Supersets should be strategic. There should be a reason behind the combined movements. The bigger and more compound the movements are, the more room for error in the way they synergize together. One of the problems with many supersets is the compression that the spinal column is forced into on two paired movements with minimal rest. This adds double the compression to the spine and places it under challenging loads for extended periods of time, essentially putting you at risk for an injury.
If you’re supersetting a movement that compresses the spine, like a barbell back squat, the paired movement should allow spinal decompression, like a pull-up. Matching these two types of movements together will do a world of good for your spinal health.
Place the compressive movement before your decompression-based movement. For back emphasis training days, a great superset is a deadlift variation with a vertical pull.
Rack Pull / Chin-Up Superset
The rack pull is considered a spinal compressive movement and the chin-up a decompression movement. If you go heavy and create as much tension as possible through your lats and back on the dead, the pull-ups should really become challenging quickly.