Physical activity and adolescents: an exploratory randomized controlled trial investigating the influence of affective and instrumental text messages.
OBJECTIVE
The present study attempts to develop and pilot the feasibility and efficacy of a novel intervention using affective messages as a strategy to increase physical activity (PA) levels in adolescents. Design An exploratory pilot randomized control trial was used to compare behaviour change over 2 weeks. A modified form of the International Physical Activity Questionnaire was used to assess PA behaviour. A total of 120 adolescents (16-19 years) from 4 sixth forms in West Yorkshire completed the field-based study.


METHODS
Participants were randomly assigned to one of three experimental conditions, or the control condition (N=28). Participants in experimental conditions received 1 short messaging service (SMS) text message per day over the 2 weeks, which included manipulations of either affective beliefs (enjoyable/unenjoyable; N=31), instrumental beliefs (beneficial/harmful; N=30), or a combination of these (N=31). Control participants received one SMS text message per week. Outcomes were measured at baseline and at the end of the 2 week intervention.


RESULTS
PA levels increased by the equivalent of 31.5  minutes of moderate (four metabolic equivalent) activity per week during the study. Main effects of condition (p=.049), and current physical activity level (p=.002) were identified, along with a significant interaction between condition and current activity level (p=.006). However, when the sample was split at baseline into active and inactive participants, a main effect of condition remained for inactive participants only (p=.001). Post hoc analysis revealed that inactive participants who received messages targeting affective beliefs increased their activity levels significantly more than the instrumental (p=.012), combined (p=.002), and control groups (p=.018).


CONCLUSIONS
Strategies based on affective associations may be more effective for increasing PA levels in inactive individuals.
Sirriyeh
Reema
R
University of Leeds, UK. psc2rhs@leeds.ac.uk
Lawton
Rebecca
R
Ward
Jane
J
D000293:Adolescent; D000339:Affect; D040421:Cell Phone; D004739:England; D015444:Exercise; D005240:Feasibility Studies; D005260:Female; D006293:Health Promotion / Q000379:methods*; D006801:Humans; D008297:Male; D010865:Pilot Projects; D055815:Young Adult