When Hearts Race and Pressures Rise: Altered Exercise Pressor Reflex with Cardiac Abnormalities and Aging

The exercise pressor reflex describes the autonomic response that stimulates the cardiovascular system to maintain perfusion of blood flow to working skeletal muscle. However, the exercise pressor reflex is exaggerated in patients with heart failure with reduced ejection fraction (HFrEF) whereas it is blunted in congenital heart disease (CHD). While HFrEF and CHD are clinically diverse, there may be phenotypic overlap that could provide a shared thread for observed pressor responses in these patient groups. Furthermore, the existing evidence on the effect of aging between healthy young (HY) and old (HO) appears to be conflicting.We hypothesized that the pressor response would be blunted with aging and the presence of cardiac conditions. A retrospective analysis of the immediate heart rate (electrocardiography) and mean arterial pressure (finger photoplethysmography) change from rest to during a short (3-5 sec) single bout of maximum voluntary isometric handgrip contraction was performed in HFrEF, CHD, HY, and HO (HFrEF; n =20 (6 F), 61±9 yrs; CHD, n =47 (21 F), 13±3 yrs; HY, n =40 (20 F), 13±3 yrs; HO, n =22 (10 F), 61±6 yrs). Data was analyzed by 2 x 2 ANOVA (health status; healthy and cardiac condition x age; young and old).Data were extracted as the average of three cardiac cycles at rest and a single cardiac cycle at peak systolic blood pressure during MVC. The data revealed heart rate increase from rest to MVC declined with age (8.6±8.1 Δ%, p =0.0004) and health status (8.0±4.8 Δ%, p =0.0023). Multiple comparisons revealed the increase in heart rate from rest to MVC was less in CHD (9.8±5.9 Δ%, p =0.0049), HO (11.2±9.4 Δ%, p =0.0117), and HFrEF (16.9±12.4 Δ%, p <0.0001) than HY. Furthermore, mean arterial pressure increase from rest to MVC declined with age ( p <0.0001), but not health status ( p =0.1086). Lastly, independent sample t-tests revealed MVC was greater in HO than HY (28±13 vs. 15±8 kg, p <0.0001), but not between HO and HFrEF (28±13 vs. 24±10 kg, p =0.2148) nor HY and CHD (15±8 vs. 14±9 kg, p =0.8337). During small skeletal muscle mass contraction at maximal intensity, the pressor response is impaired with aging and the presence of cardiac conditions. Together, these altered cardiovascular responses to exercise may be implicated in the reduced exercise capacity and tolerance known in these respective groups. Saskatchewan Centre for Patient Oriented Research, Heart and Stroke Foundation of Canada This abstract was presented at the American Physiology Summit 2025 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.