Cardiac output and arteriovenous oxygen difference contribute to lower peak oxygen uptake in patients with fibromyalgia, 2023, Lehto et al

Background

Patients with fibromyalgia (FM) exhibit low peak oxygen uptake ( ˙VO2peak). We aimed to detect the contribution of cardiac output to ( ˙Q) and arteriovenous oxygen difference [C(a-v)O2] to ˙VO2 from rest to peak exercise in patients with FM.

Methods
Thirty-five women with FM, aged 23 to 65 years, and 23 healthy controls performed a step incremental cycle ergometer test until volitional fatigue. Alveolar gas exchange and pulmonary ventilation were measured breath by-breath and adjusted for fat-free body mass (FFM) where appropriate. ˙Q (impedance cardiography) was monitored. C(a-v)O2 was calculated using Fick’s equation. Linear regression slopes for oxygen cost (Δ˙VO2/Δwork rate) and ˙Q to VO2 (Δ˙Q/Δ˙VO2) were calculated. Normally distributed data were reported as mean Å} SD and non-normal data as median [interquartile range].

Results
˙VO2peak was lower in FM patients than in controls (22.2 Å} 5.1 vs. 31.1 Å} 7.9 mL∙min−1∙kg−1, P < 0.001; 35.7 Å} 7.1 vs. 44.0 Å} 8.6 mL∙min−1∙kg FFM−1, P < 0.001). ˙Q and C(a-v)O2 were similar between groups at submaximal work rates, but peak ˙Q (14.17 [13.34–16.03] vs. 16.06 [15.24–16.99] L∙min−1, P = 0.005) and C(a-v)O2 (11.6 Å} 2.7 vs. 13.3 Å} 3.1 mL O2∙ 100 mL blood−1, P = 0.031) were lower in the FM group. No significant group differences emerged in Δ ˙VO2/Δwork rate (11.1 vs. 10.8 mL∙min−1∙W−1, P = 0.248) or Δ ˙Q/Δ˙VO2 (6.58 vs. 5.75, P = 0.122) slopes.

Conclusions
Both ˙Q and C(a-v)O2 contribute to lower ˙VO2peak in FM. The exercise responses were normal and not suggestive of a muscle metabolism pathology.

Open access, https://bmcmusculoskeletdisord.biomedcentral.com/articles/10.1186/s12891-023-06589-2

 

Wonder what they would have found if they had done two exercise tests on consecutive days.