High-intensity training focused on stepping tasks in variable contexts (tasks and environments) while targeting higher cardiovascular intensity (>75% maximum predicted heart rates) during up to 40 mins of 1-hr sessions. A total of 20 sessions will be targeted.

Conventional balance activities will consist of sitting and standing balance exercises, with selected dynamic stability exercises performed during walking tasks. Heart rates will be monitored with no targeted range. All sessions will be 1-hr long with balance activities for up to 40 minutes per session. A total of 20 sessions will be targeted.

High intensity stepping training: Training sessions will focus on maximizing stepping activities in variable contexts while targeting ≥70% HR reserve (or approximately 80% age-predicted maximum HR) calculated using the Karvonen formula. Target HR will be decreased by 10 beats if the individual is on beta-blockers. Intensity will also be monitored using the Borg RPE scale every 3-5 minutes with goals of ≥15 on a 6-20 scale. The intensity of the walking training will be primarily modulated through the treadmill speed and incline as well as addition of weights to the torso or limbs for the purpose of error augmentation and not to dampen ataxia. Sessions will focus on achieving up to 40 minutes of stepping training within each 60-minute session. Potential tasks include walking in multiple directions, over inclines and obstacles, and/or with weighted vests and leg weights with limited handrail use as tolerated and decided by the therapist and participant.

Participants will walk for 6 minutes with instructions to "cover as much ground as they can".