Exercise may lower the levels of muscle metabolites that can trigger pain in fibromyalgia patients, according to a new study.
The study, “Increased Interstitial Concentrations of Glutamate and Pyruvate in Vastus Lateralis of Women with Fibromyalgia Syndrome Are Normalized after an Exercise Intervention – A Case-Control Study,“ was published in the journal PLOS ONE.
But because the normalization of metabolites was not enough to successfully reduce all pain among participants of the study, researchers suggest that fibromyalgia pain results from changes in muscles and communications in the brain.
Increasing evidence from previous studies had linked brain and spinal cord neuron signaling to pain in fibromyalgia. Additionally, it has been suggested that muscles hold many factors that could potentially increase pain sensitivity, but few studies had investigated how they muscles relate to the disease.
Because exercise is reported to reduce pain in fibromyalgia, researchers at Linköping University in Sweden sought to explore molecular changes that might bring about such improvement.
The team recruited 29 women with fibromyalgia and 28 healthy volunteers. Concentrating on the participants’ largest thigh muscle, the researchers measured a range of muscle factors using a method called microdialysis, which can measure metabolite levels surrounding muscle cells.
Researchers also examined overall body measurements, blood pressure, level of psychological distress, and aspects of quality of life. Additionally, they established the number of tender points, duration of pain, pressure pain threshold, and physical capacity.
Tests at the start of the study showed that women with fibromyalgia had higher levels of glutamate (known to be involved in pain signaling), pyruvate, and lactate.
After a 15-week exercise intervention focusing on resistance training of the legs, fibromyalgia patients had significantly lower levels of the metabolites glutamate, pyruvate, and glucose in their thigh muscles than at study start. Pain intensity levels among patients had also dropped. There were no such changes in the control group.
The team found that the decreased pain intensity after the exercise intervention correlated with lower levels of pyruvate and glucose, indicating that changes in muscle metabolites likely produced the positive effects of exercise on pain.
“This study supports the suggestion that peripheral metabolic and algesic muscle alterations are present in FMS [fibromyalgia syndrome] patients and that these alterations contribute to pain. After an exercise intervention, alterations normalized, pain intensity decreased (but not abolished), and strength and endurance improved, all findings that suggest the effects of exercise are partially peripheral,” according to the report.
Because all patients still experienced pain after the intervention, the researchers believe that fibromyalgia pain may be the result of factors associated with both the brain and muscles.
