This paper describes high-frequency nerve block experiments carried out on rat sciatic nerves to measure the speed of recovery
of A fibres from block carryover. Block carryover is the process by which nerve excitability remains suppressed temporarily after
High Frequency Alternative (HFAC) block is turned off following its application. In this series of experiments 5 rat sciatic nerves
were extracted and prepared for ex-vivo stimulation and recording in a specially designed perfusion chamber. For each nerve
repeated HFAC block and concurrent stimulation trials were carried out to observe block carryover after signal shutoff. The nerve
was allowed to recover fully between each trial. Time to recovery from block was measured by monitoring for when relative
nerve activity returned to within 90% of baseline levels measured at the start of each trial. HFAC block carryover duration was
found to be dependent on accumulated dose by statistical test for two different HFAC durations. The carryover property of HFAC
block on A fibres could enable selective stimulation of autonomic nerve fibres such as C fibres for the duration of carryover. Block
carryover is particularly relevant to potential chronic clinical applications of block as it reduces power requirements for
stimulation to provide the blocking effect. This work characterises this process towards the creation of a model describing its
behaviour.