Kris Stallenberg 90-min Z5 (VO2 Max) Medium #10 This session is a 'mixed bag' of VO2 max intervals, with varying durations from 5 minutes down to 3 minutes. This structure keeps the body guessing and simulates the unpredictable nature of hard group rides or races. By tackling different interval lengths, you build a well-rounded and resilient top-end fitness. bike