Continue training from the checkpoint saved via export

Is there any correct way of how I could load the saved Gluon model from the checkpoint via SymbolBlock.imports and continue training? Specifically, it is about the fine-tined SSD model, but I suppose it relates to the general case. In all your tutorials I can see the .save_parameters and .load_parameters for further training.

So what about .export and SymbolBlock.imports?