Purpose: To evaluate whether excess body mass influences the heart rate variability (HRV) indexes at rest, and to correlate adiposity indicators and the aerobic fitness with cardiac autonomic variables in metabolically healthy young adults. Method: In all, 41 untrained males (M_age = 21.80, SD = 2.14 years), 14 normal weight (M_BMI = 22.28, SD = 1.86 kg∙m⁻²), 11 overweight (M_BMI = 26.95, SD = 1.43 kg∙m⁻²), and 16 obese (M_BMI = 33.58, SD = 3.06 kg∙m⁻²) metabolically healthy (normal values of blood pressure, fasting blood glucose, triglycerides, and total cholesterol), underwent evaluations of the HRV at rest and of the peak oxygen consumption (VO₂ peak) during maximal exercise on a cycle ergometer. Results: Blood pressure, heart rate, HRV indexes, casual blood glucose, oxidative stress, and antioxidant activity did not differ among the groups. The VO₂ peak (mL∙kg⁻¹∙min⁻¹) was lower in the obese group compared with the normal weight and overweight groups. The body mass (r = −.40 to −.45) and abdominal circumference (r = −.39 to −.52) were slightly to moderately correlated with SD1, SD2, RMSSD, SDNN, pNN50, LF, and HF indexes and total power. The VO₂ peak (mL∙kg⁻¹∙min⁻¹) was slightly to moderately correlated (r = .48 to .51) with SD2, SDNN, and LF indexes in the individuals with excess body mass. Conclusion: Cardiac autonomic modulation at rest was preserved in metabolically healthy obese young men. However, the indicators of adiposity, as well as the aerobic fitness were correlated with cardiac autonomic modulation in the individuals with excess body mass.

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.

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.

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 center dot 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 degrees 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.