Main red flags include unstable cardiac disease, uncontrolled hypertension, severe respiratory compromise, open or infected wounds, incontinence, uncontrolled epilepsy, severe orthostatic problems, and inability to follow safety instructions. Exercise‑specific cautions include acute joint infection, unstable fractures, and any condition where immersion‑induced volume shifts may overload the heart or lungs. (https://www.ewacmedical.com/wp-content/uploads/2017/11/Mooventhan-2014-SR-AT-scientific-evidence.pdf)
In practice
Underwater treadmills add the demands of immersion, belt motion, and sometimes higher water pressure. Screen for cardiac disease, heart failure, and uncontrolled arrhythmias because immersion shifts blood centrally and can increase preload. Also assess respiratory status, as hydrostatic pressure can increase breathing work. (https://www.ewacmedical.com/wp-content/uploads/2017/11/Mooventhan-2014-SR-AT-scientific-evidence.pdf)
Contraindications common to pools still apply: untreated infections, open wounds, recent surgery with unprotected incisions, incontinence, uncontrolled epilepsy, severe autonomic dysfunction, and severe fear of water without adequate safeguards. From a musculoskeletal perspective, avoid underwater treadmill in unstable fractures, acute joint infections, or when weight‑bearing is medically prohibited; in such cases static buoyancy exercises may be safer. (https://www.ewacmedical.com/wp-content/uploads/2017/11/Mooventhan-2014-SR-AT-scientific-evidence.pdf)
EWAC Medical references
– EWAC knowledge summary of Mooventhan 2014: details cardiovascular and respiratory effects of hydrotherapy, highlighting why cardiac and respiratory screening is critical. (https://www.ewacmedical.com/knowledge/mooventhan-2014-scientific-evidence-based-effects-of-hydrotherapy-on-various-systems-of-the-body/)]
– EWAC orthopedic treadmill article: emphasizes low‑impact loading but implies that joint loading still exists, requiring standard orthopedic precautions. (https://www.ewacmedical.com/benefits-of-the-aquatic-treadmill-exercise-in-orthopedic-patients-in-five-articles/)]
– EWAC‑hosted Stanciu 2023 review: discusses cardiopulmonary and thermoregulatory issues in SCI during hydrotherapy. (https://www.ewacmedical.com/wp-content/uploads/2024/12/Stanciu-2024-Evidence-of-Improvement-of-Lower-Limb-Functioning-Using-Hydrotherapy-on-Spinal-Cord-Injury-Patients.pdf)]
External scientific references
– Mooventhan & Nivethitha 2014 review: documents changes in heart rate, blood pressure, and respiratory parameters with immersion, guiding cardiac/respiratory precautions. (https://www.ewacmedical.com/wp-content/uploads/2017/11/Mooventhan-2014-SR-AT-scientific-evidence.pdf)
– Hydrotherapy reviews in neurologic and SCI populations highlight thermoregulation, autonomic dysreflexia, and cardiorespiratory considerations as key safety issues. (https://www.ewacmedical.com/wp-content/uploads/2025/04/Peng-2024The-glamor-of-and-insights-regarding-hydrotherapy-from-simple-immersion-to-advanced-computer-assisted-exercises-A-narrative-review.pdf)
– General aquatic‑exercise safety guidelines in OA and other cohorts stress screening for cardiovascular instability and open wounds before immersion. (https://pmc.ncbi.nlm.nih.gov/articles/PMC8955208/)]