Why are my muscles sore?

I am sore today. Really sore. I am in week 9 of a P90X run, but I decided to mix it up a bit and so some workouts from Tony Horton’s One-On-One series.

(I don’t have all these — there are two full sets of 12 DVDs each and the third set is going on now, one DVD per month. I only own some from the first two sets that looked useful, plus I have all of the third set to date, because I subscribe to it.)

Anyway, on Monday I did the 30/15 workout, which is a series of 30 pushups followed by 15 pullups. Tony does different varieties for a total of 24 sets. For me this is not 30/15, nor is it pullups. I have found that pullups are a major factor in my tendinitis problems, so I use an exercise band in place of the pullups.

So my 30/15 is actually 24/15, and the 15 are band back exercises, trying to mimic the actual motion of pullups with a isometric hold for each rep. It’s effective, lemme tell ya.

Also, btw, let me tellĀ  you, if you don’t have the DVD, Tony backs down to 25/12 about halfway through, so 30/15 is a bit of a misnomer. But let me also tell you, this is one helluva workout.

Anyway, the point is that I had not done this particular workout in about two and a half months. I’d been doing other chest and back workouts, but not this one.

And I am so sore from it.

The next day, Tuesday, I did One-On-One Plyo Legs. Again, I have been doing other lower body workouts, but not this particular workout in about two and a half months.

And I am sore from it. All the muscles in my legs hurt to move them.

I don’t know what causes muscle soreness. I’ve read several explanations, from lactic acid to minute tears in the muscles, but, according to Mark Sisson, who is a pretty informed guy, we don’t know what causes it. (You can read what he has to say about it at his website, Mark’s Daily Apple.)

So what’s to like about muscle soreness? Well, when my muscles are sore, I know I’ve exercised them in a way that I haven’t done in a while.

General fitness can only come from working all our muscles. Tony Horton attributes much of his success to what he calls “muscle confusion”. He likes to mix it up, keep the body guessing.

Use your experience as an example. Have you ever started a running program? If you have, you probably remember how sore you were the day after your first run. Eventually, as you continued your running program, you were less and less sore, until you could run quite a distance without experiencing soreness. Your muscles had become used to the strain you were putting on them. But is that a good thing? I guess so, if your primary fitness goal is to become really good at running.

But that is not my goal, to have my body be good at only pushups or pullups or bicep curls or tricep kickbacks or squats. I want to be good at them all and then some.

With that in mind, I welcome muscle soreness as a sign that I am doing something right, working my muscles in ways they are not used to. And that’s got to lead to my being more fit, right?