Subjects will receive the intervention for 40-minute sessions, 3x/week for 4 weeks. The interventions will be administered in combination of onsite group training and individualized home-based training.

Short Physical Performance Battery (SPPB) will be used to measure subjects' lower extremity function by scoring their ability to perform four tasks: double-leg standing balance (feet together, semi-tandem, tandem), single-leg standing balance, gait speed over 4 meters, and lower extremity strength (5x chair stands). Each task is scored from 0 (poor) to 4 (excellent). A total score will be generated by adding up the scores for individual tasks. We will look at overall and balance component scores.

The Physical Activity Scale for the Elderly (PASE) is a self-report measure that captures information on the frequency, duration, and intensity of various physical activities. The 10 item PASE is generally partitioned into two parts. Part one, Leisure Time Activity, has six items that capture information about individual's involvement in daily activities such as participating in light exercise during the past seven days. The response options are never, seldom, sometimes, or often. Information on the type and the average time spent engaging in the activity per day is also captured.

Part two, Household Activity, has three yes/no items which ask about participation in daily activities such as dusting or washing dishes over the past week. The last question asks about involvement in paid or volunteer work over the past week. The PASE also asks about the number of hours per week as well as the amount of physical activity involved for the job or volunteer work.

The Physical Activity Scale for the Elderly (PASE) is a self-report measure that captures information on the frequency, duration, and intensity of various physical activities. The 10 item PASE is generally partitioned into two parts. Part one, Leisure Time Activity, has six items that capture information about individual's involvement in daily activities such as participating in light exercise during the past seven days. The response options are never, seldom, sometimes, or often. Information on the type and the average time spent engaging in the activity per day is also captured.

Part two, Household Activity, has three yes/no items which ask about participation in daily activities such as dusting or washing dishes over the past week. The last question asks about involvement in paid or volunteer work over the past week. The PASE also asks about the number of hours per week as well as the amount of physical activity involved for the job or volunteer work.

Short Physical Performance Battery (SPPB) will be used to measure subjects' lower extremity function by scoring their ability to perform four tasks: double-leg standing balance (feet together, semi-tandem, tandem), single-leg standing balance, gait speed over 4 meters, and lower extremity strength (5x chair stands). Each task is scored from 0 (poor) to 4 (excellent). A total score will be generated by adding up the scores for individual tasks. We will look at overall and balance component scores.

Short Physical Performance Battery (SPPB) will be used to measure subjects' lower extremity function by scoring their ability to perform four tasks: double-leg standing balance (feet together, semi-tandem, tandem), single-leg standing balance, gait speed over 4 meters, and lower extremity strength (5x chair stands). Each task is scored from 0 (poor) to 4 (excellent). A total score will be generated by adding up the scores for individual tasks. We will look at overall and balance component scores.

The Four Square Step Test (FSST) will measure dynamic standing balance. Four canes are placed on the floor to create 4 squares. The subject will step in each square as fast as possible and with use of his/her walking aid if needed. At the end of the test, the subject would have moved forward, backward, left and right while stepping over low objects. It also involves multiple transfer of weight between feet while changing direction. This test is timed and faster times indicate better dynamic standing balance.

The HUI3 is a brief questionnaire that asks subjects about their health status.

Subjects walk flat 20 feet (six metres) on a flat course, turn around, and walk 20 feet back to the start while reciting the letters of the alphabet (a, b, c, ...) aloud. They repeat this routine while reciting alternate letters of the alphabet (a, c, e, …) aloud. Subjects will be asked to pay attention to both walking and talking. The difference in time (to the nearest second) to complete the simple and complex walks is calculated with higher differences suggesting poorer ability to cope with dual tasks (e.g., greater need to focus on walking).

This is composed of 14 items that ask questions about subject's ability to perform different locomotor activities with their prosthesis on. Items are scored on a 5-level ordinal scale from 0 (not able) to 4 (able to accomplish the activity alone without ambulation aids). The total score ranges from 0 to 56, with higher scores indicating greater locomotor capabilities with the prosthesis and less dependence on assistance.

This will be used to document the number of falls, circumstances (eg: cause, location, assistive device used or not) and consequences subject have had (eg/ medical visit, injury) over the course of study.

The Life Space Assessment is a five-item questionnaire that will be used to measure the size of the spatial area that subjects move in their daily life, as well as the frequency of their mobility within a certain time frame.

The Life Space Assessment is a five-item questionnaire that will be used to measure the size of the spatial area that subjects move in their daily life, as well as the frequency of their mobility within a certain time frame.

This will be used to document the number of falls, circumstances (eg: cause, location, assistive device used or not) and consequences subject have had (eg/ medical visit, injury) over the course of study.

The HUI3 is a brief questionnaire that asks subjects about their health status.

The HUI3 is a brief questionnaire that asks subjects about their health status.

This is composed of 14 items that ask questions about subject's ability to perform different locomotor activities with their prosthesis on. Items are scored on a 5-level ordinal scale from 0 (not able) to 4 (able to accomplish the activity alone without ambulation aids). The total score ranges from 0 to 56, with higher scores indicating greater locomotor capabilities with the prosthesis and less dependence on assistance.

This is composed of 14 items that ask questions about subject's ability to perform different locomotor activities with their prosthesis on. Items are scored on a 5-level ordinal scale from 0 (not able) to 4 (able to accomplish the activity alone without ambulation aids). The total score ranges from 0 to 56, with higher scores indicating greater locomotor capabilities with the prosthesis and less dependence on assistance.

Subjects walk flat 20 feet (six metres) on a flat course, turn around, and walk 20 feet back to the start while reciting the letters of the alphabet (a, b, c, ...) aloud. They repeat this routine while reciting alternate letters of the alphabet (a, c, e, …) aloud. Subjects will be asked to pay attention to both walking and talking. The difference in time (to the nearest second) to complete the simple and complex walks is calculated with higher differences suggesting poorer ability to cope with dual tasks (e.g., greater need to focus on walking).

Subjects walk flat 20 feet (six metres) on a flat course, turn around, and walk 20 feet back to the start while reciting the letters of the alphabet (a, b, c, ...) aloud. They repeat this routine while reciting alternate letters of the alphabet (a, c, e, …) aloud. Subjects will be asked to pay attention to both walking and talking. The difference in time (to the nearest second) to complete the simple and complex walks is calculated with higher differences suggesting poorer ability to cope with dual tasks (e.g., greater need to focus on walking).

We will be conducting optional qualitative interviews with participants from the Vancouver site. The purpose of the qualitative interviews is to learn more about their personal experiences using either the brain or physical activity video game-based training programs.