Called micro-intervals and part of Billat’s Vo2 work the 30/30 is a great workout set for several reasons. The short work periods are easy to focus and work hard through and the short recoveries allow for averages and physiological demands rivaling steady state efforts. I really like this because the ‘stochastic’ (on/off or variable) nature of these intervals can be a great simulation of mountain biking.
Billat recommended 15-30min of 30sec on / 30sec off , stopping if the 30 seconds on could not be held at vVo2 (speed/watts at vo2). Many coaches will use Cp6 wattage as a stand in for vVo2.
Coaches have taken this and used it in shorter blocks to apply the advanced principle to different athletes and abilities. E.g. 3 x 10min of 30/30 w. 5min off
2) Offroad TTs on challenging terrain
I use this all the time personally and with clients. The key is to pick challenging terrain to address limiters and situations relevant to your goal workout. I often use 3 stage, a rocky and hilly trails system. There are ups and downs, but mostly ups for up to 20min of solid work. To clean all the rocks and roots takes tremendous focus and to beat my times takes more and more fitness and skill each time I go. Using the same route also helps me build confidence and track my improvement.
3) 5 – 10 x 2-3 min ON / 2-4 min off
This range borders between traditional Anaerobic intervals and Vo2 intervals but these are quite common and relevant to the duration and RPE that we encounter in MTB racing. Whether you look at successful age groupers, pros or sets used in studies these are often close or the same to what is used. Many endurance athletes will do well to keep bumping intensity up as they get stronger and resist adding more and more repetitions. I typically rotate these ranges through, almost year round and adjust the interval/recovery duration to vary the load/focus. More reps and shorter recoveries pushes the focus towards VO2/threshold while longer recoveries and shorter work periods are more anaerobic focused.
Give these great workouts a try to spice up your routine