Figure 5. Synopsis of changes occurring in the f–I relationships of fast and slow motoneurones as a result of HU.

Slopes were not different between fast (continuous lines) and slow (dashed/dotted lines) motoneurones, and HU had no effect on slope. HU resulted in a shift of f–I relationship to the right (increased minimum current necessary for rhythmic firing), with the relationship for slow motoneurones also shifted upwards (higher minimum and maximum frequencies).