URL: http://www.clinicaltrials.gov, registration number: NCT002289625.

Introduction/Purpose We demonstrated that patients with obstructive sleep apnea (OSA) have reduced muscle metaboreflex control of muscle sympathetic nerve activity (MSNA). In addition, exercise training increased muscle metaboreflex control in heart failure patients. Objective We tested the hypothesis that exercise training would increase muscle metaboreflex control of MSNA in patients with OSA. Methods Forty-one patients with OSA were randomized into the following two groups: 1) nontrained (OSANT, n = 21) and 2) trained (OSAT, n = 20). Muscle sympathetic nerve activity was assessed by microneurography technique, muscle blood flow (FBF) by venous occlusion plethysmography, heart rate by electrocardiography, and blood pressure with an automated oscillometric device. All physiological variables were simultaneously assessed at rest, during isometric handgrip exercise at 30% of the maximal voluntary contraction, and during posthandgrip muscle ischemia (PHMI). Muscle metaboreflex sensitivity was calculated as the difference in MSNA between PHMI and the rest period. Patients in the OSAT group underwent 72 sessions of moderate exercise training, whereas patients in the OSANT group were clinical follow-up for 6 months. Results The OSANT and OSAT groups were similar in anthropometric, neurovascular, hemodynamic and sleep parameters. Exercise training reduced the baseline MSNA (34 ± 2 bursts per minute vs 25 ± 2 bursts per minute; P < 0.05) and increased the baseline FBF (2.1 ± 0.2 mL·min−1 per 100 g vs 2.4 ± 0.2 mL·min−1 per 100 g; P < 0.05). Exercise training significantly reduced MSNA levels and increased FBF responses during isometric exercise. Exercise training significantly increased MSNA responses during PHMI (Δ6.5 ± 1 vs −1.7 ± 1 bursts per minute, P < 0.01). No significant changes in FBF or hemodynamic parameters in OSANT patients were found. Conclusions Exercise training increases muscle metaboreflex sensitivity in patients with OSA. This autonomic change associated with increased muscle blood flow may contribute to the increase in exercise performance in this set of patients.

These findings suggest an association between OSA and decreased metaboreflex control of MSNA. Muscle vasodilation during handgrip static exercise is preserved in patients with OSA.

BACKGROUNDWe have recently demonstrated that patients with obstructive sleep apnea(OSA) have abnormal muscle metaboreflex control of muscle sympathetic nerve activity(MSNA).OBJECTIVETo test the hypothesis that exercise training (ET) would improve muscle metaboreflex control of MSNA in patients with OSA.METHODS41 individuals with OSA(polysomnography), age = 51±1 years, BMI = 29.5±0.6 kg/m2, were randomly divided into untrained (n=21), and trained (n=20) groups. Heart rate, blood pressure, and MSNA(microneurography) were continuously measured during 4 min at rest, 3 min of handgrip static exercise (30% maximal voluntary contraction), and 2 min post handgrip muscle ischemia(PHMI). The metaborreflex sensitivity was evaluated as the difference in MSNA between first and second min PHMI and resting period. ET program was conducted for six months, three session/week. Each session consisted of 45 min of cycle ergometer, 10 min of local strengthening exercise, and 5 min of cool down.RESULTSBaseline age, BMI, exercise capacity, and hemodynamic variables were similar between groups. Likewise, the exercise and PHMI responses were not different between groups. Of note, MSNA returned to baseline during the PHMI period in both groups, which is an indicative of impaired muscle metaboreflex control. ET significantly increased exercise capacity. ET reduced MSNA levels at rest (36±3 vs. 25± 2 bursts/min), and during exercise (43±4 vs. 32± 3 bursts/min). More interestingly, MSNA remained elevated during PHMI in comparison to rest period in the exercise‐trained individuals (29±2 vs. 25± 2 bursts/min). No change in the untrained patients was found.CONCLUSIONSET decreases sympathetic nerve activity during moderate handgrip exercise and improves muscle metaboreflex control of MSNA in patients with OSA.Supported by FAPESP # 2010/15064‐6Support or Funding InformationFAPESP # 2010/15064‐6This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.