From the Rehabilitation Research and Development Center, VA Palo Alto
Health Care System (Calif).
Correspondence to David A. Brown, PhD, PT, Rehabilitation Research and Development Center (153), VA Palo Alto Health Care System, 3801 Miranda Ave, Palo Alto, CA 94306. E-mail brown{at}roses.stanford.edu
Background and Purpose—A
principle of poststroke rehabilitation is that effort should be avoided
since it leads to increased spasticity and produces widespread
associated abnormal reactions. Although weakness also contributes to
movement dysfunction after a stroke, it has been feared that heightened
activity levels during strength training will further exacerbate the
abnormal tone imbalance present in spastic hemiplegia. The purpose
of this study was to test this hypothesis by quantifying the effects of
increased workload on motor performance during different speeds
of pedaling exercise in persons with poststroke hemiplegia.
Methods—Twelve healthy elderly subjects and 15 subjects
with poststroke hemiplegia of greater than 6 months since onset were
tested. The experimental protocol consisted of having subjects pedal at
12 randomly ordered workload and cadence combinations (45-J, 90-J,
135-J, and 180-J workloads at 25, 40, and 55 rpm). Pedal reaction
forces were measured and used to calculate work done by each leg,
including net positive and negative components. An electromyogram was
recorded from seven leg muscles.
Results—The main finding was that net mechanical work done
by the plegic leg increased as workload increased in 75 of 81 instances
without increasing the percentage of inappropriate muscle activity.
Conclusions—This study provides evidence that persons with
hemiplegia increase force output by their plegic limb when pedaling
against higher workloads without exacerbation of impaired motor
control. Therefore, exertional pedaling exercise is a beneficial
intervention for achieving gains in muscular force output without
worsening motor control impairments.
© 1998 American Heart Association, Inc.
Original Contributions
Increased Workload Enhances Force Output During Pedaling Exercise in Persons With Poststroke Hemiplegia
Key Words: exercise • hemiplegia • motor activity • muscle spasticity
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