This research publication formed part of the PhD thesis of H.L. Gerrits who was directed by a team of colleagues from the Vrije Universiteit of Amsterdam headed by Professor Anthony J Sargeant and Professor Maria Hopman from the Radboud University Nijmegen. The paper shows that (the typically) low muscle temperatures in the limbs of people with spinal cord injury will change the the contractile properties of the muscles when functional electrical stimulation is applied or the muscle properties are assessed in the laboratory.
Influence of muscle temperature on the contractile properties of the quadriceps muscle in humans with spinal cord injury
Clin Sci (Lond). 2000 Jan;98(1):31-8
Low muscle temperature in paralysed muscles of individuals with spinal cord injury may affect the contractile properties of these muscles. The present study was therefore undertaken to assess the effects of increased muscle temperature on the isometric contractile properties of electrically stimulated paralysed quadriceps muscles. When muscle temperature at a depth of 3 cm was increased from approximately 32 degrees C to approximately 36 degrees C by ultra-short-wave application, the half-relaxation time shortened and low-frequency force responses became less fused, but the maximal rate of increase in force remained unchanged. Heating had no effect upon either force decline or slowing of relaxation during fatiguing contractions. The force-frequency relationship of the paralysed quadriceps muscle was shifted to the right after the muscle was heated. Despite this shift, however, the relationship still resembled that in muscles of non-paralysed individuals, probably due to the unexplained high twitch forces. These results indicate that reduced muscle temperature in spinal-cord-injured individuals may lead to an underestimation of the changes in contractile properties in terms of relaxation rate or the degree of fusion with low-frequency stimulation. In addition, the force-frequency relationship of paralysed muscles does not accurately reflect the magnitude of these changes, even when the muscle is heated, and should therefore be treated with caution.