Something that seems to lack attention is that it is not just the amount of mileage, but also the intensity of the miles. The Ingebrigtsen’s perform a lot of reps in their ‘threshold’ workouts, but those reps are (approx.) a full minute slower than their 1500m race pace. They are being done at near their marathon pace (equivalent for a 3:28 1500m athlete.)
That is a considerably different way of training than typical Daniels, and likely much different than what Solinsky (or any other NCAA distance coach) is used to.
The following article explains it. Note also the prehab attention in consideration of running in spikes:
”Team Ingebrigtsen shuns risk and resorts to high-volume fitness-based threshold training, instead of training at competitive speed.
The threshold is where the body gets rid of lactic acid as quickly as it is produced. A lactate meter is needed to find this point.
- We have to run insanely fast in competition, but we almost never train at that speed. It only happens in the middle of summer, he continues.
Take the day before VG visits: Six-minute intervals at 20 km/h in the morning. In the evening, 500 meters at a speed of 21–22 km/h. Total volume around 32 kilometres.
Jakob maintained a speed of 25.9 km/h when he took the Olympic gold in the 1500 metres. And Filip's personal record for the same distance – 3:30.01 – corresponds to 25.7 km/h.
Their program only exceptionally contains intervals longer than six minutes, and then at an even lower speed.
- Too much and too hard, says Filip about the most common misunderstanding many people have about how to train to get fast.
This is where the Ingebrigtsen family believes there is another path to becoming the world's best than the one taken by Hicham El Guerrouj. He used to run 30–45 minutes continuously at a speed of up to 20–21 km/h and 1000 meters at 24 km/h.
- I do much of the same as I have done for the past five years, with a little tweak. But only based on the same training, I have had a progression in the results, says Jakob.”