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Allen D.1, Gee J.1, Harrell A.1, Conley N.1, Whiteford S.1, Widener G.2
1University of California San Francisco/ San Francisco State University, Graduate Program in Physical Therapy, San Francisco, United States, 2Samuel Merritt University, Physical Therapy, Oakland, United States
Background: For people with multiple sclerosis (MS) and limitations of gait and balance, customized placement of light weights using balance-based torso-weighting has improved motor ability in single-session assessment with weights on, indicating a potential orthotic effect.
Purpose: The purpose of this pilot study was to examine the effects of wearing torso-weights over a multi-week period. We hypothesized that people would show decreased postural sway with the weights on, and greater improvement in gait and balance after wearing light weights compared to a no-weight period or a period wearing sham weights. We examined the orthotic effect of this intervention via center of pressure measures with weights off and on; we examined a possible therapeutic effect by gait and balance performance with weights off.
Methods: Center of pressure, balance, and gait were assessed at baseline and after 2-4 week periods during which participants had no weights, or wore actual weights or sham weights for 2-4 hours each day. Five ambulatory participants with MS experienced all three conditions. The order of the torso weight and sham weight conditions was randomized. Participants and assessors were blinded to active or sham condition. Measures included standing for 30 seconds each with eyes open and closed on a force plate (sampling at 25 Hz), gait on an instrumented gait mat, the 6-Minute Walk Test, and the Sensory Organization Test. Torso-weighting involved applying weights (totaling 0.25-2 pounds) to a vest-like garment to improve reactive control following manual perturbations and resisted rotations at the shoulders and pelvis. Changes in performance after each of the three time periods were compared using repeated measures ANOVA; f effect size was considered large if over 0.4. Participants completed a daily activity log to record falls experienced throughout the study periods.
Results: Center of pressure measures confirmed that average postural sway showed a statistically significant decrease with weights on compared to weights off with eyes open and eyes closed after the three time periods. After the multi-week period wearing torso weights, average increases were 7.4 composite score points or 14% for the Sensory Organization Test, 47.4 meters walked or 16.6% for the 6-minute Walk Test, and 12.5 cm/sec or 15% for gait velocity. Average performance for each variable decreased or showed negligible improvement after periods of no weight (13.4% decrease to 3.5% increase) or sham weight (5.8% decrease to 1.8% increase). The effect sizes were large (f = 0.7 to 0.9). Participants reported no falls on daily activity logs during the weighted condition, while falls occurred in both no-weight and sham periods.
Conclusion(s): Regular use of strategic torso-weighting versus no weights or sham weights can improve motor performance with weights on and when assessing performance without weights.
Implications: Strategic torso-weighting does not just act as an orthotic device, supporting function when donned. Improvement noted with weights doffed implies that motor learning may occur during a period of regular use of weights. Further research is warranted. The large effect size indicates that this study would have 0.80 power with a sample of 8 people.
Funding acknowledgements: This study was partially funded by a small grant to DDA from San Francisco State University (ST649).
Topic: Neurology: multiple sclerosis
Ethics approval: The study was approved by the Institutional Review Boards of Samuel Merritt University and San Francisco State University.
All authors, affiliations and abstracts have been published as submitted.
