A Dyadic Action Control Trial in Overweight and Obese Couples (DYACTIC)

Scholz, Urte; Berli, Corina (2014). A Dyadic Action Control Trial in Overweight and Obese Couples (DYACTIC). BMC public health, 14(1321), pp. 1-9. BioMed Central 10.1186/1471-2458-14-1321

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Enhancing physical activity in overweight and obese individuals is an important means to promote health in this target population. The Health Action Process Approach (HAPA), which was the theoretical framework of this study, focuses on individual self-regulation variables for successful health behavior change. One key self-regulation variable of this model is action control with its three subfacets awareness of intentions, self-monitoring and regulatory effort. The social context of individuals, however, is usually neglected in common health behavior change theories. In order to integrate social influences into the HAPA, this randomized controlled trial investigated the effectiveness of a dyadic conceptualization of action control for promoting physical activity.


This protocol describes the design of a single-blind randomized controlled trial, which comprises four experimental groups: a dyadic action control group, an individual action control group and two control groups. Participants of this study are overweight or obese, heterosexual adult couples who intend to increase their physical activity. Blocking as means of a gender-balanced randomization is used to allocate couples to conditions and partners to either being the target person of the intervention or to the partner condition. The ecological momentary intervention takes place in the first 14 days after baseline assessment and is followed by another 14 days diary phase without intervention. Follow-ups are one month and six months later. Subsequent to the six-months follow-up another 14 days diary phase takes place.The main outcome measures are self-reported and accelerometer-assessed physical activity. Secondary outcome measures are Body Mass Index (BMI), aerobic fitness and habitual physical activity.


This is the first study examining a dyadic action control intervention in comparison to an individual action control condition and two control groups applying a single-blind randomized control trial. Challenges with running couples studies as well as advantages and disadvantages of certain design-related decisions are discussed. This RCT was funded by the Swiss National Science Foundation (PP00P1_133632/1) and was registered on 27/04/2012 at http://www.isrctn.com/ISRCTN15705531.

Item Type:

Journal Article (Original Article)


07 Faculty of Human Sciences > Institute of Psychology > Personality Psychology, Differential Psychology and Diagnostics > Professur für Gesundheitspsychologie (SNF) [discontinued]

UniBE Contributor:

Scholz, Urte and Berli, Corina


100 Philosophy > 150 Psychology
600 Technology > 610 Medicine & health




BioMed Central




Karin Dubler

Date Deposited:

24 Mar 2015 16:30

Last Modified:

24 Mar 2015 16:30

Publisher DOI:


Uncontrolled Keywords:

Physical activity, Randomized controlled trial, Action control, Couples, Health Action Process Approach, Dyadic





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