Evening chronotype predicts dropout of physical exercise: a prospective analysis.

Purpose: Eveningness preference to sleep/wake and perform physical/cognitive activities has been associated with worse health outcomes, when compared to morningness preference. Physical activity is one potential mediator that could explain this relationship; however, most of these evidences come from cross-sectional design studies. Our goal was to assess whether chronotype could predict the risk of dropout of physical exercise programs. Methods: We followed 153 newly enrolled volunteers at three different gyms, from both sexes, aged between 18 and 65 years, during 12 weeks. The daily frequency of exercises in the programs was objectively measured (gym's electronic turnstiles). Using questionnaires, we collected data of variables related to demographic characteristics, health, physical activity, sleep, anthropometric and chronobiological parameters (Morningness-Eveningness Questionnaire-MEQ). Two multivariate models were created using Cox regression analysis to test the risk of dropout of physical exercise practice. Both models accounted for age, educational level, civil status, membership plan duration, physical exercise practice frequency during week 1 and chronotype (MEQ score and chronotypes). Results: Model 1 results showed that higher MEQ score was associated with a lower chance of quitting the program (HR = 0.98; CI95% 0.95-1.00; p = 0.046). Considering the chronotypes, E-types showed the highest dropout risk compared to that of M-types (HR = 2.22; CI95% 1.09-4.52; p = 0.027). Conclusion: Our results suggest that chronotype is another variable to be considered in future studies on promoting PAs in formal environments. Likewise, the practice frequency during week 1 and duration of membership plan also deserve more attention in additional studies.

Worse sleep quality predicts early drop out from physical exercise programs.

Introduction and Objective: Sleep quality (SQ) benefits from regular physical exercise (PE) practice, but the effect of SQ over behavioral aspects of PE is not well known. In this study, we tested whether sleep variables can predict the drop out risk for PE programs during a six-week critical period for habit formation at gyms. Material and Methods: We assessed 153 volunteers, freshly enrolled at three different gyms and from both sexes, with average age of 33.6 (±11.9) years. Questionnaires provided sociodemographic, health, sleep, physical activity and circadian rhythmicity information. Daily PE practice frequency was monitored using the gym's turnstiles electronic records. We created a multivariate model using Cox regression in order to test the risk of PE program drop out during the first six weeks. Results: Worse SQ predicted a higher drop out risk (HR=1.11; 95%CI = 1.02-1.21; p<0.05), even when adjusted for other potential confounding variables. Conclusion: We found that worse SQ predicted a higher early drop out from PE programs in the formal context of gyms during the first six weeks, along with other variables related to PE practice.