Abstract
BackgroundChronic pain and fatigue improves by exercise in fibromyalgia (FM) but underlying mechanisms are not known. Obesity is increased among FM patients and associates with higher levels of pain. Symptom improvement after aerobic exercise is affected by body mass index (BMI) in FM. Metabolic factors such as insulin-like growth factor 1 (IGF-1) and leptin may be involved. In this study, the aim was to evaluate the role of metabolic factors in lean, overweight and obese women during resistance exercise, in relation to symptom severity and muscle strength in women with FM.MethodsForty-three women participated in supervised progressive resistance exercise, twice weekly for 15-weeks. Serum free and total IGF-1, IGF-binding protein 3 (IGFBP3), adiponectin, leptin and resistin were determined at baseline and after 15-weeks. Level of current pain was rated on a visual analogue scale (0–100 mm). Level of fatigue was rated by multidimensional fatigue inventory (MFI-20) subscale general fatigue (MFIGF). Knee extension force, elbow flexion force and handgrip force were assessed by dynamometers.ResultsFree IGF-1 (p = 0.047), IGFBP3 (p = 0.025) and leptin (p = 0.008) were significantly decreased in lean women (n = 18), but not in the overweight (n = 17) and the obese (n = 8). Lean women with FM benefited from resistance exercise with improvements in current pain (p= 0.039, n = 18), general fatigue (MFIGF, p = 0.022, n = 18) and improved elbow-flexion force (p = 0.017, n = 18). In overweight and obese women with FM there was no significant improvement in pain or fatigue but an improvement in elbow flexion (p = 0.049; p = 0.012) after 15 weeks of resistance exercise.ConclusionThe clearest clinical response to resistance exercise was found in lean patients with FM. In these individuals, individualized resistance exercise was followed by changes in IGF-1 and leptin, reduced pain, fatigue and improved muscular strength. In overweight and obese women FM markers of metabolic signaling and clinical symptoms were unchanged, but strength was improved in the upper limb. Resistance exercise combined with dietary interventions might benefit patients with FM and overweight.Trial registrationThe trial was registered 21 of October 2010 with ClinicalTrials.gov identification number: NCT01226784.
Highlights
Chronic pain and fatigue improves by exercise in fibromyalgia (FM) but underlying mechanisms are not known
Since muscle strength is reduced in many women with FM, graded resistance exercise adjusted to health status and symptoms, appears to be important
The levels of free Insulin-like growth factor 1 (IGF-1), IGF-binding protein 3 (IGFBP3) and leptin were reduced in lean women with FM after 15 weeks of exercise, along with improvement in pain, fatigue and upper limb muscle strength
Summary
Chronic pain and fatigue improves by exercise in fibromyalgia (FM) but underlying mechanisms are not known. Symptom improvement after aerobic exercise is affected by body mass index (BMI) in FM Metabolic factors such as insulin-like growth factor 1 (IGF1) and leptin may be involved. Increased levels of inflammatory cytokines [6] and changes in neurotropic growth factors in the central nervous system and peripherally may influence the development and maintenance of central pain hypersensitivity by affecting adaptation and neuroplasticity [7,8,9,10]. This condition leads to considerable activity limitations and is very difficult to treat effectively. A number of independent studies indicate that resistance exercise for patients with FM is safe and effective [15, 17, 18]
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