The Timed-Up-and-Go tests muscle function and mobility, predicts safe walking ability, and correlates with other mobility tests (r=0.81 correlation with Berg Balance Scale, r=-0.61 for gait speed). The test begins with the participant sitting in an armchair with his/her back resting on the back of the chair and arms resting on the arms of the chair. The participant is then asked to stand up and walk 3 m at a comfortable and safe speed, turn around, walk back and return to a seated position. The time that it takes to complete this exercise is then recorded. Lower scores indicate faster walking ability.

The Four-Square-Step-Test is a validated measure of multi-directional mobility for MS, with high interrater (ICC=0.99) and retest reliability (ICC=0.98). The test measures a person's ability to step over objects in four directions. We created 4 3-ft boxes on the floor using colored masking tape. Participants are asked to step from the first box forward to the second, then right to square 3, back to square 4, and left to square 1, and then go back in the opposite order (4 to 3 to 2 to 1) while being timed. The participant is allowed practice this sequence before being timed. The test is repeated twice, with the best time taken as the score. Lower scores indicate greater multi-directional mobility.

The Multiple Sclerosis Impact Scale (MSIS-29) is a validated core outcome measure that allows people with multiple sclerosis (MS) to self-assess the impact of MS on their physical and psychological well-being. This scale is commonly used to assess quality of life in studies of exercise and MS. The MSIS-29 was developed in 2000 as a patient-administered survey for MS, and includes 20 questions on physical impacts and 9 questions on psychological impacts of MS.55 The MSIS scales have good variability, small floor-to-ceiling effects, high internal consistency (Cronbach's alpha < 0.91), and high test-retest reliability (intraclass correlation > 0.87). Scores are adjusted to a 0 (min) to100 (max) scale. Higher scores indicate a worsening or more severe impact of MS on a person's physical and/or psychological condition.

The MS Walking Scale is a 12-question self-reported measure of impact of MS on walking ability. The test has good test-retest reliability (intraclass correlation > 0.78), and high internal consistency, criterion validity, and reliability (> 0.94). We included this measure to complement the physical tests on balance and gait. Scores are adjusted to a 0-100 scale. Higher scores indicate a greater impact of MS on walking ability (i.e., more difficulty walking).

The Modified Fatigue Impact Scale (MFIS) has been recommended by the ICM as a measure of energy and drive. The measure assesses physical, cognitive and psychosocial aspects of fatigue, and has a high internal consistency (Cronbach's alpha of 0.80). The 5-item version takes 2 minutes to complete, has an adequate test-retest reliability (r=0.76), and has been shown to capture meaningful changes in fatigue. Scores range from 0-20. Higher scores indicate higher levels of fatigue.

Patient Reported Outcomes Measurement Information System (PROMIS) are patient reported outcome surveys developed by the National Institutes for Health. The minimum raw score is 4, and maximum is 20. Raw scores are converted to standardized T-scores relative to a population mean of 50 and SD of 10 (T-scores range from 16.2 (minimum) to 67.7 (maximum) for physical measures, and 21.2-67.6 for mental). Higher T-scores represent higher levels of global health. Scores are calibrated against the general population.

Patient Reported Outcomes Measurement Information System (PROMIS) are patient reported outcome surveys developed by the National Institutes for Health. This test is a computer adaptive test. Scores are represented as standardized T-scores relative to a population mean of 50 and SD of 10, with a minimum of 15.4 and maximum of 73.3. Higher T-scores represent higher levels of physical function. Scores are calibrated against the general population.

Patient Reported Outcomes Measurement Information System (PROMIS) are patient reported outcome surveys developed by the National Institutes for Health. This test is a computer adaptive test. Scores are represented as standardized T-scores relative to a population mean of 50 and SD of 10, with a minimum of 34.4 and maximum of 84.7. Higher T-scores represent higher levels of fatigue. Scores are calibrated against the general population.

Patient Reported Outcomes Measurement Information System (PROMIS) are patient reported outcome surveys developed by the National Institutes for Health. This test is a computer adaptive test. Raw scores are converted to standardized T-scores relative to a population mean of 50 and SD of 10 (minimum T-score is 32.9, maximum is 84.9). Higher T-scores represent higher levels of anxiety. Scores are calibrated against the general population.

Patient Reported Outcomes Measurement Information System (PROMIS) are patient reported outcome surveys developed by the National Institutes for Health. This test is a computer adaptive test. Scores are represented as standardized T-scores relative to a population mean of 50 and SD of 10 (minimum T-score is 34.2, maximum is 84.4). Higher T-scores represent higher levels of depression. Scores are calibrated against the general population.