Cardiac vagal reactivation at the onset of muscle Metaboreflex activation is not further impaired in patients with Parkinson's disease

Parkinson's disease (PD) is a common neurodegenerative disorder characterized by non-motor symptoms and marked altered sympathetic and parasympathetic activity. However, it is currently unclear if inappropriate autonomic adjustments are manifested during rapid parasympathetic adjustments that occur following cessation of exercise and at the onset of isolated post-exercise ischemia (PEI). Herein, we tested the hypothesis that, compared to older and young men, PD patients would show attenuated heart rate (HR) recovery at exercise cessation due to impaired cardiac vagal reactivation. Eleven PD patients (66 ± 9 yr), 9 age-matched controls (64 ± 7 yr), and 10 young controls (21 ± 1 yr) were studied. All participants performed 90-s of isometric handgrip at 40 % of maximal voluntary contraction, followed by 3-min of PEI. HR (electrocardiography) was continuously recorded. HR recovery was defined as the difference between HR at the end of the exercise and at the end of the first 30-s of PEI. HR variability (HRV) during the first 30-s of recovery was quantified. Following the cessation of exercise, the HR recovery was significantly lower in PD and age-matched controls compared to young controls (Δ-10 ± 5 vs. Δ-14 ± 6 vs. Δ-26 ± 8 beats.min − 1 at 30s; P < 0.001; respectively). compared to controls. HRV increased less post-exercise in PD and age-matched controls compared to young controls. In summary, PD patients and age-matched controls demonstrate blunted parasympathetic reactivation. However, contrary to our hypothesis, PD patients did not exhibit further attenuation in HR recovery compared to age-matched controls, suggesting that PD does not exacerbate vagal reactivation impairments beyond those associated with aging.