High Intensity Training for Adults With ADHD in Specialised Mental Health Care (HITADHD)

High-intensity Training for Adults With ADHD in Specialised Mental Health Care: A Mixed Methods Feasibility Study

Attention-Deficit/Hyperactivity Disorder (ADHD) is a lifelong neurodevelopmental disorder characterised by persistent symptoms of inattention, hyperactivity, and impulsivity. According to the DSM-5, these symptoms must be present for at least six months, have an onset in childhood, and result in significant impairment in multiple life domains. Although ADHD may be limited to childhood in some cases, most individuals continue to have symptoms and impairments in varying degrees in adult life. The prevalence of persistent ADHD among adults is estimated to be approximately 2.58%, depending on diagnostic criteria and sample selection. The increasing awareness of ADHD has led to a marked increase in referrals to mental health services, which places greater demands on the development of effective and accessible treatment options for this group.

Pharmacological treatment, particularly the use of stimulants, is a common intervention for adults with ADHD and has been shown to be effective for many. However, there are also side effects associated with drug treatment, and there is a need for more evidence-based non-drug alternatives. In addition, discontinuation of medication is common in ADHD treatment. Psychological interventions include psychoeducation and cognitive behaviour therapy, as well as more specialised approaches based on Dialectical Behaviour Therapy and Goal Management Training, which aim to improve executive functions. Whilst pharmacotherapy and psychotherapeutic interventions help some people with ADHD, not all people experience favourable outcomes, which calls for alternative treatment approaches. Interventions targeting the core symptoms of ADHD, executive functions, and behaviour are particularly relevant to treatment provision.

One approach to improving executive functioning that has received increasing attention is physical exercise. Studies have shown that physical activity can have a positive effect on cognitive function, executive control, and behaviour in children and adolescents with ADHD. Physical exercise may also be applied as treatment for comorbid factors common in ADHD, such as mood disorders and multiple long-term physical conditions. Despite increasing interest in physical activity as a treatment modality, research on physical exercise for adults with ADHD is still limited. The findings from studies on younger age groups point to the potential for similar effects in adults, but more research is needed to examine the effects of physical exercise as a targeted intervention in the adult population with ADHD.

Among the different types of physical activity, high-intensity interval training (HIIT) has gained promise for mental health. Due to its rapid, alternating, and fast-paced style, it could prove useful for those with ADHD. However, research on high-intensity interval training interventions (HIIT) in this population is scarce. To address these unanswered questions, this project will conduct a feasibility trial for a randomised controlled trial (RCT) to assess the feasibility and acceptability of HIIT among people with ADHD.

Study Overview

• Status: Enrolling by invitation
• Conditions: Attention Deficit Disorder With Hyperactivity (ADHD)
• Intervention / Treatment: Behavioral: High intensity training

• Study Type: Interventional
• Enrollment (Estimated): 30
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Norway
  • Bergen, Norway
    • Solli DPS and Kronstad DPS

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: No

Description

Inclusion Criteria:

• Above 18 years
• An ADHD diagnosis (F90.0 in the ICD-10)

Exclusion Criteria:

• Psychiatric conditions not compatible with participation incl. ongoing psychotic episode, mania, acute suicidality etc.,
• Physical conditions precluding participation in physical testing and/or exercise
• Comprehensive ongoing substance use determined by the Alcohol Use Disorders IdentificationTest (AUDIT; Babor et al., 2001) and the Drug Use Disorder Identification Test (DUDIT; Berman et al., 2003). An AUDIT cut-off score of 16 (high risk), and/or DUDIT score of 20 (high risk) will lead to screening with MINI International Neuropsychiatric Interview (Lecrubier etal., 1997; Sheehan et al., 1998).

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: High intensity training; Fourteen weeks of high intensity strenght and endurance training after a protocol.	Behavioral: High intensity training; 14 weeks of high intensity training of strenght and endurace.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Feasibility of the intervention: Recruitment rate	Recruitment rate: Proportion of eligible participants who agree to participate in the study ((Number of participants recruited/Number of eligible participants) x 100). Aim: >50%.	through study completion, an average of 1 year
Feasibility measure: Retention rate	Retention rate: Proportion of participants who remain in the study until completion ((Number of participants completing the study/Number of participants enrolled) x 100). Aim: >80%.	through study completion, an average of 1 year
Feasibility measure: Dropout rate	Dropout rate: How many participants dropped out after inclusion. Registration of reasons of dropout.	through study completion, an average of 1 year
Feasibility measure: Compliance	Compliance: How many sessions each participant attended. Registration of reasons of sessions not attended.	through study completion, an average of 1 year
Feasibility measure: Adherence to protocol	Adherence to protocol: How many elements in the physical exercise program were conducted in each session. Physical exercise diary for registration of load and intensity of strength- and endurance training, respectively. Aim: >80%. Also, registration of adherence to the total test protocol.	through study completion, an average of 1 year

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
In depth interview	Participants will be invited to an in-depth interview lasting approx. 45 minutes, after the treatment intervention. The aim is to explore experiences with physical exercise in relation to core symptoms of ADHD. A semi-structured interview protocol with open questions and additional probes is used to promote exploratory dialogue on the participants experience with participation. All interviews will be audio recorded and transcribed verbatim. By comparing the individual accounts, we want to identify both patterns of commonalities and differences in participants' experiences, providing important descriptions of patient experiences that may contribute to detect challenges with the intervention that can be utilised for further development and implementation.	Participants are inviteted within two weeks after ending their participation
General Ability - WAIS-IV	Six sub tests from the general ability test Wecshler Adult Intelligence Scale will be used to assess General Ability Index, Verbal Comprehension Index and Perceptual Reasoning Index. The six subtests are: Block Design, Similarities, Matrix Reasoning, Vocabulary, Digit Span and Coding.	Within two weeks before initating intervention.
The Adult ADHD Self-Report Scale	The Adult ADHD Self-Report Scale (ASRS) is a patient-reported outcome measure assessing the frequency and severity of adult ADHD symptoms. Items are rated on a 5-point Likert scale (0-4), with higher total scores reflecting greater ADHD symptom severity. Lower scores reflect fewer self-reported ADHD symptoms.	Within two weeks before initating intervention. Within two weeks after ending intervention.
The Working Memory Questionnaire	The Working Memory Questionnaire (WMQ) is a patient-reported outcome measure designed to assess everyday difficulties related to working memory functioning. It evaluates the frequency of memory-related problems experienced in daily life, including difficulties with remembering information, maintaining attention, following instructions, and managing cognitive tasks. The WMQ consists of items rated on a Likert-type scale, where participants indicate how often they experience specific working memory difficulties. A total score is calculated by summing item responses. Higher scores indicate greater perceived working memory difficulties and a higher level of impairment in everyday cognitive functioning. Lower scores indicate fewer reported working memory problems and better perceived working memory functioning. The total WMQ score is calculated by summing responses across items (with item scoring depen	Within two weeks before first intervention session and within two weeks after completion of the last session.
The Generalized Anxiety Disorder-7	The Generalized Anxiety Disorder-7 (GAD-7) is a patient-reported outcome measure assessing anxiety symptom severity. Items are scored from 0-3 based on symptom frequency over the previous two weeks, producing a total score from 0-21. Higher scores indicate greater anxiety symptom severity, while lower scores indicate fewer anxiety symptoms	Within two weeks before first intervention session and within two weeks after completion of the last session.
The Patient Health Questionnaire-9	The Patient Health Questionnaire-9 (PHQ-9) is a patient-reported outcome measure assessing depressive symptom severity. Items are scored from 0-3 based on symptom frequency over the previous two weeks, producing a total score from 0-27. Higher scores indicate greater depressive symptom severity, while lower scores indicate fewer depressive symptoms.	Within two weeks before first intervention session and within two weeks after completion of the last session.
The Bergen Insomnia Scale	The Bergen Insomnia Scale (BIS) is a patient-reported outcome measure assessing insomnia symptoms and sleep-related impairment. Six items are rated from 0-7 according to symptom frequency over the previous month, producing a total score from 0-42. Higher scores indicate greater insomnia symptom severity, while lower scores indicate fewer insomnia symptoms.	Within two weeks before first intervention session and within two weeks after completion of the last session.
The International Physical Activity Questionnaire	The International Physical Activity Questionnaire (IPAQ) is a patient-reported outcome measure assessing physical activity and sedentary behavior. It measures frequency and duration of walking, moderate-intensity, and vigorous-intensity activities over a specified recall period. Scores are calculated as MET-minutes/week, with higher scores indicating greater physical activity and lower scores indicating less physical activity.	Within two weeks before first intervention session and within two weeks after completion of the last session.
The Work and Social Adjustment Scale	The Work and Social Adjustment Scale (WSAS) is a patient-reported outcome measure assessing functional impairment associated with a health condition. Five items are rated from 0-8, producing a total score from 0-40. Higher scores indicate greater impairment in work, social, and daily functioning, while lower scores indicate better functioning.	Within two weeks before first intervention session and within two weeks after completion of the last session.
The Adult ADHD Quality of Life	The Adult ADHD Quality of Life (AAQoL) is a validated self-report questionnaire designed to assess health-related quality of life in adults with attention-deficit/hyperactivity disorder (ADHD). The instrument evaluates the impact of ADHD symptoms on daily functioning and well-being across multiple domains, including life productivity, psychological health, relationships, and outlook. The AAQoL consists of 29 items, each rated on a Likert-type scale reflecting the frequency or severity of difficulties experienced over a specified recall period. Item responses are combined and transformed into domain scores and an overall total score. Item responses are aggregated and converted to standardized scores ranging from **0 to 100** for the total scale and each domain. Higher scores indicate better health-related quality of life, while lower scores indicate poorer quality of life and greater ADHD-related f	Within two weeks before first intervention session and within two weeks after completion of the last session.
Credibility/Expectancy Questionnaire	The Credibility/Expectancy Questionnaire (CEQ) is a patient-reported measure assessing perceived treatment credibility and expectancy for improvement. It consists of 5 items where patients rate themselves on a likert scale from 0-10. It produces a total scores, with higher scores indicating greater perceived credibility and stronger expectations of treatment benefit.	Within two weeks before first intervention session and within two weeks after completion of the last session.
The Negative Effects Questionnaire - Short Form	The Negative Effects Questionnaire - Short Form (NEQ-S) is a patient-reported outcome measure assessing perceived negative or unwanted effects of an intervention. Higher scores indicate a greater number and/or severity of self-reported adverse effects.	Within two weeks after completion of the last session.
The Wechsler Memory Scale - Third Edition	The Wechsler Memory Scale - Third Edition (WMS-III) Spatial Memory subtest is a clinician-administered measure of visuospatial memory. Standardized age-adjusted scores are derived, with higher scores indicating better spatial memory performance and lower scores indicating poorer spatial memory.	Within two weeks before first intervention session and within two weeks after completion of the last session.
D-KEFS Trail Making Test	The D-KEFS Trail Making Test is a clinician-administered measure of executive function assessing visual scanning, processing speed, and cognitive flexibility. Performance is measured by time to completion and standardized scaled scores, with higher scores (and faster completion times) indicating better executive functioning."	Within two weeks before first intervention session and within two weeks after completion of the last session.
D-KEFS Color-Word Interference Test	The D-KEFS Color-Word Interference Test is a clinician-administered measure of executive function assessing response inhibition and cognitive flexibility. Performance is measured by time to completion and standardized scaled scores, with higher scores (and faster completion times) indicating better executive functioning.	Within two weeks before first intervention session and within two weeks after completion of the last session.
Maximal strenght	Maximal strength is assessed using the one-repetition maximum (1RM) test for lower-body and upper-body strength. In this study, maximal lower-body strength is assessed using a leg strength exercise (e.g., leg press or squat depending on protocol), and upper-body strength is assessed using the bench press. The primary outcome is the maximal load lifted successfully for one repetition, recorded in kilograms (kg). Separate 1RM values are obtained for leg strength and bench press. Higher scores: Indicate greater maximal muscular strength and neuromuscular performance in the tested muscle groups. Lower score	Within two weeks before first intervention session and within two weeks after completion of the last session.
Maximal oxygen uptake	Maximal oxygen uptake (VO₂max) is an estimate of the maximum rate at which oxygen can be utilized during intense aerobic exercise and is a key indicator of cardiorespiratory fitness. In this study, VO₂max is estimated using the Myworkout GO mobile application (Helgerud et al., 2022), which derives VO₂max from performance data collected during a standardized treadmill-based interval protocol (4×4 endurance session). The estimation is based on recorded treadmill speed and incline during the exercise session, which are used to model aerobic capacity according to validated predictive algorithms. VO₂max is reported as an estimated continuous variable in milliliters of oxygen per kilogram of body weight per minute (mL·kg-¹·min-¹). Higher values indicate greater aerobic capacity and cardiorespiratory fitness, while lower values indicate reduced aerobic fitness.	Within two weeks before first intervention session and within two weeks after completion of the last session.

Collaborators and Investigators

• Sponsor: Solli Distriktspsykiatriske Senter
• Collaborators: Helse Bergen Hospital Trust
• Investigators: Principal Investigator: Kristine Sirevåg, PhD, Solli DPS

Study record dates

Study Major Dates

• Study Start (Actual): February 1, 2026
• Primary Completion (Estimated): June 1, 2027
• Study Completion (Estimated): June 30, 2027

Study Registration Dates

• First Submitted: January 15, 2026
• First Submitted That Met QC Criteria: June 26, 2026
• First Posted (Actual): June 30, 2026

Study Record Updates

• Last Update Posted (Actual): June 30, 2026
• Last Update Submitted That Met QC Criteria: June 26, 2026
• Last Verified: June 1, 2026

More Information

Terms related to this study

• Keywords: ADHD; Physical exercise; High intensity training
• Additional Relevant MeSH Terms: Mental Disorders; Neurodevelopmental Disorders; Attention Deficit and Disruptive Behavior Disorders; Behavior; Attention Deficit Disorder with Hyperactivity; Motor Activity; Motor Activity; Movement; Musculoskeletal Physiological Phenomena; Musculoskeletal and Neural Physiological Phenomena; Physical Conditioning, Human; Exercise; High-Intensity Interval Training
• Other Study ID Numbers: 938442

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: This has not been applied for to the ethical Committee.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No