A person who has an unfavorable genetic test for the HD, but has not yet developed any clinical signs of HD is considered to be pre-manifest. Mild gait changes can be observed in pre-manifest individuals, including decreased gait velocity and stride length; increased double support time; and increased variability in stride length and step time compared with controls [12]. In a multicenter, prospective, observational study involving a total of eight sites, test measures of functional abilities and physical impairments were proposed in 81 people with pre-manifest and manifest HD. The preliminary results showed that specific measures may be appropriate for HD, and the tools may be useful to assessing individuals in the pre-manifest stage [13].

Even in the absence of any specific motor impairment limitation, the patients should be encouraged to undergo a specific evaluation with a physiotherapist specializing in movement disorders, and test the influence of cognitive issues on functional activities. All these physical interventions may include support the maintenance of an independent exercise program; however, the evidence is not strong and little is known about the dosage, frequency, and intensity at that stage.

At the early stage, there may be progression of cognitive deficits such as memory, planning, problem-solving, organizing, new learning, and attention. A mild postural instability and falls may occur in early and mid-stages of HD, and the mean incidence is approximately 58–60 %. The patients cannot report the numbers of falls exactly and the circumstances under which these falls occurred were due to the progression of cognitive impairments [4]. The balance impairments may be multifactorial such as the correct sequencing of postural responses, delays in initiation, and prolonged anticipatory postural adjustments [14], deficits in adapting the postural response to change task demands and environment and response to chorea, increased postural sway, impaired cognitive function and behavior, and reduced ability to maintain postural stability during dual tasks [4].

Altered musculoskeletal alignment , which may be associated with chorea and dystonia, disorders of the integration of sensory information, including dependence on proprioceptive cues rather than on visual cues. Lower-limb muscle weakness and reduced activity [15] are other factors. The side effects of some medications and environmental hazards may also contribute to the high incidence of falls [16].

Individuals with HD have been found to have a reduction in the quality of functional manual activities caused by chorea, bradykinesia, and difficulties in movement sequencing [17].

Gait impairments could be marked by a gait bradykinesia, the disorder of locomotor timing demonstrated by increased difficulty in the ability to regulate cadence and an increased variability of stepping rates. The timing disorder in HD may be the result of a dysfunction of the basal ganglia cueing mechanism that signals the supplementary motor areas to prepare the next movement in the sequence [18].

The slower stepping response time (STR) in HD may become slower gait, prolonged reaction time, and slower movement time of the upper extremity, and a longer reaction time and reduction in speed of the first step of ambulation in people with HD are consistent with bradykinesia being a feature of HD. In an investigation, the authors showed that deficits in SRT were associated with impairments on clinical measures of balance, mobility, and motor performance, including a subjective measure related to balance and confidence. The correlation suggested that in people with HD, slower response times might be associated with lower balance confidence during performance of common daily activities. Good correlations were found between SRT and clinical measures, such as timed up & go (TUG) and tandem walk tests, highlighting associations between SRT and gait-related performance measures. The slower SRT was associated with poorer performance on the TUG and the tandem walk tests. The results showed that SRT may be a valid and objective marker of disease progression [19].

The assessment of motor functions may be required; thus, in some studies evaluation is performed using a specific test proposed by the Guideline for Huntington’s Disease [20] and others showed the importance of determining the efficacy of minimal detectable changes on measures before and after physical therapy interventions [21]. This evaluation should be carried out by a physical therapist specialized in neurology and movement disorders. This guideline can provide a general framework for physical therapy intervention for impairments that can have an impact on the functional activity and life participation of people with HD [20].

Gait retraining strategies for people with HD, therefore, need to target disorders of both footstep timing and amplitude [18]. There were a few exercise protocols aimed at people with HD. They suggest some strategies for training gait [22], functional activities [23, 24], and multi-sensory stimulation [25]. There are no specific balance protocols for HD; thus, we suggest the Parkinson’s disease protocols, because they may be very useful for implementing the dosage, frequency, and intensity of the physical therapy sessions [26].

Aerobic exercises (walking—treadmill and over-ground, jogging, swimming, and stationary bicycling) are recommended in a frequency of 3–5 times a week, in an intensity of 65–85 % of the maximal heart rate. Exergaming, Yoga, Pilates, Tai Chi, and relaxation are also suggested [20].

Exercise adherence in this population decreases after professional supervision stops and patients no longer receive external support or feedback about their progress [17, 27]. There is clearly a need to develop methods that facilitate patients and caregivers engagement in and adherence to an exercise program.

The benefits of regular physical activity for people with HD are widely recognized. Although regular and sustained physical activity has the potential to benefit patients with neurodegenerative conditions such as HD, there are a number of disease-specific factors that make it particularly challenging to establish regular exercise in this population. For that reason, it is important to support engagement in physical activity in people with Huntington’s disease with a study protocol for a randomized controlled feasibility trial [28].

During the mid-stage of HD, involuntary movements such as chorea increase, dystonic postures (e.g., torticollis, opisthotonus, and arching of the feet) may be present and voluntary motor tasks may become increasingly difficult. People have balance and gait deficits, including increased variability in gait parameters (e.g., stride time and length, double support time) [12], that result in frequent falls [15]. Contributing factors may include bradykinesia of gait, stride variability, and chorea in addition to cognitive and behavioral issues [4]. People may also frequently drop objects that they are holding in their hands because of motor impersistence. Motor skill learning is also often impaired at this stage, resulting in difficulties learning new tasks or sequences [29].

The chorea or hypokinesia rigidity are characteristics that are independent predictors of both cognitive and general functioning, with choreatic patients functioning significantly better. The hypokinetic HD subtypes are associated with poorer functioning than the hyperkinetic. It is possible that choreatic subjects are falsely assigned to the hypokinetic rigid group because of medication-induced hypokinesia [30].

As the disease progresses, physiotherapy is frequently directed toward maintaining or retraining the reach to grasp movement, bed mobility, transfers, and walking. When mobility becomes further compromised, wheelchair prescription and training in wheelchair use may become a priority. In a systematic review, the overall aim of physical therapy in the mild stage was to facilitate independence in activities of daily life and optimize participation in family, work, and leisure. These aims may be achieved through an education, specific advice on safety and risk management, modification of activities or environments, or the provision of assistive devices such as adaptive eating utensils or wheelchairs. Despite the potential for allied health professionals to assist people with HD, therapies are not always provided [31].

The gait disorders in HD include reduction in speed due to a decreased step length and cadence, an increased base of support, and an increased variability of step length, swing, and double-limb support time [12]. People with HD may have difficulty turning and with gait in dual tasks, and delays in gait initiation (akinesia) [29] resulting in a loss of independence in walking.

Training people with HD to allocate their attention effectively while carrying out tasks when walking may also be beneficial [25]. Patients have difficulty synchronizing their stepping to a cue, and there is inconsistency in the literature as to whether the cues result in short-term improvements in cadence, step, and stride length [29, 32]. The prescription of gait aids may be useful for people with HD, but the difficulty with allocating attention to a dual task and difficulty controlling the gait aid if chorea is severe could be a problem [20].

At this stage there will probably be impairment of the respiratory function and capacity, resulting in limitations in endurance and restrictions in functional activities [21].

At-home visits are important to assess the patient’s functional abilities and their home environment. Recommendations for equipment or modifications are made to optimize independence and safety educating the person and her family about changes and the consequent impact on function may be useful.

In the later stages people with HD frequently require assistance to complete basic bathing, grooming, dressing, mobility, and eating tasks [31]; the complications may include muscle contracture, pain and skin breakdowns because of the abnormal position associated with dystonia and rigidity. If there is a risk of aspiration, the physiotherapist will work closely with the speech pathologist to teach the person how to clear sputum and cough effectively [16].

Aspiration pneumonia could occur and respiratory dysfunctions may worsen. There is a decrease in exercise tolerance and the ability to perform functional activities such as ambulation. It is important to implement positioning that promotes safe swallowing, prevents secondary impairments of muscle contracture and skin breakdowns. Specialized seating, wheelchairs and hoists for transfers may need to be prescribed in the late stages of the disease [20]. Caregivers should be trained to assist with airway clearance techniques such as deep breathing, postural positioning, and supported coughing, which can be taught to the family and other staff who may be caring for the person with HD [16].

In the late stages of the disease, caregivers may find that they cannot provide the required care at home and residential care may be required. Predictors for requiring institutional care include reduced capacity to complete activities of daily living and poor motor function [33].

In conclusion, there is very little evidence evaluating the efficacy of physiotherapy, randomized control studies in the published literature for reducing impairment or increasing activity and participation in people with HD. There is evidence, however, that exercise may be useful in addressing specific impairments in people who are not severely affected by HD. A specialized multidisciplinary team is useful for identifying a program of treatment at all stages of HD.