A few points to add, though there has been some excellent posts on this thread.

I have a masters in physiology, with emphasis on sports medicine and cellular metabolism, so i kinda' understand this stuff.  I was also a national team alternate bicycle racer many many maaaaany years ago.

What has already been written by Moose and others is pretty much spot on, but also:

You don't exactly increase your threshold against lactic acid, but you DO increase your ability to break it down. (lactose, lactase, blah blah, blah)  It's sort of the same thing, but not quite.

A competative cyclist almost never goes into complete lactosis. You vo2 capacity (how much oxygen you can take in per minute) is much more important.  even on a breakaway you will run out of oxygen before you will ever max out your anaerobic system, but.. oh heck, that gets complicated and doesn't really matter.

What does matter is that you CAN improve your ability to work through the pain, and going into full lactosis won't hurt you and won't tighten the myosin fibers nor the muscle group as a whole.  -which is all that matters.

Realize also that there are two types of muscle cells (and, in simplistic terms, muscle groups) :  fast twitch and slow twitch.  Different people have different ratios of each.  Champion sprinters have primarily fast-twitch, and have naturally great anaerobic systems.  champion endurance athletes have primarily slow-twitch, and can never have the anaerobic systems of the sprinters, no matter how hard they train.

What does this mean to you?  i have absolutely no friggin' idea.

Bottom line: The best thing you can do is to improve your AEROBIC system, so this lactic acid problem doesn't even come up.  Interval training actually helps with aerobic as well as anaerobic systems, as you can actually increase the number of small blood vessels that feed the muscle groups.  You can also improve your ability to pull oxygen into the bloodstream.  Being physically fit is always a good idea, but especially so for drummers.

I had some other points to make, but somehow I forgot what they were.  I need to build-up more capillaries inside my skull....

Exercise it. I find banging it off a wall helps. Sometimes.

Well, I see this bounced up front again so here are my experiences: I have found that while I have been on a weight training program that my chops are more responsive and crisp and my overall playing is more balanced. For some reason that I cant really figure, my time becomes very solid.

Now, before we start a debate about weights and getting muscle bound Im not talking about power lifting in an attempt to look like The Terminator, Im talking about working out to stay in shape. A few years ago I remember reading an article in a Dr's. office about the training techniques that baseball teams were using. (besides steroids). The idea was to not only increase strength but also make those muscles faster. This technique involved training for strength for 90 days. This would build bulk as well, then the person would stop that activity. Then in another 90 days a transformation would take place that would "turn" the new bulk in to fast twitch muscles needed to hit a fast ball. (laymans explanation, which I'm sure is way off in terms of what actually happens).

So if one wanted to have a good Spring Training that begins in March. They would weight  train from Sept until Jan 1, then cease that activity. By March 1, they would have a good balance of bulk and fast twitch muscles for bat speed. The faster the bat, the better shot one has of catching up to a 95MPH fastball.

At the time I was playing in a baseball league with college aged kids who were about 5-10 yrs younger than me on the average. I tried this training approach and must say that it worked well beyond what I thought it could have. My average improved remarkably as did my ability to hit the long ball. While I had worked out before, I had never had the quickness, therefore had never hit for average.

Coincidentally, I decided to pick up the sticks and play with a band for the 1st time in nearly 5 years, I found that I hadnt lost much at all, in fact I found a great balance in my playing. My chops were strong but I also maintained a good deal of touch, yet also had really good endurance, I would never get the burning forearms even on long, fast tunes. In listening to rehearsals from that period, my time was very solid and my fills were very crisp. I dont know if this was due to the fact that my whole body was in overall better shape so I was not working as hard while playing or not. I just found it very interesting.

In the time since , I havent really worked but Ive been consistently playing with a band. While my chops are good I do notice that things dont seem as balanced and my time is not really great unless Im playing 3 times per week and I have to pace myself live to avoid the burning forearm thing. It could just be age though..

I havent played baseball either, I stopped when I noticed that some parents in the stands were looking close to my age!

Im not advocating this type of training for everyone, everyone will have a different reaction, I know Dave Weckl has said a lot of negative things about it but who knows how he was training?

Good suggestion.  I've been dabbling in weights a little myself and since I've started I've had more energy overall.

Agreed.  Just enough to tone up, get in better shape, and lower my cholesterol!     Any other benefit is gravy.  Mmmmm.... gravy.

Well if you walked on your arms all day long instead of your legs it would be a different story.

And it'd be hard to find pants that fit.