Resistance training is associated with spontaneous changes in aerobic physical activity but not overall diet quality...

Aerobic exercise interventions have been shown to result in alterations to dietary intake and non-exercise physical activity (PA). To date, the ability for resistance training (RT) to influence other health-related behaviors has not been examined. This study aimed to determine if initiation and maintenance of RT is associated with spontaneous changes in dietary quality and non-RT PA in adults with prediabetes.

Overweight/obese adults (n=170, BMI=32.9±3.8kg·m², age=59.5±5.5years, 73% female) with prediabetes were enrolled in the 15-month Resist Diabetes trial. Participants completed a supervised 3-month RT initiation phase followed by a 6-month maintenance phase and a 6-month no-contact phase. Participants were not encouraged to change eating or non-RT PA behaviors. At baseline, and months 3, 9, and 15, three 24-hour diet recalls were collected to evaluate dietary intake and quality, the Aerobics Institute Longitudinal Study Questionnaire was completed to evaluate non-RT PA, and body mass, body composition (DXA), and muscular strength were measured. At months 3, 9, and 15 social cognitive theory (SCT) constructs were assessed with a RT Health Beliefs Questionnaire. Mixed effects models were used to assess changes in dietary intake and non-RT PA over the 15-month study period.

Energy and carbohydrate intake decreased with RT initiation and maintenance phases (baseline to month 9: β=-87.9, p=0.015 and β=-16.3, p<0.001, respectively). No change in overall dietary quality (Healthy Eating Index [HEI]-2010 score: β=-0.13, p=0.722) occurred, but alterations in HEI-2010 sub-scores were detected. Maintenance of RT was accompanied by an increase in MET-min/week of total non-RT PA (month 3 to month 9: β=146.2, p=0.01), which was predicted by increased self-regulation and decreased negative outcome expectancies for RT (β=83.7, p=0.014 and β=-70.0, p=0.038, respectively).

Initiation and maintenance of RT may be a gateway behavior leading to improvements in other health-related behaviors. These results provide rationale for single-component lifestyle interventions as an alternative to multi-component interventions, when resources are limited.