The effects of a six-week exercise program on heart rate variability in adults with and without obstructive sleep apnea

Purpose Exercise training improves heart rate variability (HRV) and is recommended as a behavioral treatment option for obese adults suffering from obstructive sleep apnea (OSA). We examined whether the effects of a supervised exercise program on HRV parameters differed according to OSA severity in obese adults. Methods Obese (BMI > 33 kg*m − 2 ) adults were evaluated for OSA using overnight polysomnography and subsequently classified as exhibiting no/mild OSA (AHI < 15 events*hour − 1 ) or moderate/severe OSA (AHI > 15 events*hour − 1 ). Cardiorespiratory fitness, body composition, and short-term heart rate variability (HRV) in frequency (VLF, LF, HF, LF/HF) and time (RMSSD, SDNN) domains were measured at baseline (Pre) and following a six-week (3 days/week) comprehensive exercise program (Post). Results Twenty-seven adults (Age: 49 ± 9 years; W:14; M:13) with no/mild OSA and 29 adults (Age: 52 ± 9 years; W:15; M:14) with moderate/severe OSA completed all aspects of the trial. No significant differences in age, cardiorespiratory fitness, or HRV parameters were observed between groups at baseline. Across the sample, exercise training improved fitness (Pre: 30.5 ± 6.4 vs. Post: 32.4 ± 6.6 ml/kg/min, p < 0.001), VLF% ( p = 0.015, η p 2 = 0.11), and HF% ( p = 0.016, η p 2 = 0.11). An interaction of OSA severity and exercise training was observed for SDNN (interaction p = 0.01, η p 2 = 0.12), such that the no/mild OSA increased HRV, whereas the moderate to severe OSA decreased HRV. Conclusion These data suggest that while six weeks of exercise led to parasympathetic improvement across the sample, it was insufficient to improve sympathetic HRV signal among overweight adults with moderate to severe OSA.