The study protocol was approved by the Research Ethics Committees of the Universidade Federal do Triângulo Mineiro (UFTM, Federal University of Triângulo Mineiro) (CAAE: 14878619.4.1001.5154) and the Hospital Geral de Goiás (HGG, General Hospital of Goiás) (CAAE: 24719019.3.0000.0035). It was also submitted and approved by the Research Department of the Centro Estadual de Referência e Excelência em Dependência Química (CREDEQ, Reference and Excellence State Center in Chemical Dependency), and presented to the team of health professionals of the institution, with the objective of socializing the information, as well as to clarify possible doubts and obtain support and engagement for the stages of the study, including its ethical aspects.

The Control and Intervention groups were not different from each other in relation to the clinical, social and physiological characterization variables. The data are presented in Table 1.

The sample showed that the participants belonged to the different ABEP socioeconomic strata, with no statistically significant differences between them: class A (10.6%), B1 (8.5%), B2 (12.8%), C1 (21.3%), C2 (29.8%) and D/E (17.0%) (p = 0.65). Regarding the level of education, 5% of the participants had completed higher education, 77.5% went to high school (complete or incomplete), and 17.5% had completed elementary school (p = 0.60). No significant differences were observed in the pattern of substance use (p = 0.70), with a predominance of multi-drug users in the total sample (83%), followed by smoking cocaine (crack) (11%), alcohol (6.4%) and snorted cocaine (powder) (4.3%). No isolated case of Substance Use Disorder (SUD) related to cannabis or tobacco use was identified. Regarding the level of anxiety, the participants were classified as: 61.7% with low anxiety, 23.4% normal, 10.6% with moderate and 4.3% with severe anxiety (p = 0.58). Regarding the level of depression, 12.8% of the participants had no depression, 38.3% were classified with mild depression, 36.2% with moderate and 12.8% with severe depression; no significant differences were observed between the groups in any assessment (p = 0.62).

As for the neuropsychological tests for assessing MF, the Ctl-G did not show significant changes in any of the parameters evaluated, while the HIFT-G group showed significant outcome in all assessments. The data are presented in Table 2.

For Inhibitory Control, no significant differences were observed for any of the parameters in Ctl-G, while in HIFT-G, the three cards presented significant results for the time and interference parameters. However, for the error variable, no card showed a result below the set significance level; the relevant data are displayed in Table 3.

Regarding working memory assessed by Corsi Blocks, the groups showed significant differences between the Pre and Post time points. The data are shown in Table 4.

As to the physical effort performed and perceived in the HIFT-G, a post-PE heart rate of 162 ± 20 BPM was observed, thus reaching 90% of the BPM predicted for age; perception of effort on the Borg scale was 15.6 ± 2.9 points and positive affective response 4.2 ± 1.1.

Substance Use Disorder (SUD) is a global health concern which requires diverse approaches. Although several strategies have been proposed, they often are unsuccessful due to the difficulty many people have in maintaining abstinence and resuming a healthy lifestyle. This study was designed for a sample of individuals affected by SUD who were undergoing treatment at a referral center associated with the public health system in Brazil. When applying a single session of HIFT as an intervention, a clinically relevant benefit was observed in cognitive functions associated with reduced desire and improved decision-making for substance use.

The sample assessed reflected important characteristics of the general population with SUD. The control and the intervention groups shared demographic and socioeconomic characteristics (such as age, income and education) as well as duration of substance abuse, BMI and physiological parameters (HR, BP, VO_2max). It is noteworthy that, despite the predominance of cocaine and its derivatives as drugs of choice, a significant portion of the sample revealed the profile of multi-drug users (83%), which characterizes the simultaneous or sequential use of multiple substances. This practice is commonly adopted with the aim of enhancing the desired effects or mitigating adverse effects and withdrawal (Connor et al., 2014; Liu et al., 2019).

Compared to the general population, individuals with SUD often present cognitive impairments in EF; neuropsychological assessments, such as the TMT and the Stroop test can provide valuable information to help guide the treatment (Broyd et al., 2016; Connor et al., 2014; Liu et al., 2019). In our study, the HIFT session played a promising role in activating EF, particularly considering the visuomotor function, sustained attention, mental flexibility, and inhibitory control .

There was an improvement after the intervention, as evidenced in the TMTA and TMTB tests, and the data obtained indicate a component of task learning and mental flexibility, with greater emphasis on cognitive flexibility, especially in the group that underwent the HIFT. Although both groups showed some improvement, the control group presented a smaller delta, without statistical significance, which suggests a slight effect of familiarization with the test. On the other hand, the group submitted to the HIFT had a significantly greater improvement, indicating that the exercise directly impacted the ability to switch between different rules and patterns, reflecting an improvement in mental flexibility. This finding is in line with studies that show the positive effect of physical exercise on the EF, such as the study by Wilke (2020) which, although conducted with older adults, obtained improvements in the processing speed obtained by the TMT in cognitive function after the intervention with HIFT, which may point to a convergent direction between the studies.

Thus, these clinical results support HIFT as a strategy capable of improving mental flexibility, which may be promoted due to the increase in blood flow mediated by physical exercise, which directs greater circulation to the prefrontal cortex, notably in the dorsolateral and ventrolateral cortices, as observed in previous studies (Khandekar et al., 2022; Park & Schott, 2022). However, it is worth noting that association between HIFT and brain activation is not consistent universally and may be influenced by the time of assessment and the context in which the exercise is performed (Chang et al., 2012), as discussed below.

The present study also revealed statistically significant improvements in the Stroop Test performance after the HIFT intervention. This result suggests a potentially beneficial association between exercise and the improvement of the cognitive functions linked to attention and IC. In addition, the physiological explanation associated with the increase in blood flow described above for the TMT also benefits cognitive processing in the Stroop Test by aiming to activate brain areas, which may have contributed to the participants’ ability to filter irrelevant responses and focus on the specific task demands (Khandekar et al., 2022; Park & Schott, 2022). Biochemically, the hypothesis of the involvement of growth factors, such as BDNF, in the outcome was set up.

An increase in BDNF concentrations was observed in response to exercises like HIFT, when inibitory control was assessed (Novkovic et al., 2015; Tsai et al., 2014). Here we add the data that enhance the BDNF’s participation obtained by Vaughan and collaborators (Vaughan et al., 2014) who showed significant improvements in EF and increased BDNF concentrations in healthy elderly women undergoing HIFT, compared to a control group.

It is worth noting that, despite fast metabolization of the BDNF molecule, the activation of its signaling pathways impacts the production of intracellular messengers such as CREB (CAMP response element-binding protein), which promotes the expression of genes involved in neuronal survival and growth, as well as synaptic plasticity, effects that last longer than the lifetime of the BDNF molecule itself (Sharma et al., 2023; Xue et al., 2022). Thus, it is feasible to propose that the physiological stimulation induced by HIFT has as one of the biochemical elements the increase in the supply of BDNF, which through short and long-term mechanisms modify the neuronal response of PSUD. The coherence of these results with other previous investigations enhances the relevance of HIFT as a promising means to stimulate brain plasticity and to optimize cognitive aspects (Gilson et al., 2023; Yin et al., 2022).

In addition, the TMT assessment data revealed a significant 38% increase in post-intervention performance. This increase, in line with research data in diverse groups, including older adults and individuals with SUD, highlights the positive influence of HIFT on EF.

Thus, similar to what has previously been described, the improvement in TMT provided by HIFT can also be attributed to fast-acting factors such as increased cerebral blood flow, release of catecholamines and neurotrophins (such as BDNF), as well as stimulation of neuroplasticity, in a more extended outlook. Another factor that ought to be included in the discussion stems from the study by Da Costa et al. (2017) who observed, in individuals with SUD, improvements in cognitive flexibility after three months of running practice, highlighting the relationship between cognition and increased VO_2max. The results of studies using near infrared spectrometry and electroencephalogram confirmed greater blood flow, oxygenation and electrical activity of the prefrontal cortex, correlating with improvements in EF in the Stroop Test (D. Cabral et al., 2018; D. A. Cabral et al., 2017).

Despite the extensive documentation in the literature on the benefits of moderate-intensity aerobic PE on EF (Tian et al., 2023), a more ambiguous picture emerges when it comes to high-intensity PE, such as HIFT. This scenario is marked by both positive and negative evidence regarding cognition (Ai et al., 2021; Gilson et al., 2023), including the idea that the maximal anaerobic pathway may induce a state of central fatigue, leading to a potential decline in cognitive ability, outlining a correlation with the “inverted U” model (D. A. Cabral et al., 2017). However, Wilke (Wilke, 2020) compared three groups of healthy adults, namely: HIFT, walking and control group; they showed that HIFT is more effective than walking in improving EF.

In this connection, PE intensity emerges as a controversial topic when considering particularly the potential acute and chronic effects of PE on EF. Most traditional studies have adopted predefined PE protocols, such as the use of treadmill or cycle ergometer, performing cognitive assessments during or immediately after the exercise (Teixeira et al., 2020). In contrast, Chang et al. (2012) proposed a differentiated temporal approach for the application of cognitive tasks after PE, considering hypofrontality in regions not directly associated with PE, aiming to provide recovery of the areas most directly involved. They observed a subsequent reduction in EF performance during vigorous aerobic PE, highlighting the importance of a recovery interval for brain physiological processes, particularly in the prefrontal cortex (Wang et al., 2016). These findings suggest a theoretical physiological model that emphasizes the need for a time interval between the end of PE and the beginning of cognitive assessment.

It is worth mentioning that most studies with high-intensity stimuli that lasted more than 30 minutes used a treadmill or cycle ergometer, which is an equipment associated with monotony and displeasure, in addition to the difficulty in maintaining the stimulus (Wilke, 2020). However, HIFT exhibits a more positive relationship with EF, attributed to the complexity of the motor tasks involved (D. A. Cabral et al., 2017; Ferreira et al., 2017; Wilke, 2020). Recently, considerable uptake of HIFT has been observed, both for recreational and competition purposes, including in rehabilitation contexts (Ben-Zeev et al., 2020; Feito et al., 2018). HIFT relevance is such that the American College of Sports Medicine points to it as a sports trend that will become more established in the coming years. Nevertheless, the body of knowledge regarding the effects of HIFT is still insufficient, especially with regard to its impacts on cognitive capacity, notably on the EFs.

Some recent studies have highlighted the relevance of HIFT in relation to EF, although there are still nuances to be elucidated (Vaughan et al., 2012; Wilke, 2020). In this connection, our study focuses on the improvement of cognition and EF through HIFT, exploring HIFT’s potential physiological mechanisms and addressing methodological considerations and limitations in its use with PSUD.

The complexity of the motor tasks involved in the protocol of the present study may have induced greater cortical activation compared to simpler tasks, as suggested by studies exploring perfusion, cerebral oxygenation and BDNF during PE. Furthermore, the increase in heart rate, related to HIFT perceived effort and intensity, demanded greater attention to the execution of movements. This evidence supports the hypothesis that HIFT may have positive effects potentially superior to other forms of physical activities, such as walking, running or the use of cycle ergometers in PSUD.

Although our study yields contributions, some limitations are worth mentioning. The absence of direct comparison with classic models of treadmill or cycle ergometer EF and the lack of robust conclusions about the modality, intensity and recovery time for optimizing EF in PSUD require further investigation. The selected sample has also its limitations, as well as the frequency and intervals of data collection. The need for replication of the study considering intervening variables and the influence of the treatment offered to the participants deserves attention. However, despite these limitations, the improvement in EF observed after an acute HIFT session suggests a promising potential to promote brain plasticity and optimize cognitive aspects, which should be verified in further studies.

Finally, the positive perceptions of participants regarding HIFT, expressed by terms such as “Clears the Mind” and “Makes Walking Easier”, enhances accessibility, motivation and affective aspects of this approach. Although there is a long way to go to comprehensively understand the underlying mechanisms and the methodological considerations, the results of this study add to the scientific literature the perspective that HIFT can be an effective tool to optimize the EF of individuals with SUD, providing potential benefits to their cognition and quality of life.

The improvement in executive functions observed after a HIFT session suggests a promising potential to promote brain plasticity and optimize cognitive aspects. Although this study has limitations, it paves the way for future investigations that can further explore these effects and elucidate the mechanisms underlying these cognitive changes. Finally, the positive perceptions of participants regarding HIFT, expressed by terms such as ‘Clears the Mind’ and ‘Makes Walking Easier’, enhance accessibility, motivation and affective aspects of this approach. Although there is a long way for the comprehensive understanding of the underlying mechanisms and the methodological considerations, the results of this study add to the scientific literature the perspective that HIFT can be an effective tool to optimize the EF of individuals with SUD, providing potential benefits to their cognition and quality of life.