Seaver,
I've had to deal with this. I will give you some background that may be helpful for you, and then pass along the advice that I got from a friend that I thankfully decided to implement.
By way of background, I've been lifting weights pretty much my whole life. I was a competition powerlifter for many years, and although I have tried body building I could never get shredded enough (to get in panties and go on stage). The split routine was pretty much the holy grail until I reached 30. At 30, the split routine started failing me on two fronts. First, I started getting DOMS (others covered this). But, at 30 I could still seem to find my way around DOMS some, but it was noticeably different than even 27. Second, my travel schedule would blow things up. I'd find myself hitting Day #1, Day #2...then travel long enough to need to restart at Day #1 (meaning, there was always some group of muscles that was getting short changed). My key point is that as we get older we tend to have more responsibilities, and although we still workout, it may not be in the same facility all the time which can disrupt a split schedule. [And yes, I'm a "workout anywhere" person...but I didn't understand erratic travel until career started rolling].
I basically flailed for a few years in early 30s, going from disrupted split routines, to circuit training, and back. No gains. Then, I discovered crossfit and did this for 2.5yrs. I'm going to try to avoid provoking the xfit cult that is convinced this is the way, but, basically no gains here. Yes, the first 6mos was great and I thought I found the new thing. But, crossfit actually really sucks over the long haul and lack of progression means no real gains. (and if these guys workout in a regular gym they are so SpazTastick that you can spot them a mile away, but I digress). At some point I took a step back and thought to myself "Hell, not one of these crossfit coaches has a fraction of my background...why am I listening to them". So, I bailed and put all of that time back into a block and tackle split routine with some running/cardio. AND, the DOMS came back.
Finally, I talked to an older lifter (45). He said that it is just a fact of life that when you get older you have a harder time recovering, but, meatheads like us keep pushing it anyway. He told me what works for him, and although I was skeptical at first, it made intuitive sense. I decided to give it a shot, and now this is how I lift. Here goes:
I still use all the same lifts I would normally use if I were doing a "split" routine, but I spread them out differently. Now a 3-day routine looks like: Day 1 = Heavy, Day 2 = Light, Day 3 = Medium. I pick ONE lift per body part per day. All workouts are FULL body. And, the big compound lifts are the choice for the Heavy day. (I want to stick to the point, but as an aside an advanced lifter will quickly recognize that you may have to drop in one heavy lift on other days as it can be hard to hit heavy squat, bench, and dead all in one day).
I will pick on Chest for just one body part. In a regular split routine, you may end up with 3 exercises on chest - say, Bench, Incline DBs, and Flies. You pound the shit out of this body part (and usually one other body part like Tris). But, at 35+ you tend to get much more sore with this setup than at 25 (of which this turned you into a monster). With this rotation you would do: Heavy (Bench), Light (Flies), Medium (Incline DBs).
For me this solved my two big problems where the split routine was failing me:
1) Travel was interrupting the split routine. In every workout this is FULL body, so you really don't lose that much if you are set back a day or two (or three) from your schedule. You can easily do something else while on the road and not lose progression or feel like one group of muscles ends up getting rotated more often than another.
2) My body tends to recover much better with ONE really solid exercise for each body part than blasting it with everything and waiting a week to get back to that muscle group.
