MAF heat rate training seems to have been adapted to many of the training protocols discussed on this forum. First off MAF training is an endurance training protocol geared to developing the aerobic system. In my experience (Ironman training) it is extremely effective at developing an aerobic "base" with amazing results. The caveat is that it is meant for endurance. The book is titled "The big book of endurance training and racing" ! For a newcomer to this type of training this means a fair amount of volume. In my experience, ignoring the health benefits, it is not particularly effective for developing performance without the volume. For example if you are running 5k's 3-4 times a week with the goal of reaching the peak level of performance that this volume allows you may be better served by including intervals and tempo work as well. My experience is that you need the volume to properly develop the aerobic system, maybe 8+ hours a week as a minimum? Therefore for improving performance for marathon events MAF is extremely effective if you put in the (long) hours. In the initial phases MAF recommends eschewing all forms of speed and strength training until the aerobic base is somewhat established. After that one can add strength training but you should still try to keep it as aerobic as possible using grease the groove style training. Once speed stops improving from MAF HR training as evidenced by a monthly MAF test (you'll have to read the book!) you can add a little speed work. Keep doing that until you reach a plateau, at which point you revert to aerobic base training again. Repeat these cycles, week after week, year after year to achieve peak endurance performance. This how multiple world Ironman champion Mark Allen beat all comers year after year. (Yes, he also included strength training, but in an extended range of exercises, typically 12 exercises of 2-3 sets of 12 to 15 reps). All strength training is regarded by MAF as anaerobic, regardless of max heart rate reached. My understanding therefore is that according to MAF you cannot develop optimal aerobic conditioning for ultra-endurance via strength training. The book is littered with anecdotal evidence proving that even strength is improved when trained after first establishing an aerobic base. So in this context I'm not sure of the relevance of MAF heart rate in strength or strength endurance training unless an aerobic base has already been established (and is then maintained or re-established for each training cycle) Don't get me wrong, I've been very satisfied with the results of the Strongfirst training methods - as I was with MAF training for Ironman. I am just trying to understand how they can live together in the same space. Anyone care to chime in and enlighten me?