For example, this #ClassicPhysiologyPapers from Sandra Harms & Robert Hickson (1983)

For context, 50%VO2max is approximately equivalent to 50% of your 5K pace.

For an 18min 5K runner, most of the benefits to type I and IIa fibers come at ~12min/mi!

#EasyDoesIt #Zone1

https://journals.physiology.org/doi/abs/10.1152/jappl.1983.54.3.798?journalCode=jappl