You didn't say what her heart does when running, does it go way up, or settle down to some objective, say 150 or so if she's under 50 years old. As you know, the heart has to be held to lower HR as we get older.
I don't know anything about measuring lactic acid, or is this a subjective measure based on how the muscles feel?
I do agree that a rest HR of 85 is unusual for anyone on good physical condition, given they in the past had a lower rate. Many athletes have resting HRs below 60.
Could she be overtraining a bit? Sounds like she is very active. Does she take some recovery time? I have mentioned this on this site before, but may look into Heart Zone training. Sally Edward's has a good book, Heart Zone Training. It gives specific heart training zones to improve cardiovascular fitness. I take a medication to lower my heart rate. However, it would be preferred to lower heart rate through exercise, as side effects of mediation I do not care for. Also, continual stress may raise heart rate (Type A personality). May learn some relaxation techniques. Even though I do take medication for heart rate, I am able to exercise in the heart zones, and have seen improvement in my blood pressure. Some improvement in HR. Acutally, lately, sometimes my BP is low now. Also, look into overtraining symdrome. Hope everything improves.