Developmental Changes in Hemodynamic Responses and Cardiovagal Modulation during Isometric Handgrip Exercise

The purpose of this study was to examine differences in pressor response and cardiovagal modulation during isometric handgrip exercise (IHG) between children and adults. Beat-to-beat heart rate (HR) and blood pressure were measured in 23 prepubertal children and 23 adults at baseline and during IHG. Cardiovagal modulation was quantified by analysis of HR variability. Mean arterial pressure responses to IHG were greater in adults compared to children (P < .05) whereas there were no group differences in HR responses (P > .05). Children had a greater reduction in cardiovagal modulation in response to IHG compared to adults (P < .05). Changes in mean arterial pressure during IHG were correlated with baseline cardiovagal modulation and force produced during isometric contraction (P < .05). In conclusion, differences in pressor reflex response between children and adults cannot be solely explained by differences in autonomic modulation and appear to be associated with factors contributing to the force produced during isometric contraction

Do Overweight and Obese Individuals Select a “Moderate Intensity” Workload When Asked to Do So?

The purpose of this study was (1) to determine if overweight/obese individuals (age 26–50 y) would self-select moderate exercise intensity when asked to do so and (2) to determine how this self-selected workload compared to exercising at a workload (60% peak aerobic capacity) that is known to provide cardioprotective health benefits. Oxygen consumption (VO2) and energy expenditure were measured in 33 men/women (BMI ≥ 27 kg/m2) who completed two 30 min walking bouts: (1) self-selected walking pace on an indoor track and (2) prescribed exercise pace (60% VO2 peak) on a treadmill. The data revealed that (1) the prescribed intensity was 6% higher than the self-selected pace and elicited a higher energy expenditure (P < 0.05) than the self-selected pace (+83 kJ); (2) overweight subjects walked at a slightly lower percentage of VO2 peak than the obese subjects (P < 0.05); (3) men walked at a lower percentage of VO2 peak than the women (P < 0.05). In conclusion when asked to walk at a moderate intensity, overweight/obese individuals tended to select a lower workload in the “moderate intensity” range which could be maintained for 30 min; however, a higher intensity which would be more cardioprotective could not be maintained for 30 min by most individuals

doi:10.1155/2010/153780 Research Article Developmental Changes in Hemodynamic Responses and Cardiovagal Modulation during Isometric Handgrip Exercise

Copyright © 2010 Styliani Goulopoulou et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The purpose of this study was to examine differences in pressor response and cardiovagal modulation during isometric handgrip exercise (IHG) between children and adults. Beat-to-beat heart rate (HR) and blood pressure were measured in 23 prepubertal children and 23 adults at baseline and during IHG. Cardiovagal modulation was quantified by analysis of HR variability. Mean arterial pressure responses to IHG were greater in adults compared to children (P &lt;.05) whereas there were no group differences in HR responses (P&gt;.05). Children had a greater reduction in cardiovagal modulation in response to IHG compared to adults (P &lt;.05). Changes in mean arterial pressure during IHG were correlated with baseline cardiovagal modulation and force produced during isometric contraction (P &lt;.05). In conclusion, differences in pressor reflex response between children and adults cannot be solely explained by differences in autonomic modulation and appear to be associated with factors contributing to the force produced during isometric contraction. 1

Effects of diurnal exercise timing on appetite, energy intake and body composition: a parallel randomized trial

Objective: To determine the effect of diurnal exercise timing on appetite, energy intake and body composition in individuals with overweight or obesity. Methods: Forty sedentary, individuals with overweight or obesity (17 males, 23 females; age: 51 ± 13 years; BMI: 30.9 ± 4.2 kg/m2) were randomly allocated to complete a 12-week supervised multi-modal exercise training program performed either in the morning (amEX) or evening (pmEX). Outcome measures included appetite in response to a standardised test meal, daily energy intake (EI), body weight and body composition. Measures of dietary behaviour were assessed at baseline and post-intervention, along with habitual physical activity, sleep quality and sleep quantity. Significance was set at p ≤ .05 and Hedge's g effect sizes were calculated. Results: Regardless of timing, exercise training increased perceived fullness (AUC; g = 0.82–1.67; both p < .01), decreased daily EI (g = 0.73–0.93; both p < .01) and body-fat (g = 0.29–0.32; both p <. 01). The timing of exercise did not change the daily EI or body-fat response to training (all p ≥ .27), however, perceived fullness increased in the amEX group (p ≤ .01). Disinhibition: (g = 0.35–1.95; p ≤ .01) and Hunger (g = 0.05–0.4; p = .02) behaviours decreased following exercise training, with Disinhibition demonstrating greater improvements in the pmEX group (p = .01). Objective and subjective sleep quantity increased with training (all p ≤ .01), but sleep quality was not reported to change. Conclusions: Multi-modal exercise training improved body composition and some appetite outcomes, although changes were inconsistent and largely independent of exercise-timing. In the absence of dietary manipulation, the effect of diurnal exercise timing on appetite and body composition appear trivial compared to the overall benefits of exercise participation