Fibromyalgia

Reading time:

Fibromyalgia, also called fibromyalgia syndrome or FMS, is a fairly common musculoskeletal disorder that is characterized by chronic widespread pain at a number of anatomical locations and a reduced pain threshold. Exercise for fibromyalgia will likely lead to optimal results when it focuses on the practical considerations and is designed with adherence in mind. Where possible, aerobic exercise should be prioritized, as it has the best evidence base. Resistance training may also be useful for increasing functional capacity and for reducing the risk of falls.

CONTENTS


BACKGROUND

Introduction

Fibromyalgia, also called fibromyalgia syndrome or FMS, is a fairly common musculoskeletal disorder that is characterized by chronic widespread pain at a number of anatomical locations and a reduced pain threshold. Sufferers commonly complain of fatigue, depression, anxiety, sleep disturbances, headache, migraine, abdominal pain and increased urinary frequency. The exact cause of the condition is unknown.

Measuring severity

Various measurements are used to track the severity of fibromyalgia symptoms, including the Fibromyalgia Impact Questionnaire (FIQ), the Short Form-36 (SF-36) score, and the Visual Analogue Scale (VAS) for pain. The FIQ is a specific scale for fibromyalgia and ranges from 0 to 100, with higher scores indicating more severe symptoms. The SF-36 score is a scale that also ranges from 0 to 100 but is more generic. Also, in the SF-36, higher scores indicate better health status rather than worse symptoms. The SF-36 has both physical and mental sub-scales, which can be reported separately. The VAS for pain is a scale that ranges from 0 to 100, with higher scores indicating more severe pain. Like the SF-36 it is a non-specific test scale and is used to measure the extent of pain in many different conditions. However, it is commonly used for the assessment of fibromyalgia because pain is a common complaint in this disorder.

Prevalence

Fibromyalgia is much more prevalent in women than in men and seems to range from around 3.4 – 4.9% and 0.5 – 1.6% in normal adult women and men, respectively. Wolfe et al. investigated the prevalence of fibromyalgia in a population of 3,006 individuals in the US and reported that the prevalence was 3.4% for women and 0.5% for men across all age ranges. However, prevalence increased with age and was found to be 7.1 and 1.1% in women and men respectively, in the 60 – 69 year age group. White et al. investigated the prevalence of fibromyalgia in a populations of 3,395 non-institutionalised Canadian adults. Based on their study, they estimated that fibromyalgia affects 4.9% of adult women and 1.6% of adult men. White et al. conducted a cross sectional random mail survey of 100 Canadian rheumatologists and found that fibromyalgia was one of the 3 most common diagnoses among new patient consultations across Canada, comprising 14 – 20% of new visits, and that it was the only rheumatological disorder to have increased in proportion over the past 5 years (from 1995).

Economic burden

A small number of studies have either reviewed the economic burden of fibromyalgia. Doron et al. performed a retrospective study in a primary care clinic in a Southern district of Israel and found that patients with fibromyalgia utilize health care resources to a similar extent to patients with other major chronic diseases but typically receive less attention from the health care system. Wolfe et al. performed a 7-year, prospective longitudinal trial in 538 fibromyalgia patients being treated in 6 rheumatology centres up to 1997. They found found that fibromyalgia patients averaged around 10 outpatient medical visits per year and that the average cost was US$2,274 per patient per year (in 1996 costs terms). A similar later study performed by Boonen et al. found that in 2002 costs terms, the average total societal costs per patient per year for fibromyalgia were €7,813 . This was similar to the costs for chronic lower back pain (€8,533) but higher than those for ankylosing spondylitis (€3,205). Robinson et al. assessed the direct (i.e. medical and pharmaceutical claims) and indirect (i.e. disability claims and work days lost) costs associated with fibromyalgia from a total of 4,699 patients between 1996 – 1998. They found that total annual costs for fibromyalgia claimants were US$5,945, which is similar to the figure reported by Boonen et al. but higher than that reported by Wolfe et al.

Economic validity of exercise for fibromyalgia

Assessing the economic validity of a treatment is a difficult task. Nevertheless, Gusi and Tomas-Carus assessed whether it was appropriate to prescribe fibromyalgia patients with a 1 hour, supervised, water-based exercise session, 3 times per week for 8 months. They found that the mean incremental treatment costs of the water-based exercise group exceeded those for usual care per patient by €517 for health care costs and by €1,032 for societal costs. However, the additional cost was justified on the basis of an acceptable cost per quality-adjusted life-years (QALY). The Spanish Efficiency Threshold was €23,153 per QALY for the 8 month period at the time of the study and the total average cost of the proposed treatment was just €7,878 per QALY, indicating that it was cost-effective from an economic point of view.

GENERAL EXERCISE FOR FIBROMYALGIA

Introduction

Several general exercise interventions have been explored for the treatment of fibromyalgia. Broadly, they can be subdivided into either land-based or water-based exercise types.

Meta-analyses

A small number of meta-analyses have been performed in relation to the benefits of exercise in the treatment of various outcome measures relevant to fibromyalgia (Rossy et al.; Häuser et al.). Rossy et al. carried out a meta-analysis in order to evaluate the efficacy of both pharmacological and non-pharmacological treatments for fibromyalgia. They investigated four different outcome measurements: physical status, self-reported fibromyalgia symptoms (i.e. pain and fatigue), psychological status and daily function. They reported that non-pharmacological treatments (including exercise and cognitive behavioural therapy) were found to be significantly superior for self-reported fibromyalgia symptoms (i.e. pain and fatigue) than pharmacological treatment alone. They also found a similar trend for daily function. Rossy et al. therefore concluded that the appropriate intervention for fibromyalgia is therefore exercise and cognitive-behavioural therapy with appropriate medication as may be deemed necessary for helping with sleep loss and pain symptoms.

Systematic reviews

A great many systematic reviews have been performed in relation to the benefits of exercise in the treatment of various outcome measures relevant to fibromyalgia (Sim and Adams; Jones et al.; Häuser et al.; Perraton et al.; Goldenberg et al.; Schneider et al.). In general, these reviews have concluded that exercise appears to be effective for the treatment of various outcome measures used to assess the severity of symptoms in individuals with fibromyalgia. In addition, most of the reviews support the superior benefits of aerobic exercise over other modalities (e.g. Sim and Adams) and note that most trials have a large number of dropouts (e.g. Jones et al.). Importantly, it has been noted that the methodological quality of studies included in the reviews is generally fairly low mainly because of small sample sizes and a failure to perform blinding (Sim and Adams). Interestingly, Jones et al. found that low intensity exercise was superior to high intensity exercise for reduction in symptoms while Häuser et al. found no significant difference between the effects produced by low and moderate intensity exercise.

Land-based exercise

Several studies have reported successful outcomes using land-based exercise interventions with a focus on aerobic exercise (e.g. McCain et al.; Richards and Scott; Valim  et al.; Wigers et al.; Mannerkorpi et al.) or using non-specific or combined interventions (e.g. Martin et al.; Burckhardt  et al.; Buckelew et al.; Schachter et al.; Gowans et al.; Da Costa et al.; Rooks et al.; Hammond and Freeman). In contrast, flexibility interventions have largely not produced such beneficial results in comparison with aerobic exercise (McCain et al.; Valim et al.). Both Pilates (Altan et al.) and the gentle martial art tai chi (Wang et al.; Taggart et al.) have been reported to produce beneficial effects. Moreover, both Pilates (Altan et al.) and tai chi (Wang et al.) appear to be superior to flexibility interventions. Importantly, while adverse events are not commonly reported, it has been often noted that exercise interventions in populations with fibromyalgia often display a high proportion of dropouts (e.g. Schachter et al.; Hammond and Freeman).

Water-based exercise

Several studies have reported successful outcomes using water-based exercise interventions for outcomes relevant to the treatment of fibromyalgia. The nature of the water-based exercise varies between interventions and includes deep water running (e.g. Assis et al.) and other forms of general water-based exercise (De Andrade et al.; Tomas-Carus et al.; Tomas-Carus et al.; Gusi et al.; Munguía-Izquierdo and Legaz-Arrese; Evcik et al.; Altan et al.). Some studies have reported that water-based exercise is superior to land-based exercise for the treatment of outcomes relevant to fibromyalgia (e.g. Assis et al.; Saltskår Jentoft et al.; Evcik et al.) and some studies have suggested that sea water may be superior to swimming pool water for certain outcome measures (De Andrade et al.). Like the interventions studying land-based exercise, however, it is often noted that there are many dropouts from the study protocols (e.g. Assis et al.).

RESISTANCE TRAINING

A number of studies have investigated the use of land-based resistance training interventions for the treatment of fibromyalgia, as follows:

Study Description Finding
Valkeinen et al. The researchers recruited 13 elderly women with fibromyalgia and 10 healthy elderly women as controls who performed a heavy-resistance training protocol (5 sets of leg presses with 10RM) before and after a 21-week strength training intervention. The researchers reported that the 21-week strength training intervention led to large increases in both maximal isometric force, EMG activity and 10RM during the leg press exercise. At the outset of the trial, the resulting muscular pain (i.e. delayed onset muscle soreness or DOMS) caused by the heavy-resistance training protocol was much higher in the subjects with fibromyalgia than in the healthy subjects. However, after the 21-week trial, the resulting muscular pain was substantially reduced in the subjects with fibromyalgia and it was much closer to the levels experienced by the healthy subjects (although still higher).
Valkeinen et al. The researchers recruited 26 elderly women with fibromyalgia and 11 healthy elderly women as controls. All of these subjects carried out supervised strength training twice a week for 21 weeks. They also recruited 13 elderly women with fibromyalgia as non-training controls. The researchers reported that maximal isometric knee extension force increased in the fibromyalgia and healthy groups by 32 ± 33% and 24 ± 12% respectively and maximal isometric knee flexion force increased by 13 ± 20% and 24 ± 17% respectively. They also found that walking speed, stair-climbing time and the self-reported physical function capacity as assessed by the Health Assessment Questionnaire index improved in the fibromyalgia group.
Valkeinen et al. The researchers recruited 26 elderly women with fibromyalgia and randomly assigned them to either a strength-training group or to a control group. The strength-training group performed progressive strength training twice a week for 21 weeks. The researchers reported that all patients completed the intervention and there were no drop outs. The strength-training group displayed a 36% and 33% increase in maximal isometric and concentric leg extension force, respectively, while quadriceps  cross-sectional increased by 5%. However, there were no significant changes in the subjective measures commonly tested in fibromyalgia.
Kingsley et al. The researchers randomly allocated 29 females with fibromyalgia to either a control group or to a strength-training group for a 12-week intervention. The strength-training protocol involved 11 exercises of 1 set of 8 – 12 reps with 40 – 80% of 1RM, twice per week. The researchers reported that 47% subjects in the strength-training group dropped out after just 4 weeks. Those in the strength group that completed the trial significantly improved upper- and lower-body strength but tender point sensitivity and Fibromyalgia Impact Questionnaire scores did not change.
Hakkinen et al. The researchers randomly assigned 21 female patients with fibromyalgia to either an experimental group or to a control group, while 12 healthy women served as training controls. The training groups performed progressive strength training twice a week for 21 weeks. The researchers reported that both the fibromyalgia and healthy subjects increased maximal strength, explosive strength and EMG activity similarly. Additionally, the researchers reported that the progressive strength training intervention displayed improvements in subjectively perceived fatigue, depression, and neck pain in the subjects with fibromyalgia.
Bircan  et al. The researchers compared the effects of 8 weeks of aerobic exercise or strength training in 30 female patients with fibromyalgia. The researchers reported that both types of exercise were similarly effective for improving symptoms, tender point count, fitness, depression, and quality of life in fibromyalgia.
Jones et al. The researchers randomly allocated 68 female patients with fibromyalgia to either a strength training group or to a stretching group. They tested improvements in muscular strength, flexibility, weight, body fat, tender point count, and disease and symptom severity scales. The researchers found that the strength training group displayed greater improvements than the stretching group in all measures, although the stretching group also displayed some improvements, albeit of a lesser degree.
Figueroa et al. The researchers assigned 10 females with fibromyalgia to a supervised resistance training group and 9 healthy control subjects to a control group. The resistance training group performed strength training 2 days per week for 16 weeks. The researchers reported that in the resistance training group, upper and lower body strength increased by 63% and 49% respectively, while pain perception decreased by 39%. The researchers also reported that both total power of heart rate variability (HRV) increased and the natural logarithm of high-frequency power increased. Total power of HRV is typically taken as an estimate of the global activity of the autonomic nervous system while high-frequency power is typically taken as an estimate of cardiac parasympathetic activity. The researchers therefore concluded that resistance training improved autonomic function in females with fibromyalgia.

Based on these interventions, strength training appears to be efficacious for the treatment of fibromyalgia, although some studies indicate poor adherence and high drop-out rates from the interventions. Since strength training does not appear to hold significantly greater benefits than aerobic exercise, it may be appropriate to program either aerobic or strength training on the basis of individual preference or on the probability of greatest adherence.


EVIDENCE-BASED RECOMMENDATIONS FOR EXERCISE

Some reviews have made evidence-based recommendations for the treatment of fibromyalgia that include non-pharmacological treatments.

Study Description Finding
Carville et al. The reviewers produced the EULAR guidelines for the management of fibromyalgia and made 9 recommendations, including 2 general, 4 non-pharmacological and 3 pharmacological. Only the 4 non-pharmacological recommendations are reported here. The reviewers recommended the use of heated pool treatment with or without concomitant exercise, the use of individually-tailored exercise programmes including both aerobic exercise and strength training, the use of cognitive behavioral therapy, and the use of other therapies such as relaxation, rehabilitation, physiotherapy and psychological support as appropriate. However, they only ascribed a low level of evidence to the non-pharmacological treatments.
Fitzcharles et al. The reviewers prepared the 2012 Canadian Guidelines for the treatment of fibromyalgia and produced 46 recommendations. Only the 2 exercise-specific recommendations are reported here. The reviewers recommended that persons with fibromyalgia should participate in a graduated exercise program of their choosing, and they recommended that patients with fibromyalgia on sick leave should be encouraged to participate in an appropriate rehabilitation program with a focus on improving function, leading to a return to work if possible.
Häuser et al. The reviewers made a recommendation on the basis of their meta-analysis. The reviewers suggested that an exercise program for the treatment of fibromyalgia should include aerobic exercise consisting of either land-based or water-based exercises of low-to-moderate intensity and with a frequency of 2 – 3 times per week.
Busch et al. The reviewers performed a Cochrane review and meta-analysis for the role of exercise in the treatment of fibromyalgia. They included 34 studies. The reviewers found that there was moderate quality evidence that aerobic-only exercise training at recommended intensity levels has positive effects global well-being, physical function and possibly also on pain and tender points. They concluded that there is gold level evidence that supervised aerobic exercise training has beneficial effects on physical capacity and symptoms of fibromyalgia. They also reported that it is possible that strength training may also have benefits on some symptoms of fibromyalgia.
Goldenberg et al. The reviewers performed a literature review of 505 randomized controlled trials and meta-analyses of randomized controlled trials for the treatment of fibromyalgia using an interdisciplinary panel comprising 13 experts selected by the American Pain Society (APS). On the basis of their view, the reviewers recommended a stepwise program of education, certain medications, exercise, cognitive behavioral therapy, or all of the above. They concluded that there is strong evidence that cardiovascular exercise is an effective treatment for fibromyalgia.
Jones and Liptan The reviewers made 10 recommendations for the clinical prescription of exercise in the treatment of fibromyalgia. The reviewers advised: exercise should be modified to minimize aggravation of the peripheral pain generators; eccentric contractions should be avoided; high-intensity and/or repetitive movements can lead to painful episodes so exercise should be low-intensity and non-repetitive, where possible; exercise should be structured to avoid exacerbating sleep problems; exercise should be structured to help avoid periods of dizziness, such as occur during prolonged periods of standing; exercise should be structured to avoid the risk of falling (see Jones et al.); exercise programs should avoid exercises that involve jarring movements, pressure on the pelvic area or areas that involve loud noises; similar interventions as are necessary in obese populations should be considered; exercise should be performed in a structured fashion rather than included in daily activities; and exercise should promote self-efficacy and involve a sense of achievement where possible.

Other researchers have analysed the guidelines, as follows:

Häuser et al. performed a review of the various guidelines for the management of fibromyalgia, including those recommendations that had been commissioned by a scientific organization and which were based on scientific evidence. They assessed the guidelines of the American Pain Society (APS), the European League Against Rheumatism (EULAR) and the Association of the Scientific Medical Societies in Germany (AWMF). The reviewers observed that the APS and AWMF gave the highest level of recommendation to (1) aerobic exercise, (2) cognitive-behavioural therapy, (3) amitriptyline, and (4) multicomponent therapy. They observed that EULAR gave the highest level of recommendation to a set of pharmacological treatments, a B-strength recommendation to aerobic exercise and a D-strength recommendation to cognitive-behavioural therapy. They observed that EULAR did not recommend multicomponent treatment, patient education, hypnotherapy, biofeedback, or other complementary and alternative medicine approaches. The reviewers explained that the failure of EULAR to recommend aerobic exercise as highly as the APS and AWMF was a result of the grading systems used: the APS and AWMF assigned the highest level of evidence to systematic reviews and meta-analyses of RCTs but EULAR did not use these sources as they deemed the trials involved to be of insufficient quality. The reviewers observed that this approach has led to the EULAR guidelines being contradictory to the observations of a recent Cochrane review performed by Busch et al. They therefore recommend that future guidelines do not follow this pattern and instead follow the usual method of assigning the highest level of evidence to systematic reviews and meta-analyses of RCTs.

Based on these evidence-based guidelines, exercise intervention for fibromyalgia appears to be a recommended treatment method. Additionally, practical considerations seem to be most important, and the exercise program should be designed with adherence in mind.


REFERENCES

  1. Altan, L., Bingöl, U., Aykac, M., Koc, Z., & Yurtkuran, M. (2004). Investigation of the effects of pool-based exercise on fibromyalgia syndrome. Rheumatology international, 24(5), 272-277.
  2. Altan, L., Korkmaz, N., Bingol, Ü., & Gunay, B. (2009). Effect of pilates training on people with fibromyalgia syndrome: a pilot study. Archives of physical medicine and rehabilitation, 90(12), 1983-1988.
  3. Assis, M. R., Silva, L. E., Alves, A. M. B., Pessanha, A. P., Valim, V., Feldman, D., & Natour, J. (2006). A randomized controlled trial of deep water running: clinical effectiveness of aquatic exercise to treat fibromyalgia. Arthritis Care & Research, 55(1), 57-65.
  4. Bircan, C., Karasel, S. A., Akgün, B., El, O., & Alper, S. (2008). Effects of muscle strengthening versus aerobic exercise program in fibromyalgia. Rheumatology international, 28(6), 527.
  5. Boonen, A., van den Heuvel, R., van Tubergen, A., Goossens, M., Severens, J. L., van der Heijde, D., & van der Linden, S. (2005). Large differences in cost of illness and wellbeing between patients with fibromyalgia, chronic low back pain, or ankylosing spondylitis. Annals of the rheumatic diseases, 64(3), 396-402.
  6. Buckelew, S. P., Conway, R., Parker, J., Deuser, W. E., Read, J., Witty, T. E., & Kay, D. R. (1998). Biofeedback/relaxation training and exercise interventions for fibromyalgia: a prospective trial. Arthritis care and research: the official journal of the Arthritis Health Professions Association, 11(3), 196.
  7. Burckhardt, C. S., Mannerkorpi, K., Hedenberg, L., & Bjelle, A. (1994). A randomized, controlled clinical trial of education and physical training for women with fibromyalgia. The journal of Rheumatology, 21(4), 714-720.
  8. Busch, A. J., Barber, K. A., Overend, T. J., Peloso, P. M., & Schachter, C. L. (2007). Exercise for treating fibromyalgia syndrome. Cochrane Database Syst Rev, 4(4).
  9. Carville, S. F., Arendt-Nielsen, S., Bliddal, H., Blotman, F., Branco, J. C., Buskila, D., Da Silva, J. A. P.,  Danneskiold-Samsøe, B., Dincer, F., Henriksson, C., Henriksson, K., Kosek, K., Longley, K., McCarthy, G. M. Perrot, S., Puszczewicz, M. J. Sarzi-Puttini, P., Silman, A., Späth, M., & Choy, E. H. (2008). EULAR evidence-based recommendations for the management of fibromyalgia syndrome. Annals of the Rheumatic Diseases, 67(4), 536-541.
  10. Da Costa, D., Abrahamowicz, M., Lowensteyn, I., Bernatsky, S., Dritsa, M., Fitzcharles, M. A., & Dobkin, P. L. (2005). A randomized clinical trial of an individualized home-based exercise programme for women with fibromyalgia. Rheumatology, 44(11), 1422-1427.
  11. De Andrade, S. C., de Carvalho, R. F., Soares, A. S., de Abreu, F. R., de Medeiros, G. L., & Vilar, M. J. (2008). Thalassotherapy for fibromyalgia: a randomized controlled trial comparing aquatic exercises in sea water and water pool. Rheumatology international, 29(2), 147.
  12. Doron, Y., Peleg, R., Peleg, A., Neumann, L., & Buskila, D. (2004). The clinical and economic burden of fibromyalgia compared with diabetes mellitus and hypertension among Bedouin women in the Negev. Family practice, 21(4), 415-419.
  13. Evcik, D., Yigit, I., Pusak, H., & Kavuncu, V. (2008). Effectiveness of aquatic therapy in the treatment of fibromyalgia syndrome: a randomized controlled open study. Rheumatology international, 28(9), 885-890.
  14. Figueroa, A., Kingsley, J. D., McMillan, V., & Panton, L. B. (2008). Resistance exercise training improves heart rate variability in women with fibromyalgia. Clinical physiology and functional imaging, 28(1), 49-54.
  15. Fitzcharles, M. A., Ste-Marie, P. A., Goldenberg, D. L., Pereira, J. X., Abbey, S., Choinière, M., & Shir, Y. 2012 Canadian Guidelines for the diagnosis and management of fibromyalgia syndrome.
  16. Goldenberg, D. L., Burckhardt, C., & Crofford, L. (2004). Management of fibromyalgia syndrome. JAMA: the journal of the American Medical Association, 292(19), 2388-2395.
  17. Gowans, S. E., DeHueck, A., Voss, S., Silaj, A., Abbey, S. E., & Reynolds, W. J. (2001). Effect of a randomized, controlled trial of exercise on mood and physical function in individuals with fibromyalgia. Arthritis Care & Research, 45(6), 519-529.
  18. Gusi, N., Tomas‐Carus, P., Häkkinen, A., Häkkinen, K., & Ortega‐Alonso, A. (2006). Exercise in waist‐high warm water decreases pain and improves health‐related quality of life and strength in the lower extremities in women with fibromyalgia. Arthritis Care & Research, 55(1), 66-73.
  19. Gusi, N., & Tomas-Carus, P. (2008). Cost-utility of an 8-month aquatic training for women with fibromyalgia: a randomized controlled trial. Arthritis Research and Therapy, 10(1), R24.
  20. Hakkinen, A., Hakkinen, K., Hannonen, P., & Alen, M. (2001). Strength training induced adaptations in neuromuscular function of premenopausal women with fibromyalgia: comparison with healthy women. Annals of the Rheumatic Diseases, 60(1), 21.
  21. Hammond, A., & Freeman, K. (2006). Community patient education and exercise for people with fibromyalgia: a parallel group randomized controlled trial. Clin Rehabil, 20, 835-846.
  22. Häuser, W., Klose, P., Langhorst, J., Moradi, B., Steinbach, M., Schiltenwolf, M., & Busch, A. (2010). Efficacy of different types of aerobic exercise in fibromyalgia syndrome: a systematic review and meta-analysis of randomised controlled trials.
  23. Häuser, W., Thieme, K., & Turk, D. C. (2010). Guidelines on the management of fibromyalgia syndrome–a systematic review. European Journal of Pain, 14(1), 5-10.
  24. Jones, K. D., Burckhardt, C. S., Clark, S. R., Bennett, R. M., & Potempa, K. M. (2002). A randomized controlled trial of muscle strengthening versus flexibility training in fibromyalgia. The Journal of rheumatology, 29(5), 1041.
  25. Jones, K. D., Adams, D., Winters-Stone, K., & Burckhardt, C. S. (2006). A comprehensive review of 46 exercise treatment studies in fibromyalgia (1988–2005). Health and Quality of life outcomes, 4(1), 67.
  26. Jones, K. D., & Liptan, G. L. (2009). Exercise interventions in fibromyalgia: clinical applications from the evidence. Rheumatic Disease Clinics of North America, 35(2), 373-391.
  27. Jones, K. D., Horak, F. B., Winters, K. S., Morea, J. M., & Bennett, R. M. (2009). Fibromyalgia is associated with impaired balance and falls. Journal of clinical rheumatology: practical reports on rheumatic & musculoskeletal diseases, 15(1), 16.
  28. Kingsley, J. D., Panton, L. B., Toole, T., Sirithienthad, P., Mathis, R., & McMillan, V. (2005). The effects of a 12-week strength-training program on strength and functionality in women with fibromyalgia. Archives of physical medicine and rehabilitation, 86(9), 1713-1721.
  29. Mannerkorpi, K., Nordeman, L., Cider, Å., & Jonsson, G. (2010). Does moderate-to-high intensity Nordic walking improve functional capacity and pain in fibromyalgia? A prospective randomized controlled trial. Arthritis Research and Therapy, 12(5), R189.
  30. Martin, L., Nutting, A., MacIntosh, B. R., Edworthy, S. M., Butterwick, D., & Cook, J. (1996). An exercise program in the treatment of fibromyalgia. The Journal of rheumatology, 23(6), 1050-1053.
  31. McCain, G. A., Bell, D. A., Mai, F. M., & Halliday, P. D. (1988). A controlled study of the effects of a supervised cardiovascular fitness training program on the manifestations of primary fibromyalgia. Arthritis & Rheumatism, 31(9), 1135-1141.
  32. Munguía-Izquierdo, D., & Legaz-Arrese, A. (2008). Assessment of the effects of aquatic therapy on global symptomatology in patients with fibromyalgia syndrome: a randomized controlled trial. Archives of physical medicine and rehabilitation, 89(12), 2250-2257.
  33. Perraton, L., Machotka, Z., & Kumar, S. (2009). Components of effective randomized controlled trials of hydrotherapy programs for fibromyalgia syndrome: A systematic review. Journal of pain research, 2, 165.
  34. Richards, S. C., & Scott, D. L. (2002). Prescribed exercise in people with fibromyalgia: parallel group randomised controlled trial. BMJ (Clinical research ed.), 325(7357), 185.
  35. Robinson, R. L., Birnbaum, H. G., Morley, M. A., Sisitsky, T., Greenberg, P. E., & Claxton, A. J. (2003). Economic cost and epidemiological characteristics of patients with fibromyalgia claims. The Journal of rheumatology, 30(6), 1318-1325.
  36. Rooks, D. S., Gautam, S., Romeling, M., Cross, M. L., Stratigakis, D., Evans, B., & Katz, J. N. (2007). Group exercise, education, and combination self-management in women with fibromyalgia: a randomized trial. Archives of internal medicine, 167(20), 2192.
  37. Rossy, L. A., Buckelew, S. P., Dorr, N., Hagglund, K. J., Thayer, J. F., McIntosh, M. J., Hewett J. E., & Johnson, J. C. (1999). A meta-analysis of fibromyalgia treatment interventions. Annals of Behavioral Medicine, 21(2), 180-191.
  38. Saltskår Jentoft, E., Grimstvedt Kvalvik, A., & Marit Mengshoel, A. (2001). Effects of pool‐based and land‐based aerobic exercise on women with fibromyalgia/chronic widespread muscle pain. Arthritis Care & Research, 45(1), 42-47.
  39. Schachter, C. L., Busch, A. J., Peloso, P. M., & Sheppard, M. S. (2003). Effects of Short Versus Long Bouts of Aerobic Exercise in Sedentary Women With Fibromyalgia: A Randomized Controlled Trial. Physical Therapy, 83(4), 340-358.
  40. Schneider, M., Vernon, H., Ko, G., Lawson, G., & Perera, J. (2009). Chiropractic Management of Fibromyalgia Syndrome: A Systematic Review of the Literature. Journal of Manipulative and Physiological Therapeutics, 32(1), 25-40.
  41. Sim, J., & Adams, N. (2002). Systematic review of randomized controlled trials of non-pharmacological interventions for fibromyalgia. The Clinical journal of pain, 18(5), 324-336.
  42. Taggart, H. M., Arslanian, C. L., Bae, S., & Singh, K. (2002). Effects of T’ai Chi exercise on fibromyalgia symptoms and health-related quality of life. Orthopaedic nursing/National Association of Orthopaedic Nurses, 22(5), 353-360.
  43. Tomas-Carus, P., Hakkinen, A., Gusi, N., Leal, A., Hakkinen, K., & Ortega-Alonso, A. (2007). Aquatic training and detraining on fitness and quality of life in fibromyalgia. Medicine and science in sports and exercise, 39(7), 1044.
  44. Tomas-Carus, P., Gusi, N., Häkkinen, A., Häkkinen, K., Leal, A., & Ortega-Alonso, A. (2008). Eight months of physical training in warm water improves physical and mental health in women with fibromyalgia: a randomized controlled trial. J Rehabil Med, 40(4), 248-252.
  45. Valim, V., Oliveira, L., Suda, A., Silva, L., de Assis, M., Feldman, D., & Natour, J. (2003). Aerobic fitness effects in fibromyalgia. The Journal of rheumatology, 30(5), 1060-1069.
  46. Valkeinen, H., Häkkinen, A., Hannonen, P., Häkkinen, K., & Alén, M. (2006). Acute heavy‐resistance exercise–induced pain and neuromuscular fatigue in elderly women with fibromyalgia and in healthy controls: Effects of strength training. Arthritis & Rheumatism, 54(4), 1334-1339.
  47. Valkeinen, H., Alen, M., Hannonen, P., Häkkinen, A., Airaksinen, O., & Häkkinen, K. (2004). Changes in knee extension and flexion force, EMG and functional capacity during strength training in older females with fibromyalgia and healthy controls. Rheumatology (Oxford, England), 43(2), 225.
  48. Valkeinen, H., Häkkinen, K., Pakarinen, A., Hannonen, P., Häkkinen, A., Airaksinen, O., & Alén, M. (2005). Muscle hypertrophy, strength development, and serum hormones during strength training in elderly women with fibromyalgia. Scandinavian journal of rheumatology, 34(4), 309.
  49. Van Santen, M., Bolwijn, P., Verstappen, F., Bakker, C., Hidding, A., Houben, H., & Van der Linden, S. (2002). A randomized clinical trial comparing fitness and biofeedback training versus basic treatment in patients with fibromyalgia. The Journal of rheumatology, 29(3), 575.
  50. Wang, C., Schmid, C. H., Rones, R., Kalish, R., Yinh, J., Goldenberg, D. L., & McAlindon, T. (2010). A Randomized Trial of Tai Chi for Fibromyalgia. N Engl J Med, 363(743), 54.
  51. White, K. P., Speechley, M., Harth, M., & Ostbye, T. (1999). The London Fibromyalgia Epidemiology Study: the prevalence of fibromyalgia syndrome in London, Ontario. The Journal of rheumatology, 26(7), 1570-1576.
  52. White, K. P., Speechley, M., Harth, M., & Ostbye, T. (1995). Fibromyalgia in rheumatology practice: a survey of Canadian rheumatologists. The Journal of rheumatology, 22(4), 722.
  53. Wigers, S. H., Stiles, T. C., & Vogel, P. A. (1996). Effects of aerobic exercise versus stress management treatment in fibromyalgia. A 4.5 year prospective study. Scandinavian journal of rheumatology, 25(2), 77.
  54. Wolfe, F., Ross, K., Anderson, J., Russell, I. J., & Hebert, L. (1995). The prevalence and characteristics of fibromyalgia in the general population. Arthritis & Rheumatism, 38(1), 19-28.
  55. Wolfe, F., Anderson, J., Harkness, D., Bennett, R. M., Caro, X. J., Goldenberg, D. L., & Yunus, M. B. (1997). A prospective, longitudinal, multicenter study of service utilization and costs in fibromyalgia. Arthritis & Rheumatism, 40(9), 1560-1570.