Creatine and HIIT could promote high-intensity training!

High-intensity interval training (HIIT) causes rapid changes in endurance capacity, maximum oxygen consumption, muscle glycogen stores and oxidative enzyme activity. Creatine monohydrate supplements increase capacity for high-intensity training and promote recovery after repeated interval training sessions.
Kristina Kendall and colleagues from the University of Oklahoma in Norman found that the effects of HIIT and creatine may be more effective than either alone. Creatine plus interval training increased critical power (the theoretical power release that can be sustained indefinitely), but had no effect on maximal power release. The results were small and may not necessarily be significant in practice, but this technique may be more effective in highly trained athletes.
(Journal Strength Conditioning Research, 23: 1663-1669, 2009)