Hey Nancy:
seems a lot of us agree here that the S & H legs just doesn't quite cut it for fatiguing the muscles, even with the pre-exhaust exercises. But S & H upper body gave me tremendous results this Summer, I've never been stronger!
Since you already have found that the PLB works great for you, just keep going with it and alternate it with leaner Legs and you will continually challenge your legs. Leaner legs, with just a 35 pound barbell is exhausting, I love this workout as is. And PLB is fabulous too, isn't it?
Sherry has a good approach too and it's on I often use: make up your own pre-exhausting session, either with a previous strength training workout, or with some cardio. I often do a CTX cardio, such as Att Atep or 10 10 10, as my warm up for either PLB or LL. A longer tape like Powermax is too much I find, and takes too long. I don't want to spend my life working out and nothing else!
When I do PLB I still have to go up to 50 or 55 pounds for the squats and when I do S & H with 50 all the way through, I cannot lift that much onto my shoulders and I am not going to cause an injury trying. I can safely lift to 45 pounds but after that, I lift the loaded barbell onto my work/dining table (it's old so there's no marking problem), and then squat beneath the table and roll the barbell onto my shoulders and then push up out of the squat, which is part of the exercise anyway, thereby eliminating all risk of injury to myself and to my husband, who began a second career as my spotter but lacks the patience for the job!
Hope some of these idea may work for you,
Clare
