Quadriceps muscle deoxygenation during functional electrical stimulation in adults with spinal cord injury.
METHODS
Cross-sectional study comparing healthy subjects with age and gender matched subjects with spinal cord injury (SCI, injury levels from C5 to T12).


OBJECTIVE
To compare the acute cardiorespiratory responses and muscle oxygenation trends during functional electrical stimulation (FES) cycle exercise and recovery in the SCI and healthy subjects exercising on a mechanical cycle ergometer.


METHODS
Seven volunteers in each group participated in one exercise test at the Rick Hansen Center, University of Alberta, Edmonton, Canada.


METHODS
Both groups completed a stagewise incremental test to voluntary fatigue followed by 2 min each of active and passive recovery. Cardiorespiratory responses were continuously monitored using an automated metabolic cart and a wireless heart rate monitor. Tissue absorbency, an index of muscle oxygenation, was monitored non-invasively from the vastus lateralis using near infrared spectroscopy.


RESULTS
The healthy subjects showed significant (P<0.05) increases in the oxygen uptake (VO2), heart rate (HR) and ventilation rate (VE) from rest to maximal exercise. The SCI subjects showed a twofold increase in VO2 (P>0.05), a threefold increase in VE (P<0.05) and a 5 beats/min increase in HR (P>0.05) from the resting value. The SCI subjects demonstrated a lesser degree (P<0.05) of muscle deoxygenation than the healthy subjects during the transition from rest to exercise. Regression analysis indicated that the rate of decline in muscle deoxygenation with respect to the VO2 was significantly (P<0.05) faster in the SCI subjects compared to healthy subjects.


CONCLUSIONS
FES exercise in SCI subjects elicits: (a) modest increases in the cardiorespiratory responses when compared to resting levels; (b) lower degree of muscle deoxygenation during maximal exercise, and (c) faster changes in muscle deoxygenation with respect to the VO2 during exercise when compared to healthy subjects.
Bhambhani
Y
Y
Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, Canada, T6G 2G4.
Tuchak
C
C
Burnham
R
R
Jeon
J
J
Maikala
R
R
D000328:Adult; D000368:Aged; D004599:Electric Stimulation Therapy; D005080:Exercise Test; D017079:Exercise Tolerance / Q000502:physiology; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D007866:Leg / Q000294:innervation / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000294:innervation / Q000378:metabolism* / Q000503:physiopathology; D010101:Oxygen Consumption / Q000502:physiology*; D010243:Paralysis / Q000378:metabolism / Q000503:physiopathology / Q000534:rehabilitation; D013119:Spinal Cord Injuries / Q000150:complications / Q000503:physiopathology / Q000534:rehabilitation*