Objective: To investigate the effects of a single session of moderate-intensity and high-intensity interval exercise in cardiovascular reactivity to the cold pressor test in young adults with excess body weight. Methods: Twenty-two subjects with excess body weight (23 ± 2 years; 30.0 ± 3.4 kg·m−2) performed three sessions: (1) moderate-intensity exercise (30-minute cycling at 50%–60% of heart rate reserve); (2) high-intensity exercise (four series of 3-minute cycling at 80%–90% of heart rate reserve, interspersed by 2-minute recovery) and (3) control (i.e. 30-minute seated). Before and 30 minutes after the interventions, subjects undertook assessments of SBP/DBP and heart rate in response to the cold pressor test (1-minute rest + 1-minute hand immersed in 4°C water). Reactivity was calculated as the absolute response of SBP, DBP and heart rate to cold pressor test and compared between interventions using a two-way analysis of variance (P < 0.05). Results: Neither moderate-intensity exercise or high-intensity interval exercise attenuated SBP/DBP reactivity to cold pressor test compared with control. On the other hand, heart rate reactivity was reduced after moderate-intensity exercise compared with control (1.36 ± 8.35 bpm vs. 5.18 ± 9.45 bpm). Furthermore, moderate-intensity exercise reduced absolute levels of SBP/DBP from pre- to post-intervention. Conclusion: A single session of moderate-intensity exercise or high-intensity interval exercise did not reduce the SBP/DBP reactivity to cold pressor test. However, absolute levels of SBP/DBP were lower after moderate-intensity exercise, indicating a hypotensive effect promoted by a single session of moderate-intensity exercise in young adults with excess body weight.

Despite the growing evidence for the beneficial effects of high-intensity interval exercise (HIIE) on vascular health of overweight and obese individuals, it is not clear whether the autonomic stress promoted by HIIE during the ambulatory period is higher than that by moderate-intensity continuous exercise (MICE). Therefore, this study compares the 24 hour (h) ambulatory heart rate variability (HRV) following HIIE and MICE in young overweight and obese men. Eleven untrained men aged 23.2 ± 1.9 years, with average body mass index (BMI) of 31.6 ± 3.9 kg/m² (three overweight and eight obese), underwent three exercise sessions: HIIE, MICE and Control (CT). HRV was recorded in the laboratory and for the next 24 h following laboratory recovery. There were no differences in HRV indices in the rest period between the sessions (p > .05). During the ambulatory period, the area under the curve (AUC) of the low-frequency band transformed into natural logarithm (Ln-LF) during sleep was higher after HIIE than after CT (43.31 ± 8.59 vs. 41.11 ± 7.28 ms²*h, p = .034). The HRV followed by MICE did not differ from other sessions (p > .05). In conclusion, the 24 h ambulatory HRV did not differ after HIIE and MICE. However, despite the small effect, HIIE increased the cardiac autonomic modulation during the sleep period, as a protector of cardiovascular system. Highlights. 24 h ambulatory HRV could add important information about the cardiovascular safety of the exercise protocols in overweight and obese individuals. . There was no disturbances in the cardiac autonomic modulation during the awake period, regardless of the exercise protocol. . LnLF index was higher in HIIE compared to CT in the sleep period.. 24 h ambulatory HRV did not differ between the HIIE and MICE sessions.

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Abstract--This study aimed to assess the blood pressure (BP), cardiac autonomic modulation at rest, in physical exercise and in the recovery in untrained eutrophic (E) and overweight (O) youth. The body mass index (BMI), waist circumference (WC), systolic BP-SBP (E: 109.80 ± 10.05; O: 121.85 ± 6.98 mmHg) and diastolic BP -DBP (E: 65.90 ± 7.28; O: 73.14 ± 12.22 mmHg) were higher in overweight and the heart rate recovery (%HRR) was lower as compared with E volunteers. The BMI was associated with SBP (r= 0.54), DBP (r= 0.65), load on the heart rate variability threshold -HRVT (r= -0.46), %HRR 2' (r= -0.48) and %HRR 5' (r= -0.48), and WC was associated with SBP (r= 0.54), DBP (r= 0.64) and HRR 2' (r= -0.49). The %HRR was associated to SBP, DBP and HRVT. In summary, the anthropometric variables, BP and cardiac autonomic modulation in the recovery are altered in overweight youth.

List of abbreviations: AC-abdominal circumference; BMI-body mass index; BP-blood pressure; DBP-diastolic blood pressure; HF-high frequency; HR-heart rate; HRV-heart rate variability; LF-low frequency; pNN50: percentage of adjacent R-R intervals with a duration difference of > 50 ms; TP-total power; RMSSDsquare root of squared mean of differences between adjacent normal R-R intervals; SBP-systolic blood pressure; SD1-standard deviation of the instantaneous beat-to-beat variability; SD2-long-term standard deviation of the continuous R-R intervals; VLF: very low frequency; WC-waist circumference. Background: Obesity triggers alterations in hemodynamic and autonomic control. There are few studies that investigate the effects of overweight and obesity in early adulthood on hemodynamic and autonomic variables. Aim: The aim of this study was to determine whether overweight and obesity in young individuals cause alterations in hemodynamic parameters and heart rate variability (HRV) in supine and seated position, and to correlate these variables with anthropometric features. Methods: Measurements were performed in 40 young untrained male study participants. The subjects were eutrophic (22.8 ± 0.3 kg/m 2 , N = 19), overweight (27.0 ± 0.5 kg/m 2 , N = 10), and obese (33.5 ± 0.8 kg/m 2 , N = 11). After 5 min in supine and seated position, the R-R intervals and blood pressure (BP) were recorded. Results: The systolic blood pressure were higher in overweight (supine, 122.9 ± 2.3 mmHg) and obese (supine, 123.9 ± 2.2; seated, 121.7 ± 2.3 mmHg) individuals compared to eutrophic individuals (supine, 111.8 ± 1.64; seated, 111.3 ± 1.8 mmHg) (p ≤ 0.05). Obese subjects exhibited lower HRV (SD1, RMSSD, pNN50) compared to eutrophic individuals when seated. In obese subjects, the heart rate (HR) increased and HRV decreased (p ≤ 0.05) when seated versus supine position. The body mass, body mass index (BMI), and waist and abdominal circumferences correlated positively with BP (r = 0.40−0.64, p ≤ 0.05), while the BMI, waist circumference, BP, and HR were negatively correlated (r = −0.32 − −0.62, p ≤ 0.05) with HRV (pNN50 and HF) in both body positions. BMI, waist circumference, BP and HR correlated negatively with additional HRV indices (SD1, SD2, RMSSD, TP, and LF) when seated. Conclusions: Obese and overweight individuals presented higher SBP, and obese individuals had lower HRV and cardiac vagal activity, associated with anthropometric variables. Relevance for patients: The monitoring of HRV in obese subjects in seated position allows improved prognosis of metabolic consequences to cardiac autonomic control.