Mixed

Using external momentum (cheat repetitions) during single-joint upper body resistance training produces muscle hypertrophy equivalent to strict form, despite significantly higher total volume load.

If you are doing single-joint exercises like bicep curls or tricep pushdowns, using controlled momentum (cheat reps) to get more reps or heavier loads will likely build muscle just as well as strict form. You don't need to fear cheat reps for hypertrophy purposes, but be aware that the extra stress goes to other muscles (like shoulders or back) and may increase injury risk over time. Use them strategically to increase volume, but prioritize strict form for joint health if you are prone to injury.