Deconditioning syndrome is the condition of physical, psychological and functional decline that occurs as a result of complex physiological changes induced by inactivity and immobility, or bed rest*.

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Hospital Acquired Deconditioning (HAD) refers to reductions in functional performance, or loss of independence in Activities of Daily Living (ADLs) after an acute hospitalisation*.

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However, a recent scoping review in 2025 identified 63 unique definitions of HAD in the literature* highlighting the need for further work to develop a shared definition of HAD, enabling for better understanding, treatment  and mitigation against this harm.

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The field of deconditioning research has transitioned from identifying deconditioning as a problem and a harm, to increasing awareness of the problem and harm, and now to developing methods of preventing deconditioning, i.e. 'reconditioning'*.

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