Physiologic responses to electrically assisted and frame-supported standing in persons with paraplegia.
BACKGROUND
Systems of functional electrical stimulation (FES) have been demonstrated to enable some persons with paraplegia to stand and ambulate limited distances. However, the energy costs and acute physiologic responses associated with FES standing activities have not been well investigated.


OBJECTIVE
To compare the physiologic responses of persons with paraplegia to active FES-assisted standing (AS) and frame-supported passive standing (PS).


METHODS
Fifteen persons with paraplegia (T6-T11) previously habituated to FES ambulation, completed physiologic testing of PS and AS. The AS assessments were performed using a commercial FES system (Parastep-1; Altimed, Fresno, Calif); the PS tests used a commercial standing frame (Easy Stand 5000; Altimed, Fresno, Calif). Participants also performed a peak arm-cranking exercise (ACE) test using a progressive graded protocol in 3-minute stages and 10-watt power output increments to exhaustion. During all assessments, metabolic activity and heart rate (HR) were measured via open-circuit spirometry and 12-lead electrocardiography, respectively. Absolute physiologic responses to PS and AS were averaged over 1-minute periods at 5-minute intervals (5, 10, 15, 20, 25, and 30 minutes) and adjusted relative to peak values displayed during ACE to determine percentage of peak (%pk) values. Absolute and relative responses were compared between test conditions (AS and PS) and across time using two-way analysis of variance.


RESULTS
The AS produced significantly greater values of VO2 (43%pk) than did PS (20%pk). The mean HR responses to PS (100-102 beats per minute [bpm] throughout) were significantly lower than during AS, which ranged from 108 bpm at 5 minutes to 132 bpm at test termination.


CONCLUSIONS
Standing with FES requires significantly more energy than does AS and may provide a cardiorespiratory stress sufficient to meet minimal requirements for exercise conditioning.
Jacobs
Patrick L
PL
Department of Neurologic Surgery, University of Miami School of Medicine, Miami, Florida 33136, USA. pjacobs@miamiproject.med.miami.edu
Johnson
Brad
B
Mahoney
Edward T
ET
D000328:Adult; D004734:Energy Metabolism / Q000502:physiology*; D004867:Equipment Design; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood*; D010264:Paraplegia / Q000503:physiopathology / Q000534:rehabilitation*; D011187:Posture / Q000502:physiology*; D013119:Spinal Cord Injuries / Q000503:physiopathology / Q000534:rehabilitation*; D004561:Transcutaneous Electric Nerve Stimulation / Q000295:instrumentation*; D014853:Walkers; D016138:Walking / Q000502:physiology*
D010100:Oxygen