# Aquatic Therapy as a Programmable Multisensory Environment for Arousal and Postural Control After Severe Acquired Brain Injury: A Perspective

## TL;DR

Aquatic therapy is proposed as a controllable environment to help patients with severe brain injuries manage arousal and posture during early rehabilitation.

## Contribution

The paper introduces the Arousal–Alignment–Action loop as a novel framework for aquatic rehabilitation in severe acquired brain injury.

## Key findings

- Aquatic therapy can be programmed using water depth, turbulence, and support as controllable inputs.
- A minimal outcomes/confounders set is proposed to improve study transparency and comparability.
- The framework highlights boundary conditions like sedation and autonomic instability.

## Abstract

What are the main findings?
Aquatic therapy is framed as a programmable multisensory rehabilitation medium in sABI.The Arousal–Alignment–Action loop offers testable links between state, posture, and action.

Aquatic therapy is framed as a programmable multisensory rehabilitation medium in sABI.

The Arousal–Alignment–Action loop offers testable links between state, posture, and action.

What are the implications of the main findings?
Reporting core dosing parameters can improve transparency and study comparability.A minimal outcomes/confounders set enables pragmatic, cumulative evaluation of protocols.

Reporting core dosing parameters can improve transparency and study comparability.

A minimal outcomes/confounders set enables pragmatic, cumulative evaluation of protocols.

Background/Objectives: Severe acquired brain injury (sABI) disrupts early rehabilitation because arousal fluctuates, trunk control is fragile, and agitation limits therapy tolerance; land-based practice is frequently constrained by fall risk and staffing. We aim to reframe aquatic therapy as a programmable multisensory environment to stabilize arousal and support axial alignment before conventional impairment targets are feasible. Here, programmable denotes the deliberate titration and reporting of water depth, turbulence or perturbation, temperature, body orientation, and flotation and manual support as intervention inputs. Methods: This perspective integrates principles from neurobehavioral assessment, motor control, and immersion physiology to propose the Arousal–Alignment–Action loop as a falsifiable model and to define manipulable aquatic inputs (water depth, turbulence or perturbation, temperature, body orientation, and flotation and manual support) as dosing parameters. We outline a pragmatic testing ladder (within-session micro-experiments, feasibility studies, and embedded evaluations) and a minimal outcomes and confounder set to support cumulative evidence. Results: The framework links state regulation to alignment and goal-directed behavior, specifies predictions that can fail, and highlights boundary conditions (sedation, autonomic instability, pain, recent surgery or wounds, and cervical or cardiopulmonary constraints). A minimal outcome package spanning arousal/responsiveness, trunk control, behavioral dysregulation, participation/tolerance, and basic physiology is proposed, with optional objective adjuncts for mechanism-oriented studies. Conclusions: Treating water as a measurable and titratable medium, rather than a generic modality, may reduce early intensity bottlenecks and improve implementability and comparability of aquatic neurorehabilitation research in medically stable sABI; however, the model is intended as hypothesis-generating until supported by stronger direct clinical evidence.