Thank you for your reply.

1) I probably was using poor form in a way: I was doing power work, sets of 12 with heavy weights, done very fast. I don't do any power work anymore. It seems to me that the very short period of high acceleration when one reverses direction could overstress connective tissue, and did once for me. Deadlifts from the floor or rack, or similar lifts, would be excepted.

2) Friel calls it the Anatomic Adaptation (AA) phase, 2-3 circuits of 20-30 reps. "Its purpose is to prepare the muscles and tendons for the greater loads of the next phase." Friel goes right into Maximum Strength (MS) after AA, but I interpose the trad phase of hypertrophy, 3 X 12, to more gradually bring the weights up. After MS and Power Endurance, Friel puts in a final phase of Muscular Endurance (ME) of 40-60 reps. I tried that, but found I got more out of moving back to 30 reps, but at much higher weights than during the AA phase, just because I could do more following the intense middle phases. OTOH I'm just a wussy. Penseyres was able to do 50 reps at 450 on the sled.

3) I do move right along. When I started doing these, long ago, I'd almost pass out toward the end of the first circuit.

4) I've never done Tabata like that or heard of it. I've always done 20" X 10" X 12, one set. Same power for each "on" period, set by experience to almost barf after #12 . I hate barfing on the rollers.

5) I think I get plenty of spinal loading squatting with less than bodyweight. Heck, they say walking or running is enough. It's true, the sled does load the spine, as do planks and pretty much all ab work. I use the sled to isolate my legs and do maximum strength work without the potential of damaging myself over the decades of lifting. That said, I'm still 2" shorter than I was at 20.

I'm was unfamiliar with the term "Russian deadlifts." I looked it up and there seems to be two variations: one variation looks exactly how I've always done them, the other like the SLDLs I do, but with a 5° knee bend. Not sure why the 5°.

I have also found weight work to be of benefit, which is why I've continued with it. As many racers have pointed out on these forums, a typical pedal load is seldom more than 50 lbs. and usually much, much less than that. Thus, as that study found, one gets a much bigger bang for the training expenditure from intervals and similar hard aerobic work. I've always been mindful that weight work contributes greatly to one's training load, so I only do it in winter, when my road training load is much less due to dark, weather, etc. As soon as I can start doing intervals outdoors, I drop down to strength maintenance, and then to nothing when things get more intense and longer. I've found it good to incorporate weights into the base mesocycles.

This side discussion started out about my recommendation of starting with sets of 30. Just saying, you might try that yourself next October and see how that goes. It's not particularly easy. Same weight, almost to exhaustion, all three circuits. Each circuit of 8 lifts in ~25 minutes or less.