See this excellent video from Dr. Jordon Feigenbaum's (Barbell Medicine) recent presentation on low back pain injury and preparing for the ACFT:
https://www.youtube.com/watch?v=l9poXGU11ms
The short answer to the question of how best to prepare for the trap bar portion would be to do the same movements over a linear progression (increasing weight over time), with the same/similar equipment to prepare for the test. I realize that may not be possible in your situation. If it were me and I had to prepare without a trap bar I would low-bar squat and deadlift using the same form taught in the Starting Strength method. The main thing you want would want to learn is how to properly set your low back. Lots of videos on that. The cues a coach would use is "chest up" and "drop your belly between your thighs". You also want to make sure you're looking out about 4 to 6 feet in front of you.
Good luck on your test!
Bookmarks