K-man
That will help DURING the race. You'll probably get into a few situations in the marathon-going up a hill or the last few miles-where your legs will burn from the lactic acid surplus. Pyruvate will function as a buffer and you might not feel it at all.
I have used Twin Labs Pyruvate Fuel and I'd take 3 tabs before a race and notice that the lactic burn was lessened. It is possible that you might not push yourself to the point where you'll have a lot of lactic acid build up. You would get lactic acid build up by running the entire marathon right at your aerobic threshold. If you could do that in your first marathon...that'd be impressive. That level of effort is difficult for experienced runners to achieve.
I think it is more useful for shorter faster events like 5-15k races. I wonder if it would help for lifting? It may help your post run recovery. It has no negative sides in the dosage I suggested so I think its worth a try.
What marathon are you going to do and when? I am hoping to doone this fall, but I don't know if I want to risk injury. I am also unsure if I want to run for 3.5 hours too!!!
FHG