Cardiovascular Autonomic Modulation After Acute Resistance Exercise in Women With Fibromyalgia

Objective: To test the hypothesis that autonomic modulation after resistance exercise (RE) would be reduced in women with fibromyalgia (FM) compared with controls. Design: Before-after trial. Setting: Testing occurred in a university setting. Participants: Women with FM (n=9) and healthy controls (n=9) underwent testing before (pre) and 20 minutes after (post) RE. Interventions: Not applicable. Main Outcome Measures: Normalized low-frequency (LFnu) and normalized high-frequency (HFnu) oscillations and the LFnu/HFnu ratio were indicative of sympathetic modulation, parasympathetic modulation, and sympathovagal balance, respectively. Baroreceptor reflex sensitivity (BRS) was also measured. Results: Variables were similar in both groups at rest. HFnu decreased in controls (pre, 55.0+/-4.2%; post, 35.0+/-4.7%; P<.05) and increased in women with FM (pre, 57.0+/-5.7%; post, 63.2+/-4.6%; P<.05). LFnu increased in controls (pre, 43.3 +/-4.4%; post, 63.2+/-4.8%; P<.05) and decreased in women with FM (pre, 41.8+/-5.6%; post, 35.6+/-4.7%; P<.05). The LFnu/HFnu ratio increased in controls (pre, 0.89+/-0.17; post, 2.43+/-0.64; P<.05) with no change in women with FM (pre, 0.90+/-0.22; post, 0.64+/-0.13; P=.13). BRS decreased in controls (pre, 8.78+/-1.42ms/mmHg; post, 5.49+/-0.66ms/mmHg; P<.05), but not in women with FM (pre, 5.91+/-1.22ms/mmHg; post, 9.23+/-2.4ms/mmHg; P=.16). Conclusions: After acute RE, women with FM responded differently from controls, demonstrated by lower sympathetic and higher vagal modulation without altering BRS. These post-exercise responses may be attributed to the altered autonomic responsiveness to physiologic stress that characterizes FM.