Korean J Pain.  2016 Oct;29(4):249-254. 10.3344/kjp.2016.29.4.249.

The acute effect of maximal exercise on plasma beta-endorphin levels in fibromyalgia patients

  • 1Department of Rheumatology, Iran University of Medical Sciences, Tehran, Iran. bidari.a@iums.com
  • 2Rheumatology Research Center, Razi Hospital, School of Medicine, Guilan University of Medical Sciences, Rasht, Iran.
  • 3Medical Laser Research Center, Iranian Center for Medical Laser (ICML), Academic Center for Education, Culture and Research (ACECR), Tehran, Iran.
  • 4Golestan Research Center of Gastroenterology and Hepatology, Golestan University of Medical Sciences, Gorgan, Iran.


This study aimed to investigate the effect of strenuous exercise on β-endorphine (β-END) level in fibromyalgia (FM) patients compared to healthy subjects.
We enrolled 30 FM patients and 15 healthy individuals. All study participants underwent a treadmill exercise test using modified Bruce protocol (M.Bruce). The goal of the test was achieving at least 70% of the predicted maximal heart rate (HRMax). The serum levels of β-END were measured before and after the exercise program. Measurements were done while heart rate was at least 70% of its predicted maximum.
The mean ± the standard deviation (SD) of exercise duration in the FM and control groups were 24.26 ± 5.29 and 29.06 ± 3.26 minutes, respectively, indicating a shorter time to achieve the goal heart rate in FM patients (P < 0.003). Most FM patients attained 70% HRMax at lower stages (stage 2 and 3) of M.Bruce compared to the control group (70% versus 6.6%, respectively; P < 0.0001). Compared to healthy subjects, FM patients had lower serum β-END levels both in baseline and post-exercise status (Mean ± SD: 122.07 ± 28.56 µg/ml and 246.55 ± 29.57 µg/ml in the control group versus 90.12 ± 20.91 µg/ml and 179.80 ± 28.57 µg/ml in FM patients, respectively; P < 0.001).
We found that FM patients had lower levels of β-END in both basal and post-exercise status. Exercise increased serum the β-END level in both groups but the average increase in β-END in FM patients was significantly lower than in the control group.


Beta-endorphin; Exercise; Fibromyalgia; Healthy subjects; Pain; Serum

MeSH Terms

Exercise Test
Healthy Volunteers
Heart Rate
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