I'm new to the forum, and my friend did the lactate threshold test on a treadmill recently where you measure the average HR for the last 20 minutes of a 30 minute hard run. She's not very fit (yet) but her average HR over that 20 minute period was 175. It seems really high to me and if she calculates her training zones based on that I'm worried that she will be training in zone 3 instead of her 'real' zone 2.
What's a good lactate threshold for a 30 something year old who has so far only participated in half marathons (usually finishing in around 2:05)? I know this is a very general question... but I'd love to hear some input.