Physical activity self-monitoring and weight loss: 6-month results of the SMART trial

Med Sci Sports Exerc. 2011 Aug;43(8):1568-74. doi: 10.1249/MSS.0b013e31820b9395.

Abstract

Introduction: Weight loss has been associated with higher physical activity (PA) levels and frequent dietary self-monitoring. Less is known about how PA self-monitoring affects adherence to PA goals, PA levels, and weight change.

Methods: The SMART Trial is a clinical weight loss trial in which 210 overweight adults were randomized equally to one of three arms: 1) paper record (PR), 2) personal digital assistant with self-monitoring software (PDA), and 3) PDA with daily tailored feedback message (PDA + FB). PA self-monitoring and adherence to PA goals were based on entries in weekly submitted diaries. PA levels were measured via self-report by the past 6-month Modifiable Activity Questionnaire at baseline and 6 months.

Results: Data are presented on 189 participants with complete 6-month PA data (84% female, 77% white, mean age = 47.3 ± 8.8 yr, mean body mass index = 34.1 ± 4.5 kg·m(-2)). Median PA level was 7.96 MET·h·wk(-1) at baseline and 13.4 MET·h·wk(-1) at 6 months, with significant PA increases in all three arms. PDA + FB arm had a higher mean number of weekly self-monitoring entries than the PR arm (3.4 vs 2.4, P = 0.003) and were more likely to maintain high (i.e., 100%) adherence to PA goals over time than the PDA (P = 0.02) or PR arms (P = 0.0003). Both PA self-monitoring and adherence to PA goals were related to higher PA levels at 6 months. A higher mean rate of PA self-monitoring was associated with a greater percentage of weight decrease (ρ = -0.49, P < 0.0001) at 6 months.

Conclusions: PA self-monitoring and adherence to PA goals were more likely in participants in the PDA + FB arm and in turn predicted higher PA levels and weight loss.

Publication types

  • Randomized Controlled Trial
  • Research Support, N.I.H., Extramural

MeSH terms

  • Adult
  • Body Mass Index
  • Diagnostic Self Evaluation*
  • Feeding Behavior / physiology
  • Female
  • Humans
  • Male
  • Middle Aged
  • Monitoring, Physiologic / methods*
  • Motor Activity / physiology*
  • Overweight / therapy*
  • Patient Compliance
  • Surveys and Questionnaires
  • Weight Loss / physiology*