Abstract
Objective
To evaluate the relationship between long-term maintenance of moderate-vigorous physical activity (MVPA) and clinical outcomes in fibromyalgia (FM).
Methods
Patients with FM (n=170) received individualized exercise prescriptions and completed baseline and follow-up physical activity assessments using the Community Health Activities Model Program for Seniors (CHAMPS) questionnaire at weeks 12, 24, and 36. The primary outcome was the change in the Fibromyalgia Impact Questionnaire-Physical Impairment (FIQ-PI) score. Secondary outcomes included improvements in overall well-being (FIQ-Total), pain severity ratings, and depression.
Results
Using a threshold increase in MVPA of ≥10 metabolic equivalent hours per week (MET h/wk) above usual activities, 27 subjects (15.9%) increased and sustained (SUS-PA), 68 (40%) increased, but then declined (UNSUS-PA), and 75 (44.1%) did not achieve this benchmark (LO-PA). Compared to LO-PA subjects, both SUS-PA and UNSUS-PA subjects reported greater improvement in FIQ-PI (p<0.01) and FIQ-Total (p<0.05). Additionally, the SUS-PA group reported greater improvement in pain severity compared to the LO-PA group (p<0.05). However, there were no significant group differences between SUS-PA and UNSUS-PA for any primary or secondary outcome measure.
Conclusion
Increased participation in MVPA for at least 12 weeks improves physical function and overall well-being in patients with FM. Although sustained physical activity was not associated with greater clinical benefit compared to unsustained physical activity, these findings also suggest that performing greater volumes of physical activity is not associated with worsening pain in FM. Future research is needed to determine the relationship between sustained MVPA participation and subsequent improvement in patient outcomes.
A great deal of interest has been generated in recent years supporting the role of a physically active lifestyle as part of the overall treatment approach in fibromyalgia (FM) (1–6). Although the majority of studies have focused primarily on the effects of structured exercise programs in FM, recent evidence suggests that clinically significant improvements in physical function and pain also can be achieved with increases in lifestyle physical activity (e.g. household activities, cleaning, yard work, etc.) (7). Unfortunately, despite the reported clinical benefits of increased physical activity, many people with FM report that the pain associated with increased activity often prevents them from attempting to achieve, or follow through with recommendations to be more active (8–10). Of those that begin physical activity programs, long-term adherence is often suboptimal and frequently associated with a worsening of FM symptoms (11). The reasons behind poor adherence are likely multifactorial, including the potential for worsening symptoms. Although most exercise trials have reported clinical benefits in FM, the majority of these studies have not evaluated the sustainability of these benefits long-term (i.e. >12 weeks). Therefore, the main purpose of this paper was to determine whether increasing and maintaining higher levels of physical activity over a longer time period is associated with improvement or worsening of symptoms.
The Research to Encourage Exercise for Fibromyalgia (REEF) study was a randomized attention-controlled clinical trial, of which the main objective was to evaluate the efficacy of Motivational Interviewing (MI), a client-centered counseling approach designed to elicit a specific behavioral change (12), to encourage a more physically active lifestyle in FM patients in order to improve important patient-oriented clinical outcomes (13, 14). 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 voluntary physical activity levels after 36 weeks. The specific aim of this paper was to compare changes in self-reported physical function and symptom severity in FM subjects who: (1) increased and sustained participation in moderate-vigorous physical activity (MVPA); (2) increased, but did not sustain MVPA levels; or (3) did not increase MVPA levels. Our primary hypothesis was that patients with FM who increased and sustained physical activity participation of at least moderate intensity would report greater improvement in physical function compared to subjects who were unable to maintain or increase MVPA levels. Our secondary hypothesis was that pain severity would not worsen in FM subjects who are able to maintain increased levels of MVPA compared to those unable to maintain or increase MVPA levels.
METHODS
Experimental design
Details of the aims, experimental design, measurement protocols, and inclusion and exclusion criteria of the REEF study have been described previously (13, 14). Briefly, study subjects were randomized to either the MI intervention group or an attention control (AC) group. The MI group received six exercise-based telephone calls spread over a 12-wk period. To control for attention, the AC group received the same number of telephone contacts centered on FM-related health education. To evaluate the long-term effects of the primary intervention, phone calls (both groups) were discontinued at week 12 and subsequent outcome assessments were conducted at week 12 (immediate post-intervention), week 24 (3-month follow-up) and week 36 (6-month follow-up). Participants in both groups received an individualized exercise prescription and two supervised exercise sessions prior to the telephone-counseling phase of the study. The study protocol was approved by the Indiana University Institutional Review Board and carried out in accordance with The Code of Ethics of the World Medical Association (Declaration of Helsinki).
Subjects and eligibility criteria
All subjects were referred from specialty or primary care clinics with an initial diagnosis of fibromyalgia (by a rheumatologist) and verified by the study physician (also a rheumatologist). To be included, participants (aged 18 to 65 years) had to meet the American College of Rheumatology classification criteria for FM (15), Brief Pain Inventory (BPI) pain score ≥4; Fibromyalgia Impact Questionnaire–Physical Impairment (FIQ-PI) score ≥2; and be on stable doses of FM medications for ≥4 weeks. Participants were excluded with (a) known cardiovascular disease; (b) moderate-severe chronic lung disease; (c) uncontrolled hypertension; (d) orthopedic or musculoskeletal conditions that would prohibit moderate-intensity physical activity; (e) active suicidal ideation; (f) planned elective surgery during the study period; (g) ongoing unresolved disability claims; (h) inflammatory rheumatic conditions (e.g. rheumatoid arthritis, systemic lupus erythematosus, or other connective tissue disease); (i) current use of medications that may affect the chronotropic response to exercise/physical activity (e.g. beta-blockers or select calcium channel blockers); (j) pregnancy; (k) schizophrenia or other psychosis; and (l) self-reported participation in MVPA more than two days a week during the previous six months (13).
Exercise training program
All subjects received two supervised exercise sessions and an individualized exercise prescription that included the initial exercise intensity, duration, and frequency, as well as the progression of the exercise program over the ensuing 36 weeks. The exercise prescription included the beginning exercise intensity (40–50% of heart rate reserve/HRR), duration (10–12 min/session) and frequency (2–3 d/wk). Subjects were instructed to gradually increase their total volume of exercise to a maximum of 55–65% of HRR, 28–30 min/session, and 3–4 d/wk over the ensuing 36 weeks (13, 14).
Physical activity assessment
The self-report Community Health Activities Model Program for Seniors (CHAMPS) is a 15-minute self-administered questionnaire that asks about the frequency, intensity, and duration of physical activity usually performed in a typical week during the previous four weeks. In older adults, CHAMPS has demonstrated content and construct validity, internal consistency, and responsiveness to change (16–18). In the current study, CHAMPS was used due to its ability to capture a wide range of physical activities, including occupational, household, daily tasks, as well as structured exercise. CHAMPS provides an estimate of the typical number of hours per week spent performing sedentary-light physical activity (e.g. sitting, walking slowly, stretching) and MVPA (e.g. brisk walking, jogging, sport activities) (19). Using the original scoring algorithms from CHAMPS, each activity was assigned a metabolic equivalent (MET) value (20), which represents the ratio of energy expended during each specific activity to the metabolic rate of sitting quietly (1 MET = 3.5 ml O2·kg−1·min−1). Estimates of time spent in sedentary-light (<3 METS), moderate (3 – 6 METS) and vigorous (>6 METS) intensity physical activity were determined by multiplying the reported hours (h) spent performing each activity by its corresponding MET value and summed across all activities to determine the total number of MET hours per week (MET h/wk) and those specifically from activities of at least moderate intensity (≥ 3 METS).
Physical activity group classifications
For most adults, 150 min/wk of moderate intensity physical activity, or 75 min/wk of vigorous-intensity physical activity, or an equivalent combination of MVPA is the minimum amount of activity recommended to achieve substantial health benefits over and above routine daily activities. Importantly, because physical activity is defined to include all types of muscular activity that substantially increase energy expenditure, individuals can achieve this recommendation by accumulating bouts of moderate or vigorous intensity daily activities (e.g. using the stairs, increasing the amount of walking in their daily routine, performing yard work, etc.) or through structured exercise, a subset of physical activity performed deliberately with the intention of improving or maintaining physical fitness (e.g. treadmill walking for 30 min/day, 5 d/wk). When moderate and vigorous intensity activities are combined to meet this recommendation, the minimum goal is approximately 10 MET h/wk above usual daily activities (range 7.5 to 12.5 MET h/wk) (21, 22).
In the current study, changes in CHAMPS data were analyzed at each assessment period (baseline to week 12; week 12 to week 24; and week 24 to week 36) to determine the number of subjects who successfully increased (from baseline) and sustained a higher volume of MVPA. In the current study, sustained physical activity was defined as an increase in MVPA of at least 10 MET h/wk for at least two 12-wk periods, up to and including retesting at week 36. Using this threshold, three physical activity groups were defined based on subjects who: (1) achieved a minimum increase of 10 MET h/wk that was subsequently sustained or increased for an additional 12 weeks (SUS-PA); (2) achieved a minimum increase of 10 MET h/wk that was followed by a decrease in physical activity for at least one 12-wk period (UNSUS-PA); or (3) did not achieve an increase of at least 10 MET h/wk from baseline (LO-PA) (Figure 1).
Figure 1.
Definitions of the three physical activity groups: Sustained PA (SUS-PA), Unsustained PA (UNSUS-PA), and low PA (LO-PA).
Scenarios in which subjects would be included in (or excluded from) each of the physical activity (PA) groupings after 36 weeks.
Abbreviations: SUS-PA: ≥10 MET h/wk increment of MVPA and sustained; UNSUS-PA, ≥10 MET h/wk increment in MVPA, followed by decline; LO-PA, did not achieve ≥10 MET h/wk increment in MVPA.
Primary outcome measure
The Fibromyalgia Impact Questionnaire (FIQ) is an instrument designed to quantitate the overall impact of FM over many dimensions (23). Frequently used in FM clinical trials, the FIQ contains 10 items each with a maximum possible score of 10 (FIQ score range 0–100). The first item contains 11 questions that inquire about the patient’s ability to perform different types of physical activity. These questions are scored and summed to yield a physical impairment score (FIQ-PI). Higher scores on the FIQ-PI indicate a greater degree of physical impairment from FM on the individual.
Secondary outcomes measures
The overall impact of FM was assessed with the FIQ total score (FIQ-Total). Higher scores on the FIQ-Total indicate a greater impact of FM on the individual.
Pain severity was assessed with the Brief Pain Inventory (BPI), a self-administered assessment tool designed to assess the severity and impact of pain on daily functions. The BPI rates pain severity on 4 items (current, worst, least, and average pain in past week) (24). The BPI has been proven reliable, valid and responsive to change among patients with chronic non-malignant pain (25).
Depression severity was assessed with the Patient Health Questionnaire 8-item Depression Scale (PHQ-8), a brief self-administered questionnaire designed to evaluate major depressive disorder symptoms. The PHQ-8 allows a score (range: 0 to 24) based on the total number and severity of depressive symptoms noted over the previous two weeks (26–28).
Statistical analyses
Comparisons of baseline continuous outcomes and categorical outcomes between the three PA groups were performed by ANOVAs and chi-square tests, respectively. To evaluate relationships between changes in physical activity and clinical outcomes, Pearson correlation coefficients were computed and t-tests used to evaluate for possible associations between change in physical activity (from baseline) at 36 weeks (MET h/wk) and changes in the primary and secondary outcome measures. Separate correlation analyses were performed to evaluate for potential relationships between the total volume of physical activity performed during each time period and changes (from baseline) in the primary and secondary outcome measures in the following 12-wk time period. Multiple regression models were used to analyze changes in clinical outcomes and the three physical activity groups were compared after being adjusted for baseline values of the response variable, treatment group, baseline physical activity level, and use of antidepressant medication. The Tukey method was applied to adjust p-values for multiple pairwise comparisons.
RESULTS
Baseline characteristics of study sample
A total of 216 patients met the inclusion criteria and were enrolled in the original study. Of these, 170 subjects (78% of the original cohort) completed the outcome measures at baseline and each follow-up period. As shown in Figure 2, 15 subjects were excluded for not completing the primary or secondary outcome measures at one or more of the post-intervention time periods. An additional 31 subjects were excluded for not falling into any one of the three group definitions (Figure 1). Except for self-perceived physical impairment, which was slightly higher in those excluded (p=0.03), no differences existed for any baseline demographic, clinical, or physical activity characteristics for those subjects not included in the final analyses (data not shown). Table 1 shows that most of the remaining 170 participants were female (94.7%) and white (87.1%) with a mean (SD) age of 46 (10.9) years. The majority of participants had some education beyond high school (78.2%) and 54.1% were employed. At study entry, the sample had a mean disease duration of 9.2 (7.1) years; 32.9% were on opioid analgesics; 27.7% on anticonvulsant; and 59.4% on an antidepressant other than tricyclics. Clinically, the study subjects represented a FM population that was moderately depressed [PHQ-8=12.6 (5.1)] with moderate-to-severe physical impairment [(FIQ-PI=5.5 (1.5)] and pain severity [(BPI=6.0 (1.3)].
Figure 2.
Participant Enrollment and Self-report Physical Activity Characteristics
Table 1.
Baseline characteristics of 170 subjects with data at all 3 time periods (≥10 MET h/wk increment in MVPA)*
| SUS-PA (n=27) | UNSUS-PA (n=68) | LO-PA (n=75) | p | All Participants (n=170) | |
|---|---|---|---|---|---|
| Demographics | |||||
| Age (yr) | 45.3 (11.7) | 46.6 (10.5) | 45.8 (11.0) | 0.34 | 45.9 (10.9) |
| Gender (% female) | 96.3% | 92.7% | 96.0% | 0.62 | 94.7% |
| Ethnicity (% non-Hispanic) | 96.3% | 97.1% | 100.0% | 0.29 | 98.2% |
| Race (% white) | 92.6% | 85.3% | 86.7% | 0.63 | 87.1% |
| Education (% >high school) | 81.5% | 83.8% | 72.0% | 0.21 | 78.2% |
| Marital status (% married) | 70.4% | 60.3% | 58.7% | 0.55 | 61.2% |
| Employment (% employed) | 44.4% | 50.0% | 61.3% | 0.48 | 54.1% |
| Clinical Variables | |||||
| BMI (kg/m2) | 30.5 (6.9) | 31.4 (6.6) | 31.3 (7.9) | 0.86 | 31.2 (7.2) |
| Duration of FM (yr) | 8.2 (7.2) | 9.3 (6.6) | 10.2 (7.7) | 0.54 | 9.2 (7.1) |
| PHQ-8 depression (range 0–24)† | 13.0 (5.3) | 12.2 (5.1) | 12.3 (5.1) | 0.36 | 12.6 (5.1) |
| BPI pain (range 0–10)† | 6.0 (1.1) | 6.1 (1.3) | 6.0 (1.4) | 0.58 | 6.0 (1.3) |
| FIQ-PI (range 0–10)† | 5.2 (1.6) | 5.7 (1.4) | 5.5 (1.7) | 0.30 | 5.5 (1.5) |
| FIQ-Total (range 0–100)† | 66.6 (11.9) | 68.4 (12.5) | 66.4 (14.7) | 0.08 | 67.4 (12.8) |
| Medications, Anticonvulsants | 22.2% | 30.9% | 26.7% | 0.67 | 27.7% |
| % prescribed Antidepressants | 29.6% | 63.2% | 66.7% | <0.01 | 59.4% |
| Opiates | 22.2% | 27.9% | 41.3% | 0.10 | 32.9% |
Values are the means (standard deviation) for continuous variables and percentage for categorical variables.
Higher score indicates a worse state of health. Antidepressants: Non-tricyclic antidepressants Abbreviations: SUS-PA: ≥10 MET h/wk increment in MVPA and sustained; UNSUS-PA, ≥10 MET h/wk increment in MVPA, followed by decline; LO-PA, did not achieve ≥10 MET h/wk increment in MVPA; CHAMPS, Community Health Activities Model Program for Seniors; PHQ-8, Patient Health Questionnaire-8; BPI, Brief Pain Inventory; FIQ-PI, Fibromyalgia Impact Questionnaire-Physical Impairment.
At baseline, the study participants represented a primarily underactive FM population, reporting mean MVPA participation below the recommended minimum levels in terms of duration (1.8 h/wk vs. 2.5 h/wk recommended) and volume (6.6 MET h/wk vs. 10 MET h/wk recommended). After 36 weeks, 27 subjects (15.9%) reported a sustained increase of at least 10 MET h/wk (SUS-PA) for ≥12 weeks. Sixty-eight subjects (40.0%) reported an increase that was not sustained (UNSUS-PA). The remaining subjects (n=75, 44.1%) were unable to achieve an increase in MVPA (LO-PA). Except for antidepressant use, baseline demographic and clinical characteristics were similar between groups at baseline. Compared to the UNSUS-PA and LO-PA groups, the SUS-PA group was receiving fewer antidepressant medications (p<0.01) (Table 1).
Bivariate Relationships between changes in MVPA and improvement in clinical outcomes
Increased participation in activities of moderate-vigorous intensity was significantly related to improvements in self-reported physical impairment (FIQ-PI; r =0.41, p<0.001), FIQ-Total (r=0.29, p<0.001), pain intensity (BPI; r=0.26, p<0.001), and depression severity (PHQ-8; r=0.22, p<0.01). However, no significant associations were observed between changes in MET h/wk during any previous 12-wk period and changes in any primary or secondary outcome variable during the subsequent 12-wk period (p>0.25).
Changes in physical activity after 36 weeks
There were no statistically significant differences between groups in total baseline physical volume in terms of MET hours per week (Table 2). Beginning at week 12 and continuing through week 36, patients in the SUS-PA and UNSUS-PA groups reported significantly higher levels of total physical activity and MVPA in terms of MET h/wk relative to the LO-PA group (p<0.01). At week 36, the SUS-PA group reported significantly greater amounts of total physical activity and MVPA compared to the UNSUS-PA group (p<0.01, Table 2).
Table 2.
Physical activity volume (MET h/wk) at baseline and weeks 12, 24, and 36*
| SUS-PA (n=27) | UNSUS-PA (n=68) | LO-PA (n=75) | p-value (group)‡ | p-value (pairwise) ↑ SUS-PA vs. UNSUS-PA, SUS-PA vs. LO-PA, UNSUS-PA vs. LO-PA | |
|---|---|---|---|---|---|
| All physical activity (MET h/wk) | |||||
| Baseline | 14.2 (12.7) | 18.9 (23.4) | 22.3 (21.0) | 0.14 | 0.42, 0.11, 0.62 |
| Week 12 | 36.8 (21.1) | 40.0 (32.6) | 20.1 (17.8) | <0.01 | 0.77, <0.01, <0.01 |
| Week 24 | 43.7 (28.1) | 36.8 (26.1) | 16.2 (14.0) | <0.01 | 0.27, <0.01, <0.01 |
| Week 36 | 49.7 (23.4) | 24.7 (22.0) | 12.2 (12.6) | <0.01 | <0.01, <0.01, <0.01 |
|
| |||||
| All MVPA (MET h/wk) | |||||
| Baseline | 4.7 (10.3) | 7.6 (19.2) | 6.5 (11.8) | 0.69 | 0.67, 0.86, 0.90 |
| Week 12 | 18.3 (10.2) | 23.3 (25.0) | 6.4 (9.2) | <0.01 | 0.42, <0.01, <0.01 |
| Week 24 | 24.4 (21.7) | 22.9 (18.9) | 4.8 (7.1) | <0.01 | 0.90, <0.01, <0.01 |
| Week 36 | 32.4 (16.7) | 13.1 (15.6) | 2.8 (5.5) | <0.01 | <0.01, <0.01, <0.01 |
Values are the means (standard deviation).
Abbreviations: MET h/wk: equal to the sum of the average time spent per week in each physical activity multiplied by the MET value for each activity; SUS-PA, ≥10 MET h/wk increment in moderate-vigorous physical activity (MVPA)/wk and sustained; UNSUS-PA, ≥10 MET h/wk increment in MVPA, followed by decline; LO-PA, did not achieve ≥10 MET h/wk increment in MVPA.
MVPA participation and FIQ-physical impairment (FIQ-PI)
The magnitude of improvement in the FIQ-PI score from study entry to week 36 was significantly greater for both the SUS-PA and UNSUS-PA groups compared to the LO-PA (p<0.01); however, no statistically significant differences were observed between the SUS-PA and UNSUS-PA groups (p=0.15) (Table 3).
Table 3.
Group comparisons (≥10 MET h/wk increment in MVPA) and changes in clinical outcomes
| SUS-PA (n=27) | UNSUS-PA (n=68) | LO-PA (n=75) | p-value (group)‡ | p-value (pairwise) ↑ SUS-PA vs. UNSUS-PA, SUS-PA vs. LO-PA, UNSUS-PA vs. LO-PA | |
|---|---|---|---|---|---|
| Primary Outcome | |||||
| FIQ-PI† | 3.1 (0.4) | 2.1 (0.3) | 0.6 (0.3) | <0.01 | 0.15, <0.01, <0.01 |
| Secondary Outcomes | |||||
| FIQ-Total | 21.2 (3.7) | 17.3 (2.3) | 8.6 (2.2) | <0.01 | 0.64, <0.05, <0.05 |
| BPI pain† | 2.0 (0.4) | 1.4 (0.2) | 0.9 (0.2) | <0.05 | 0.36, <0.05, 0.27 |
| PHQ-8† | 4.3 (1.1) | 3.1 (0.7) | 1.7 (0.7) | 0.09 | 0.66, 0.11, 0.28 |
Values represent adjusted mean changes (standard error) from baseline to week 36, with positive values indicating improvement.
P-values were from multiple linear regression analyses and were adjusted for treatment group assignment, response variable value at study entry, baseline level of MVPA, and use of antidepressants.
Pairwise p-values were from Tukey adjusted multiple comparisons, to control for inflated type I error.
Abbreviations: SUS-PA, ≥10 MET h/wk increment in moderate-vigorous physical activity (MVPA)/wk and sustained; UNSUS-PA, ≥10 MET h/wk increment in MVPA, followed by decline; LO-PA, did not achieve ≥10 MET h/wk increment in MVPA; FIQ-PI, Fibromyalgia Impact Questionnaire-Physical Impairment; BPI, Brief Pain Inventory; PHQ-8, Patient Health Questionnaire-8.
MVPA participation and global well-being (FIQ-Total)
The degree of improvement in FIQ-Total was significantly greater for both the SUS-PA and UNSUS-PA groups compared to the LO-PA group (p<0.05); however, no statistically significant differences were observed between SUS-PA and UNSUS-PA (p=0.64) (Table 3).
MVPA participation and pain severity (BPI)
Patients in the SUS-PA group reported a clinically meaningful improvement in pain severity compared to the LO-PA group [2.0 (0.4) vs. 0.9 (0.2); p<0.05]. Compared to the UNSUS-PA group [1.4 (0.2)], however, the magnitude of pain severity improvement in the SUS-PA group was not statistically significant (p>0.05). No statistically significant differences were observed between UNSUS-PA and LO-PA (p=0.27) (Table 3).
MVPA participation and depression severity (PHQ-8)
The overall change in depression severity was not different between groups after 36 weeks (p>0.05) (Table 3).
DISCUSSION
The results of this study were unable to document the clinical benefits of increasing and sustaining MVPA for longer than 12 weeks. Rather, this study provides further evidence that increasing MVPA for at least one 12-wk period produces significant improvements in physical impairment (FIQ-PI) and overall well-being (FIQ-Total). Although sustaining higher volumes of physical activity appears to provide significant improvements in pain severity compared to not increasing physical activity, our results do not demonstrate that sustaining MVPA participation longer than 12 weeks produces greater improvements in the degree of physical impairment, overall well-being, or pain severity compared to FM patients increasing, but not sustaining physical activity of at least moderate intensity. It is encouraging, however, that patients who increased physical activity participation to levels widely recommended for promoting improvements in health outcomes (≥ 10 MET h/wk) did not report worsening pain symptoms.
Compared to the UNSUS-PA group, the SUS-PA group demonstrated greater improvement for all primary and secondary outcome measures, albeit the mean group differences were not statistically significant. However, on our primary clinical outcome (FIQ-PI), we observed a medium effect size of 0.43 between the SUS-PA and UNSUS-PA groups. Further, a moderate correlation was observed between increased MVPA participation and improvement in FIQ-PI. In this regard, since the direction of increased MVPA participation also was toward an improvement in other clinical outcome measures, the lack of significance could have been related to the small sample size in the SUS-PA group.
In the current study, it is reassuring to note that existing pain severity did not worsen with continued long-term participation in activities of at least moderate intensity, and perhaps, may even help to reduce pain in patients with FM. Interestingly, patients in the SUS-PA group experienced a 2-point (33%) reduction in pain severity, which is considered a clinically meaningful improvement in pain severity in FM patients presenting with moderate-to-severe pain (29). Although previous FM exercise studies have reported improvements in FM-related pain severity (30, 31), widespread support for this finding is less consistent (10). The reasons for this discrepancy are unclear; however, differences in study design (population, sample size, outcome measures), study duration and follow-up frequency, and exercise program design (modes, frequency, intensity, duration, progression) are likely contributing factors. The current study evaluated patients over a longer follow-up time period (36 weeks) and included an individualized exercise prescription that progressed gradually in terms of frequency, intensity, and duration over a 36-wk period.
This study does have several limitations that should be considered when interpreting the results. First, CHAMPS only assesses physical activity patterns over one week and is intended to be representative of the total volume of physical activity performed during the previous 4 weeks. Therefore, it is possible that some subjects may have been misclassified if the level of physical activity reported from CHAMPS during a particular assessment period was atypical compared to the level of physical activity performed during the previous 11 weeks. However, given that the clinical benefits were greatest for those who increased and sustained physical activity levels, followed by those unable to sustain (or increase) physical activity levels, any misclassifications may actually contribute to an underestimation of the magnitude of the association between physical activity maintenance and clinical benefits. Second, although not statistically different, mean MVPA levels in terms of MET hours per week were higher at baseline in the LO-PA (6.5 MET h/wk) and UNSUS-PA (7.6 MET h/wk) groups compared to the SUS-PA group (4.7 MET h/wk). Given that the greatest improvements in health outcomes are typically seen when people who are least active become more physically active, the potential exists, particularly in the UNSUS-PA and LO-PA groups, for a ceiling effect in terms of improvement in overall physical function and symptom improvement. In this regard, patients already performing higher levels of physical activity may need other treatment approaches, (e.g. cognitive behavior therapy) to receive additional symptom relief. Finally, we cannot rule out the possibility that some subjects may have overestimated their level of physical activity. Previous research indicates that greater than 60% of adults, who do not currently meet recommended PA guidelines, overestimate their physical activity levels (32). This rate could be even higher in patients with FM, who are typically sedentary and frequently report cognitive deficiencies in attention, concentration, and memory (33, 34). However, even if subjects did overestimate their physical activity, it was more likely that the overestimate rate in each group would be about the same; and therefore, should not confound our study results. Moreover, whether FM subjects did or did not overestimate their physical activity levels, significant improvements in physical function and pain severity were reported in the SUS-PA group compared to the LO-PA group.
Research to support the beneficial effects of physical activity in FM continues to mount. To our knowledge, this is the first study to examine the longitudinal relationship between long-term maintenance of MVPA and subsequent improvement and preservation of FM-related clinical benefits. Additionally, compared to most FM exercise trials, the results of this study are based on a large sample size and longer study duration. Although we were unable to document that sustaining MVPA produced greater improvements in clinical outcomes than increasing, but not sustaining MVPA, our study demonstrates that participation in higher volumes of physical activity is not associated with worsening pain, which may lessen concerns for some FM patients with an aversion toward beginning a physical activity program or increasing their current levels of physical activity. Future randomized controlled trials are warranted to better elucidate the relationship between sustained physical activity participation and subsequent improvement in important patient-oriented outcomes for fibromyalgia.
Significance and Innovation.
To our knowledge, this is the first study to examine the longitudinal relationship between long-term maintenance of moderate-vigorous physical activity and improvement and preservation of fibromyalgia-related clinical benefits.
Patients with fibromyalgia who increased moderate-vigorous physical activity levels had greater improvements in clinical symptoms compared to patients unable to achieve higher volumes of physical activity.
Long-term moderate-vigorous physical activity participation is not associated with worsening pain symptoms in fibromyalgia.
Acknowledgments
Funding Support:
This study was supported by a grant from the National Institute of Arthritis and Musculoskeletal and Skin Diseases (Grant number: 1RO1AR054324-01A1)
Footnotes
Conflict of Interest
No professional relationships or conflicts of interest exist with any companies or manufacturers who will benefit from the results of the present study.
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