starting to run

Question
I am a big guy, about 280 lb 6'1" tall. I have weight trained extensively in the past, but I recently started running to shed some pounds and build a leaner body. My goal is to run a complete 5k in several months. When I started I couldn't run a quarter lap of the track, now I am up to running two laps and then alternating running with walking. When I get to laps 6 and 7 my legs are so tight and sore (lactic acid build up) that my pace of walking 1/2 and running 1/2 is slower than people who are just briskly walking the whole lap. It takes two or three days for the soreness to go away. I have been at it for about two months and I feel like I'm not making progress. Sometimes I am not winded but I just can't seam to keep running because my legs are so sore.I know my weight probably has allot to do with it, and I have lost about 15 lb since I started but it seams like I am hitting a wall. PLease help.

Answer
First, Dennis, great job on working so hard. You've obviously improved your health and your fitness level. I have 4 suggestions.

1) Take 2 days off from exercise. Follow those with 2 days of mild walking. Don't push yourself on those 2 days of walking.

2) After performing step 1 start to increase your workout intensity again. Vary it up more though. Here are a few ways to vary it up.
2a) After performing 4 laps of your typical workout sit down and rest for 15 minutes. Then, perform 4 more laps of your typical workout.
2b) Try just walking 3 times the number of laps you typically do. Here you're just looking to walk for a long time and expand greatly what you've done in the past.
2c) Try running faster than you are used to for a quarter of a lap and then walk for 3/4 of a lap.

3) Eat differently before you exercise. Try drinking more water. Try drinking more juice. Try eating fruit or having gatorade before you workout.

4) Eat an abnormal amount of fruits and vegetables for these next 2 weeks. (Abnormal means 2-3 times what you've been eating.)

If you don't seen any difference after 2-3 weeks of this then I recommend you see a physical therapist. This would indicate that there may be more occurring than lactic acid build up.

Good luck and don't hesitate to follow-up with further questions.