Cardiac vagal activation during post exercise ischemia in young healthy Hispanic/Latino adults

The lifetime likelihood of developing hypertension is higher among Hispanic/Latino (H/La) adults than non-Hispanic White (NHW) adults in the United States. Delayed heart rate recovery (HRR) is considered a marker of autonomic nervous system dysfunction, a key pathological factor contributing to hypertension. Furthermore, slow HRR is an independent marker of hypertension, diabetes and is directly correlated with cardiovascular mortality. In this study, we investigated the HRR during post-exercise ischemia (PEI) in age and sex matched young healthy Hispanic and non-Hispanic White adults. Twenty-two H/La (age = 20 ± 2 years; BMI = 24 ± 2 kg/m2; women = 7) and 19 NHW (age = 21 ± 4 years, p = 0.52; BMI = 24 ± 3 kg/m2, p = 0.69; women = 6) adults performed static handgrip exercise (HG) for 2 minutes at 30% and 40% of maximum voluntary contraction (MVC) followed by 2 minutes and 15 seconds of PEI. Heart rate (II-lead electrocardiogram) was measured continuously for 2 minutes before exercise, during HG, and during PEI following HG. PEI was analyzed over the first 30 seconds averaged for every 10 seconds. Cardiac vagal activity was analyzed using change in heart rate (HR) and metrics of heart rate variability (RMSSD) immediately after the cessation of exercise. Baseline HR (H/La = 61 ± 7 beats/min; NHW = 57 ± 9 beats/min; p = 0.051) and RMSSD (H/La = 70 ± 31 ms; NHW = 90 ± 46 ms; p = 0.12) averaged over 10 minutes, were similar between the H/La and NHW adults. Increase in HR from baseline to 30% HG exercise was similar between the H/La and NHW adults (H/La = 17 ± 7 beats/min; NHW = 21 ± 12 beats/min; p = 0.12) but H/La had a trend for a smaller increase during HG 40% MVC (H/La = 29 ± 13 beats/min; NHW = 38 ± 16 beats/min; p = 0.08). However, after the cessation of exercise, the decrease in HR during the 20-second and 30-second windows was significantly slower in H/La adults compared to NHW adults following both 30% HG (Δ20 s: H/La = -12 ± 6 beats/min, NHW = -19 ± 13 beats/min, p = 0.03; Δ30 s: H/La = -14 ± 7 beats/min, NHW = -22 ± 13 beats/min, p = 0.01) and 40% HG (Δ20 s: H/La = -23 ± 10 beats/min, NHW = -32 ± 13 beats/min, p = 0.04; Δ30 s: H/La = -26 ± 11 beats/min, NHW = -35 ± 14 beats/min, p = 0.04). The increase in RMSSD after the cessation of exercise was significantly lower in H/La adults during PEI following HG at 30% MVC (Δ10 s: H/La = 28 ± 42 ms, NHW = 63 ± 67 ms, p = 0.048; Δ30 s: H/La = 37 ± 57 ms, NHW = 87 ± 81 ms, p = 0.03) and 40% MVC (Δ30 s: H/La = 71 ± 64 ms, NHW = 136 ± 99 ms, p = 0.03). These findings suggest that slow HRR and attenuated increase in heart rate variability following the cessation of exercise in Hispanic/Latino adults may contribute to their higher risk of hypertension and cardiovascular mortality. Supported by: Kinesiology and Health Education UT Austin 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.