clinical outcomes, a valid and reliable measure of physical activity is necessary. Objective monitoring of physical activity using accelerometry technology overcomes some of the limitations associated with subjective measures (e.g. recall error) and currently provides the most accurate and efficient means of documenting both the quantity and quality of physical activity within a given population. However, despite the enormity of data that actigraphy can provide, accelerometry use for clinical applications may not be highly valued by physicians (or patients) since they are relatively expensive, require additional time and expertise to manipulate the data, and the interpretation of the data is not necessarily straightforward or clinically intuitive. In recent years, the assessment and interpretation of the number of steps taken per day (steps/day) has gained increased acceptance by both researchers and healthcare professionals as a clinically relevant metric to use for the classification of a “sedentary lifestyle” and for prescribing step-based physical activity recommendations (11, 12). Categories of step-defined sedentary behavior (<5,000 steps/day) and different levels of physical activity (low active: 5,000–7,499; somewhat active: 7,500–9,999; active: 10,000–12,499; and highly active ≥12,500) have been developed and validated (11). Walking is the most frequently reported leisure-time activity among the general population (13) and is regarded as having the greatest likelihood of becoming a sustained exercise program in FM (14). In this regard, measurement of steps/day offers an easily understood, objective metric of daily physical activity that may provide clinically important information regarding the relationship between walking behavior and improvement in key health outcomes in FM. Therefore, the main purpose of this paper was to examine the relationship between steps/day and self-report measures of physical function and pain symptoms in adult patients with FM. In our recently completed randomized clinical trial that evaluated the efficacy of motivational interviewing (MI) to increase physical activity participation in adults with FM, an objective measure of physical activity (actigraphy) was included as part of the overall assessment (15). In this trial, both intervention groups received a structured exercise prescription at the onset of the study, but only one group was given MI, which we hypothesized would increase adherence to the prescribed exercise program and increase overall levels of voluntary physical activity. Actigraphy was used as a secondary outcome measure to objectively measure the quantity and quality of physical activity performed. The specific aims of this paper were to: 1) examine the concurrent relationship between the change in the number of steps/day and improvement in physical function and pain symptoms; and 2) examine the predictive association between the change in the number of steps/day and subsequent changes in physical function and pain symptoms. Our primary hypothesis was that patients with FM who increased the number of steps/day would report greater improvement in physical function and pain symptoms. Our secondary hypothesis was that the change in the number of steps/day would predict better outcomes in terms of physical function and pain symptoms.