That article doesn't even make sense.
half the riders performed intervals at 80 percent of their peak power while the other group used their heart-rate readings that coincided with 80 percent of peak power. Their twice-a-week workouts consisted of eight four-minute intervals with 90 seconds of rest.
80% of your peak power for 4 minutes? I don't think that is humanly possible.
Do they mean 80% of your peak 4 minute power?