The purpose of the study is to see if a person can stand better on their weaker leg does this improve their walking ability following treatment specifically aimed at standing on leg. This will be compared to people who receive normal physiotherapy treatment not treatment specifically focusing on their ability to stand on their weaker leg. The study is being carried out as part of the researcher's Masters Degree. Participants will be allocated to either the control group (normal physiotherapy treatment) or the experimental group (normal physiotherapy plus physiotherapy working specifically on standing on the weaker leg). There is currently some evidence to show that working specifically on standing on one leg can improve a person's walking but this evidence is limited. Consequently, further research is warranted to identify any links between this treatment approach and walking ability.

Acquired brain injury (ABI) incidence is 369 per 100,000 people internationally and 260 per 100,000 in the UK resulting in more than 900,000 people living with the long term effects of a cerebrovascular accident (CVA) and over 380,000 with impairments following traumatic brain injury. The ABI population often experience long term health problems affecting physical functioning, cognition, communication, emotion and behaviour with a loss of physical functioning and an inability to walk highlighted as the most negative aspect by patients. Several studies have identified people with neurological impairment who regain walking often mobilise at slower speeds with a mean gait velocity of 73.07cm/s for CVA survivors (60cm/s slower than healthy adults).

The gait cycle is described as having two major components, stance and swing phase. Stance has been determined as a pre-requisite for gait and a literature review found reduced stance ability correlates with gait abnormalities in CVA survivors. Consequently, given that a stronger and longer stance phase leads to a better swing phase and stance accounts for 60% of the gait cycle, stance can be considered the most important part of the gait cycle.

A person's ability to achieve SLS can be measured using the SLS test which assesses the time a person can stand on one leg. SLS test has excellent intra-rater reliability with an intraclass correlation coefficient (ICC) of 0.83 and excellent validity with a correlation of <10 seconds being a high predictor of mobility impairments for people with ABI. There is currently no definitive minimal clinical important difference (MCID) for the SLS test - current literature varies from 5.5 - 16.0 seconds - but as this study will assess the quality of each person's SLS test as opposed to the time the results will still be clinically relevant.

Goal Attainment Scale (GAS) based on the single leg stance (SLS) test will be used to assess quality as it is responsive to change, person-specific and quantitative, able to assess treatment interventions at the impairment and functional level, and is suitable for assessing and evaluating patient outcomes in the ABI population and is frequently used within neuro-rehabilitation. GAS has excellent intra-rater reliability (ICC 0.88-0.93) and inter-rater reliability (ICC 0.95) with good concurrent and predictive and moderate to good content and construct validity (r=0.28-0.63) across the ABI population.

The ten metre walk test (10MWT) will be used to assess gait efficiency. The 10MWT requires a patient to walk ten metres at a comfortable speed and the time taken to cover that distance is measured. Studies have found a relationship between reduced SLS and reduced speed in the 10MWT with improvements in gait speed demonstrated following intervention based on SLS. It is also hypothesised that increased gait speed results in a more efficient and fluent gait pattern. Consequently, 10MWT will be used in this study to demonstrate gait velocity and efficiency improvements. 10MWT is also one of the most common, reliable, efficient and robust outcomes measures within neuro-rehabilitation. 10MWT demonstrates excellent test-retest reliability (ICC 0.95-0.99) and excellent intra-rater (ICC 0.87-0.98) and inter-rater reliability (ICC 0.99). 10MWT also has excellent criterion validity of r=0.76-0.78 and excellent construct validity (r=0.62-0.92) for various outcome measures within the ABI population with an MCID of 0.14-0.16m/s.

Consequently, ABI results in a reduced ability to achieve SLS which has a negative influence on gait speed and efficiency. Studies of predominantly small samples have demonstrated working on SLS can improve gait speed and efficiency in CVA survivors and to a lesser extent the traumatic brain injury (TBI) population meaning there is a gap in the research surrounding the ABI population as a whole including TBI. Therefore, this study will aim to answer the question 'does improved ability to achieve SLS lead to a more efficient gait pattern in adults with acquired brain injury?' The null hypothesis is 'improved ability to achieve SLS does not lead to a more efficient gait pattern in patients with ABI'. The experimental hypothesis is 'improved ability to achieve SLS does lead to a more efficient gait pattern in patients with ABI'. This is a two-tailed hypothesis due to limited evidence regarding the testing direction.

This will be an exploratory pre-test - post-test experimental design as it allows testing of two variables (dependent and independent) to identify the cause and effect of specific events. This research design also helps determine if the subjects' performance is better, worse or unchanged and the inclusion of a control group will provide more convincing evidence of success or failure of treatment. The control group will receive an individualised physiotherapy treatment approach, but it will not work specifically on SLS i.e. they will receive their normal physiotherapy treatment.

Inclusion Criteria:

• Patients with an ABI as diagnosed by a doctor following a brain scan
• Adults aged eighteen years or over
• Patients can be male or female
• Mobile >10m with or without assistance/walking aid
• Willing and able to provide written informed consent and scores >5 on orientation on FIM+FAM (FIM+FAM is an outcome measure used in all neuro-rehabilitation units in England, consequently, these data are already captured by the unit)
• Medically stable - able to fully take part in regular therapy - as determined by the unit's medical team

Exclusion Criteria:

• Diagnosed with a progressive neurological condition by a doctor
• Below eighteen years of age
• Mobile <10m or not mobile
• Unable or unwilling to give informed consent or scores <5 on orientation on FIM+FAM Medically unwell

Participants will not know if thy have been allocated to the control or experimental group