Fed and fasted states on heart rate variability, hemodynamic heart rate and blood pressure in adults submitted to moderate aerobic exercise

Effects of Breakfast Omission on Resting, Exercise, and Postexercise Autonomic and Hemodynamic Profile in Men

Purpose: The acute effects of fasting interventions on metabolic dynamics have been widely investigated. However, knowledge about the acute effect of overnight fasting on hemodynamic and cardiac autonomic modulation is limited, especially during and after exercise. Our objective was to investigate the effects of breakfast omission on hemodynamic and cardiac autonomic modulation during different stress conditions. Method: Twenty-one young men [age: 20.3 (20.1, 26.5 years); body mass index: 22.7 (21.4, 24.4 kg/m²)] underwent resting and postexercise blood pressure assessments and heart rate variability (HRV) analysis, using the SD1 and SD2 indices of Poincaré plots, at rest in supine and standing positions, every 10 minutes during moderate cardiorespiratory training and every 10 minutes throughout the postexercise recovery phase, for a total of 30 minutes for each phase (exercise and recovery). All measurements were performed in a randomized order after overnight fasting or 60 minutes after a breakfast containing ~20% of the total recommended daily calories. The normality hypothesis was rejected, and the Wilcoxon test was conducted to compare the interventions (p < .05). Results: No differences between interventions were observed for resting and postexercise blood pressures (p = .21 to 0.87) or for resting, exercise, and postexercise SD1 (p = .10 to 0.82) and SD2 indices (p = .14 to 0.71). Conclusions: We concluded that overnight fasting does not promote significant changes in resting and postexercise blood pressures or cardiac autonomic modulation in young men at rest (in supine and standing positions), during 30 minutes of moderate cardiorespiratory training and throughout a 30-minute postexercise recovery phase.

Effects of Walking Football During Ramadan Fasting on Heart Rate Variability and Physical Fitness in Healthy Middle-Aged Males

This study aimed to investigate the effect of a walking football (WF) program during Ramadan fasting (RF) on heart rate variability (HRV) indices, body composition, and physical fitness in middle-aged males. Thirty-one healthy sedentary men were randomized to WF (n = 18) and control (n = 13) groups. Both groups participated in RF. The WF group were involved in a training program (small-sided games) of three sessions a week during RF. The time and frequency domains of HRV, body composition, handgrip, lumbar strength, Modified Agility Test (MAT), and 6-minute walk test (6MWT) were measured before Ramadan (BR), during Ramadan (DR), and after Ramadan (AR). We reported that RF has significantly altered some parameters of HRV DR; the mean HR decreased while the mean RR, LF, and HF increased. WF had a significant effect on HRV and mean HR DR compared with BR and AR decreased while mean RR, HF and LF increased. DR, body mass decreased in both groups, while body mass index (BMI) decreased and lean mass increased only in WF group. Lower body mass and BMI levels were reported AR only in WF group. Physical capacity improved AR, compared with BR, only in the WF group with longer distance in 6MWT, shorter time(s) in MAT, and higher lumbar strength levels. We conclude that RF increases parasympathetic system activity. WF practice during RF is safe and might improve body composition, physical fitness, autonomic cardiac function, and physical fitness in middle-aged males.

Time-Restricted Feeding and Aerobic Performance in Elite Runners: Ramadan Fasting as a Model

A distance runner's performance is generally limited by energy availability when competing or training. Modifying meal frequency and timing by abstaining from eating or drinking, from dawn to dusk, during Ramadan fasting is hypothesized to induce hypohydration and reduced caloric and nutrient intake. The purpose of this study was to investigate the impact of Ramadan fasting on runners' performances. Fifteen trained male distance runners who observed Ramadan participated in this study (Age = 23.9 ± 3.1 years; Peak VO₂ = 71.1 ± 3.4 ml/kg/min). Each participant reported to the human performance lab on two testing occasions (pre-Ramadan and the last week of Ramadan). In each visit, participants performed a graded exercise test on the treadmill (Conconi protocol) and their VO₂, Heart Rate, time to exhaustion, RPE, and running speed were recorded. Detailed anthropometrics, food records, and exercise logs were kept for the entire period of the study. Repeated measure ANOVA, paired t-test, and Cohen's effect size analysis were carried out. Results indicated no significant influence for Ramadan fasting on body mass (p = 0.201), body fat (p = 0.488), lean body mass (p = 0.525), VO₂max (p = 0.960), energy availability (p = 0.137), and protein intake (p = 0.124). However, carbohydrate (p = 0.026), lipid (p = 0.009), water (p < 0.001), and caloric intakes (p = 0.002) were significantly reduced during Ramadan Fasting. Daily training duration (p < 0.001) and exercise energy expenditure (p = 0.001) were also reduced after Ramadan. Time to exhaustion (p = 0.049), and maximal running speed (p = 0.048) were improved. Overall, time to exhaustion and maximal running speed of the distance runners was improved during Ramadan fasting, independent of changes in nutrients intake observed during the current study. With proper modulation of training, distance runners performance can be maintained or even slightly improved following the month of Ramadan fasting.