The key to any strong athlete, whether it is rowing or , is a solid core. Train the core using “flexion moments” not “flexion movements”. To differentiate the two, make a fist and squeeze really hard. That is a flexion moment. Notice that the wrist does not go through a range of motion, but the forearm muscles are still working. Now flex your wrist back and forth. That is a flexion movement.
The core is better trained through movements that stimulate flexion moments, not flexion movements. Here’s Joe with some nasty barbell roll outs during yesterday’s training session. Three sets of 8-10 reps.