Do "iso hold" dropsets
 

Hold a weight in the contracted position (usually the top of the lift) and have a partner take off plates or reduce the load. It forces your muscles to keep working through the weight change. Unlike with regular dropsets in which the lifter will usually get a few seconds to recover, you get no rest doing this. This technique works well for machine exercises like Hammer Strength or Smith machine chest or shoulder presses. It's also great for barbell curls.

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