Sitting for prolonged periods of time impairs people’s health. Prior research has mainly investigated sitting behavior on an aggregate level, for example, by analyzing total sitting time per day. By contrast, taking a dynamic approach, here we conceptualize sitting behavior as a continuous chain of sit-to-stand and stand-to-sit transitions. We use multilevel time-to-event analysis to analyze the timing of these transitions. We analyze ∼30,000 objectively measured posture transitions from 156 people during work time. Results indicate that the temporal dynamics of sit-to-stand transitions differ from stand-to-sit transitions, and that people are quicker to switch postures later in the workday, and quicker to stand up after having been more active in the recent hours. We found no evidence for associations with physical fitness. Altogether, these findings provide insights into the origins of people’s stand-up and sit-down decisions, show that sitting behavior is fundamentally different from exercise behavior, and provide pointers for the development of interventions.

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Despite having good intentions, people fail at times to self-regulate. Most of these instances of everyday selfregulation failure are in themselves trivial. However, the ensuing chain of attributions, thoughts, and subsequent behaviors that people experience after an instance of failure may be detrimental to their longterm self-regulation success. In two studies, we examined the potential of intervening in the aftermath of failure to prevent this so-called "setback effect" by instructing people that setbacks may occur and to attribute future incidents of failure to external causes. In Study 1, we tested whether the intervention indeed decreased the frequency of self-regulation failure in the context of dieting and procrastination. In Study 2, we aimed to replicate the findings from Study 1 in the context of procrastination, and we explored the mediating role of self-efficacy. In both studies, participants in the intervention condition experienced less self-regulation failure and more subjective self-regulation success in the days after the intervention. Study 2 demonstrated that this effect was partly mediated by an increase in self-efficacy. Taken together, findings suggest that a simple mindset manipulation promoting external Marieke A. Adriaanse and Pam ten Broeke shared first authorship.

Purpose: To identify how and when to intervene in cardiovascular disease (CVD) patients' sedentary behavior, we moved beyond studying total volume of sitting and examined sitting patterns. By analyzing the timing of stand-to-sit and sit-tostand transitions, we compared sitting patterns (a) between CVD patients and healthy controls, and (b) before and after cardiac rehabilitation (CR).Methods: One hundered twenty nine CVD patients and 117 age-matched healthy controls continuously wore a tri-axial thigh-worn accelerometer for 8 days (>120 000 posture transitions). CVD patients additionally wore the accelerometer directly and 2 months after CR. Results: With later time of the day, both CVD patients and healthy controls sat down sooner (i.e., shorter standing episode before sitting down; HR = 1.01, 95% CI [1.011, 1.015]) and remained seated longer (HR = 0.97, CI [0.966, 0.970]). After more previous physical activity, both groups sat down later (HR = 0.97, CI [0.959, 0.977]), and patients remained seated longer (HR = 0.96; CI [0.950, 0.974]). Immediately and 2-months following CR, patients sat down later (HR post-CR = 0.96, CI [0.945, 0.974]; HR follow-up = 0.96, CI [0.948, 0.977]) and stood up sooner (HR post-CR = 1.04, CI [1.020, 1.051]; HR follow-up = 1.03, CI [1.018, 1.050]).These effects were less pronounced with older age, higher BMI, lower sedentary behavior levels, and/or higher physical activity levels at baseline. Conclusion:Cardiac rehabilitation programs could be optimized by targeting CVD patients' sit-to-stand transitions, by focusing on high-risk moments for prolonged sitting (i.e., in evenings and after higher-than-usual physical activity) and attending to the needs of specific patient subgroups.

People experience minor instances of self-regulation failure, i.e., setbacks. While in itself trivial, a single setback may trigger a maladaptive chain of cognitions and emotions leading to more self-regulation failure. In the present article, we investigated (a)whether the experience of a setback indeed increases the chance of subsequent failure, and (b) what psychological mechanisms underly this effect. We conducted three studies in the context of eating behaviour, exercising, and saving. At T1 we assessed participants intentions, self-efficacy, and perceived usefulness to self-regulate in response to a recent setback (versus an instance of self-regulation success). At T2 we assessed subsequent self-regulation failure and success using retrospective recall.Experiencing a setback increased the likelihood of subsequent failure and decreased the chances of subsequent success. Our results most consistently highlight a decrease in self-efficacy as an underlying mechanism, and therefore as a promising target for interventions to prevent the setback effect from occurring.