Innovative Physical Activity Interventions for Overweight Latinos

Latinos are the fastest growing ethnic group in the US and are disproportionately impacted by
chronic conditions (e.g., overweight/obesity, diabetes) that can be mitigated by physical
activity. While evidence-based programs are available to improve physical activity,
dissemination is constrained by reliance on costly, limited resources. Short message service
(SMS or text messaging) has strong potential as an intervention medium for Latinos, as they
are dominant users of mobile phones and text messaging, including those with limited literacy
and computer skills. The investigators propose to develop a personalized,
culturally-congruent and interactive SMS program to promote the adoption and maintenance of
physical activity for overweight, underactive Latino adults and test it for comparable
efficacy to an evidence-based telephone-based advising program that has been used
successfully with Latinos. Grounded in Social Cognitive and Self-Determination Theories, both
programs will include a core set of self-regulatory skill building, social support, and
autonomous motivation enhancement, and will be tailored for cultural, linguistic and literacy
appropriateness. Randomized at the individual level, 376 sedentary, overweight Latinos ages
45 years and older will be assigned to one of three arms: the SMS-delivered physical activity
program, the Human-delivered physical activity program, or an attention-control arm of
SMS-delivered basic healthful nutrition advice. They will receive their assigned program for
12 months, and then will be followed for a 6-month maintenance phase, with a final assessment
at 18 months. Analyses will determine if the two physical activity programs result in
equivalent efficacy in adoption and maintenance of clinically meaningful physical activity
increases, and superiority over the attention-control arm at 12 and 18 months. The two
physical activity interventions will also be compared for equivalency in prevention of weight
gain and reduction in abdominal adiposity. The investigators will explore the relative costs
of the programs to determine which program increases physical activity for a lower cost.
While health promotion programs delivered by professional staff may be more expensive than
those delivered electronically, it is unclear if the automated version can produce more
cost-efficient outcomes (i.e., comparable improvements in outcomes for significantly reduced
cost). This study will determine if SMS is equivalent in efficacy to the traditional
human-delivery channel in increasing physical activity and preventing weight gain, and if it
results in a more cost-efficient program. If achieved, this research can significantly reduce
health disparities associated with physical activity for Latinos by providing an efficacious,
tailored and culturally appropriate program poised for widespread dissemination and rapid
uptake.

Inclusion Criteria:

- Self-identified Latino ethnicity;

- Body Mass Index between 25 and 40;

- Aged greater than or equal to 35 years

- Physically inactive (i.e., not engaged in moderate- or greater intensity PA at least
60 minutes/week over the past 6 months);

- Stable on all medications over the past 3 months;

- Regular access to a mobile phone;

- Willing to accept random assignment, and willing to complete all assessments.

Exclusion Criteria:

- Aged less than 40 years

- Body Mass Index greater than 40

- Physically active (i.e., engaged in moderate- or greater intensity PA for more than 60
minutes/week over the past 6 months);

- Not stable on all medications over the past 3 months;

- No regular access to a mobile phone;

- Not willing to accept random assignment and/or willing to complete all assessments.

- Medical contraindications to regular unsupervised PA, including uncontrolled metabolic
disorders;

- Unable to understand English or Spanish sufficiently to provide informed consent