I've been using 5lb dumbbells on the YTWLs, though I don't have an incline bench so I'm leaning on a Swiss ball, and it might be affecting my range of motion in ways that let me lift more. (For reference, your lifts on pretty much everything else are better than mine are, and I'm doing the four reps for stage five rather than the six reps for stage three, so I can't be stronger than you are overall. Though I did better on the body-weight matrix, so possibly my endurance is better?)
For planks -- I guess I started out doing them for a minute with little problem because my mother had started doing yoga and showed me planks and I could suffer for a minute right away, so after doing them for a minute at the ends of workouts for several weeks I could suffer through 90 seconds. So I guess I didn't take four workouts to get there -- I just got better at them doing stage one and two. When I looked ahead and went 'ha ha no two minutes' I took my 90 seconds and added five. Then I tried adding ten. Fifteen seconds feels like a big jump, but five feels more manageable. Even adding a second or two would work -- if you hold the plank for a second longer every set and do three sets each workout, then by the end of the four workouts you've added twelve seconds, which is three seconds short of fifteen, so you just need to tough it out for three more seconds to finish out the jump from 60 to 90 or from 90 to 120.
For hip extensions I started doing hip thrusts -- I've been doing them with my feet raised, and using a dumbbell rather than a barbell. I've been thinking that I should be doing them with a barbell since recently I had to push with my arms to keep the dumbbell from rolling off my hips, and this probably affects how much weight I'm lifting with my hips.
no subject
For planks -- I guess I started out doing them for a minute with little problem because my mother had started doing yoga and showed me planks and I could suffer for a minute right away, so after doing them for a minute at the ends of workouts for several weeks I could suffer through 90 seconds. So I guess I didn't take four workouts to get there -- I just got better at them doing stage one and two. When I looked ahead and went 'ha ha no two minutes' I took my 90 seconds and added five. Then I tried adding ten. Fifteen seconds feels like a big jump, but five feels more manageable. Even adding a second or two would work -- if you hold the plank for a second longer every set and do three sets each workout, then by the end of the four workouts you've added twelve seconds, which is three seconds short of fifteen, so you just need to tough it out for three more seconds to finish out the jump from 60 to 90 or from 90 to 120.
For hip extensions I started doing hip thrusts -- I've been doing them with my feet raised, and using a dumbbell rather than a barbell. I've been thinking that I should be doing them with a barbell since recently I had to push with my arms to keep the dumbbell from rolling off my hips, and this probably affects how much weight I'm lifting with my hips.