Hi D3NZAK,
It’s as reliable as the GPS system providing the grade changes (ie your watch). “NGP reflects the grade and intensity that contribute to the psychological cost of running on varied terrain” . As a coach if I have an athlete not using power for running then my next best way to measure the true intensity of a run over varied terrain is NGP.
So in your case here, if the 5:15 pace was from the track or a flat road and the race was on hills – a 5:18 is a very good effort. I would then dig slightly deeper to see where the NGP actually dropped off – for example some athletes are very strong on hills but not efficient on downhills (eccentric load is hard on the legs). Could also be a pacing issue, going out too hard, attacking the first hills and/or downhills and fading in back. So NGP is great – but I would not just review it for the whole run, I would diving into the segments of the run to see pacing and areas for that may require continued improvement.
If you want to nerd out on NGP check out this link from the creator of the algorithm.
https://www.trainingpeaks.com/learn/articles/what-is-normalized-graded-pace/
Coach Leyla
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