Six-Minute Walk as a Measure of Walking Capacity and Endurance in Patients With Pediatric-Onset Multiple Sclerosis

Abstract

BACKGROUND:Despite low levels of disability, youth with pediatric-onset MS (POMS) engage in less physical activity compared to peers. The contribution of walking capacity, endurance, behavior, and MS co-morbidities remain relatively undefined and may provide valuable insights into the limitations toward physical activity in youth with MS.OBJECTIVE:Investigate differences in walking capacity, endurance and real-world behaviors of daily activity between youth with POMS and controls. DESIGN/METHODS: Youth diagnosed with MS prior to 18 years and aged ≤21 years were recruited in addition to healthy controls. Subjects completed questionnaires to quantify fatigue, depression, and physical activity levels and the timed 2- and 6-minute walk (2MW, 6MW) as an assessment of walk capacity and endurance. Subjects were sent home with a waist-worn accelerometer to assess real-world walking behavior.RESULTS:Forty-five POMS and 85 control subjects were enrolled. The POMS cohort had a mean age of 16.9±2.7 years with a mean disease duration of 2.8±2.6 years. A greater proportion of the POMS cohort was overweight/obese compared to controls (60% versus 33%). Subjects with MS walked a significantly shorter distance in 6 minutes compared to controls (1848 feet vs 2134 feet, p<0.0001) and, unlike controls, were unable to accelerate to their peak speed at the end of the 6MW. BMI category and MS disease significantly impacted 6MW performance. Using continuous accelerometry, subjects with MS spent less time in moderate-to-vigorous physical activity compared to controls (20.4 minutes/day vs 35.4 minutes/day, p=0.0003). The POMS cohort reported significantly higher levels of depression and fatigue, but self-reported similar levels of daily physical activity as controls.CONCLUSIONS:Youth with POMS exhibit slower 6MW performance and less daily engagement in moderate-to-vigorous physical activity, suggesting limitations in functional walking capacity, endurance, and daily activity behavior. Limitations in walking endurance and capacity are most prominent in those youth who are overweight/obese and living with MS.CLASSIFICATION OF EVIDENCE:This study provides Class III evidence that, compared to healthy controls, patients with pediatric-onset MS walk shorter distances on the 6 minute walk test, are less able to accelerate to peak speed at the end of the test, and are less physically active.