Training & Nutrition - exercising at high HR

I have been hitting the training hard the last 7 months and have a question. I am doing tri's and I exercise at about 80-95% of max HR. The beginning training programs I have read recommend training at 60-80% of max HR why would you not push yourself harder than 60-80%. Also if I train at Lactate threshold for 30 min running will my aerobic conditioning improve in the bike portion of race also or do I need to bike at my LT threshold also

can anyone give me some love here?

Ok - I'm not an expert but have read quite a bit on this. In a nutshell, when you train anaerobically your muscles are not getting enough oxygen, are producing lactic acid and the main energy they are getting is from glycerin stored in your muscles. You can only train for so long above your anaerobic threshhold until you bonk. Your muscles just won't do it.

On the other hand, when you train aerobically, your muscles are getting enough oxygen and are getting energy mainly from usual sources (fat and carbs in your system).

Over the course of a season, you have to eercise both ways. Build an aerobic base so that you can do more and more effort within your aerobic range. This is how you build endurance. An example from a triathlon training book I read said something to the effect of: "at the beginning of the season when I train at my anaerobic threshhold I average 20mph - by midseason I average 26mph at the same anaerobic threshhold."

After you build an aerobic base its good to do intervals above your anaerobic threshhold to increase speed and help to raise your anaerobic threshhold.

Like you, I used to train almost exclusively anaerobically (swimming). I could swim about 1/2 hour and would get out of the pool feeling totally spent. I felt that if I couldn't "feel the burn" I wasn't getting a good workout. The most helpful stuff I've read has been on the anaerobic threshhold - I eased up on my intensity swimming and it has paid great dividends. I can swim much much longer and interestingly, I am now able to swim 1500m at my anaerobic threshhold 3 minutes faster than I could swim 1500m going full out 9 months ago (of course much of this is due to switching to total immersion swimming). Same for biking. I have a 6 mile loop around a park that is part of my ride on occasion. In february averaging 140bpm that loop took me 24 minutes (slow - I'm a newbie) and now it takes me just under 19 minutes at the same 140bpm average. This increase is the result of doing mostly aerobic training - I've just started adding intervals.

I have been hitting the training hard the last 7 months and have a question. I am doing tri's and I exercise at about 80-95% of max HR. The beginning training programs I have read recommend training at 60-80% of max HR why would you not push yourself harder than 60-80%. Also if I train at Lactate threshold for 30 min running will my aerobic conditioning improve in the bike portion of race also or do I need to bike at my LT threshold also

This isn't something I'm terribly knowledgable about, but hopefully my post will trigger others. At 60-80%, I believe you're training your lungs and heart more than your lactate threshold. At 80-95%, the opposite is true. What you're doing is good for your muscles and how much they can handle before they crap out, but it isn't helping your lungs much. If you want/need to improve your lungs, bring your intensity down a bit.