The effect of aerobic and resistance exercises on heart rate variability in patients with fibromiyalgia

Fibromyalgia syndrome (FMS) is a chronic condition characterized by widespread musculoskeletal pain. Previous research has demonstrated sympathetic nervous system predominance in this patient population, which has been associated with reduced heart rate variability (HRV) values (10). The present study aimed to investigate the effects of two different exercise modalities—aerobic and resistance training—on HRV parameters in patients with FMS. Participants aged 18–45 years who met the inclusion criteria were randomly allocated using sequential randomization into three groups of fifteen each: aerobic exercise, resistance exercise, and control. Two participants from the aerobic group and three from the resistance group discontinued due to transportation or personal reasons. The study was completed with 13 participants in the aerobic group, 12 in the resistance group, and 15 in the control group.Before and after the intervention, all participants underwent cardiopulmonary exercise testing (CPET) and 24-hour Holter monitoring for HRV assessment. In addition, body mass index (BMI) was calculated, and the 6-minute walk test (6MWT) was performed. Symptom severity and functional status were evaluated using VAS, FIQ, BDI, EBSS, and IPAQ scales. The aerobic exercise protocol was carried out on a cycle ergometer three times per week for eight weeks. Each session consisted of a 10-minute warm- up, 30 minutes of moderate-intensity cycling, and a 10-minute cool-down period. Exercise intensity was determined based on 60–70% of the peak workload (Watt) obtained during CPET, corresponding to moderate intensity. Participants exercised within the target heart rate range corresponding to this intensity. At the end of each week, workloads were progressively increased by approximately 5–10 Watts to maintain the same relative intensity.Resistance training was prescribed using the DeLorme method. The initial load for each muscle group was established as the individual's one-repetition maximum (1RM). Sessions were performed three times per week, consisting of three sets of 10 repetitions at 50% of the current 1RM, with two-minute rest intervals between sets. The 1RM value was reassessed weekly, and loads were adjusted accordingly for subsequent sessions.After the 8-week intervention, the aerobic group showed a significant improvement in HRV indices and a reduction in mean heart rate on 24-hour Holter monitoring. HRV parameters in the aerobic group differed significantly compared with both the resistance and control groups, whereas no significant changes were observed in the latter two.Regarding CPET outcomes, significant improvements were found in the aerobic group for FEV₁, FVC, VO₂peak, Watt output, resting heart rate (HRrest), and heart rate recovery (HRR) values, although between-group differences did not reach statistical significance.Both the aerobic and resistance groups demonstrated a notable reduction in VAS scores compared with the control group. Improvements in FIQ and BDI scores were also observed in both exercise groups, again without significant differences between them. The aerobic group additionally showed a significant increase in IPAQ scores, indicating enhanced physical activity levels, while no changes were detected in the other groups. In the 6-minute walk test, significant improvements were recorded in both the aerobic and resistance exercise groups, accompanied by a reduction in BMI within these groups. In conclusion, this study demonstrates that regular exercise—particularly aerobic-based training—is effective in improving autonomic balance, enhancing cardiopulmonary capacity, alleviating pain severity, and improving quality of life in individuals with FMS. Incorporating personalized aerobic exercise programs into routine treatment strategies may therefore be beneficial as an adjunct to pharmacological management. Resistance training, on the other hand, appears to play a supportive role, particularly in improving muscle strength, reducing pain, and mitigating depressive symptoms. Further large-scale, long-term studies with extended follow-up are warranted to confirm these findings.