Hi Dave, congrats on your race. It is always nice to PB especially at Age 49. That is amazing…but I think you are confusing me with someone else. I don’t think I ever said anywhere on this forum for anyone to focus on a negative split. I like to race with something in “'reserve” and this is what I recommend to people (don’t burn all your matches early), but I certainly have not said to focus on a negative split, as I am still not convinced that this the more efficient strategy for your average age grouper trying to achieve a marathon or triathlon PB (on long races), given all the constraints of the real world (increasing heat, winds, lack of training, solar effects, cramps, cramping, electrolyte management, calorie management, improper training, day to day life streses etc etc). I still believe that on a long event, most of us will slow down, and it is all about balancing what your body can do early in a race versus later.
But…let me get this straight though…you walked 18x15 seconds. That would be 4 min and 30 seconds of walking total in the first 18 miles?
If you did nothing but run continuously for the final 8 miles, it would be pretty easy to negative split as you would have effectively left time on the table in the first half and you are not losing 15 seconds per mile walking. In fact, you could actually go ~10 second slower per mile and “negative split”, just by virtue of taking no walking breaks.
So as I mentioned in the thread that Rappstar refers to, 98% of the field positive split. Some elites negative split (keep in mind they are highly trained and run the race is 2:0x vs 2:50-5 hours for many age groupers) and there are the odd age groupers who negative split, but a bunch of them (age groupers) negative split by leaving a whole whack of time on the table in the first half. Do you think that by simply running continuously for the first 18 miles that you or anyone might be ~4 min faster at the end of the day? People who negative split always talk about how great they felt etc etc, but maybe its cause they took it so easy for the first part of the race and left time on the table?
For example, is it better for a 3:30 runner to run 1:40 + 1:50, 1:45+ 1:45 or 1:50 + 1:40…or could the 1:45 + 1:45 guy just as easily have gone 1:40+1:45 and done a 3:25 and if the person fades, 3:30? Going 1:45 for the first half never gives the guy a chance to hit 3:25 unless he is REALLLLLLY sandbagging it.
Taking things to an extreme, if negative splitting is the best strategy (and it is for short events), then all the top Ironman guys would be doing it. The reality, is that ZERO Ironman pros negative split. So we can chose to extrapolate up from the even/negative split strategy from mile races and apply it to marathons, or one could arguably take the positive split strategy that everyone does in a REALLY long event (ironman) and scale that downwards and come to the conclusion that positive splitting is actually a more efficient strategy. This is not to say go nuts beyond the pace that is reasonable and puts you so far in the redzone that you have to walk in the second half…well, in your example, you did 4:30 of walking in the first half. But how is this any worse/better than walking 4:30 in the second half? What if you just chose to run at the chosen pace for as long as possible with no walking breaks, and then slowed down by 10 seconds per mile with 8 miles to go (which it appears you may have)…you still end up 4:30 faster…throw in a few walking breaks in the second half and even then maybe 2 min faster?
Of course, everyone will keep believing that negative splitting is the fastest strategy, but my point in the thread that Rappstar pointed to is that the real world evidence from 98% of the masses is that positive splitting is what is going on out there.
Anyway, I am truly happy for you that you PB’d, and sorry for this long winded explanation of where I stand on this topic but before anyone accused me of having changed my mind, I thought I’d set the record straight 