Exercise in Young Adulthood with Simultaneous and Future Changes in Fruit and Vegetable Intake.

OBJECTIVES
Regarding weight management, changes in exercise behavior can also influence nutrition behavior by application of self-regulatory psychological resources across behaviors (transfer effect). This study aimed to determine: (1) if changes in exercise frequency in young adulthood predict simultaneous changes in fruit/vegetable intake (transfer as co-occurrence); and (2) if exercise frequency affects future fruit/vegetable intake (transfer as carry-over).

METHODS
6244 respondents of the National Longitudinal Survey of Youth 1997 were followed at ages 18-22 (Time-1), 23-27 (Time-2), and 27-31 (Time-3). Repeated measures analysis of variance and hierarchical multiple regression determined if the change in exercise frequency between Time-1 and Time-2 was associated with simultaneous and sequential changes in fruit/vegetable intake frequency, controlling for sex, race/ethnicity, education, income, body mass index, and baseline fruit/vegetable intake.

RESULTS
Only 9% continued exercising for 30 minutes more than 5 days/week, while 15% transitioned to adequate exercise and another 15% transitioned to inadequate exercise; for both fruits and vegetables, intake of once per day or more increased with age. Males were more likely to exercise adequately and females to consume fruits/vegetables adequately. Exercise frequency transition was linearly associated with concurrent fruit/vegetable intake during Time-1 and Time-2. The highest increase in mean fruit/vegetable intake occurred for participants who transitioned from inadequate to adequate exercise. A significant Time-2 exercise frequency effect on Time-3 fruit/vegetable intake emerged, after accounting for baseline intake. Increase in Time-2 exercise by one day/week resulted in increased Time-3 fruit and vegetable intakes by 0.17 and 0.13 times/week, respectively.

CONCLUSION
Transfer effects, although usually discussed in interventions, may also be applicable to voluntary behavior change processes. Newly engaging in and continuing exercise behavior over time may establish exercise habits that facilitate improved fruit/vegetable consumption. Interventions that facilitate transferring resources across behaviors likely will enhance this effect.