Dissertation Defence: The Power of Exercise Choice on Perceived Autonomy Support, Motivation Regulation, Physical Activity Adherence, and Cardiorespiratory Fitness Among Individuals at Risk of Type 2 Diabetes

Alexandre Santos, supervised by Dr. Mary Jung, will defend their dissertation titled “The Power of Exercise Choice on Perceived Autonomy Support, Motivation Regulation, Physical Activity Adherence, and Cardiorespiratory Fitness Among Individuals at Risk of Type 2 Diabetes” in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Kinesiology.

An abstract for Alexandre Santos’ dissertation is included below.

Examinations are open to all members of the campus community as well as the general public. Registration is not required for in person defences.

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ABSTRACT

High-intensity interval training (HIIT) and moderate-intensity continuous training (MICT) are exercise modalities that elicit positive physiological changes and help manage chronic conditions such as type 2 diabetes (T2D). However, it is unknown whether HIIT is a feasible exercise option for individuals who are insufficiently active or have a chronic condition. According to self-determination theory, providing a choice between exercise modalities may foster desired outcomes by improving individuals’ perceived autonomy support and motivation regulation. The purposes of this dissertation were to assess the feasibility of HIIT in supervised and free-living conditions and determine whether providing a choice between such exercises would impact psychological, behavioural, and physiological outcomes compared to prescriptive practices among individuals at risk of T2D.

A systematic review and meta-analyses of 188 articles revealed no significant differences in supervised compliance [Hedge’s g=0.026 (95%CI: -0.090–0.143), p=.66] or free-living adherence rates [Hedge’s g=-0.313 (95%CI: -0.681–0.056), p=.096] between HIIT and MICT. Sub-group analyses on compliance suggest HIIT is favoured in supervised settings for individuals with no chronic medical condition [Hedge’s g=0.262 (95%CI: 0.048–0.476), p=.017], while sub-group analysis on adherence suggests MICT is favoured in free-living conditions when measured using an activity tracker [Hedge’s g=-0.487 (95%CI: -0.876–-0.098), p=.014]. A very low quality of evidence rating for free-living adherence warrants further research.

Through a three-arm pragmatic randomized trial including 77 participants at risk of T2D, providing a choice between HIIT and MICT during a 4-week diabetes prevention program did not significantly improve perceived autonomy support, motivation regulation, free-living physical activity adherence, or cardiorespiratory fitness 6 months post-intervention compared to exercise prescription (ps>.05). Free-living physical activity adherence was higher among individuals expressing more autonomous forms of motivation regulation compared to more controlled forms of regulation according to Fitbit [F(2,35)=6.806, p=.003, ηp2=0.28] and self-report data [F(2,23)=3.909, p=.035, ηp2=0.25].

HIIT and MICT are both feasible exercise options. Providing a choice between HIIT and MICT did not influence long-term exercise adherence among individuals at risk of T2D. Other factors influencing one’s motivation may be more predictive of free-living exercise behaviour. Advancements in physical activity measurements are needed to address current limitations.