MHR / Health Questions ?!?

Well my immediate question is if it's ok that my heart rate is in the 180s for extended periods while doing cardio on a recumbent bicycle. At the moment I'm doing two 30 minute sessions where I sweat profusely, but can still talk to people and so on. I should probably mention that I'm 22 years old, and I think I need to also give some back ground on why I'm asking about this and how I arrived at being so worried about this kind of thing. About six months ago I found out I have pretty bad hypothyroidism, right now I'm taking 75mcg of synthroid, and my doctor told me flat out that she's about 99% sure I'll need at least 100mcg. I also gained a lot of weight in the past year because I tore some stuff in my knee and after getting a horrible diagnosis from a doctor I basically ignored what was said about surgery and just didn't do anything with that knee for a long time. A year later, or about a month ago, I go to another doctor who says that my knee looks fine, and that I should be alright to exercise. Also about three years I was in really good shape, however I'm pretty sure that my behavior in getting into that kind of shape is what set in motion the biological / epigenetic changes that led me toward hypothyroidism. When I was 19 I basically decided that I was going to get into the best shape possible, and after reading about ultra-low calorie diets and their benefits in terms of aging I thought it was a healthy way to live. So eating only between 800-1200 calories a day I would weight lift for hours, run around 7 miles, and swim at least 2km every day and go rock climbing for hours a couple of times a week. I basically just smoked weed / worked out all the time and ate nothing but fruit and protein powder (I don?t eat meat). I lost over 50lbs in about 2 months, and felt amazing but after that I started getting really unstable and **** just got weird. I now think I probably pushed my body past some breaking point by acting out of ignorance, thinking that what I was doing was actually healthy. The synthroid has made a huge difference in how I feel , think, and act. However, I do feel rather weird a lot of the time and think maybe it's the synthroid or maybe it's simply some other side effect from beating the **** out of myself 3 years ago. Anyways if in addition to answering my original question about heart rate and cardio, you could point me to some material or give me some advice on how to develop healthy parameters for working out it would be greatly appreciated. Also please don't get me wrong, I?m totally appreciative if you simply answer the first question or have even read this far into my semi-hysterical rant about how I destroyed my body and my resulting paranoid fears about my health.

Hi. Welcome to the boards.

A lot of people maintain a high heart rate when doing cardio. There is a spinner on the boards who heeps her heart rate ~180 or so for most of her session (60 minutes).

When I do high intensity interval training on the elliptical, I'll easily get my HR between 175 - 210. I can't do it for 30 minutes though - I'll call it quits after 20 minutes of HIIT! I move onto solid state arfter that, 100 - 130 on the treadmill.

When you were really cutting back on your caloric intake and training quite hard, you really gave the system a shock - I have been there myself, but did about 40 lbs in two months - never again! Long slow road to recovery, since I developed an eating disorder from it! Got over the anorexia with a carefully managed clean bulk, but I've had to keep the training and diet both in check.

So I take it I can do two 30min sessions of biking with an average heart rate in the 180s without dying… Does anyone know if this is good for weight loss / rebuilding cardio vascular health or rather what is ideal? Also I definitely wasn’t anorexic at the time. I actually thought what I was doing was healthy and that I was extending my lifespan by practicing such a diet. While I was in college I read a bunch of stuff on the reactions involved in metabolism, oxidative damage, etc. and how they are related to the physical properties associated with aging, as well as a ton of studies out there that support the idea of low calorie diets to extend life. They test this diet on animals a lot and it works quite well, there are also a lot of people out there trying it. I think however its best to do it when you are not very active, or don’t have the genetics of someone who will develop hypothyroidism as a result. Also despite eating so little and working out so much I managed to maintain my strength, which is what made me think while I was doing it that my body wasn’t pissed off although clearly this was not the case. Additionally I did manage to injure the **** out of my myself working out all the time running such a deficit. I definitely realize now that slow and steady is the best path to fitness, and that calorie restriction diets are not good for young active people.