Adolescents’ Perceptual and Physiological Responses to High-Intensity Interval Exercise

Abstract

High-intensity interval exercise (HIIE) has been shown to promote multiple health benefits and well-being in youth. However, HIIE is proposed to elicit negative affect responses (unpleasant feelings) as predicted by the dual mode theory (DMT), and may negatively impact on future exercise adherence. Previous studies have explored how perceptual, physiological and cognitive factors are associated to negative affect responses during continuous high-intensity exercise, but affect experience (pleasure/displeasure) during HIIE is poorly understood in adolescents. The purpose of this thesis is to evaluate acute affect responses to HIIE in adolescents, and to examine the influence of physiological (i.e. heart rate (HR) and prefrontal cortex (PFC)), perceptual (i.e. enjoyment and rating of perceived exertion (RPE)), and cognitive (i.e. self-efficacy and personality traits) factors. Chapter 4 demonstrates that HIIE (work intervals performed at 90% of peak power (PPO)) is perceived to be more enjoyable due to elevated feelings of reward, excitement and success than continuous moderate-intensity exercise, which was perceived to be more boring in adolescents. Chapter 5 examined the acute affect, enjoyment and RPE responses to HIIE (work intervals performed at 90% of maximal aerobic speed) compared with moderate-intensity interval exercise (MIIE). Chapter 5 reports that HIIE elicits less pleasurable feelings at the later stages of work intervals but greater post-enjoyment than MIIE, extending and reinforcing the findings in Chapter 4. The findings from Chapter 5 are furthered in Chapters 6 and 7, which identified that the affect responses during HIIE are dependent on the intensity and delivery (decreasing vs increasing) of the HIIE protocol. Chapter 6 revealed that HIIE performed at 100% PPO elicited a greater decline and lower affect responses across all work intervals than HIIE performed at 85% and 70% PPO. However, all HIIE conditions generated similar enjoyment responses during and after exercise. Chapter 7 showed that affect and enjoyment responses improve (more pleasurable and enjoyable) near the end of HIIE with decreasing work intensity compared to HIIE with increasing work intensity. Moreover, the increases in positive affect experienced during HIIE were positively related to an increase in PFC oxygenation. Chapters 5-7 also demonstrate that RPE and HR responses were inversely related to changes in the affect responses in all HIIE conditions. Finally, Chapter 8 identified that both individual self-efficacy and personality traits may decrease or increase the likelihood that a person will experience positive affective and enjoyment responses to HIIE at the later stages of work intervals in adolescents. Collectively, the studies presented in this thesis demonstrate that affect responses during HIIE are dependent on the work intensity, work delivery, and changes in enjoyment, RPE, PFC oxygenation and cognitive factors. Given that some permutations of HIIE protocols do not elicit prominent and entirely negative affective responses, HIIE protocols could serve as a strategy to encourage exercise adoption and promote health benefits in adolescents.