Table 1 Parkinson’s disease (PD) specific balance components, constraints affecting balance and exercises designed to reduce these constraints

SENSORY INTEGRATION

Integration of sensory information (somatosensory, visual and vestibular) for estimation of body position

- Impaired somatosensory integration

Walking tasks on varying surface with or without visual constraints

Improve interpretation of and reliance on somatosensory information

- Poor proprioception

- Visual dependency

APAs

Prediction and control of perturbation related to voluntary movements

- Poorly timed and scaled APAs

Voluntary arm/leg/trunk movements focusing on movement velocity and amplitude, and postural transitions

Improve APA strategies regarding quality (timing, amplitude) and task- specific adaptation

- Bradykinesia

MOTOR AGILITY

Coordination between body parts and movement adaptation, e.g. regulation of movement and quick shifts between tasks

- Bradykinesia

Whole-body coordination during varying gait conditions and reciprocal movements. Quick shifts of movement characteristics (velocity, amplitude and direction) during predictable and unpredictable conditions

Improve whole-body coordination, ability to adapt movement and quick shifts between different tasks

- Impaired whole-body coordination

- Biomechanical constraints

- Inflexible motor programming

STABILITY LIMITS

Whole-body regulation relative to the BoS

- Reduced functional stability limits

Voluntary leaning tasks in standing with varying BoS-stimulating weight shifts in multiple directions through arm and trunk movements

Improve the ability to safely control CoM within BoS to increase functional limits of stability

- Biomechanical constraints

- Poor proprioception

- Impaired somatosensory integration