This randomized controlled trial will evaluate the efficacy of a Transtheoretical Model (TTM)-based behavior-change intervention, delivered through stage-matched counseling sessions, on anabolic-androgenic steroid (AAS) use among gym-goers, compared with a control group receiving standard health education. Non-medical AAS use is a growing public health concern in gym and fitness settings and is associated with serious cardiovascular, endocrine, hepatic, and psychiatric harms. Participants will be randomly assigned to either a TTM-based intervention group or a control group. The intervention will tailor counseling content to each participant's stage of change (precontemplation, contemplation, preparation, action, or maintenance) regarding AAS use. The findings of this study will provide evidence on the effectiveness of stage-based behavioral counseling in reducing AAS use and progressing gym-goers toward safer, drug-free training practices.

Anabolic-androgenic steroid (AAS) use for aesthetic and performance-enhancing purposes has become an increasingly recognized problem among recreational and competitive gym-goers worldwide, with prevalence reported to be substantially higher in bodybuilding and fitness-center populations than in the general population. Non-medical AAS use is associated with cardiovascular disease, hepatotoxicity, endocrine disruption, and psychiatric sequelae including depression, aggression, and dependence. Despite this burden, few theory-driven behavioral interventions targeting AAS use in gym settings have been rigorously evaluated.

The Transtheoretical Model (TTM) proposes that behavior change unfolds through a sequence of stages (precontemplation, contemplation, preparation, action, and maintenance), and that interventions matched to an individual's current stage - using stage-specific processes of change, decisional balance, and self-efficacy strategies - are more effective than generic, one-size-fits-all education. TTM-based interventions have demonstrated efficacy in other health behaviors such as smoking cessation, weight management, and physical activity promotion, but their application to AAS use reduction among gym-goers remains limited.

This study will be conducted as a randomized controlled trial at fitness centers/gyms in Mosul city, Iraq. A total of [N, e.g., 120] adult gym-goers who report current or recent non-medical AAS use, or who are identified as being at risk of AAS use, will be enrolled and randomly assigned to one of two groups: a TTM-based intervention group or a control group. The intervention group will receive a structured, multi-session program of individualized counseling matched to participants' baseline stage of change, incorporating motivational interviewing techniques, decisional-balance exercises, and self-efficacy building strategies delivered over [e.g., 8 weeks]. The control group will receive standard printed health education materials on the risks of AAS use.

Data will be collected using validated self-report questionnaires assessing stage of change (e.g., a URICA-type or AAS-adapted staging algorithm), decisional balance (pros and cons of AAS use), self-efficacy to resist AAS use, and self-reported AAS use behavior (frequency, dose, and duration). Assessments will occur at baseline, immediately post-intervention, and at a follow-up time point. The study will compare the effect of the TTM-based intervention versus control on stage progression and AAS use behavior, and will examine the relationship between stage of change, decisional balance, self-efficacy, and actual reduction or cessation of AAS use.

Inclusion Criteria:

● Adult gym members regularly attending the study fitness center(s)

● Male or female, aged 18 years or older

● Current or past-year non-medical use of anabolic-androgenic steroids, or identified as at risk of initiating use

● Willing to participate and provide informed consent

● Able to attend the assigned intervention sessions and complete study assessments

Exclusion Criteria:

● Nurses/participants who do not agree to participate in the study

● Use of AAS under current medical supervision/prescription for a diagnosed condition

● Not available during the study intervention or follow-up period

● Unable to attend the assigned intervention sessions

● Do not complete the required study assessments

● Participated in the pilot study

Individual participant data will not be shared because the study involves a relatively small sample from specific gym/fitness-center settings, and data sharing may increase the risk of participant identification even after de-identification.