I returned to actual endurance training in early 2015 to prepare for professional Speedgolf competition, after ~20 years of fooling around. I limited my heart rate to 145 bpm or below for my training runs, but it was still too high for an old guy and I suffered from overtraining my May.
Dr. Phil Maffetone, author of the Big Book of Endurance Training and Racing and legendary endurance coach, suggested that his MAF formula for determining the all-important maximum aerobic heart rate would deliver a more accurate value than calculating a percentage of maximum heart rate–especially for me because I have a higher than predicted max heart rate for a 50-year-old due to my athletic background.
Maffetone formula is 180-age, so I started running at 130 bpm. This is extremely slow and pretty frustrating to have to slow to a walk during an already slow run, or walk up hills instead of jog. After months of devoted effort and limiting heart rate however, my energy and general health improved greatly, as did my fitness. I filmed this video because I was particularly pleased to notice running along at a decent pace with a heart rate of only 123!
Many endurance athletes have trouble slowing down the pace of their workouts, especially to the extremely low intensity that 180-age dictates. In my case, the benefits of my aerobic base building have been validated not only by steady improvement on the trails, but in my blood values.
In April, in the midst of my chronic training patterns, my all-important testosterone values were 686 serum and 6.8 free-testosterone. 6.8 drew a low flag as clinically hypotestosteronemia! Not cool! In October, my values were 1,013 serum and 14.7 free-testosterone. For reference, during my professional triathlon career I ranged from 200-300 on serum testosterone. Even during my supposed peak hormonal years of my 20s, the extreme training and transcontinental travel suppressed my testosterone and in turn elevated stress hormones like cortisol that antagonize testosterone. Delivering a 1,000 serum level is legit for a high school dude, forget about a 50-year-old!
Bottom line: SLOWING DOWN will help you improve as an endurance athlete, it will help protect against overtraining and burnout, and it will optimize your hormones so you experience an anti-aging effect instead of accelerated aging that comes from chronic cardio training. These topics are some of the central elements of Primal Endurance, which is releasing in January to hopefully revolutionize the world of endurance training and help athletes following the conventional chronic approach embrace Primal Blueprint principles!