Cardiorespiratory Fitness Moderates the Relation Between Years of Drug Use and Stress in Drug Abusers

Abstract

Substance use disorders (SUD) have increased worldwide and is currently a major global issue. In SUD, stress is linked to drug-seeking behaviors and greater rates of relapse. Physical activity has been related with increased self-esteem, mood and reduced stress levels in SUD. However, it remains unclear whether the relation between the time of drug use over the years and stress might be under influence of cardiorespiratory capacity. PURPOSE: This study investigated whether cardiorespiratory fitness has a moderate function over the relation between years of drug use and stress levels. METHODS: Sixth-two male SUD individuals (34.17±8.82years; 24.62±2.91m/kg2) have participated in the study. We took a collection of measures in one visit including: (1) anthropometric measures of height and weight to compute BMI; (2) self-reported demographics and drug use history, including years of drug use, days of abstinence, and number of hospitalizations; (3) a questionnaire to measure negative emotional states; and (4) a shuttle run test to estimate the maximum consumption of oxygen (VO2max). For this study, we tested a moderation analysis using the Macro PROCESS plugin for SPSS (Model 1), in which the independent variable was the years of drug use, the dependent variable was stress levels and the moderator was VO2max. The moderation analysis was adjusted for age, days in abstinence, BMI and number of hospitalizations. RESULTS: It was found that VO2max moderates the relation between years of drug use and stress levels (β=-0.82, p=0.03, 95% confidence interval (-0.15 to -0.007). The conditional effect at each level of the moderator (one SD below the mean, at the mean and one SD above the mean) showed that for those individuals with lower VO2max the negative relation between years of drug use and stress was not significant (β=-0.23, p>0.05), for those with an average VO2max it was significant (β=-0.81, p=0.04) and for those with higher VO2max the relation was even more significant (β=-2.03, p<0.01). CONCLUSION: For those SUD individuals with an average and higher VO2max, the negative relation between years of drug use and stress is more pronounced. Therefore, fitness level seems to have a protective effect over stress in SUD individuals, which may minimize the chances of relapse and enhance the rehabilitation process.