Trunk Isometric Endurance Testing Affects Postural Control in Persons with Multiple Sclerosis and Healthy Individuals.

Research Report
Population: Adult

Jane Freund, PT, DPT, MS, NCS, Associate Professor, Elon University

Deborah Stetts, PT, DPT, OCS FAAOMPT, Associate Professor, Elon University

John Magill, PT, DPT, Staff Physical Therapist, Duke Raleigh Hospital

Srikant Vallabhajosula, PhD, Assistant Professor, Elon University

Keywords: Prediction, Trunk Endurance, Postural Control

Purpose/Hypothesis: Persons with multiple sclerosis commonly have impaired balance with subsequent decreased mobility and increased falls risk. Trunk muscles provide stabilization for posture and mobility and when fatigued impair postural control in healthy persons. It is unknown how trunk isometric endurance testing affects postural control in persons with multiple sclerosis. The purpose of this study was to determine the effects of a trunk isometric endurance protocol on postural control in persons with multiple sclerosis compared to healthy individuals.

Subjects: 15 ambulatory persons with multiple sclerosis (mean Patient Administered Expanded Disability Status Scale of 4.13 ± 3.53) and age and gender-matched healthy controls [mean age ± SD (years), persons with multiple sclerosis 51.13 ± 14.82, Controls 51.06 ± 13.46; 13 females].

Materials/Methods: Subjects performed timed trunk flexion and extension isometric endurance tests. Their postural control was assessed using center of pressure data that was collected during a 1-minute quiet standing trial on a Biodex Balance System both before and after trunk endurance testing. Range and mean velocity in the medio-lateral and antero-posterior directions along with sway area were analyzed for each trial. Time (Pre, Post) X Group (persons with multiple sclerosis, Controls) mixed ANOVA was performed to estimate the effects on postural sway due to trunk endurance testing. Trunk flexion and extension endurance times were compared between both the groups using an independent samples T-test.

Results: Significant group main effect showed that persons with multiple sclerosis had greater medio-lateral range (58%) and velocity (39%), antero-posterior range (32%) and velocity (42%), and sway area (103%; all P < 0.05). Significant time main effect showed that on an average both groups increased their range in medio-lateral (31%) and antero-posterior (19%) directions (both P < 0.05). No significant time x group interactions were found. Also, persons with multiple sclerosis could perform trunk endurance tests for a significantly lesser time (flexion: 241±62s, extension: 124±65s) compared to healthy individuals (flexion: 500±45s, extension: 181±79s; both P < 0.05).

Conclusions: Persons with multiple sclerosis had lesser trunk isometric endurance and greater postural sway than healthy individuals. However, trunk endurance testing had similar effects on postural control in persons with multiple sclerosis and healthy individuals. Continued research is needed to investigate the relationship between trunk muscle performance, postural control and functional mobility in persons with multiple sclerosis.

Clinical Relevance: Due to decreased trunk isometric endurance and related impairments in  postural control, trunk flexion and extension endurance testing and training should be considered in persons with multiple sclerosis.

Freund, Jane , PT, DPT, MS, NCS; Stetts, Deborah , PT, DPT, OCS FAAOMPT; Magill, John , PT, DPT; Vallabhajosula, Srikant , PhD. Trunk Isometric Endurance Testing Affects Postural Control in Persons with Multiple Sclerosis and Healthy Individuals.. Poster Presentation. IV STEP Conference, American Physical Therapy Association, Columbus, OH, July 17, 2016. Online.