ObjectiveRegulating health behavior change often occurs in a dyadic context of romantic relationships. Dyadic approaches to standard health behavior change models are, however, barely considered. We investigated volitional processes of the Health Action Process Approach model for two health behaviors within a dyadic context of romantic couples. Specifically, we tested whether day-to-day volitional self-regulation predicted one’s own and one’s partner’s cigarettes smoked (Study 1) and physical activity (Study 2).MethodsIn two dyadic intensive longitudinal studies (Study 1: 83 dual-smoker couples intending to jointly quit smoking; Study 2: 61 overweight couples intending to become physically active), heterosexual partners independently reported on intention, self-efficacy, action planning, and action control in end-of-day diaries. In Study 1, daily number of cigarettes smoked was assessed via self-report. In Study 2, daily moderate-to-vigorous physical activity (MVPA) was assessed objectively via accelerometers. In both studies, dyadic cross-lagged intensive longitudinal analyses based on the Actor-Partner Interdependence Model were applied.ResultsAcross both studies, individual’s own volitional self-regulation positively predicted one’s own health behavior (less cigarettes smoked and more MVPA). One’s partner’s action control and intention also positively predicted one’s own health behavior. A marginal partner effect for self-efficacy was found in the context of smoking only.ConclusionsBehavioral self-regulation is not only relevant for individuals themselves, but some volitional processes may spill over to their partners. This highlights the need to specify couple-level processes involved in health behavior change, and to consider a social context of self-regulation.

Little is known about how couples' social support facilitates the pursuit of important goals in daily life. Using an interpersonal perspective, we examined the effects of support provision and receipt on same-day physical activity, and studied the role of partners' joint engagement in activities. One hundred nineteen heterosexual couples reported on target persons' received and partners' provided support across 28 diary days, yielding 2,854 valid days. A dyadic report on couples' joint engagement was obtained from a subset of 88 couples. Target persons' daily activity was objectively assessed via accelerometers. On days with high versus low levels of provided support, target persons' activity was 25 min higher. Support receipt mediated 20% of this effect. Joint engagement accounted for around half of the effects of provided and received support. Support provision is uniquely linked to goal implementation in everyday life. Joint engagement in activities may be one explanation for how support is facilitated.

Interventions facilitating action control via text messages seem to be an effective tool for increasing adherence to physical activity guidelines in everyday life. The comparable effects for the dyadic and individual intervention suggest that automated text messages may be just as effective as personalized messages from the romantic partner. Further investigation is needed to examine the usefulness of a dyadic conceptualizing of action control. (controlled-trials.com ISRCTN15705531).

Findings emphasise the relevance of examining CHBs in the context of an established health behaviour change model and suggest that CHBs are of particular importance in the process of intention formation.

A common form of social regulation of an individual's health behavior is social control. The contextual model of social control assumes that higher relationship quality goes along with more beneficial effects of social control on health behavior. This study examined potential differential moderating effects of different dimensions of relationship quality on the associations between positive and negative social control and smoking behavior and hiding smoking. The sample consisted of 144 smokers (n = 72 women; mean age = 31.78, SD = 10.04) with a nonsmoking partner. Positive and negative social control, dimensions of relationship quality consensus, cohesion and satisfaction, numbers of cigarettes smoked (NCS), hiding smoking (HS), and control variables were assessed at baseline. Four weeks later NCS and HS were assessed again. Only for smokers with high consensus, but not cohesion and satisfaction, a negative association between positive control and NCS emerged. Moreover, smokers with high consensus tended to report more HS when being positively and negatively socially controlled. This also emerged for cohesion and positive control. Satisfaction with the relationship did not display any interaction effects. This study's results emphasize the importance of differentiating not only between positive and negative social control but also between different dimensions of relationship quality in order to gain a comprehensive understanding of the dynamics in romantic dyads with regard to social regulation of behavioral change.