Article

Ventilation-to-carbon dioxide ratio is comparable with peak oxygen
uptake in the prognosis of cardiovascular disorders. Currently, there are no
established indices to determine the submaximal effects of functional electrical
stimulation on cardiovascular performance in persons with spinal cord injury.
OBJECTIVE: To determine the effects of an acute bout of functional electrical
stimulation-lower extremity cycling on ventilation, carbon dioxide production,
ventilation-to-carbon dioxide ratio, and substrate utilization in people with
motor complete spinal cord injury. DESIGN: Observational cross-sectional design.
SETTING: Clinical laboratory setting. PARTICIPANTS: Ten individuals with motor
complete spinal cord injury. METHODS: Participants were allowed to cycle until
fatigue. The effects of functional electrical stimulation on ventilation, carbon
dioxide production, ventilation-to-carbon dioxide ratio, and substrate
utilization were measured with a portable metabolic cart (COSMED K4b2). Body
composition was determined with bioelectrical impedance. RESULTS: Resting and
warm-up ventilation were 8.15 +/- 3.5 L/min and 8.15 +/- 2.8 L/min, respectively.
Functional electrical stimulation increased ventilation significantly (14.5 +/-
6.4 L/min), which remained significantly elevated (13.3 +/- 4.3 L/min) during the
recovery period. During resting and warm-up phases, the ventilation-to-carbon
dioxide ratios were 41 +/- 4.8 and 38 +/- 5.4, respectively. Functional
electrical stimulation decreased the ventilation-to-carbon dioxide ratio
significantly to 31.5 +/- 4, which remained significantly reduced during the
recovery period (34.4 +/- 3). Functional electrical stimulation relied primarily
on carbohydrate utilization (188 +/- 160 g/day to 574 +/- 324 g/day; P = .001)
with no changes in fat utilization (77.5 +/- 28 g/day to 93.5 +/- 133.6 g/day; P
= .7) from resting to exercise periods. Significant relationships were noted
between carbohydrate utilization during functional electrical stimulation and
carbon dioxide (r = 0.98; P = .00010) production. The percentage whole body
fat-free mass was negatively related to the exercise ventilation-to-carbon ratio
(r = -0.66; P = .045). CONCLUSIONS: An acute bout of functional electrical
stimulation resulted in a significant drop in the ventilation-to-carbon ratio,
accompanied with a reliance on carbohydrate utilization and a diminished capacity
to utilize fat as a substrate. Fat-free mass may be associated with a decrease in
ventilation to carbon dioxide ratio and an increase in carbohydrate utilization
in persons with spinal cord injury.
CI - Copyright (c) 2016 American Academy of Physical Medicine and Rehabilitation.
Published by Elsevier Inc. All rights reserved.

Langue : ANGLAIS