# Effects of Physical Exercise on Substance Use Disorder: A Comprehensive Review
## 3 Results
### Assessment and Impact of Physical Exercise on Crawings in Individuals with SUD
#### 3.3.2. Craving and Duration, Frequency, and Intensity of Intervention Programs
Regarding physical fitness, the literature suggests that regular physical exercise programs, especially those incorporating aerobic and strength activities, contribute to improvements in endurance, muscular strength, and cardiovascular capacity in individuals recovering from SUD [43; 54]. These benefits are particularly significant as many individuals with SUD experience deteriorated physical fitness due to prolonged substance use, which can affect both cardiovascular health and general strength and endurance. Additionally, individuals with SUD often exhibit high levels of sedentary behavior, making improvements in physical fitness more pronounced. Cardiovascular variables studied in the reviewed literature include resting heart rate (RHR), blood pressure, and maximal oxygen uptake (VO2 max). These are key indicators of both cardiovascular and overall health [104]. Regarding RHR, lower values (below 60 ppm) are associated with better cardiovascular health and greater life expectancy [105]. Significant reductions in RHR have been observed in most studies analyzing individuals with SUD following physical exercise programs [42; 43; 57; 97]. VO2 max is an indicator of the body's ability to supply oxygen to active muscles and is considered a strong predictor of longevity [106; 107]. Among male SUD populations aged around 30, VO2 max values range from 29 to 36.5 mL-kg-min-1, which is below the average for the general population [42; 106; 107; 108]. Physical exercise is key to increasing this variable, with studies reporting its effectiveness in SUD populations [42; 108]. For blood pressure, favorable reductions have been observed in SUD populations [42; 57; 109]. Some articles differentiate between systolic blood pressure (SBP; pressure in the arteries during heart contraction) and diastolic blood pressure (DBP; pressure when the heart is at rest between beats). SUD populations tend to exhibit average values within the normal range (120-125 mmHg for SBP and <80 mmHg for DBP) [57; 109]. Several studies have analyzed the effects of physical exercise on heart rate variability (HRV) in individuals with SUD, using both time-domain and frequency-domain measures [73; 108; 109; 110]. In the time domain, variables such as SDNN (standard deviation of NN intervals) and RMSSD (root mean square of successive differences between NN intervals) are frequently evaluated. Higher values of these variables are associated with better cardiovascular health and parasympathetic activity, respectively. Frequency-domain variables include LFn (low-frequency component influenced by sympathetic nervous system activity) and HFn (high-frequency component reflecting parasympathetic activity). SUD populations exhibit an impaired HRV compared to the general population, with lower SDNN, RMSSD, and HF values and higher LF values (\(p\) < 0.01) [108]. Physical exercise programs have demonstrated significant improvements in HRV variables in SUD populations. Interventions resulted in significant increases in SDNN (\(p\) < 0.01), RMSSD (\(p\) < 0.01), and HF (\(p\) < 0.01), along with significant reductions in LF (\(p\) < 0.01) compared to control groups [108; 109]. Numerous studies support the notion that regular physical exercise can improve key aspects of cognitive function, including memory, attention, and executive control, all of which are frequently impaired in individuals with SUD [111, 112]. Cognitive function is often assessed using tasks such as the Go/NoGo task (evaluating inhibitory control and reaction time) [113], the Stroop test (measuring inhibitory control and reaction time) [114], and the N-back test for working memory [115]. Physical activities requiring coordination, concentration, and sustained effort appear to influence cognitive function positively, enhancing essential daily life skills and decision-making abilities, which are crucial in the recovery context [111]. These findings underscore the effectiveness of exercise as a tool for promoting cardiovascular health and recovery.