Perceived Exertion during Exercise Is Associated with Children's Energy Intake

Abstract

PURPOSE To examine the individual-level factors that predict energy intake (EI) following imposed exercise (EX) and sedentary time (SED) in children. METHODS Healthy-weight children ages 9-12 years (n = 20) reported to the laboratory for 1 baseline and 2 experimental visits (EX and SED) each separated by 1 week in a randomized crossover design. Percent body fat, weight (kg), and height (m) were used to calculate fat-mass index (FM index) and fat-free mass index (FFM index; kg/m2). On the EX day, children exercised at 70% estimated VO2peak for 30 minutes on a cycle ergometer while cardiovascular responses and ratings of perceived exertion (RPE) were measured. Objective EI (kcal) was measured at identical meals (breakfast, lunch, snack, and dinner) on the EX and SED days. RESULTS Total EI was not statistically different between the EX and SED days (t = 1.8, p = 0.09). FFM index was positively associated with EI on the EX day (r = 0.54, p < 0.05). RPE was also positively associated with EI on the EX day (r = 0.82, p < 0.001). Together, FFM index and RPE explained 77% of the variability in EX day EI (F(2,17) = 26.4, p < 0.001). For each unit increase in RPE, children consumed ~270 more calories on the EX day. A similar pattern of associations was observed on the SED day. CONCLUSION FFM index was positively associated with EI on the EX day. Despite experiencing the same 70% relative exercise intensity, increased perceived difficulty predicted greater EI on both the EX and SED day. These findings demonstrate a role for both FFM and RPE in explaining EI variability in children.

Effect of Exercise Duration on Subsequent Appetite and Energy Intake in Obese Adolescent Girls

“…Although previous studies have shown in obese adolescent boys and girls (Fearnbach, Silvert, et al, 2016; Thivel, Isacco, et al, 2012; Thivel, et al, 2011) that an acute bout of exercise was able to induce a transient anorexigneic effect by decreasing subsequent food intake, this was only after moderate-to-high intensity exercises, which may explain the present divergent results. Indeed, the two exercise bouts proposed here were set at the individually determined ventilatory threshold, representing about 54.1 ± 5.4 % of VO 2 peak, which is certainly not intensive enough to observe such effects.…”

“…Few studies have been so far methodologically designed to assess relative EI in youth. Recently, Fearnbach and collaborators showed that while a 30-minute cycling exercise (set at 70% VO 2 peak) did not affect subsequent absolute EI in children at risk for obesity, relative EI was significantly lower compared with a rest condition (Fearnbach, Masterson, Schlechter, Ross, et al, 2016). REI was also significantly reduced after 45 minutes of cycling at moderate-to-high intensity in both lean and obese adolescents despite unchanged absolute food consumption in the obese sample (Chaput, Tremblay, et al, 2015).…”

“…The available evidence demonstrates the crucial role of exercise intensity, with moderate-to-high-intensity exercises favoring a transient anorexigenic effect in obese children and adolescents (Prado et al, 2015; Thivel et al, 2012). This effect has been attributed to higher post-exercise anorexigenic gastro-peptides concentrations (Prado, et al, 2015) and lower neurocognitive responses to food cues (Fearnbach, Silvert, et al, 2016). However, the potential role of exercise duration on the control of food intake and appetite sensations in children and adolescents has not been studied.…”

“…Moreover, by calculating Relative Energy Intake (REI = energy intake minus exercise-induced expenditure), the energy expended during exercise can be considered, which provides a better view of the effects of exercise not only on energy intake but on the participants’ overall energy balance, which has important implications for weight loss. For instance, Fearnbach and collaborators did not show any effect of an acute 30-minute cycling exercise on absolute energy intake in children at risk for obesity, but they did demonstrate a significantly lower REI following exercise compared with a rest condition (Fearnbach, Masterson, Schlechter, Ross, et al, 2016). Similarly, REI has been found significantly reduced after 45 minutes of cycling (moderate-to-high intensity) in obese adolescents despite unchanged absolute intake (Chaput, Tremblay, et al, 2015).…”

The Role of Physical Exercise to Improve the Browning of White Adipose Tissue via POMC Neurons

“…Despite the benefits of physical exercise in reducing hypothalamic inflammation, which might improve WAT browning and its thermogenesis, it is important to highlight that the energy expenditure promoted by practicing physical exercise might often increase energy intake to achieve energy homeostasis. Furthermore, a recent study showed a positive correlation between rate of perceived exertion (RPE) and energy intake in healthy (not obese) children after practicing imposed exercise (Fearnbach et al, 2017 ). However, the effects of physical exercise in reducing energy intake depend on the metabolic status, since several studies are showing that only obese people decrease caloric intake as a consequence of practicing physical exercise practice (Fearnbach et al, 2015 ; Schwartz et al, 2016 ; Thivel et al, 2016 ) (Figure 1 ).…”