Shawnna Patterson

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Poster #21

Category: Post-Doctoral Social Science/Clinical/Behavioral

IMPORTANCE OF CARDIOVASCULAR FITNESS, STRENGTH, BALANCE AND BODY COMPOSITION TO AMBULATORY FUNCTION IN HEMIPARETIC STROKE

Patterson SL, Forrester LW, Rodgers MM, Ryan AS, Ivey FM, Sorkin JD, Macko RF

Departments of Neurology and Medicine, Veteran's Administration Maryland Healthcare System; Departments of Neurology, Medicine and Physical Therapy & Rehabilitation Science, University of Maryland School of Medicine, Baltimore, Maryland

Background: Stroke impairs ambulatory function, both at home and in the community, as refelcted by reduced performance on short distance (e.g. 30') and longer distance (6-minute) timed walk capacity. Age, gender, fitness, strength and balance predict 6-minute walk distance in healthy elderly; however, little is known regarding determinants of ambulatory function after stroke, and that these relationships differ between those with milder versus more severe gait deficits.

Methods: We evaluated mobility function in 70 (41 men and 29 women, 64 + 10 years old) individuals with chronic hemiparetic stroke using 30' walks, six-minute walks, and Berg Balance Scores. Cardiovascular fitness levels (VO₂peak) were measured by open circuit spirometry during treadmill testing. Bilateral composite quadriceps concentric strength scores were calculated from isokinetic dynamometry, and body composition including total and regional lean mass and percent fat were measured by dual x-ray absorptiometry. Regression analysis was used to examine relationships between fitness, strength, balance, body composition, walking function, with median split analysis to compare subjects with milder versus more severe deficits.

Results: Six-minute walk distance was strongly related to VO₂peak (r=0.71, p=0.0001), balance (r=0.68, p=0.0001), and paretic leg strength (r=0.61, p=0.0001), and less so with percent body fat (r=-0.28, p=0.03). Stepwise regression revealed that variance in 6-minute walk was largely explained by balance for those with more severe gait impairment (r²=0.32), and by cardiovascular fitness for those with milder gait impairment (r²=0.51).

Conclusions: Gait speed after stroke cannot be predicted by standard reference equations, but rather is related most rebustly to measures of balance, fitness and paretic leg strength. Determinants of ambulatory function may differ by gait deficit severity, with balance more important in those with more severe gait deficits, and cardiovascular fitness playing a greater role in those with milder deficits. Improved understanding of the factors that predict ambulatory function may assist the design of individualized rehabilitation strategies across the spectrum of gait deficit severity in those with hemiparetic stroke.