Lactic acid is not your enemy...some myths
I worked out with a friend of mine last week and after putting her through a training session, she told me the next day that she was very sore. She said "stupid lactic acid" at some point. In fact a lot of people complain about it. In reality it's not a bad thing at all. Lactic acid is actually always being produced. We simply notice it more when we workout because the production of it is greater than the removal of it. And it can be used as fuel for slow twitch muscles. Everyone will produce it in greater quantities during intense exercise. The elite atheletes often have a much better system which clears out the lactic acid. Here's basically how it works. You're in a boat rowing as hard as you possibly can. At this point you have a higher concentration of lactic acid in your muscles...this causes you to slow down. Now your fast twitch muscle fibers have slowed and your slow twitch kick in (very general and I'm not gettin into the details here). The slow twitch can then actually reuse it as energy. Once the acid is removed...you can pick the pace back up.
Is lactic acid what causes soreness after a workout? Well, no. The causes of soreness are tough to say and sort of all over the board. The basics thought and understood to be a combination of direct damage to the muscles (small tears) and some other chemical byproducts...but primarly the damaged muscle. Stretching, coolling down, or whatever other things you think will help prevent soreness...won't. And no supplements will directly help either.
Lactic acid is another reason that a smoker or someone living in a highly polluted environment will most likely never be a top athelete. Long endurance sports such as running, biking, soccer, etc...all produce a good amount of lactic acid of course. Smoking generally leaves your system lacking oxygen, and well oxygenated muscles are one of the first steps to good lactic acid "recycling". So if one twin smokes and the other doesn't...it's not simply that one will have "better" lungs. It's that the muscles in the non-smoking twin will be much more effecient during work.