Gender and racial/ethnic differences in physiologic responses in the Stimulant Reduction Intervention using Dosed Exercise Study

Exercise may be beneficial for individuals in substance use disorder (SUD) treatment given the higher rates of both medical and psychiatric comorbidity, namely mood and anxiety disorders, compared to the general population. Gender and/or racial/ethnic differences in health benefits and response to prescribed exercise have been reported and may have implications for designing exercise interventions in SUD programs. Method: Data are from the National Drug Abuse Treatment Clinical Trials Network (NIDA/CTN) Stimulant Reduction Intervention using Dosed Exercise (STRIDE) trial. Gender differences across racial/ethnic groups in physiological responses and stimulant withdrawal severity across time were analyzed using linear mixed effects models. Results: Males completed significantly more exercise sessions than females and were more adherent to the prescribed exercise dose of 12 Kcal/Kg/Week. Controlling for age, race/ethnicity, treatment group and stimulant withdrawal severity, there was a significant gender by time interaction for body mass index (BMI) (p < 0.001), waist circumference (p < 0.001) and heart rate measured prior to exercise sessions (p < 0.01). For females, body mass index (BMI) and waist circumference increased over time while for males BMI and waist circumference stayed unchanged or slightly decreased with time. Heart rate over time significantly increased for females at a higher rate than in males. Stimulant withdrawal severity was similar in males and females at baseline but males exhibited a significant decrease over time while females did not. Although baseline differences were observed, there were no time by race/ethnicity differences in physiologic responses. Discussion: Gender differences in response to exercise may have implications for developing gender specific exercise interventions in SUD programs.