Submitted on June 4, 2003
Accepted on September 15, 2003
Increasing Blood Flow Prior to Exercise in Spinal Cord Injured Individuals Does Not Alter Muscle Fatigue
Jennifer L Olive1*, Jill M Slade2, C. Scott Bickel2, Gary A Dudley3, and Kevin K McCully2
1 Department of Radiology, University of Washington Medical Center, Seattle, WA, USA
2 Department of Exercise Science, University of Georgia, Athens, GA, USA
3 Department of Exercise Science, University of Georgia, Athens, GA, USA; Shepherd Center, Atlanta, GA, USA
* To whom correspondence should be addressed. E-mail: jolive{at}u.washington.edu.
Previous studies have shown increased fatigue in paralyzed muscle of spinal cord injured (SCI) patients. Our purpose was to determine if the increased muscle fatigue could be due to a delayed rise in blood flow at the onset of exercise in SCI individuals. Isometric electrical stimulation was used to induce fatigue in the quadriceps femoris muscle of seven male, chronic (> 1 year post injury), complete (ASIA A) SCI subjects. Cuff occlusion was used to elevate blood flow prior to electrical stimulation and the magnitude of fatigue was compared to a control condition of electrical stimulation without prior cuff occlusion. Blood flow was measured in the femoral artery by Doppler ultrasound. Prior cuff occlusion increased blood flow in the first 30 seconds of stimulation compared to the No Cuff condition (1,350 ml/min vs. 680 ml/min, respectively; p < 0.001) although blood flow at the end of stimulation was the same between conditions (1260 ± 140 ml/min vs. 1160 ± 370 ml/min, Cuff and No Cuff condition, respectively; p = 0.511). Muscle fatigue was not significantly different between prior cuff occlusion and the control condition (32 ± 13% versus 35 ± 10%, p = 0.670). In conclusion, increased muscle fatigue in SCI individuals is not associated with a delayed rise in blood flow at the onset of exercise.
