A new study published in the Journal of Affective Disorders provides evidence that a brief but structured physical exercise program can help reduce stress levels in adolescents diagnosed with attention-deficit/hyperactivity disorder. The researchers found that after just three weeks of moderate to vigorous physical activity, participants reported lower levels of stress and showed a measurable increase in salivary cortisol, a hormone linked to the body’s stress response.

Adolescence is widely recognized as a time of dramatic psychological and biological development. For teens with ADHD, this period often comes with heightened emotional challenges. In addition to the typical symptoms of inattention and hyperactivity, many adolescents with the condition also struggle with internal feelings such as anxiety and depression. These emotional difficulties can interfere with daily functioning at school and at home, placing them at greater risk for long-term mental health problems.

Although stimulant medications are commonly used to manage symptoms, they often cause side effects such as sleep problems and mood shifts. Due to these complications, many families and young people stop using medication or seek alternative approaches. One such approach gaining traction is physical exercise. Prior research suggests that structured activity may benefit brain function and emotional regulation. However, most studies have focused on children rather than adolescents, and few have examined whether exercise influences cortisol, a stress hormone thought to be dysregulated in young people with ADHD.

Cortisol plays an important role in how the body manages stress. Low levels of cortisol in the morning have been found in children and adolescents with ADHD, and this pattern has been associated with fatigue, anxiety, and greater symptom severity. The researchers behind the new study wanted to know whether a short physical exercise intervention could influence both subjective stress levels and objective stress markers like cortisol in teens with ADHD.

“Adolescents with ADHD face stress-related challenges and appear to display atypical cortisol patterns, yet most exercise studies focus on younger children and rarely include biological stress markers,” explained study author Cindy Sit, a professor of sports science and physical education at The Chinese University of Hong Kong.

“We wanted to test a practical, low-risk intervention that schools and families could feasibly implement and to examine both perceived stress and a physiological marker (salivary cortisol) within a randomized controlled trial design. In short, we aimed to examine whether a brief, feasible program could help regulate stress in this under-researched group through non-pharmacological methods.”

The researchers recruited 82 adolescents, aged 12 to 17, who had been diagnosed with ADHD. Some of the participants also had a diagnosis of autism spectrum disorder, which often co-occurs with ADHD. The teens were randomly assigned to one of two groups. One group participated in a structured physical exercise program lasting three weeks. The other group served as a control and continued with their normal routines.

The exercise group attended two 90-minute sessions each week, totaling 540 minutes over the course of the program. These sessions included a variety of activities designed not only to improve physical fitness but also to engage cognitive functions such as memory, reaction time, and problem-solving. Exercises included circuit training as well as games that required strategic thinking and teamwork. Participants were guided to maintain moderate to vigorous intensity throughout much of the sessions, and their heart rates were monitored to ensure appropriate effort.

To measure outcomes, the researchers used both self-report questionnaires and biological samples. Stress, depression, and anxiety levels were assessed through a validated scale. Cortisol was measured using saliva samples collected in the afternoon before and after the intervention, as well as three months later.

The findings showed that immediately following the exercise program, participants in the exercise group reported lower levels of stress compared to their baseline scores. At the same time, their cortisol levels increased.

The increase in cortisol following exercise was interpreted not as a sign of increased stress but as a reflection of more typical hormonal activity. The researchers noted that this pattern aligns with the idea of exercise as a “positive stressor” that helps train the body to respond more effectively to real-life challenges. Importantly, the teens felt less stressed, even as their cortisol levels rose.

“The combination of lower perceived stress alongside an immediate rise in cortisol was striking,” Sit told PsyPost. “It supports the idea that exercise can feel stress-relieving while still producing a normal physiological stress response that may help calibrate the HPA axis. We also noted a baseline positive association between anxiety and cortisol in the control group only, which warrants further investigation.”

However, by the three-month follow-up, the improvements in self-reported stress had faded, and cortisol levels had returned to their initial levels. There were no significant changes in self-reported depression or anxiety in either group at any point.

“A short, three-week exercise program (90-minute sessions twice a week at moderate to vigorous intensity) reduced perceived stress in adolescents with ADHD immediately after the program,” Sit said. “Cortisol levels increased right after the intervention, consistent with a healthy, short-term activation of the stress system during exertion (often called ‘good stress’). The positive effects on perceived stress did not last for three months without continued physical exercise, and we did not observe short-term changes in depression or anxiety. This suggests that ongoing participation is necessary to sustain these benefits.”

Although the results suggest benefits from the short-term exercise program, there are some limitations to consider. Most of the participants were male, and this gender imbalance could affect how the findings apply to a broader group of adolescents. The study also relied on self-report questionnaires to assess stress, anxiety, and depression, which can be affected by personal bias. Additionally, there was no “active” control group, meaning the control participants were not given an alternate activity that involved social interaction or structure, which might have helped isolate the effects of the exercise itself.

Future studies might benefit from longer intervention periods to examine whether extended participation can produce lasting changes. Collecting saliva samples multiple times during the day could also help map out how cortisol behaves in response to both daily routines and interventions. Incorporating interviews or observer-based assessments could provide a more complete understanding of emotional changes, especially in teens who have difficulty expressing their feelings through questionnaires.

“Our team is currently conducting a large randomized controlled trial testing physical‑activity interventions for people with intellectual disability, with co‑primary outcomes of mood and physical strength,” Sit explained. “The broader aim is to develop scalable, low‑cost programs that can be implemented in schools, day services, and community settings. Ultimately, we aim to increase access for underserved populations so that structured movement becomes a feasible part of everyday care and improves their quality of life.”

“We see exercise as a useful adjunct, not a replacement, for standard ADHD care,” she added. “In practice, that involves incorporating structured movement alongside evidence-based treatments (e.g., medication, psychoeducation, behavioural supports) and working with families, schools, and healthcare providers. Exercise is accessible and generally has low risk; it can assist with stress regulation, sleep, attention, and fitness. However, it should be individualized and monitored, especially for individuals with special needs like ADHD, to support rather than replace routine care.”

The study, “Efficacy of a short-term physical exercise intervention on stress biomarkers and mental health in adolescents with ADHD: A randomized controlled trial,” was authored by Sima Dastamooz, Stephen H.S. Wong, Yijian Yang, Kelly Arbour-Nicitopoulos, Rainbow T.H. Ho, Jason C.S. Yam, Clement C.Y. Tham, Liu Chang, and Cindy H.P. Sit.