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When It Hurts, a Positive Attitude May Help. The Moderating Effect of Positive Affect on the Relationship Between Walking, Depression, and Symptoms in Women with Fibromyalgia

Open AccessPublished:July 13, 2022DOI:https://doi.org/10.1016/j.pmn.2022.05.007

      Abstract

      Background: Increased exercise is a marker of health in fibromyalgia (FM). However, patients frequently avoid physical activity as a way of minimizing the pain they feel. This deprives them of opportunities to obtain positive reinforcement, increasing functional impact. Aims: This study examines the mediating role of depressive symptoms between walking (as physical exercise), functional impact, and pain, at different levels of positive affect (PA) among women with fibromyalgia. Design: Cross-sectional correlational study. Settings: Mutual aid associations for fibromyalgia in Spain. Participants: 231 women diagnosed with FM. Methods: Moderate mediation analyses were conducted using PROCESS. Results: First, a simple mediation model showed that depression mediated the effect of walking on functional impact, but not on pain. Additionally, the moderated mediated model showed that this effect was significant at medium and high levels of PA, but not when levels of PA were low. Conclusions: Provision of resources focused on positive affect seem to increase the positive effects of walking on functional impact through the reduction of depressive symptoms. Nurses can improve adherence of patients with FM to walking behavior through increasing positive affect.

      Keywords

      Abbreviations:

      FM (Fibromyalgia)
      Fibromyalgia (FM) is a chronic condition with no well-established etiology, typified by widespread musculoskeletal pain throughout the body (
      • Jobski K.
      • Luque Ramos A.
      • Albrecht K.
      • Hoffmann F.
      Pain, depressive symptoms and medication in German patients with rheumatoid arthritis-results from the linking patient-reported outcomes with claims data for health services research in rheumatology (PROCLAIR) study.
      ;
      • McDonald D.D.
      • Shellman J.M.
      • Graham L.
      • Harrison L.
      The relationship between reminiscence functions, optimism, depressive symptoms, physical activity, and pain in older adults.
      ;
      • Wolfe F.
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      • Katz R.S.
      • Mease P.
      • Russell A.S.
      • Russell I.J.
      • Winfield J.B.
      • Yunus M.B.
      The American College of Rheumatology Preliminary Diagnostic Criteria for Fibromyalgia and Measurement of Symptom Severity.
      ), that leads to changes in the individual's ability to function physically (
      • Catala P.
      • Lopez-Roig S.
      • Ecija C.
      • Suso-Ribera C.
      • Peñacoba Puente C.
      Why do some people with severe chronic pain adhere to walking prescriptions whilst others won't? A cross-sectional study exploring clinical and psychosocial predictors in women with fibromyalgia.
      ;
      • Suso-Ribera C.
      • Catalá P.
      • Ecija C.
      • Sanromán L.
      • López-Gómez I.
      • Pastor-Mira Á.
      • Peñacoba-Puente C.
      Exploring the contextual role of pain severity as a moderator of the relationship between activity patterns and the physical and mental functioning of women with fibromyalgia.
      ). Studies have identified several psychological and physical factors as potential determinants of FM severity (
      • Lee J.-W.
      • Lee K.-E.
      • Park D.-J.
      • Kim S.-H.
      • Nah S.-S.
      • Lee J.H.
      • Kim S.-K.
      • Lee Y.-A.
      • Hong S.-J.
      • Kim H.-S.
      • Lee H.-S.
      • Kim H.A.
      • Joung C.-I.
      • Kim S.-H.
      • Lee S.-S.
      Determinants of quality of life in patients with fibromyalgia: A structural equation modeling approach.
      ), having argued that functional impact should be conceptualized within a more comprehensive biopsychosocial perspective (
      • Sturgeon J.A.
      • Zautra A.J.
      Resilience: A new paradigm for adaptation to chronic pain.
      ), where health care professionals play an essential role (
      • Olivé Ferrer M.C.
      • Isla Pera M.
      El Modelo Watson para un cambio de paradigma en los cuidados enfermeros.
      ).
      An active lifestyle has been proposed as a resilience factor in FM (
      • Pulido-Martos M.
      • Luque-Reca O.
      • Segura-Jiménez V.
      • Álvarez-Gallardo I.C.
      • Soriano-Maldonado A.
      • Acosta-Manzano P.
      • Gavilán-Carrera B.
      • McVeigh J.G.
      • Geenen R.
      • Delgado-Fernández M.
      • Estévez-López F.
      Physical and psychological paths toward less severe fibromyalgia: A structural equation model.
      ), and it has shown that increased exercise is a marker of health in FM (
      • Castro-Piñero J.
      • Aparicio V.
      • Estévez-López F.
      • Álvarez-Gallardo I.
      • Borges-Cosic M.
      • Soriano-Maldonado A.
      • Delgado-Fernández M.
      • Segura-Jiménez V.
      The potential of established fitness cut-off points for monitoring women with fibromyalgia: The al-Ándalus Project.
      ;
      • Doerr J.M.
      • Fischer S.
      • Nater U.M.
      • Strahler J.
      Influence of stress systems and physical activity on different dimensions of fatigue in female fibromyalgia patients.
      ;
      • Esteve R.
      • López-Martínez A.E.
      • Peters M.L.
      • Serrano-Ibáñez E.R.
      • Ruíz-Párraga G.T.
      • González-Gómez H.
      • Ramírez-Maestre C.
      Activity pattern profiles: Relationship with affect, daily functioning, impairment, and variables related to life goals.
      ). One of the recommended primary treatments is to perform aerobic physical exercise, specifically walking (
      • O'Connor S.R.
      • Tully M.A.
      • Ryan B.
      • Bleakley C.M.
      • Baxter G.D.
      • Bradley J.M.
      • McDonough S.M.
      Walking exercise for chronic musculoskeletal pain: Systematic review and meta-analysis.
      ), because of its low musculoskeletal impact (
      • Gusi N.
      • Parraca J.
      • Adsuar J.
      • Olivares P.
      Ejercicio físico y Fibromialgia.
      ). Unfortunately, patients with FM rarely meet the guidelines for physical activity, including walking (
      • Peñacoba C.
      • Pastor M.-Á.
      • López-Roig S.
      • Velasco L.
      • Lledo A.
      Walking beliefs in women with fibromyalgia: Clinical profile and impact on walking behavior.
      ), and patients frequently avoid walking as a way of minimizing the pain they feel (
      • Lami M.J.
      • Martínez M.P.
      • Miró E.
      • Sánchez A.I.
      • Guzmán M.A.
      Catastrophizing, acceptance, and coping as mediators between pain and emotional distress and disability in fibromyalgia.
      ). However, pain is not the only factor that explains adherence to walking in FM (
      • Peñacoba C.
      • Pastor M.-Á.
      • López-Roig S.
      • Velasco L.
      • Lledo A.
      Walking beliefs in women with fibromyalgia: Clinical profile and impact on walking behavior.
      ), and avoidance of physical activity may also deprive women of opportunities to obtain positive reinforcement, increasing the functional impact of the illness (
      • Cheng S.T.
      • Leung C.M.C.
      • Chan K.L.
      • Chen P.P.
      • Chow Y.F.
      • Chung J.W.Y.
      • Law A.C.B.
      • Lee J.S.W.
      • Leung E.M.F.
      • Tam C.W.C.
      The relationship of self-efficacy to catastrophizing and depressive symptoms in community-dwelling older adults with chronic pain: A moderated mediation model.
      ).
      In this context, multidisciplinary research in FM, where nursing has an important role (
      • Menzies V.
      Fibromyalgia syndrome: Current considerations in symptom management.
      ), has shown that there is a subset of patients that do not complete treatment or fail to achieve satisfactory results in functioning during or after the treatment (
      • Morley S.
      • Williams A.
      • Eccleston C.
      Examining the evidence about psychological treatments for chronic pain: time for a paradigm shift?.
      ). According to this, new emerging models focused on contextual variables have shown that the relationships are not linear per se and may be affected by additional variables that give rise to complex models in chronic pain (
      • Écija C.
      • Luque-Reca O.
      • Suso-Ribera C.
      • Catala P.
      • Peñacoba C.
      Associations of cognitive fusion and pain catastrophizing with fibromyalgia impact through fatigue, pain severity, and depression: An exploratory study using structural equation modeling.
      ;
      • Ecija C.
      • Catala P.
      • Lopez-Gomez I.
      • Bedmar D.
      • Peñacoba C.
      What does the psychological flexibility model contribute to the relationship between depression and disability in chronic pain? The role of cognitive fusion and pain acceptance.
      ;
      • Ecija C.
      • Catala P.
      • López-Roig S.
      • Pastor-Mira M.Á.
      • Gallardo C.
      • Peñacoba C.
      Exploring the contextual role of pain acceptance and pain catastrophizing in women with fibromyalgia.
      ;
      • McCracken L.M.
      • Morley S.
      The psychological flexibility model: A basis for integration and progress in psychological approaches to chronic pain management.
      ,
      • Esteve R.
      • López-Martínez A.E.
      • Peters M.L.
      • Serrano-Ibáñez E.R.
      • Ruíz-Párraga G.T.
      • González-Gómez H.
      • Ramírez-Maestre C.
      Activity pattern profiles: Relationship with affect, daily functioning, impairment, and variables related to life goals.
      ). In this context, nursing researchers have widened their approach to pain, suggesting that contextual and personal variables could explain the inability of some individuals to implement adaptive coping methods in the presence of pain or related symptoms (
      • Carvalho S.A.
      • Trindade I.A.
      • Gillanders D.
      • Pinto-Gouveia J.
      • Castilho P.
      Cognitive fusion and depressive symptoms in women with chronic pain: A longitudinal growth curve modelling study over 12 months.
      ).
      As a result, researchers have recently sought to better understand predictors of treatment outcomes by searching for them in a theoretical grounding, studying whether certain variables can indicate for whom, or under what circumstances, a treatment can have its best effect (
      • Écija C.
      • Luque-Reca O.
      • Suso-Ribera C.
      • Catala P.
      • Peñacoba C.
      Associations of cognitive fusion and pain catastrophizing with fibromyalgia impact through fatigue, pain severity, and depression: An exploratory study using structural equation modeling.
      ;
      • Gilpin H.R.
      • Keyes A.
      • Stahl D.R.
      • Greig R.
      • McCracken L.M.
      Predictors of treatment outcome in contextual cognitive and behavioral therapies for chronic pain: A systematic review.
      ,
      • Gilpin H.R.
      • Stahl D.R.
      • McCracken L.M.
      A theoretically guided approach to identifying predictors of treatment outcome in contextual Cognitive Behavioural Therapy for chronic pain.
      ). In this context, depressive symptoms have been shown to have a profound negative impact on the ability to function physically in patients with chronic pain (
      • Cane D.
      • McCarthy M.
      • Mazmanian D.
      Obstacles to activity pacing: Assessment, relationship to activity and functioning.
      ;
      • Esteve R.
      • López-Martínez A.E.
      • Peters M.L.
      • Serrano-Ibáñez E.R.
      • Ruíz-Párraga G.T.
      • González-Gómez H.
      • Ramírez-Maestre C.
      Activity pattern profiles: Relationship with affect, daily functioning, impairment, and variables related to life goals.
      ;
      • Pulido-Martos M.
      • Luque-Reca O.
      • Segura-Jiménez V.
      • Álvarez-Gallardo I.C.
      • Soriano-Maldonado A.
      • Acosta-Manzano P.
      • Gavilán-Carrera B.
      • McVeigh J.G.
      • Geenen R.
      • Delgado-Fernández M.
      • Estévez-López F.
      Physical and psychological paths toward less severe fibromyalgia: A structural equation model.
      ), interfering with their ability to achieve valued goals (
      • Kroska E.B.
      A meta-analysis of fear-avoidance and pain intensity: The paradox of chronic pain.
      ). However, a recent study in chronic pain has also demonstrated that exercise can help relieve depressive symptoms in people with high pain intensity (
      • Juan W.
      • Rui L.
      • Wei-Wen Z.
      Chronic neck pain and depression: the mediating role of sleep quality and exercise.
      ). Interestingly, depression has been repeatedly associated with poorer functioning in FM, which explains why it was added as part of the newer diagnostic criteria published in 2010 by the American College of Rheumatology (
      • Wolfe F.
      • Clauw D.J.
      • Fitzcharles M.-A.
      • Goldenberg D.L.
      • Katz R.S.
      • Mease P.
      • Russell A.S.
      • Russell I.J.
      • Winfield J.B.
      • Yunus M.B.
      The American College of Rheumatology Preliminary Diagnostic Criteria for Fibromyalgia and Measurement of Symptom Severity.
      ).
      Similarly, apart from the interest on how psychological contextual variables as depression can influence the effect of walking on functioning, researchers have also insisted on the need to move from the exclusive focus on individual vulnerabilities (“fixing what's wrong”) to an interest in what protects people in challenging circumstances (“building what's strong”) (
      • Hanssen M.M.
      • Peters M.L.
      • Boselie J.J.
      • Meulders A.
      Can positive affect attenuate (persistent) pain? State of the art and clinical implications.
      ;
      • Ecija C.
      • Catala P.
      • López-Roig S.
      • Pastor-Mira M.Á.
      • Gallardo C.
      • Peñacoba C.
      Exploring the contextual role of pain acceptance and pain catastrophizing in women with fibromyalgia.
      ). In this line, the positive psychology perspective has increased in the context of (chronic) pain, focusing on positive affect (PA). PA seems to be a resilience mechanism that buffers against stress and negative emotions, functioning as a resource for positive short- and long-term outcomes in multiple life domains (
      • Finan P.H.
      • Garland E.L.
      The role of positive affect in pain and its treatment.
      ;
      • Goubert L.
      • Trompetter H.
      Towards a science and practice of resilience in the face of pain.
      ;
      • Hassett A.L.
      • Finan P.H.
      The role of resilience in the clinical management of chronic pain.
      ;
      • Molinari G.
      • García-Palacios A.
      • Enrique Á.
      • Roca P.
      • Fernández-Llanio Comella N.
      • Botella C
      The power of visualization: back to the future for pain management in fibromyalgia syndrome.
      ;
      • Ong A.D.
      • Zautra A.J.
      • Reid M.C.
      Chronic pain and the adaptive significance of positive emotions.
      ).
      The buffering effect of positive emotions has been suggested to have an effect by means of behavioral mechanisms (i.e., carrying out a greater number of activities) (
      • Rowe G.
      • Hirsh J.B.
      • Anderson A.K.
      Positive affect increases the breadth of attentional selection.
      ;
      • Waugh C.E.
      • Fredrickson B.L.
      Nice to know you: Positive emotions, self–other overlap, and complex understanding in the formation of a new relationship.
      ), which have long-term repercussions in greater personal resources and better health and quality of life (
      • Kok B.E.
      • Coffey K.a.
      • Cohn M.a.
      • Catalino L.I.
      • Vacharkulksemsuk T.
      • Algoe S.B.
      • Brantley M.
      • Fredrickson B.L.
      How positive emotions build physical health: perceived positive social connections account for the upward spiral between positive emotions and vagal tone.
      ). Specifically in FM population, the Dynamic Model of Affect developed by
      • Zautra A.
      • Smith B.
      • Affleck G.
      • Tennen H.
      Examinations of chronic pain and affect relationships: Applications of a dynamic model of affect.
      (
      • Davis M.C.
      • Zautra A.J.
      • Smith B.W.
      Chronic pain, stress, and the dynamics of affective differentiation.
      ;
      • Reich J.W.
      • Zautra A.J.
      • Davis M.
      Dimensions of affect relationships: models and their integrative implications.
      ;
      • Sturgeon J.A.
      • Zautra A.J.
      Resilience: A new paradigm for adaptation to chronic pain.
      ) postulates that PA has the strongest beneficial effects under conditions of high stress situations, such as in the context of high levels of pain. According to this, positive emotions may be enhanced to act as a direct buffer for negative feelings (
      • Ong A.D.
      • Zautra A.J.
      • Reid M.C.
      Psychological resilience predicts decreases in pain catastrophizing through positive emotions.
      ;
      • Zautra A.
      • Smith B.
      • Affleck G.
      • Tennen H.
      Examinations of chronic pain and affect relationships: Applications of a dynamic model of affect.
      ). Moreover, from the broaden-and-build model (
      • Fredrickson B.L.
      Positive Emotions Broaden and Build.
      ), promoting positive emotions may broaden attention towards positive aspects of one's life that are still present. Hence, positive emotions potentially interfere with, or buffer against the downward spiral of negative feelings and disability, while they simultaneously support an upward spiral of goal-directed action based on personal values (
      • Finan P.H.
      • Garland E.L.
      The role of positive affect in pain and its treatment.
      ).
      From this perspective, two meta-analyses have indicated that positive psychology interventions that include PA and exercise significantly increase well-being and decrease depressive symptoms (
      • Bolier L.
      • Haverman M.
      • Westerhof G.J.
      • Riper H.
      • Smit F.
      • Bohlmeijer E.
      Positive psychology interventions: a meta-analysis of randomized controlled studies.
      ;
      • Sin N.L.
      • Lyubomirsky S.
      Enhancing well-being and alleviating depressive symptoms with positive psychology interventions: a practice-friendly meta-analysis.
      ). Moreover, a recent study in FM has shown that patients who walked despite pain reported significantly less impact of FM and depression, along with other outcomes (
      • Catala P.
      • Lopez-Roig S.
      • Ecija C.
      • Suso-Ribera C.
      • Peñacoba Puente C.
      Why do some people with severe chronic pain adhere to walking prescriptions whilst others won't? A cross-sectional study exploring clinical and psychosocial predictors in women with fibromyalgia.
      ).
      According to recent literature, walking (as exercise) and PA have been recognized as resilience variables in chronic pain (
      • Davis M.C.
      • Zautra A.J.
      An online mindfulness intervention targeting socioemotional regulation in fibromyalgia: Results of a randomized controlled trial.
      ;
      • Goubert L.
      • Trompetter H.
      Towards a science and practice of resilience in the face of pain.
      ). However, there are no studies analyzing these variables together, or in relation to FM symptoms. Thus, following researchers that have focused on mediation and moderation analysis to better understand predictors of treatment outcome (
      • Gilpin H.R.
      • Keyes A.
      • Stahl D.R.
      • Greig R.
      • McCracken L.M.
      Predictors of treatment outcome in contextual cognitive and behavioral therapies for chronic pain: A systematic review.
      ;
      • Gilpin H.R.
      • Stahl D.R.
      • McCracken L.M.
      A theoretically guided approach to identifying predictors of treatment outcome in contextual Cognitive Behavioural Therapy for chronic pain.
      ), the main purpose of this study has been to analyze the effect of walking on depressive symptoms, functional impact, and pain, taking into account the contextual effect of PA. Results from this study could be crucial for the nursing community to identify for whom or under what circumstances a treatment could produce its best effects, information that gives nurses the opportunity to do specific promotion of interventions focused on PA with women diagnosed with FM, teaching them how to live more successfully despite pain, looking to improve adherence to treatments (
      • Dwarswaard J.
      • Bakker E.J.
      • van Staa A.
      • Boeije H.R.
      Self-management support from the perspective of patients with a chronic condition: A thematic synthesis of qualitative studies.
      ).

      Specific Aims

      The main aim of this study was to analyze whether positive affect has a moderating effect on walking, functional impact, and pain, through depressive symptoms (see Fig. 1). As a preliminary step to the main aim, the role of depressive symptoms as a mediating variable between walking and both dependent variables (pain and functional impact) was tested (Fig. 2).
      Figure 1
      Figure 1Hypothesized of model of the moderated mediated effect of walking behavior on functional impact (A) and pain (B), by depression symptoms at different levels of positive affect.
      Figure 2
      Figure 2Hypothesized model of the mediation role. of depression symptoms among walking behavior and functional impact (A) and pain (B).

      Methods

      Participants

      According to the American College of Rheumatology (ACR) criteria (
      • Wolfe F.
      • Smythe H.A.
      • Yunus M.B.
      • Bennett R.M.
      • Bombardier C.
      • Goldenberg D.L.
      • Tugwell P.
      • Campbell S.M.
      • Abeles M.
      • Clark P.
      • Fam A.G.
      • Farber S.J.
      • Fiechtner J.J.
      • Franklin Michael
      • C Gatter
      • R A.
      • Hamaty D.
      • Lessard J.
      • Lichtbroun A.S.
      • Masi A.T.
      • McCain G.
      • A Reynolds
      • W J.
      • Romano T.J.
      • Russell O.J.
      • Sheon R.P
      The American College of Rheumatology 1990 Criteria for the Classification of Fibromyalgia.
      ,
      • Wolfe F.
      • Clauw D.J.
      • Fitzcharles M.-A.
      • Goldenberg D.L.
      • Katz R.S.
      • Mease P.
      • Russell A.S.
      • Russell I.J.
      • Winfield J.B.
      • Yunus M.B.
      The American College of Rheumatology Preliminary Diagnostic Criteria for Fibromyalgia and Measurement of Symptom Severity.
      ), a final sample of 231 women with FM was recruited from different FM mutual aid associations in Spain. Women were contacted via email and telephone, gave informed consent to take part in the project, and were given a booklet of questionnaires (this booklet contained questions from the measures noted below), which took 20-30 minutes to complete. The University Committee on Ethics [Reference number PI17/00858] approved this study.

      Measures

      Walking

      The walking behavior proposed by
      • Gusi N.
      • Parraca J.
      • Adsuar J.
      • Olivares P.
      Ejercicio físico y Fibromialgia.
      for patients with FM was selected (“at least 60 minutes in bouts of 20 minutes, with a small rest between bouts, four times a week, over a minimum of six consecutive weeks”). However, the minimum daily time was reduced to 30 minutes and at least 2 days a week because the targeted population was highly sedentary and because of the difficulties in adherence to physical exercise in patients with FM (
      • O'Connor S.R.
      • Tully M.A.
      • Ryan B.
      • Bleakley C.M.
      • Baxter G.D.
      • Bradley J.M.
      • McDonough S.M.
      Walking exercise for chronic musculoskeletal pain: Systematic review and meta-analysis.
      ). An ad hoc self-report item was used to assess whether they adhered to walking according to the prescribed pattern (1 = “yes”/0 = “no”). Specifically, we asked participants to indicate whether, in the past month and a half, they adhered to the components of the minimum walking program: ”to walk with the aim of doing exercise, for at least 30 minutes, in bouts of 15 minutes with a small rest between bouts, at least twice a week over a minimum of six consecutive weeks’, as this is the recommended fixed program.

      Positive affect

      The positive affect subscale of the positive and negative affect scale (PANAS) (
      • Watson D.
      • Clark L.A.
      • Tellegen A.
      Development and validation of brief measures of positive and negative affect: The PANAS scales.
      ) was used. The positive affect subscale includes 10 items that evaluate feelings that reflect a level of pleasurable engagement with the environment, such as joy, happiness, or enthusiasm (in a theoretical range of 0 to 40). The Spanish version of this subscale has demonstrated good reliability (α = 0.87) (
      • Sandín B.
      • Chorot P.
      • Lostao L.
      • Joiner T.E.
      • Santed M.A.
      • Valiente R.M.
      Escalas PANAS de afecto positivo y negativo: validación factorial y convergencia transcultural.
      ;
      • Sandín B.
      Escalas Panas de afecto positivo y negativo para niños y adolescentes (PANASN).
      ). Moreover, a recent study in chronic pain shows an excellent reliability (α = 0.92) for positive affect (
      • Ramírez-Maestre C.
      • Esteve R.
      • López-Martínez A.E.
      • Miró J.
      • Jensen M.P.
      • de la Vega R.
      Beyond pain intensity and catastrophizing: The association between self-enhancing humour style and the adaptation of individuals with chronic pain.
      ). In our study, the positive affect subscale obtained a high internal consistency score (0.91).

      Depressive symptoms

      The Depression subscale of the Spanish version of the Hospital Anxiety and Depression Scale (HADS) (
      • Herrero M.J.
      • Blanch J.
      • Peri J.M.
      • De Pablo J.
      • Pintor L.
      • Bulbena A.
      A validation study of the hospital anxiety and depression scale (HADS) in a Spanish population.
      ) was administered. The HADS is a brief and widely used instrument to measure the possible presence of anxiety and depressive states in medical, non-psychiatric, outpatient clinic settings. High scores in this 7-item subscale, with a 4-point Likert response format, denote high depressive symptoms. Cronbach's alpha for this scale in previous research in FM was high (α = 0.85) (
      • Cabrera Perona V.
      • Martín-Aragón M.
      • Terol Cantero M.C.
      • Núñez R.M.N.
      • Pastor-Mira M.A
      La Escala de Ansiedad y Depresión Hospitalaria (HAD) en fibromialgia: Análisis de sensibilidad y especificidad.
      ), obtaining the same value in our research.

      Pain severity

      To assess pain severity, we used the mean score of the four pain severity items from the Brief Pain Inventory (
      • Cleeland C.S.
      • Ryan K.M.
      Pain assessment: Global use of the Brief Pain Inventory.
      ): maximum, minimum, overall pain intensity during the last 7 days, and pain intensity at the current time. Each rating is evaluated using an 11-point numerical scale (0 = “no pain” and 10 = “the worst pain you can imagine”). This procedure to measure pain severity has been widely used in pain literature (
      • Jensen M.P.
      • Turner L.R.
      • Turner J.A.
      • Romano J.M.
      The use of multiple-item scales for pain intensity measurement in chronic pain patients.
      ). Studies have shown an excellent internal consistency in previous studies in Spanish population with chronic pain (α = 0.93) (
      • de Andrés Ares J.
      • Cruces Prado L.M.
      • Canos Verdecho M.A.
      • Penide Villanueva L.
      • Del Valle Hoyos M.
      • Herdman M.
      • Traseira Lugilde S.
      • Velázquez Rivera I.
      Validation of the Short Form of the Brief Pain Inventory (BPI-SF) in Spanish patients with non-cancer-related pain.
      ). In this study, the internal consistency of this scale was high (0.86).

      Functional impact

      The Spanish adaptation of the Revised Fibromyalgia Impact Questionnaire (FIQ-R) has been used to evaluate the impact of FM on functioning (
      • Bennett R.M.
      • Bushmakin A.G.
      • Cappelleri J.C.
      • Zlateva G.
      • Sadosky A.B.
      Minimal clinically important difference in the fibromyalgia impact questionnaire.
      ). In the FIQ-R, dimensions are answered on an 11-point numerical rating scale from zero to 10, with different verbal anchors depending on the item. The FIQ-R assesses both physical (fatigue, pain, or muscular stiffness among others) and psychological symptoms (anxiety, depression) of fibromyalgia and their interference in daily living tasks and in quality of life. Higher scores represent higher impact perception. The Validation of a Spanish version of the Revised Fibromyalgia Impact Questionnaire (FIQ-R) showed a high internal consistency score (α = 0.95) (
      • Salgueiro M.
      • García-Leiva J.M.
      • Ballesteros J.
      • Hidalgo J.
      • Molina R.
      • Calandre E.P.
      Validation of a Spanish version of the Revised Fibromyalgia Impact Questionnaire (FIQR).
      ). This was also found in our study (α = 0.92).

      Data Analysis

      All analyses in this study were conducted using SPSS 27 (Windows). First, descriptive, bivariate Pearson correlation and t tests analyses with Cohen's d effect sizes (
      • Rosnow R.L.
      • Rosenthal R.
      • Rubin D.B.
      Contrasts and correlations in effect-size estimation.
      ) were performed. Second, the mediation role of depressive symptoms among walking behavior and functional impact (A) and pain (B) were tested (Fig. 2) using the SPSS macro-PROCESS (model 4). These models were tested using regression (to calculate statistics for specific paths) and bootstrapping (to generate a confidence interval [CI] for the mediation effects). All variables were centered before the analyses, and statistical significance was set at an alpha level of 0.05. Correlation analyses were evaluated, showing that the preconditions for this mediation analysis were fulfilled (
      • Hayes A.F.
      Beyond Baron and Kenny: Statistical mediation analysis in the new millennium.
      ). Third, based on these results, a moderated mediation analysis was run by model 7 of SPSS macro-PROCESS (Fig. 1) to test if the indirect effect of walking on functional impact, by way of depression symptoms, depended on the level of PA. Product terms of waking (centered) x PA (centered) were added to the regression model predicting depressive symptoms and functional impact. Simple slope analyses were subsequently performed to illustrate significant interaction effects (
      • Aiken L.S.
      • West S.G.
      • Reno R.R.
      Multiple regression: Testing and interpreting interactions.
      ). An index of moderated mediation, which is a measure of the association between an indirect effect and a moderator, was estimated, together with a 95% CI, from bootstrapping 10,000 samples (
      • Hayes A.F.
      An index and test of linear moderated mediation.
      ).

      Results

      Participant Characteristics

      In our sample of women diagnosed with FM, aged from 30 to 78 years, with a mean age 56.91 years (standard deviation [SD] = 8.9 years). In relation to educational level, 53.2% of them had completed primary studies, and 26.4% had secondary studies. Regarding their employment status, 12% of the women were employed, 33.8% were homemakers, 32% were retired (of them 18.8% due to chronic pain), and 12.1% were unemployed. A small percentage (10%) was on sick leave. Finally, more than half of the women (53%) were married or in a stable relationship, 36% were divorced or widowed, and 11% were single. Regarding the clinical variables, women had experienced fibromyalgia for an average of 12.14 years (SD = 8.45; 146 years range).

      Descriptive Data and Correlations

      Table 1 shows means, SDs, and Pearson correlations between continuous variables. Depression was positively correlated with functional impact (p < .001) and pain (p = .05), and negatively with PA (p < .001). PA was found to be negatively correlated with functional impact (p = .004). In relation to walking, 58.1% of the women reported walking, while 41.9% did not. Moreover, when the participants were compared based on walking (walking vs not walking), differences from t-tests analyses (using Cohen's d effect sizes) showed impact significant in relation to function [walk: mean 68.97 (SD 17.48), no walk: mean 76.74 (SD 15.45); t = 3.46; p = .001; d = 16.66], pain [walk: mean 6.94 (SD 1.54), no walk: mean 7.45 (SD 1.48); t = 2.51; p = .013; d = 1.51] and depression [walk: mean 8.39 (SD 4.49), no walk: mean 10.33 (SD 3.68); t = 3.45; p < .001; d = 4.17]. However, differences related to positive affect were not significant (t = -.812; p = .418).
      Table 1Means, Standard Deviations, and Pearson Correlations Between Study Variables.
      Mean (SD)Theoretical range1234
      1. Depression (D)9.22 (4.27)0-21-.52b.49b.13a
      2. Positive affect (PA)20.88 (9.02)0-40-.18b.05
      3. Functional impact (FI)72.35 (17)0-100.50b
      4. Pain7.15 (1.52)0-10
      ap <.05.
      bp < .01.

      Test of the Models

      Mediation model of walking on functional impact and pain by depressive symptoms

      In line with the main aim of this study, the mediating role of depression between walking and both outcomes was first tested (Fig. 2). Functional impact and pain were used as covariates in each model, depending on the outcome variable. Results showed that depression significantly mediated the relationship between walking and functional impact because the bootstrap CI was above zero while controlling for demographic variables and pain. The total effect model was significant (c = -4.72, t = -2.49, p < .01, [95% CI = -8.4687/-.9875]). However, related to pain, depression did not mediate this relationship and total effect of walking on pain was not significant (c = -.11, t = -.66, p = .50, [95% CI = -0.4616/0.2289]). The regression coefficient estimated (based on the use of a 95% bias-corrected CI as evidence of the mediation of total indirect effect) was also calculated for both outcomes (functional impact ß = -3.70, SE = 1,22; [95% CI= -6.3282/-1.5369]); pain ß=-.06, standard error [SE] =.04; [95% CI = -.0029/.1626]). Total amount of variance accounted for by the overall models was 34% (F = 58.95; p < .0001) for functional impact, and 32% (F = 54.48; p < .0001) for pain.

      Moderation mediation model of walking on functional impact by depression, at different levels of PA

      Based on the results of the mediation models, only the indirect effect of walking on functional impact by way of depressive symptoms, depending on the level of PA, was tested. Pain was used as a covariate in the model. Results showed that the contribution of walking to depression varied at different values of PA, after controlling the covariates. Specifically, walking was significantly associated with depressive symptoms when PA was medium (value: .15; ß = -1.52, p = .001) and high (value: 10.15; ß = -2.92, p = .0001). The index of moderated mediation using Hayes' algorithm was estimated for functional impact (ß= -.23 [95% CI = -.43/-.05]). This result (Table 2, Fig. 1) showed that the strength of the relationship between walking and functional impact was increased at higher levels of PA. Specifically, walking was significantly associated with functional impact, mediated by depressive symptoms, when PA was medium (PA value: .15: ß = -2.50) and high (PA value: 10.15: ß = -4.81). Thus, the indirect effect of walking on functional impact via depression was higher in individuals with higher PA.
      Table 2Moderate Mediation Model: Regression of Depression Symptoms (Mediator) on Functional Impact and Positive Affect (Moderator).
      B (SE)tp[LLCI-ULCI]
      VD: Walking behavior (WB)-1.50(.47)-3.17.001[-2.43 /-.05]
      M: Positive affect (PA)-.24(.02)-9.67.000[-.29 /-.19]
      WB x PA (interaction)-.14(.05)-2.70.007[-.24 /-.03]
      Pain (covariate).43(.15)2.84.004[.13/.73]
      Conditional effects of the focal predictor (WB) at valuesa of the moderator (PA)
      -9.84-.11(.69)3.36.862[-1.48/1.24]
      .15*-1.52(.47)6.53.001[-2.45/-.59]
      10.15*-2.92(.71)7.12.0001[-4.33/-1.52]
      Regression of depression on functional impact and PA
      B (SE)tp[LLCI-ULCI]
      Walking behavior (WB)-1.86(1.69)-1.10.271[-5.19/1.46]
      Depression (D)1.64(.19)8.41.000[1.25/2.02]
      Pain (covariate)5.49(.53)10.22.000[4.43/6.55]
      Model summaryR2: .50
      Indirect effects at valuesb of PA
      -9.84-.19 (1-10)[-2.38/1.94]
      .15*-2.50 (.88)[-4.37/-.92]
      10.15*-4.81 (1.48)[-7.98/-2.21]
      Indexes of moderated mediation-.23(.09)[-.43/-.05]
      Pairwise contrast between conditional indirect effects (Effect 1 minus Effect2)
      Effect 1Effect2contrast[LLCI/ULCI]
      -2.50

      -4.81

      -4.81
      -.19

      -.19

      -2.50
      -2.30

      -4.61

      -2.30
      [-4.30/-.58]

      [-8.61/-1.16]

      [-4.30/-.58]
      Models include controls for age, sex, education level, employment status; conditional effects of the focal predictor at valuesa of the moderator (PA); Indirect effects of Walking on Functional impact at valuesb of PA; * statistically significant results.
      LLCI = bootstrapping lower limit confidence interval; ULCI = bootstrapping upper limit confidence interval; SE = standard error.

      Discussion

      The main purpose of this study was to analyze the effect of walking on depressive symptoms, functional impact, and pain, taking into account the contextual effect of PA. In general, results have shown that the effect of walking on functional impact was mediated by depression. Interestingly, results also found that effects were significant at medium and high levels of PA, but not when levels of PA were low.
      In line with the main aim of this study, results confirm that levels of PA play a moderating role in the influence of walking on depressive symptoms and functional impact. First, these results are in concordance with the Dynamic Model of Affect (
      • Davis M.C.
      • Zautra A.J.
      • Smith B.W.
      Chronic pain, stress, and the dynamics of affective differentiation.
      ;
      • Reich J.W.
      • Zautra A.J.
      • Davis M.
      Dimensions of affect relationships: models and their integrative implications.
      ;
      • Zautra A.
      • Smith B.
      • Affleck G.
      • Tennen H.
      Examinations of chronic pain and affect relationships: Applications of a dynamic model of affect.
      ), in which the beneficial role of PA has been well recognized in chronic pain conditions. According to this, our results show that, specifically, medium or high levels of PA may be enhanced to act as a direct buffer for depressive symptoms (
      • Fredrickson B.L.
      • Cohn M.A.
      • Coffey K.A.
      • Pek J.
      • Finkel S.M.
      Open hearts build lives: Positive emotions, induced through loving-kindness meditation, build consequential personal resources.
      ;
      • Ong A.D.
      • Zautra A.J.
      • Reid M.C.
      Psychological resilience predicts decreases in pain catastrophizing through positive emotions.
      ;
      • Zautra A.
      • Smith B.
      • Affleck G.
      • Tennen H.
      Examinations of chronic pain and affect relationships: Applications of a dynamic model of affect.
      ). Second, our study confirms recent studies about the moderating effect of walking on functional impact through depressive symptoms (
      • Écija C.
      • Luque-Reca O.
      • Suso-Ribera C.
      • Catala P.
      • Peñacoba C.
      Associations of cognitive fusion and pain catastrophizing with fibromyalgia impact through fatigue, pain severity, and depression: An exploratory study using structural equation modeling.
      ), and studies where PA has also had a moderating effect on depression (
      • Thong I.S.K.
      • Jensen M.P.
      • Miró J.
      • Tan G.
      The validity of pain intensity measures: what do the NRS, VAS, VRS, and FPS-R measure?.
      ). Although to our knowledge there are no studies such as ours, results point to the fact that PA may constitute a contextual variable of interest when understanding the complex relationships that walking may have with functional impact, considering depressive symptoms as some of the most frequent in FM. Different studies have shown emotional symptoms as one of the main inhibitors of walking, and its adherence, preventing patients from obtaining the beneficial results of the behavior.
      In this line, a novel aspect of the current study is that it indicates the mechanisms of action (in this case through depression) of the improvement that physical exercise (walking) produces in functional impact (
      • Hassett A.L.
      • Finan P.H.
      The role of resilience in the clinical management of chronic pain.
      ;
      • Lee J.-W.
      • Lee K.-E.
      • Park D.-J.
      • Kim S.-H.
      • Nah S.-S.
      • Lee J.H.
      • Kim S.-K.
      • Lee Y.-A.
      • Hong S.-J.
      • Kim H.-S.
      • Lee H.-S.
      • Kim H.A.
      • Joung C.-I.
      • Kim S.-H.
      • Lee S.-S.
      Determinants of quality of life in patients with fibromyalgia: A structural equation modeling approach.
      ). Specifically, it is interesting that the effect of walking on functional impact is through depression, but only at medium or high levels of PA. In this line,
      • White D.K.
      • Keysor J.J.
      • Neogi T.
      • Felson D.T.
      • LaValley M.
      • Gross K.D.
      • Niu J.
      • Nevitt M.
      • Lewis C.E.
      • Torner J.
      • Fredman L.
      When it hurts, a positive attitude may help: association of positive affect with daily walking in knee osteoarthritis. Results from a multicenter longitudinal cohort study.
      observed significantly higher daily activity (measured by the number of steps) in osteoarthritis patients with high PA as opposed to low PA, showing that patients with high PA walked an equivalent number of steps per day regardless of their pain levels (
      • White D.K.
      • Keysor J.J.
      • Neogi T.
      • Felson D.T.
      • LaValley M.
      • Gross K.D.
      • Niu J.
      • Nevitt M.
      • Lewis C.E.
      • Torner J.
      • Fredman L.
      When it hurts, a positive attitude may help: association of positive affect with daily walking in knee osteoarthritis. Results from a multicenter longitudinal cohort study.
      ). Following this evidence, the fact that in our study the moderated mediation model is significant in functional impact but not related to pain could be in accordance with studies that have suggested that PA might reduce engaging rigidly in specific action tendencies and create behavioral flexibility (
      • Vlaeyen J.W.S.
      • Crombez G.
      • Linton S.J.
      The fear-avoidance model of pain.
      ), and enhance (continued) engagement in valued activities despite the experience of pain (
      • Pastor-Mira M.A.
      • López-Roig S.
      • Martínez-Zaragoza F.
      • Lledó A.
      • Velasco L.
      • León E.
      • Écija Gallardo C.
      • Peñacoba C.
      Promoting unsupervised walking in women with fibromyalgia: A randomized controlled trial.
      ).
      The results obtained have, in our opinion, important clinical repercussions. In accordance with the notion that a neural process is disturbed in FM (
      • de la Coba P.
      • Bruehl S.
      • Galvez-Sánchez C.M.
      • Paso Reyes del
      • G A
      Slowly repeated evoked pain as a marker of central sensitization in fibromyalgia: Diagnostic accuracy and reliability in comparison with temporal summation of pain.
      ;
      • Montoro C.I.
      • Duschek S.
      • de Guevara C.M.L.
      • Paso Reyes del
      • G A
      Patterns of cerebral blood flow modulation during painful stimulation in fibromyalgia: A transcranial Doppler sonography study.
      ), research suggests that patients diagnosed with FM may be at higher risk for a deficit in PA and an inability to sustain PA in the face of pain (
      • Finan P.H.
      • Garland E.L.
      The role of positive affect in pain and its treatment.
      ;
      • van Middendorp H.
      • Lumley M.A.
      • Jacobs J.W.G.
      • van Doornen L.J.P.
      • Bijlsma J.W.J.
      • Geenen R.
      Emotions and emotional approach and avoidance strategies in fibromyalgia.
      ;
      • Zautra A.J.
      • Johnson L.M.
      • Davis M.C.
      Positive affect as a source of resilience for women in chronic pain.
      ). Extrapolating these findings into a clinical context, it has been suggested that patients diagnosed with FM could have better pain-related outcomes if they would reliably engage their PA resources (
      • Hassett A.L.
      • Finan P.H.
      The role of resilience in the clinical management of chronic pain.
      ). From this perspective, many psychosocial interventions for pain such as cognitive behavioral therapy (CBT), acceptance and commitment therapy (ACT) (
      • Hassett A.L.
      • Finan P.H.
      The role of resilience in the clinical management of chronic pain.
      ), or behavioral activation (BA) (among others) have targeted PA as resilience to one degree or another, focusing on increasing positive feelings, positive cognitions, or positive behavior (
      • Sin N.L.
      • Lyubomirsky S.
      Enhancing well-being and alleviating depressive symptoms with positive psychology interventions: a practice-friendly meta-analysis.
      ). A common aspect of these treatments is that patients are guided to choose valued activities for which they set graduated goals for their participation (
      • Hassett A.L.
      • Finan P.H.
      The role of resilience in the clinical management of chronic pain.
      ).
      Focusing on nursing, a recent study in women with FM has shown that, for these women, exercise self-efficacy, perceived barriers, and intention to exercise are important constructs for increasing physical activity (
      • Kaleth A.S.
      • Bigatti S.M.
      • Slaven J.E.
      • Kelly N.
      • Ang D.C.
      Predictors of physical activity in patients with fibromyalgia: A path analysis.
      ). The need to reduce barriers and promote more facilitators to help patients’ pain management have promoted the inclusion of non-pharmacologic treatments in nursing care plans (
      • Liu K.
      The Impact of Psychological Interventions Given to ICU Patients to Help with Pain Management, Senior thesis.
      ). Nurse's advice in relation to walking is easy to follow by patients, and this intervention changes patients' perception of chronic pain management, learning that it can be improved with self-management (
      • Nomikos P.A.
      • Hall M.C.
      • Fuller A.
      • Ogollah R.
      • Valdes A.M.
      • et al.
      Acceptability of a nurse-led non-pharmacological complex intervention for knee pain: Nurse and patient views and experiences.
      ). Thus, the roles nurses play in chronic pain can strongly influence a positive outcome and should provide quality patient care, being one of the most important aspects related to adherence (
      • Liu K.
      The Impact of Psychological Interventions Given to ICU Patients to Help with Pain Management, Senior thesis.
      ).
      In this line, following the interest mentioned regarding what protects people in challenging circumstances, our results show that interventions specifically targeting increasing PA might be a promising complementary alternative for existing interventions (
      • Flink I.K.
      • Smeets E.
      • Bergboma S.
      • Peters M.L.
      Happy despite pain: Pilot study of a positive psychology intervention for patients with chronic pain.
      ;
      • Galvez-Sánchez C.M.
      • Reyes del Paso G.A.
      • Duschek S.
      Cognitive impairments in fibromyalgia syndrome: Associations with positive and negative affect, alexithymia, pain catastrophizing and self-esteem.
      ). For example, two meta-analyses of positive activity interventions (PAIs) based on the premise that simple cognitive and/or behavioral strategies can improve people's resources (
      • Layous K.
      • Chancellor J.
      • Lyubomirsky S.
      • Wang L.
      • Doraiswamy P.M.
      Delivering happiness: translating positive psychology intervention research for treating major and minor depressive disorders.
      ), found that increasing PA resulted in improvements in pain intensity, pain interference, PA, and depression (
      • Müller R.
      • Gertz K.J.
      • Molton I.R.
      • Terrill A.L.
      • Bombardier C.H.
      • Ehde D.M.
      • Jensen M.P.
      Effects of a tailored positive psychology intervention on well-being and pain in individuals with chronic pain and a physical disability.
      ), and that these benefits could persist for up to 6 months (
      • Bolier L.
      • Haverman M.
      • Westerhof G.J.
      • Riper H.
      • Smit F.
      • Bohlmeijer E.
      Positive psychology interventions: a meta-analysis of randomized controlled studies.
      ;
      • Sin N.L.
      • Lyubomirsky S.
      Enhancing well-being and alleviating depressive symptoms with positive psychology interventions: a practice-friendly meta-analysis.
      ). In the same line, a recent study conducted by nurses showed that music therapy increases PA, and it was very popular among patients with chronic pain. Nursing can implement noninvasive techniques with their patients to help make their stay at the hospital more acutely comforting, which may help reduce any future emotional symptoms related to pain (
      • Hardy S.
      Mental health and wellbeing: A guide for nurses and healthcare professionals working with adults in primary care.
      ;
      • Atta A.
      • Atia N.
      • El-sadany H.
      • Ibrahim R.
      Effect of nursing care by using swedish massage, kinesio tape for knee osteoarthritis patients on pain, functional status and quality of life.
      ).
      Taking all the above into account, our study may be another step toward recognizing that effective actions to improve adherence could be delivered by nursing staff (
      • Kizza I.B.
      • Muliira J.K.
      Nurses' pain assessment practices with critically ill adultpatients.
      ;
      • Jacq G.
      • Melot K.
      • Bezou M.
      • Foucault L.
      • Courau-Courtois J.
      • Cavelot S.
      • Lang A.
      • Bedos J.P.
      • Le-Boeuf D.
      • Boussard J.M.
      • Legriel S.
      Music for pain relief during bed bathing of mechanically ventilated patients: A pilot study.
      ;
      • Atta A.
      • Atia N.
      • El-sadany H.
      • Ibrahim R.
      Effect of nursing care by using swedish massage, kinesio tape for knee osteoarthritis patients on pain, functional status and quality of life.
      ). With non-invasive, safe, and low-cost nonpharmacologic interventions focused on increase PA, nursing could promote physical activity in chronic pain (
      • Otmanowski J.A.
      • Chase J.A.D.
      Systematic review and meta-analysis of primary care-based physical activity interventions among older adults.
      ;
      • Hardy S.
      Mental health and wellbeing: A guide for nurses and healthcare professionals working with adults in primary care.
      ), allowing patients to find ways to reduce pain levels without having to visit their doctors for a prescription, or spending more time and money on medications. Access to positive psychology interventions prior to, during, or post nursing intervention might offer solutions to problems such as long waiting lists, passive treatment participation, or difficulties to maintain long-term treatment effects.
      Additionally, treatment interruptions for patients with chronic pain due to the COVID-19 pandemic have included adjustments to the patient care model, and emergent technologies such as telemedicine have included PA as an important resilience variable (
      • Micó Segura J A
      Coronavirus COVID-19 y dolor crónico: Incertidumbres.
      ) that has generated promising results (
      • de Moraes É.B.
      • Garcia J.B.S.
      • de Macedo Antunes J.
      • Daher D.V.
      • Seixas F.L.
      • Ferrari M.F.M.
      Chronic pain management during the COVID-19 pandemic: A scoping review.
      ;

      American Psychological Association (APA) (2020a). Guidance on psychological assessment and management of chronic pain during the COVID-19 crisis. Retrieved Month XX, XXXX, from https://www.apaservices.org/practice/news/chronic-pain-covid-19 Accessed 26 March 2022.

      ,

      American Psychological Association (APA) (2020b). Pain management in a crisis. Retrieved Month XX, XXXX, from https://www.apaservices.org/practice/news/pain-management-covid-19 Accessed 26 March 2022.

      ). These results open up other possibilities to increase positive affect in nursing interventions and could provide low-cost internet-based treatment with or without guidance of a therapist though PA interventions (
      • Peters M.L.
      • Smeets E.
      • Feijge M.
      • van Breukelen G.
      • Andersson G.
      • Buhrman M.
      • Linton S.J
      Happy despite pain: a randomized controlled trial of an 8-week internet delivered positive psychology intervention for enhancing well-being in patients with chronic pain.
      ;
      • Hausmann L.R.
      • Parks A.
      • Youk A.O.
      • Kwoh C.K.
      Reduction of bodily pain in response to an online positive activities intervention.
      ;
      • Müller R.
      • Gertz K.J.
      • Molton I.R.
      • Terrill A.L.
      • Bombardier C.H.
      • Ehde D.M.
      • Jensen M.P.
      Effects of a tailored positive psychology intervention on well-being and pain in individuals with chronic pain and a physical disability.
      ). PA could easily be introduced in any treatment to enhance the effects of interventions or to prevent dropout (by means of shaping participants’ motivation or treatment expectations).

      Limitations

      Some limitations of this study need to be mentioned. First, the results were obtained from self-reported data, this limitation being especially relevant in the case of walking. It should be noted in this regard that the current study is part of a larger project that previously assessed this same behavior by means of self-administered questionnaires and pedometers, and a high consistency was found between measures (
      • Pastor-Mira M.A.
      • López-Roig S.
      • Martínez-Zaragoza F.
      • Lledó A.
      • Velasco L.
      • León E.
      • Écija Gallardo C.
      • Peñacoba C.
      Promoting unsupervised walking in women with fibromyalgia: A randomized controlled trial.
      ;
      • López-Roig S.
      • Pastor-Mira M.Á.
      • Núñez R.
      • Nardi A.
      • Ivorra S.
      • León E.
      • Peñacoba C.
      Assessing self-efficacy for physical activity and walking exercise in women with fibromyalgia.
      ). Moreover, the cross-sectional design prevents the establishment of cause-effect relationships. Second, since the findings are based on women with FM, more research is needed in men (even though FM in men is scarce) and, especially, in other populations with pain to explore whether the findings are generalizable. Third, sampling through pain associations may have introduced a sampling bias towards women who are already relatively well adjusted to their chronic pain, which may not reflect typical presentations in secondary care settings. Finally, even though several clinical and psychosocial factors potentially relevant for adherence to walking were investigated, the list is of course incomplete. For instance, it has been shown that clinical conditions that often coexist with FM, might impose difficulties in walking (
      • Costa I.
      • da S.
      • Gamundí A.
      • Miranda J.G.V.
      • França L.G.S.
      • De Santana C.N.
      • Montoya P.
      Altered functional performance in patients with fibromyalgia.
      ;
      • Mahgoub M.Y.
      • Elnady B.M.
      • Abdelkader H.S.
      • Abdelhalem R.A.
      • Hassan W.A.
      Comorbidity of fibromyalgia in primary knee osteoarthritis: Potential impact on functional status and quality of life.
      ).
      Despite these limitations, walking is the treatment of choice for these patients, and our results indicate a positive influence on functional impact through a decrease in depression levels. However, to achieve these effects, behavioral continuity is required. In this sense, assuming that adherence in these populations is very low, and considering that the women with FM are mostly sedentary (
      • Esteve R.
      • López-Martínez A.E.
      • Peters M.L.
      • Serrano-Ibáñez E.R.
      • Ruíz-Párraga G.T.
      • González-Gómez H.
      • Ramírez-Maestre C.
      Activity pattern profiles: Relationship with affect, daily functioning, impairment, and variables related to life goals.
      ), it is especially advisable to start walking gradually (
      • Sanz-Baños Y.
      • Pastor-Mira M.Á.
      • Lledó A.
      • López-Roig S.
      • Peñacoba C.
      • Sánchez-Meca J.
      Do women with fibromyalgia adhere to walking for exercise programs to improve their health? Systematic review and meta-analysis.
      ). Specifically for this population, the initial goal is to walk a minimum of 30 minutes daily (in two sets of 15 minutes each) and at least twice a week (

      World Health Organization (WHO) (2018). Global Strategy on Diet, Physical Activity and Health 2017. Available from: Physical activity (who.int). Accessed 26 March 2022.

      ;
      • Brosseau L.
      • Wells G.A.
      • Tugwell P.
      • Egan M.
      • Wilson K.G.
      • Dubouloz C.J.
      • Veilleux L.
      Ottawa Panel evidence-based clinical practice guidelines for strengthening exercises in the management of fibromyalgia: part 2.
      ;
      • Bidonde J.
      • Busch A.J.
      • Schachter C.L.
      • Overend T.J.
      • Kim S.K.
      • Goes S.M.
      • Boden C.
      • Foulds H.J.
      Aerobic exercise training for adults with fibromyalgia.
      ). Based on the evidence found, interventions in promoting positive affect would improve the effects of walking on functional impact as an important component of contemporary multidisciplinary interventions. In this context, within the medical recommendation of walking, nursing professionals are the main ones involved in the initiation and follow-up of walking behavior in these patients. Results suggest that when women with FM are dealing with depressive symptoms, interventions should be focused by health care professionals on increasing PA through positive activities such as walking, rather than being overly focused on reducing pain symptoms.
      Knowing that Positive Activity Interventions (PAIs) are non-stigmatizing, and do not require a mental health professional for their provision, this study gives professionals, and specifically nurses, the opportunity to better understand which domains of activity management are most closely associated with which symptoms (i.e., depression and functional impact). This study supports the need to analyze positive psychology variables such as PA in more comprehensive models, to better understand how these variables may be used to define FM profiles, understanding specifically the role that these variables could have on FM multicomponent interventions. Nevertheless, more studies are needed to unequivocally establish the causal relationships between these variables, and future research should include longitudinal designs with several waves with carefully spaced-out intervals to test moderated mediation and reverse causation simultaneously.
      Taking all the above into account and based on recent studies in which PA influences individual differences in FM symptomatology and, ultimately, in overall functioning (i.e., mediators) (
      • Catala P.
      • Lopez-Roig S.
      • Ecija C.
      • Suso-Ribera C.
      • Peñacoba Puente C.
      Why do some people with severe chronic pain adhere to walking prescriptions whilst others won't? A cross-sectional study exploring clinical and psychosocial predictors in women with fibromyalgia.
      ;
      • Écija C.
      • Luque-Reca O.
      • Suso-Ribera C.
      • Catala P.
      • Peñacoba C.
      Associations of cognitive fusion and pain catastrophizing with fibromyalgia impact through fatigue, pain severity, and depression: An exploratory study using structural equation modeling.
      ;
      • Suso-Ribera C.
      • Catalá P.
      • Ecija C.
      • Sanromán L.
      • López-Gómez I.
      • Pastor-Mira Á.
      • Peñacoba-Puente C.
      Exploring the contextual role of pain severity as a moderator of the relationship between activity patterns and the physical and mental functioning of women with fibromyalgia.
      ); this study may be another step towards finding evidence that explicitly promoting PA and behavioral activation (as walking) are important targets so that nursing interventions in chronic pain can fulfill a comprehensive role (
      • Dwarswaard J.
      • Bakker E.J.
      • van Staa A.
      • Boeije H.R.
      Self-management support from the perspective of patients with a chronic condition: A thematic synthesis of qualitative studies.
      ).

      Conclusions

      Firstly, because the experience of FM differs among people and within the same individual over time, adopting patient-centered approaches, such as in this study, is highly recommended for this disease (
      • Esteve R.
      • López-Martínez A.E.
      • Peters M.L.
      • Serrano-Ibáñez E.R.
      • Ruíz-Párraga G.T.
      • González-Gómez H.
      • Ramírez-Maestre C.
      Activity pattern profiles: Relationship with affect, daily functioning, impairment, and variables related to life goals.
      ). We have tested a sophisticated and dynamic model that supports the notion that a more flexible treatment approach may be warranted, with individual treatments tailored to individual affective profiles. For patients with deficits in positive affectivity, such as those with FM, interventions aimed at increasing PA are crucial for restoring function in the face of chronic pain.
      Secondly, research focusing on factors associated with the discordance between how people feel and how they actually perform (
      • Larsen J.T.
      • McGraw A.P.
      • Cacioppo J.T.
      Can people feel happy and sad at the same time?.
      ) has called for increased attention to mechanisms for maintaining patients’ functioning despite ongoing pain (
      • Burns J.W.
      • Nielson W.R.
      • Jensen M.P.
      • Heapy A.
      • Czlapinski R.
      • Kerns R.D.
      Specific and general therapeutic mechanisms in cognitive behavioral treatment of chronic pain.
      ). Our results suggest that cognitive-emotional factors such as PA and positive behaviors can control neural processes underlying the feeling of being physically impaired, being key aspects within the interdisciplinary approach in FM.
      Finally, walking is safe, well tolerated by most patients with FM, and recommended by national and international guidelines for pain management, demonstrating meaningful improvements in symptoms (
      • Clauw D.J.
      Fibromyalgia: A clinical review.
      ;
      • Häuser W.
      • Thieme K.
      • Turk D.C.
      Guidelines on the management of fibromyalgia syndrome - A systematic review.
      ). Moreover, researchers have argued that strategies such as walking have to be included in nursing care practices in chronic pain (
      • Hardy S.
      Mental health and wellbeing: A guide for nurses and healthcare professionals working with adults in primary care.
      ). By enhancing awareness of positive experiences such as walking, PA may increase access to new contextual information with which to reappraise current circumstances and reframe them as benign, meaningful, or even beneficial (
      • Flink I.K.
      • Smeets E.
      • Bergboma S.
      • Peters M.L.
      Happy despite pain: Pilot study of a positive psychology intervention for patients with chronic pain.
      ). Navigating adversity through this “positive attitude” may ameliorate chronic negative emotionality, enhance self-efficacy of walking, and promote well-being by establishing a sense of coherence and meaning in life (
      • Hassett A.L.
      • Finan P.H.
      The role of resilience in the clinical management of chronic pain.
      ), all of which are important components of any treatment that may be included in nursing domains to improve treatment adherence in chronic pain (
      • Kaleth A.S.
      • Bigatti S.M.
      • Slaven J.E.
      • Kelly N.
      • Ang D.C.
      Predictors of physical activity in patients with fibromyalgia: A path analysis.
      ).

      Acknowledgments

      The authors gratefully acknowledge all participants for their collaboration.
      This study was funded by the Health Research Fund (Fondo de Investigación en Salud), grant number PI17/00858 from the Instituto de Salud Carlos (Spain), co-financed by the European Union through the Fondo Europeo de Desarrollo Regional (FEDER). Mª Angeles Pastor-Mira's contribution was supported by a research grant from MINECO (PSI2016-79566-C2-1-R).
      All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki Declaration and its later amendments or comparable ethical standards. The study was approved by the Bioethics Committee of Rey Juan Carlos University (Reference PI17/00858).

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