There is little evidence of much inquisition-inflicted torture outside those directly related to the conditions of imprisonment in 13/14th century.
The papal bull Ad exterpanda restricted torture in its same authorization of it: no breaking bones. It doesn’t say what one should do, but emphasizes imprisonment. The unstated concomitant tortures of prison were variously hunger, disease, cold, close confinement and shackling.
In fact the most famous of inquisitors and author of key inquisition manuals, Bernardo Gui, explicitly states in the early 14th c in his Practica inquisitionis that imprisonment is the most effective method for extracting confession. A review of Gui’s registers the Liber sententiarum, which are fairly detailed, shows imprisonment being highly varied in type (from a style of short house arrest to multi-year). Gui also suggests psychological techniques such as threats against family and friends being discovered as heretics, or threats they will be ‘outed’ by family and friends, all driving to the ‘relief’ of confession, ‘relief’ that the worst punishment for everyone in your social circle has been avoided.
Although we should generally dismiss the view that torture such as the ‘rack’ or ‘flaying’ or other such dramatic ideas for this period of inquisition for lack of evidence, or rather misinterpretation of the use of the word ‘torture’ found in sources, we should see clearly the totality of the consequences of imprisonment mentioned above. The best source on this is James Given’s Inquisition and Medieval Society: Power, Discipline, and Resistance in Languedoc (Cornell, 1997), in particular chapter ‘Inquisitor’s Techniques’.
Below is the letter from the consuls of Carcassonne complaining about the local inquisitor Jean Galand at the end of the 13th century, 50 years on since the establishment of the first real inquisitions at Toulouse. This is wholly taken from Given’s book above, and he suggests there is perhaps some exaggeration in it:
We feel ourselves aggrieved in that you, contrary to the use and custom observed by your predecessors in the inquisition, have made a new prison, called the mur. Truly this could be called with good cause a hell. For in it you have constructed little cells for the purpose of tormenting and torturing people. Some of these cells are dark and airless, so the those lodged there cannot tell if it is day or night, and they are continuously deprived of air and light. In other cells there are kept miserable wretches laden with shackles, some of wood, some of iron. Nor can they lie down except on the frigid ground. They have endured torments like these day and night for a long time. In other miserable places in the prison, not only is there no light or air, but food is rarely distributed, and then only bread and water.
Many prisoners have been put in similar situations, in which several, because of severity of their tortures, have lost limbs and have been completely incapacitated. Many, because of the unbearable conditions and their great suffering, have died a most cruel death. In these prisons there is constantly heard an immense wailing, weeping, groaning, and gnashing of teeth. What more can one say? For these prisoners life is a torment and death a comfort. And thus coerced they say that what is false is true, choosing to die once rather than endure more torture. As a result of these false and coerced confessions not only do those making the confessions perish, but so do the innocent people named by them […]
In this we can see the use of the verb ‘torture’ in its abstracted, descriptive sense. This use has been co-opted into historiographical narrative about medieval inquisition as a capital-t ‘Torture’, divorcing it from context. It has thus been merged with our understanding of medieval secular torture and punishment which did involve various (famous) forms of corporal torture.
At the same time, we can see this as skillful use of the concept of ‘torture-that-isn’t-really-torture’ by ecclesiastics; it allowed claims by popes, legates, inquisitors that it was simply ‘imprisonment’ and that the conditions of imprisonment were the fault of the imprisoned: they inflict it upon themselves. This is a more subtle view, but makes clearer our understanding of the relationship between Christian notions of sin and punishment within an ethic of self-punishment that are distinctly medieval, and which we live with today.