Using the Health Action Process Approach (HAPA) to understand and change sedentary behaviour in office workers: Effects on motivation, behaviour, and health outcomes

Sedentary behaviour (SB) is positively associated with all-cause mortality, as well as numerous chronic diseases, including fatal and non-fatal cardiovascular disease, type 2 diabetes, certain types of cancer, and metabolic syndrome. Interventions targeting reductions in sedentary time among office workers who are an at-risk population for high levels of SB are needed. The main objective of this dissertation was to contribute to the body of knowledge surrounding theory-based behavioural interventions targeting SB among office working adults. First, a systematic review of the literature (study 1, chapter 2) was conducted that highlighted important cognitive and motivational factors associated with SB, which should be targeted in theory-based interventions designed to reduce SB. Using the motivational phase of the Health Action Process Approach (HAPA), a randomized controlled trial (RCT – study 2, chapter 3) demonstrated that SB and diabetes information can be a meaningful source of motivation among preintender office workers (n = 96). Those in the intervention reported significantly higher intentions for reducing daily sedentary time (ps ≤ .05, ɳp2 values ≥ .08) than their control counterparts. Using the volitional phase of the HAPA, a subsequent RCT (study 3, chapter 4) showed that action and coping planning, augmented with tailored text messages reduced workplace sitting time and increased specific non-SBs in office workers (n = 60). Relative to the controls, participants who received the intervention reported significantly greater reductions in time spent sitting (87.54 min/workday) and accompanying increases in time spent standing (32.56 min/workday) and stretching (11.34 min/workday) at work over an 8-week period (ps \u3c .05, ɳp2 range = .05-.08). Finally, study 3 (chapter 4) also revealed that the intervention targeting reductions in SB can lead to significant improvements in office workers’ perceived emotional well-being and role limitations due to emotional health problems (ps \u3c .05, ɳp2 range = .08-.10). Avenues for future research will be discussed