Muscle perfusion of posterior trunk and lower-limb muscles at rest and during upper-limb exercise in spinal cord-injured and able-bodied individuals.

STUDY

DESIGN

Nonrandomized-controlled trial.

OBJECTIVES

To assess muscle perfusion at rest and during arm-cranking exercise (ACE) in upper and lower posterior trunk and vastus lateralis (VL) muscles in individuals with spinal cord injury (SCI) and controls (C).

SETTING

Exercise Physiology-Biochemistry Laboratory.

METHODS

Eight SCI with thoracic lesion and eight C received injections of radioactive tracer to trapezius (TRAP), latissimus dorsi (LAT) and VL. Radioactive counts were recorded with a γ-camera for 10 min at rest and during ACE (60% VO(2max) for 20 min). Time-count curves were generated and the isotope clearance rate, expressed as half-life time (T(1/2),min), was calculated to assess muscle perfusion.

RESULTS

Resting T(1/2) was lower in TRAP and LAT vs VL (P<0.05) in SCI, however, there were no differences among muscles in C. Arm-cranking increased (P<0.001) the isotope clearance in TRAP and LAT in SCI and C, whereas no effect was found on T(1/2) in VL in both groups. T(1/2) was longer (P<0.05) in SCI vs C in VL at rest and during ACE, whereas there were no differences between groups in posterior trunk muscles.

CONCLUSIONS

Resting muscle perfusion was reduced in the paralyzed limbs of SCI compared with C, whereas there was no evidence of impaired microcirculation in upper and lower back muscles in SCI. Although ACE did not induce a hyperemic response in VL, it increased hyperemia in upper and lower posterior trunk muscles in SCI, suggesting beneficial effects of this type of activity on muscle microvasculature in this region.