My old college chum who was dedicated distance runner had both his knees replaced last year at age 56. He was also obsessed with maintaining an ultra-low body fat which gained him some endocrine related medical problems later on. Nothing exceeds like excess. Sometimes you pay a price for overdoing it.
It can be a fine line and don't think I'll ever get to that extreme. My goals are to hit the weight room and play pickup basketball each weekly and try to do at least 5-7 of the following monthly - tennis, volleyball, Frisbee golf (which is usually by myself running the course with hills), golf, Bodypump, Bodyattack, Bodycombat, swimming, kayaking. It may sound like a lot to some but I usually combine two of the above in the same day, which results in at least 10 off days each month. Also probably closer to 15% body fat with no desire to get close to 10%. Everyone is different with what works for them. My co-worker recently completed a full Ironman and pretty sure I could never do that, even if trained properly.
I was running way before his book came out. My dad used to jog after work on the high school track and I would go with him. Probably started in 4th grade or so.
Are you a Kenyan or an Ethiopian? I'm guessing that your are naturally thin with less than normal body fat. An ectomorph. We mesomorphs sliding into endomorphism have a much harder time maintaining that kind of endurance. I was on the track team in high school. I was on the 440, 880 and mile relay teams as well as running the quarter mile. We were undefeated in the relays my senior year and I thought running those 4 events in one day was a pretty grueling test of endurance. But even then I couldn't run even 1 mile without stopping.
Here is a guy who set a record by running the Appalachian Trail from Georgia to Maine in 46 days running over mountains, wading rivers and through the woods. You have to wonder what these kind of people do for a living that they can take weeks off at a time. I want a job like that to take the time to relax and watch TV. https://www.yahoo.com/travel/colorado-man-sets-appalachian-trail-record-on-124067823782.html
See, you were the guy I envied. Playing chase in grammar school, I was easy to catch. I was slow in the sprints, I could just run forever. When I chased people, I couldn't have been much fun. I would pick a target and just wear them down. In 73, a heart study was started by Dr. Gerald Beronson and Tulane University. They examined almost all of the children from Bogalusa. They measured everything from body fat percentage to resting heart rate, and everything in between. It was an extremely thorough physical, complete with EKG and such. They also did a very thorough questionnaire to find out what you ate, did you smoke, did you live with smokers, all of that stuff. They would examine us every year while we were still in the Bogalusa school system, then annually or whenever we could get home. It is still going on today. I went back for the most thorough physical I have ever had. The questionnaire took almost 2 hours this time. Here is a quote from their website: Link Aaaaanyway..... The reason I brought all of that up is during my examination in '77, I'm laying on the exam table and this Korean doctor checks my pulse. He abruptly drops my arm and starts calling for the nurses. I was freaking out because I thought something was major wrong. Turns out that he was calling them in there to let them check the pulse of the "dead man"! He said I had the slowest resting heart rate he had ever taken. I was at 36 BPM. I was 6 feet tall and about 135, so as you can imagine, had really low body fat. However, my resting heart rate has always been slow. Even today at 54 and way out of shape, my resting heart rate is still in the 58 - 62 range. Sorry about the longevity, but I was in a mood
