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Abstract

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. SUBJECTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. AUTHOR CONTRIBUTIONS
  8. REFERENCES

Objective

To evaluate the relationship between long-term maintenance of moderate to vigorous physical activity (MVPA) and clinical outcomes in fibromyalgia (FM).

Methods

Patients with FM (n = 170) received individualized exercise prescriptions and completed baseline and followup physical activity assessments using the Community Health Activities Model Program for Seniors questionnaire at weeks 12, 24, and 36. The primary outcome was the change in the Fibromyalgia Impact Questionnaire-Physical Impairment (FIQ-PI) score. The secondary outcomes included improvements in overall well-being (FIQ total score), pain severity ratings, and depression.

Results

Using a threshold increase in MVPA of ≥10 metabolic equivalent hours/week 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 (LO-PA) this benchmark. Compared to LO-PA subjects, both SUS-PA and UNSUS-PA subjects reported greater improvement in FIQ-PI (P < 0.01) and FIQ total score (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 improved physical function and overall well-being in patients with FM. Although sustained physical activity was not associated with greater clinical benefit compared with 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.


INTRODUCTION

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. SUBJECTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. AUTHOR CONTRIBUTIONS
  8. REFERENCES

A great deal of interest supporting the role of a physically active lifestyle as part of the overall treatment approach in fibromyalgia (FM) has been generated in recent years ([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 can also 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]). Among the people 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 long-term sustainability of these benefits (i.e., >12 weeks). Therefore, the main purpose of this study was to determine whether increasing and maintaining higher levels of physical activity over a longer time period is associated with the improvement or worsening of symptoms.

The Research to Encourage Exercise for Fibromyalgia (REEF) study was a randomized attention-controlled clinical trial, the main objective of which was to evaluate the efficacy of motivational interviewing (MI), a client-centered counseling approach designed to elicit a specific behavioral change ([12]), by encouraging a more physically active lifestyle in FM patients 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 1 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 study was to compare the changes in self-reported physical function and symptom severity in FM subjects who either increased and sustained participation in moderate to vigorous physical activity (MVPA), increased but did not sustain MVPA levels, or 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 with 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 with those unable to maintain or increase MVPA levels.

Box 1. Significance & Innovations

  • To our knowledge, this is the first study to examine the longitudinal relationship between long-term maintenance of moderate to vigorous physical activity and improvement and preservation of fibromyalgia-related clinical benefits.
  • Patients with fibromyalgia who increased moderate to vigorous physical activity levels had greater improvements in clinical symptoms compared with patients unable to achieve higher volumes of physical activity.
  • Long-term moderate to vigorous physical activity participation is not associated with worsening pain symptoms in fibromyalgia.

SUBJECTS AND METHODS

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. SUBJECTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. AUTHOR CONTRIBUTIONS
  8. REFERENCES

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 6 exercise-based telephone calls spread over a 12-week period. To control for attention, the AC group received the same number of telephone calls 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 postintervention), week 24 (3-month followup), and week 36 (6-month followup). The participants in both groups received an individualized exercise prescription and 2 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 FM by a rheumatologist and verified by the study physician (also a rheumatologist). To be included, participants (ages 18–65 years) had to meet the American College of Rheumatology classification criteria for FM ([15]), have a Brief Pain Inventory (BPI) pain score ≥4, have a Fibromyalgia Impact Questionnaire-Physical Impairment (FIQ-PI) score ≥2, and be receiving stable doses of FM medications for ≥4 weeks. Participants were excluded if they had known cardiovascular disease, had moderate to severe chronic lung disease, had uncontrolled hypertension, had orthopedic or musculoskeletal conditions that would prohibit moderate-intensity physical activity, had active suicidal ideation, had planned elective surgery during the study period, had ongoing unresolved disability claims, had inflammatory rheumatic conditions (e.g., rheumatoid arthritis, systemic lupus erythematosus, or other connective tissue disease), were currently receiving medications that may affect the chronotropic response to exercise/physical activity (e.g., beta-blockers or select calcium-channel blockers), were pregnant, had schizophrenia or another psychosis, or had self-reported participation in MVPA >2 days/week during the previous 6 months ([13]).

Exercise training program.

All subjects received 2 supervised exercise sessions and an individualized exercise prescription that included initial levels of exercise intensity, duration, and frequency that progressed over the ensuing 36 weeks of the exercise program. The exercise prescription included the beginning exercise intensity (40–50% of heart rate reserve [HRR]), duration (10–12 minutes/session), and frequency (2–3 days/week). Subjects were instructed to gradually increase their total volume of exercise to a maximum of 55–65% of HRR, 28–30 minutes/session, and 3–4 days/week over the ensuing 36 weeks ([13, 14]).

Physical activity assessment.

The self-reported 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 4 weeks. In older adults, the CHAMPS questionnaire has demonstrated content and construct validity, internal consistency, and responsiveness to change ([16-18]). In the current study, the CHAMPS questionnaire was used because of its ability to capture a wide range of physical activities, including occupational activities, household activities, daily tasks, as well as structured exercise. The CHAMPS questionnaire provides an estimate of the typical number of hours/week spent performing sedentary to light physical activity (e.g., sitting, walking slowly, and stretching) and MVPA (e.g., brisk walking, jogging, and sport activities) ([19]). Using the original scoring algorithms from the CHAMPS questionnaire, 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 still (1 MET = 3.5 ml O2 × kg−1 × minute−1). Estimates of time spent in sedentary to light (<3 METS), moderate (3–6 METS), and vigorous (>6 METS) physical activity intensity were determined by multiplying the reported hours spent performing each activity by the activity's corresponding MET value and adding these values for all activities to determine the total number of MET hours/week and the MET hours/week specifically from activities of at least moderate intensity (≥3 METS).

Physical activity group classifications.

For most adults, 150 minutes/week of moderate-intensity physical activity, 75 minutes/week of vigorous-intensity physical activity, or an equivalent combination of MVPA is the minimum amount of activity recommended to achieve more substantial health benefits than routine daily activities. Importantly, because physical activity is defined as including all types of muscular activity that substantially increase energy expenditure, individuals can achieve the recommended amount of activity 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, which is defined as a subset of physical activity performed deliberately with the intention of improving or maintaining physical fitness (e.g., treadmill walking for 30 minutes/day for 5 days/week). When moderate- and vigorous-intensity activities are combined to meet the recommended amount of activity, the minimum goal is ∼10 MET hours/week above usual daily activities (range 7.5–12.5 MET hours/week) ([21, 22]).

In the current study, changes in the 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 hours/week for at least two 12-week periods, up to and including retesting at week 36. Using this threshold, 3 physical activity groups were defined based on subjects who achieved a minimum increase of 10 MET hours/week that was subsequently sustained or increased for an additional 12 weeks (SUS-PA), achieved a minimum increase of 10 MET hours/week that was followed by a decrease in physical activity for at least one 12-week period (UNSUS-PA), or did not achieve an increase of at least 10 MET hours/week from baseline (LO-PA) (Figure 1).

image

Figure 1. Scenarios in which subjects would be included in (or excluded from) each of the physical activity (PA) groups after 36 weeks. SUS-PA = sustained PA (≥10 metabolic equivalent [MET] hours/week increase of moderate to vigorous PA [MVPA] and sustained); UNSUS-PA = unsustained PA (≥10 MET hours/week increase in MVPA, followed by decline); LO-PA = low PA (did not achieve ≥10 MET hours/week increase in MVPA).

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Primary outcome measure.

The 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, with each having 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 added to yield an FIQ-PI score. Higher scores on the FIQ-PI indicate a greater degree of the patient's physical impairment from FM.

Secondary outcome measures.

The overall impact of FM was assessed using the FIQ total score (FIQ-Total). Higher scores on the FIQ-Total indicate a greater effect of FM on the individual.

Pain severity was assessed using the BPI, a self-administered assessment tool designed to assess the severity and impact of pain on daily functioning. The BPI rates pain severity on 4 items (current, worst, least, and average pain in the past week) ([24]). The BPI has been proven to be reliable, valid, and responsive to change among patients with chronic nonmalignant pain ([25]).

Depression severity was assessed using 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 0–24) based on the total number and severity of depressive symptoms noted within the previous 2 weeks ([26-28]).

Statistical analyses.

Comparisons of baseline continuous outcomes and categorical outcomes between the 3 physical activity groups were performed by analyses of variance and chi-square tests, respectively. To evaluate the relationships between changes in physical activity and clinical outcomes, Pearson's correlation coefficients were computed and t-tests were used to evaluate for possible associations between the change in physical activity (from baseline) at 36 weeks (MET hours/week) and changes in the primary and secondary outcome measures. Separate correlation analyses were performed to evaluate the 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-week period. Multiple regression models were used to analyze changes in the clinical outcomes, and the 3 physical activity groups were compared after being adjusted for baseline values of the response variable, treatment group, baseline physical activity level, and antidepressant medication. Tukey's method was applied to adjust P values for multiple pairwise comparisons.

RESULTS

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. SUBJECTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. AUTHOR CONTRIBUTIONS
  8. REFERENCES

Baseline characteristics of the study sample.

A total of 216 patients met the inclusion criteria and were enrolled in the original study. Of these patients, 170 subjects (78% of the original cohort) completed the outcome measures at baseline and each followup period. As shown in Figure 2, 15 subjects were excluded for not completing the primary or secondary outcome measures at ≥1 postintervention time periods. An additional 31 subjects were excluded for not fulfilling any one of the 3 group definitions (Figure 1). Except for self-perceived physical impairment, which was slightly higher in those excluded (P = 0.03), no differences existed among any baseline demographic, clinical, or physical activity characteristics for the subjects not included in the final analyses (data not shown). Table 1 shows that most of the remaining 170 participants were women (94.7%) and white (87.1%), with a mean ± SD age of 46 ± 10.9 years. The majority of the participants (78.2%) had some education beyond high school and 54.1% were employed. At study entry, the sample had a mean ± SD disease duration of 9.2 ± 7.1 years; 32.9% were taking opioid analgesics, 27.7% anticonvulsants, and 59.4% antidepressants other than tricyclics. Clinically, the study subjects represented an FM population that was moderately depressed (mean ± SD PHQ-8 score 12.6 ± 5.1), with moderate to severe physical impairment (mean ± SD FIQ-PI score 5.5 ± 1.5) and pain severity (mean ± SD BPI score 6.0 ± 1.3).

image

Figure 2. Participant enrollment and self-reported physical activity characteristics. MI = motivational interviewing; AC = attention control; MET = metabolic equivalent; MVPA = moderate to vigorous physical activity.

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Table 1. Baseline characteristics of 170 subjects with data at all 3 time periods (≥10 MET hours/week increase in MVPA)*
 SUS-PA (n = 27)UNSUS-PA (n = 68)LO-PA (n = 75)PAll participants (n = 170)
  1. SUS-PA = sustained physical activity (≥10 metabolic equivalent [MET] hours/week increase in moderate to vigorous PA [MVPA] and sustained); UNSUS-PA = unsustained PA (≥10 MET hours/week increase in MVPA, followed by decline); LO-PA = low PA (did not achieve ≥10 MET hours/week increase in MVPA); BMI = body mass index; FM = fibromyalgia; PHQ-8 = Patient Health Questionnaire 8-Item Depression Scale; BPI = Brief Pain Inventory; FIQ-PI = Fibromyalgia Impact Questionnaire-Physical Impairment; antidepressants = nontricyclic antidepressants.

  2. a

    A higher score indicates a worse state of health.

Demographics     
Age, mean ± SD years45.3 ± 11.746.6 ± 10.545.8 ± 11.00.3445.9 ± 10.9
Sex, % women96.392.796.00.6294.7
Ethnicity, % non-Hispanic96.397.1100.00.2998.2
Race, % white92.685.386.70.6387.1
Education, % >high school81.583.872.00.2178.2
Married, %70.460.358.70.5561.2
Employed, %44.450.061.30.4854.1
Clinical variables     
BMI, mean ± SD kg/m230.5 ± 6.931.4 ± 6.631.3 ± 7.90.8631.2 ± 7.2
Duration of FM, mean ± SD years8.2 ± 7.29.3 ± 6.610.2 ± 7.70.549.2 ± 7.1
Mean ± SD PHQ-8 depression score (range 0–24)a13.0 ± 5.312.2 ± 5.112.3 ± 5.10.3612.6 ± 5.1
Mean ± SD BPI pain score (range 0–10)a6.0 ± 1.16.1 ± 1.36.0 ± 1.40.586.0 ± 1.3
Mean ± SD FIQ-PI score (range 0–10)a5.2 ± 1.65.7 ± 1.45.5 ± 1.70.305.5 ± 1.5
Mean ± SD FIQ total score (range 0–100)a66.6 ± 11.968.4 ± 12.566.4 ± 14.70.0867.4 ± 12.8
Medications, % prescribed     
Anticonvulsants22.230.926.70.6727.7
Antidepressants29.663.266.7< 0.0159.4
Opiates22.227.941.30.1032.9

At baseline, the study participants were representative of a primarily underactive FM population, reporting mean MVPA participation levels below the recommended minimum levels in terms of duration (1.8 hours/week versus 2.5 hours/week recommended) and volume (6.6 MET hours/week versus 10 MET hours/week recommended). After 36 weeks, 27 subjects (15.9%) reported a sustained increase of at least 10 MET hours/week (SUS-PA) for ≥12 weeks, 68 subjects (40.0%) reported an increase that was not sustained (UNSUS-PA), and the remaining 75 subjects (44.1%) were unable to achieve an increase in MVPA (LO-PA). Except for the use of antidepressants, baseline demographic and clinical characteristics were similar between the 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 to vigorous intensity was significantly related to improvements in self-reported physical impairment (FIQ-PI r =0.41 [P < 0.001] and 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 hours/week during any previous 12-week period or changes in any primary or secondary outcome variables during the subsequent 12-week period (P > 0.25).

Changes in physical activity after 36 weeks.

There were no statistically significant differences in total baseline physical volume in terms of MET hours/week between the groups (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 hours/week 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 hours/week) at baseline and weeks 12, 24, and 36*
 SUS-PA (n = 27)UNSUS-PA (n = 68)LO-PA (n = 75)Group PPairwise Pa
  1. Values are the mean ± SD. Metabolic equivalent (MET) hours/week = equal to the sum of the average time spent per week performing each physical activity multiplied by the MET value for each activity; SUS-PA = sustained physical activity (≥10 MET hours/week increase in moderate to vigorous PA [MVPA] and sustained); UNSUS-PA = unsustained PA (≥10 MET hours/week increase in MVPA, followed by decline); LO-PA = low PA (did not achieve ≥10 MET hours/week increase in MVPA).

  2. a

    Values are SUS-PA versus UNSUS-PA/SUS-PA versus LO-PA/UNSUS-PA versus LO-PA. Pairwise P values were from Tukey's adjusted multiple comparisons to control for inflated Type I error.

All physical activity, MET hours/week     
Baseline14.2 ± 12.718.9 ± 23.422.3 ± 21.00.140.42/0.11/0.62
Week 1236.8 ± 21.140.0 ± 32.620.1 ± 17.8< 0.010.77/< 0.01/< 0.01
Week 2443.7 ± 28.136.8 ± 26.116.2 ± 14.0< 0.010.27/< 0.01/< 0.01
Week 3649.7 ± 23.424.7 ± 22.012.2 ± 12.6< 0.01< 0.01/< 0.01/< 0.01
All MVPA, MET hours/week     
Baseline4.7 ± 10.37.6 ± 19.26.5 ± 11.80.690.67/0.86/0.90
Week 1218.3 ± 10.223.3 ± 25.06.4 ± 9.2< 0.010.42/< 0.01/< 0.01
Week 2424.4 ± 21.722.9 ± 18.94.8 ± 7.1< 0.010.90/< 0.01/< 0.01
Week 3632.4 ± 16.713.1 ± 15.62.8 ± 5.5< 0.01< 0.01/< 0.01/< 0.01

MVPA participation and 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 with the LO-PA group (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 hours/week increase in MVPA) and changes in clinical outcomes*
 SUS-PA (n = 27)UNSUS-PA (n = 68)LO-PA (n = 75)Group PaPairwise Pb
  1. SUS-PA = sustained physical activity (≥10 metabolic equivalent [MET] hours/week increase in moderate to vigorous PA [MVPA] and sustained); UNSUS-PA = unsustained PA (≥10 MET hours/week increase in MVPA, followed by decline); LO-PA = low PA (did not achieve ≥10 MET hours/week increase in MVPA); FIQ-PI = Fibromyalgia Impact Questionnaire-Physical Impairment; BPI = Brief Pain Inventory; PHQ-8 = Patient Health Questionnaire 8-Item Depression Scale.

  2. a

    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 antidepressants.

  3. b

    Values are SUS-PA versus UNSUS-PA/SUS-PA versus LO-PA/UNSUS-PA versus LO-PA. Pairwise P values were from Tukey's adjusted multiple comparisons to control for inflated Type I error.

  4. c

    Values are the adjusted mean change (SE) from baseline to week 36, with positive values indicating improvement.

Primary outcome     
FIQ-PIc3.1 (0.4)2.1 (0.3)0.6 (0.3)< 0.010.15/< 0.01/< 0.01
Secondary outcomes     
FIQ total scorec21.2 (3.7)17.3 (2.3)8.6 (2.2)< 0.010.64/< 0.05/< 0.05
BPI painc2.0 (0.4)1.4 (0.2)0.9 (0.2)< 0.050.36/< 0.05/0.27
PHQ-8c4.3 (1.1)3.1 (0.7)1.7 (0.7)0.090.66/0.11/0.28

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 with 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 mean ± SD improvement in pain severity compared with the LO-PA group (2.0 ± 0.4 versus 0.9 ± 0.2; P < 0.05). However, compared with the UNSUS-PA group (mean ± SD 1.4 ± 0.2), 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 the UNSUS-PA and LO-PA groups (P = 0.27) (Table 3).

MVPA participation and depression severity (PHQ-8).

The overall change in depression severity was not different between the groups after 36 weeks (P > 0.05) (Table 3).

DISCUSSION

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. SUBJECTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. AUTHOR CONTRIBUTIONS
  8. REFERENCES

From the results of this study, we 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-week period produces significant improvements in physical impairment (FIQ-PI) and overall well-being (FIQ-Total). Although sustaining higher volumes of physical activity appeared to provide significant improvements in pain severity compared with not increasing physical activity, our results did 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 with FM patients increasing but not sustaining physical activity of at least moderate intensity. However, it is encouraging that patients who increased physical activity participation to levels widely recommended for promoting improvements in health outcomes (≥10 MET hours/week) did not report worsening pain symptoms.

Compared with 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, we observed a medium effect size of 0.43 between the SUS-PA and UNSUS-PA groups on our primary clinical outcome (FIQ-PI). Further, a moderate correlation was observed between increased MVPA participation and improvement in FIQ-PI. In this regard, because 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 long-term participation in these activities may even have helped 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 studies of exercise in FM have reported improvements in FM-related pain severity ([30, 31]), widespread support for these findings is less consistent ([10]). The reasons for this discrepancy are unclear; however, differences in study design (population, sample size, and outcome measures), study duration and followup frequency, and exercise program design (modes, frequency, intensity, duration, and progression) are likely contributing factors. The current study evaluated patients over a longer followup time period (36 weeks) and included an individualized exercise prescription that progressed gradually in terms of frequency, intensity, and duration over a 36-week period.

This study does have several limitations that should be considered when interpreting the results. First, the CHAMPS questionnaire only assesses physical activity patterns over 1 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 on the CHAMPS questionnaire during a particular assessment period was atypical compared with 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/week were higher at baseline in the LO-PA (6.5 MET hours/week) and UNSUS-PA (7.6 MET hours/week) groups compared with the SUS-PA group (4.7 MET hours/week). Considering that the greatest improvements in health outcomes are typically observed when people who are least active become more physically active, the potential exists for a ceiling effect in terms of improvement in overall physical function and symptom improvement, particularly in the UNSUS-PA and LO-PA groups. In this regard, patients already performing higher levels of physical activity may need other treatment approaches (e.g., cognitive–behavioral therapy) to receive additional symptom relief. Finally, we cannot rule out the possibility that some subjects may have overestimated their level of physical activity. A previous study has indicated that >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 because they are typically sedentary and frequently report cognitive deficiencies in attention, concentration, and memory ([33, 34]). However, even if subjects in our study did overestimate their physical activity, it is 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 with the LO-PA group.

Research supporting 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 with most FM exercise trials, the results of this study were based on a larger 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 demonstrated that participation in higher volumes of physical activity was not associated with worsening pain, which may lessen concerns for some FM patients who have an aversion to beginning a physical activity program or increasing their current levels of physical activity. Future randomized controlled trials are needed to better elucidate the relationship between sustained physical activity participation and subsequent improvement in important patient-oriented outcomes for FM.

AUTHOR CONTRIBUTIONS

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. SUBJECTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. AUTHOR CONTRIBUTIONS
  8. REFERENCES

All authors were involved in drafting the article or revising it critically for important intellectual content, and all authors approved the final version to be published. Dr. Kaleth had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.

Study conception and design. Kaleth, Saha, Ang.

Acquisition of data. Kaleth, Saha, Ang.

Analysis and interpretation of data. Kaleth, Saha, Jensen, Slaven, Ang.

REFERENCES

  1. Top of page
  2. Abstract
  3. INTRODUCTION
  4. SUBJECTS AND METHODS
  5. RESULTS
  6. DISCUSSION
  7. AUTHOR CONTRIBUTIONS
  8. REFERENCES
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