You’ll find this study interesting then. I have yet to try this experiment though…it look brutal, absolutely brutal.
Effects of a Seven Day Overload-Period of High-Intensity Training on Performance and Physiology of Competitive Cyclists
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4270748/
Conclusions
“Seven days of overload HIT induces substantial enhancements in time-trial performance despite non-significant increases in physiological measures with competitive cyclists.”