Muscle strength, flexibility, aerobic fitness impact physical pain and negative attitudes
by Contributing Writer
A strong association exists between higher physical fitness and lower levels of pain, less psychological over-reaction (catastrophizing) to pain, and higher chronic-pain self-efficacy in women with fibromyalgia (FM), according to a recent Spanish study.
In addition, muscle strength and flexibility and aerobic fitness had independent and combined effects on pain levels and negative pain-associated psychological factors. Hence, fitness might have a positive role in the physical experience and the negative attitudes of FM patients toward their chronic pain.
“These results might have implications for future intervention studies in this population,” wrote investigators online in Arthritis Care and Research, calling for prospective studies to investigate the potential of improved fitness to modify the natural course of FM or mediate treatment responses.
Led by Alberto Soriano-Maldonado, BSc, a doctoral candidate in biomedicine in the University of Granada’s physical education and sport department in Granada, Spain, researchers undertook a population-based, cross-sectional study of 468 female FM patients from the southern region of Andalusia. Mean age was 52.1 years, mean weight was 71.2 kg, and mean BMI was 28.6 kg/m2.
Patients were asked to refrain from taking their pain medications for 24 hours before testing.
In pain measurements, the mean score on the 0–10 Visual Analog Scale (VAS) was 6.0 (higher=worse pain), and the mean bodily pain score on the 0–100 Short Form 36-Item Health Survey subscale was 20.9 (lower score=higher pain). The average score on the Pain Catastrophizing Scale (0–52, higher= ore negative) came in at about the middle at 25.0. As for impact, the mean score on the 0–10 Fibromyalgia Impact Questionnaire was 7.6 (higher=worse pain), and the mean score on the Chronic Pain Self-Efficacy Scale, a coping assessment, was 135.4 (range 0–300, higher=better).
Researchers computed a standardized composite score for each fitness component (aerobic, muscle strength, flexibility, and motor agility), with their average constituting a clustered global fitness profile.
Overall, higher performance on fitness tests correlated with lower levels of pain, regardless of the assessment tool. The average pain intensity in the group with the highest global fitness profile (quintile 5) was 1.8 units lower on VAS than in the group with lowest fitness (quintile 1). Muscle strength and flexibility were independently associated with pain, while aerobic fitness and flexibility were independently associated with pain-related psychosocial issues.
“In general, there was a linear (dose-response) relationship so that higher levels of fitness were associated with lower levels of pain and catastrophizing and higher self-efficacy,” the authors wrote. The FM-pain-fitness connection has been unclear, they added. Previous studies reported that the distance covered in the 6-minute walk test was inversely associated with pain sensitivity, self-reported pain intensity, and pain interference in function and quality of life, while peak maximum oxygen consumption was found to be associated with pain sensitivity but not with clinical pain intensity.
“Our exploratory analyses suggest that muscle strength and flexibility could be the fitness components most strongly associated with pain levels, while aerobic fitness and flexibility could be the fitness components most strongly associated with the psychological experience (i.e., catastrophizing and self-efficacy) of pain,” wrote Soriano-Maldonado and his associates. They added, however, that other research has shown equal reductions in pain severity with both strength and aerobic training.
The authors offered several possible mechanisms by which pain might be worsened or alleviated by fitness levels. Among these, a low basal muscle tone could reduce connectivity in sensory-motor systems and lead to greater peripheral sensitization to painful stimuli. Enhancing it might improve connectivity. Similarly, abnormal peripheral mechanisms in microcirculatory capillaries could reduce peripheral tissue oxygenation and lead to central sensitization in FM patients. “Thus, it might be speculated that increasing tissue oxygenation as a result of aerobic exercise could potentially diminish peripheral and central sensitization and reduce clinical pain,” the researchers wrote. In addition, exercise-induced endogenous opioid activity in the central and peripheral nervous systems might also partially explain pain mitigation following exercise programs.
Addressing the study’s limitations, the investigators noted its all-female cohort and its cross-sectional design, which cannot establish causality, as well as the possibility that the low fitness levels measured in some patients might have been influenced by fear and avoidance in the test setting.
This work was supported by grants from ministries in the Spanish and Andalusian governments and from the European Union’s 7th Framework Program.
The authors declared no conflicts of interest.
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