# Effects of Physical Exercise on Substance Use Disorder: A Comprehensive Review
## 3 Results
### Assessment and Impact of Physical Exercise on the Quality of Life of Individuals with SUD
#### 3.1.2 Assessment and Effects of Physical Exercise on Anxiety and Stress
A current systematic review and meta-analysis [45] focusing on the effects of different exercise intensities in SUD populations reported that moderate-intensity cardiovascular programs produced a moderate effect on reducing anxiety levels (SMD = \(-\)0.58; Z = 4.24; \(p<\) 0.01), though no significant effect was observed for stress reduction (SMD = \(-\)0.33; Z = 1.56; \(p=\) 0.12). In contrast, high-intensity aerobic programs did not reduce anxiety levels (SMD = \(-\)0.03; Z = 0.28; \(p=\) 0.78), but they did show a large effect size in reducing stress (SMD = \(-\)1.13; Z = 2.04; \(p<\) 0.05). It is worth noting that the high-intensity programs in this meta-analysis were calculated based on 60-85% of heart rate reserve, a range that in most cases falls below the optimal thresholds for inducing adaptations and being classified as high intensity. This result should be interpreted cautiously due to the wide confidence interval, indicating substantial uncertainty about the effect of this type of exercise on stress reduction (95% CI = \(-\)2.22, \(-\)0.04) [45]. Conversely, the only study identified as genuinely high-intensity demonstrated significant anxiety reductions compared to the control group following a 21-day HIIT program (five total sessions), as measured by the Hamilton Anxiety Rating Scale (HAM-A) [62]. Finally, although anxiety and stress are related concepts in the literature, the effects of physical exercise on these dimensions in individuals with SUD are inconsistent. Regarding anxiety reduction, moderate-intensity cardiovascular exercise has shown the most significant results in the reviewed literature. However, more research is needed on concurrent strength and aerobic training, which may prove to be an optimal combination. Interventions lasting at least 12 weeks are necessary to explore these effects further. Similarly, the impact of physical exercise on stress in individuals with SUD requires more investigation, particularly the potential of high-intensity exercise, which could be the most promising approach. The following table (Table 2) summarizes the most effective exercise modalities identified in the literature for each quality of life domain, highlighting their potential benefits in rehabilitation programs. In summary, physical exercise is an effective strategy for improving the quality of life in individuals with SUD, with positive effects on dimensions such as depression, anxiety, and stress. Although the optimal type, intensity, and duration of exercise have not been fully defined, studies suggest that moderate-intensity aerobic exercise programs lasting a minimum of 12 weeks tend to yield significant improvements. However, it may be possible to reduce the number of weeks provided the weekly session frequency increases to a maximum of 40 total sessions. Nevertheless, the heterogeneity of interventions complicates the establishment of clear consensus. Mind-body disciplines and concurrent exercise have also shown positive effects in specific areas, albeit with less consistency. Individualizing interventions to meet the needs and capabilities of this population is crucial for maximizing benefits. Despite advances, further research is required to explore standardized protocols and evaluate specific mechanisms underlying the improvements observed in QOL.