“We compared the effect of cycling endurance training of disparate intensities on high-intensity exercise endurance capacity and the associated limiting central and peripheral fatigue mechanisms.”
“20 adults were randomly assigned to 6 weeks of either high-intensity interval training (HIIT, 6 to 8 × 5 minutes at halfway between lactate threshold and maximal oxygen uptake [50%Δ]) or volume-matched moderate-intensity continuous training (CONT, ~ 60 – 80 minutes at 90% lactate threshold).”

“Pre- and post-exercise responses to femoral nerve and motor cortex stimulation were examined to determine peripheral and central fatigue, respectively.”

High-intensity interval training resulted in greater increases in total time to exhaustion at the same absolute and relative intensities as pre-training (148% and 43%, respectively) compared with moderate-intensity continuous training (38% and −4%, respectively).”

“Compared with pre-training, high-intensity interval training increased the level of potentiated quadriceps twitch reduction (−34% vs −43%, respectively) and attenuated the level of voluntary activation reduction (−7% vs −3%, respectively) following the total time to exhaustion trial at the same relative intensity.”

“There were no other training effects on neuromuscular fatigue development. This suggests that central fatigue resistance contributes to enhanced high-intensity exercise endurance capacity after high-intensity interval training by allowing greater performance to be extruded from the muscle.”

T.J.O’Leary, J Collett, K Howells, M.G.Morris
Endurance capacity and neuromuscular fatigue following high- vs moderate-intensity endurance training: A randomized trial
Scandinavian Journal Of Medicine & Science In Sports – Volume 27 #12 – page 1648