The m-FIM evaluates a person’s ability to perform motor activities of daily living.56 Items include performance in self-care, sphincter control and mobility.57

13 items, each assessed against a 7-point ordinal scale.

Maximum score of 91 (complete independence) and a minimum of 13 (complete dependence).

High validity and inter-rater reliability36 58.

More responsive to change after rehabilitation than the total FIM score for individuals with FRDA.14

Exhibited strong correlations with level of disability in neurological populations and can predict amount of help required.36 59–61

The SARA is a semiquantitative clinical assessment of ataxia, measuring ataxia of upper limb, lower limb, gait, balance and speech.

Eight items; score range 0–40, with a higher score indicating more severe ataxia.39

Excellent inter-rater and test–retest reliability in individuals with ataxia.39

Excellent construct validity in ataxias of multiple aetiologies62 63.

The BBS evaluates performance in sitting and standing balance activities.

14 items; score ranging 0–56 with a higher score indicating better balance.

Responsive to change after intensive coordinative training in degenerative ataxias.17

Good intra- and inter-rater reliability when assessing balance in people with ataxia secondary to multiple sclerosis.64

The PGIC is 7-point numerical rating scale measuring global benefit from the participant’s perspective.

Maximum score of 7 (a great deal better, and a considerable improvement that has made all the difference) and a minimum of 0 (no change).

Cut-off for clinically meaningful change will be 5 (moderately better, and a slight but noticeable change).

High face validity.65

Responsive to change following a 6 week rehabilitation programme in individuals with FRDA.14

Used as an external criterion for determining smallest detectible and clinically meaningful change after rehabilitation and 1 year of natural decline in individuals with multiple sclerosis and spinocerebellar ataxia respectively66 67.

The SF-36 v2 measures self-perceived health-related quality of life.

36 items; yields scores for eight multiitem dimensions and two summary scale scores (physical and mental health).42

Responsive to reduction in quality of life in individuals with ataxia68 69.

The physical component of the SF-36 v2 has been shown to be highly correlated with disease duration and ataxia severity in individuals with FRDA.68

The Sf-36 v1 has shown acceptable internal consistency among subscales in individuals with FRDA.70

Measured with the Fitbit Flex 2, a commercial grade tri-axial accelerometer worn on the wrist.

Worn for 24 hours per day for seven consecutive days.

A valid day=Fitbit Flex 2 worn for ≥90% of the day. Wear time will be recorded by participant self-report.

3–5 days of accelerometer monitoring in adults is necessary to achieve a between day intra-class correlation of 0.80.71

Moderate validity for measuring physical activity relative to the Actigraph.72 Good to excellent significant positive correlations and agreement with the Actigraph, although it overestimates number of steps.73

Excellent reliability in an older population.74

The FIST is a clinical measure of sitting balance.43

14 items; score ranging 0–56 with a higher score indicating better sitting balance.43

Excellent concurrent validity with the BBS and moderate to good validity with the m-FIM in adults with neurological deficits and impaired sitting balance.75

Excellent test–retest reliability in individuals with various neurological disorders76 77.

Responsive to change following rehabilitation and a minimal detectible change of 5.5 points.75

Measured with the BioKin system, a wireless motion capture device.44

Four test conditions include: sitting 30 s, no foot contact on the floor, arms out straight: (1) eyes open and (2) eyes closed; standing 30 s, feet together: (3) eyes open and (4) eyes closed.

An exploratory outcome used in this trial, not previously validated in this population.