The effect of duration of exercise at the ventilation threshold on subjective appetite and short-term food intake in 9 to 14 year old boys and girls

Abstract

Background: The effect of exercise on subjective appetite and short-term food intake has received little investigation in children. Despite a lack of reported evaluation of short-duration activity programs, they are currently being implemented in schools as a means to benefit energy balance. The purpose of this study was to determine the effect of duration of exercise at the ventilation threshold (VeT) on subjective appetite and short-term food intake in normal weight boys and girls aged 9 to 14 years.

Methods: On 4 separate mornings and in random order, boys (n = 14) and girls (n = 15) completed 2 rest or 2 exercise treatments for 15 (short-duration; SD) or 45 min (long-duration; LD) at their previously measured VeT, 2 h after a standardized breakfast. Subjective appetite was measured at regular intervals during the study sessions and food intake from a pizza meal was measured 30 min after rest or exercise.

Results: An increase in average appetite, desire to eat, and hunger (p < 0.05) was attenuated by SD exercise, but was further increased (p < 0.05) by LD exercise. However, food intake after SD and LD exercise was similar to after rest in both boys and girls (p = 0.55). The energy cost of SD and LD exercise resulted in a lower net energy balance compared to resting during the study measurement period in boys (SD: Delta = -418 +/- 301 kJ; LD: Delta = -928 +/- 196 kJ) and in girls (SD: Delta = -297 +/- 105 kJ; LD: Delta = -432 +/- 115 kJ).

Conclusion: Neither SD nor LD exercise at the VeT increased short-term food intake and SD exercise attenuated increases in appetite. Thus, SD exercise programs in schools may be an effective strategy for maintaining healthier body weights in children.

Figure 1

Effect of short-duration exercise at the VeT on subjective appetite scores. ¹Average appetite (a) desire to eat (b) hunger (c) fullness (d) PFC (e) at 15, 30, and 45 min during short-duration sessions. ²SDRT = short-duration rest, SDEX = short-duration exercise, PFC = prospective food consumption. ³Change from baseline appetite scores increased with time for average appetite (p = 0.0005), desire to eat (p = 0.011), hunger (p = 0.0027), and PFC (p = 0.0047), and subjective fullness decreased (p < 0.0001). SDEX attenuated the increase in average appetite (p = 0.027), desire to eat (p = 0.049), and hunger (p = 0.0072) when compared with SDRT, but did not affect fullness (p = 0.98) or PFC (p = 0.15). Sex was not a factor on change from baseline average appetite (p = 0.11), desire to eat (p = 0.41), hunger (p = 0.46), fullness (p = 0.81), or PFC (p = 0.22). However, there was a significant treatment × sex interaction on PFC (p = 0.013). ⁴Test meal began at 45 min.

Figure 2

Effect of long-duration exercise at the VeT on subjective appetite scores. ¹Average appetite (a) desire-to-eat (b) hunger (c) fullness (d) PFC (e) at 15, 30, 45, 60, and 75 min during long-duration sessions. ²LDRT = long-duration rest, LDEX = long-duration exercise, PFC = prospective food consumption. ³ Change from baseline average appetite (p < 0.0001), desire to eat (p < 0.0001), hunger (p < 0.0001), and PFC (p < 0.0001) increased with time, and fullness decreased (p < 0.001). LDEX stimulated a greater rate of increase in average appetite (p = 0.0045), desire to eat (p = 0.047), and hunger (p < 0.0001) compared with LDRT, however there was no effect on fullness (p = 0.19) or PFC (p = 0.18). Sex was not a factor on change from baseline average appetite (p = 0.22), desire to eat (p = 0.15), hunger (p = 0.80), fullness (p = 0.17), or PFC (p = 0.17). ⁴Test meal began at 75 min.

Figure 3

Physical comfort during (a) short- and (b) long-duration sessions in boys and girls. ¹SDRT = short-duration rest, SDEX = short-duration exercise, LDRT = long-duration rest, LDEX = long-duration exercise. ² Change from baseline physical comfort increased over time during SD (a) (p = 0.036), but not LD (b) (p = 0.26) sessions. Neither treatment (p = 0.49), nor sex (p = 0.58) was a factor affecting physical comfort during SD sessions. Physical comfort during LD sessions was affected by treatment (p < 0.0001), but not sex (p = 0.73), and there was a significant treatment × sex interaction (p = 0.0007). ³Test meals began at 45 min (a) and 75 min (b).