Back, Biceps and HIIT Skipping/Sprinting

Wide Grip Negative Pull up practice

BB Pendlay Row / band side walk or monster walk
45x15- warm up
55x10
60x 10
65x8
70 x 6
70 x 6

DB One Arm Row
2x20lbsx15@each- practice moves
4x25lbsx10@each/ band standing hip abdct 3x20@each

Question: A guy told me that I shouldn't arch my back when doing One Arm DB Row- esp since I am not wearing any lifting belt - need to keep my back in neutral or kinda more hunch??? Thoughts? I usually keep my back arch just like how I do Deadlift.

Wide Lat Pulldown
45lbsx8
3x45lbsx6/ knee hugs 3x20

Seated Cable Row/ side crunch
27.5lbs x 10 - hard last 2 reps
3x27.5lbs x 8- hard last 2 reps / 3x15@each

Close Grip Pull up practice

DB Biceps Curls
10lbs x 10
3x10lbs x 8- right arm almost fail at last rep

DB Hammer Curl
3x10lbs x8 - arms were fatigue twds last rep- didn't get full ROM

20 min HIIT high knees skips/sprinting (1 min hard/ 30 sec easy -14 rounds)