Medium duration is 3-5mins. Effort is maximal for the duration = Zone 5 or VO2
Zone 5 basically describes the range of maximal sustained effort your body can do for 3-8mins, 3mins at high-Z5 -> 8mins at low-Z5.
During this workout do 3-6 efforts in this range. A lighter version of this workout would be 3x3min, while a heavier version would be 6x5min.
Take full recovery between efforts. This should be at least the duration of the ON effort, up to 10mins or so.
This workout can be both long and hard because you'll have a couple days to recover before racing on the weekend.
Adjust the duration based on residual fatigue but get out there and get some time in before you decide you are too tired to make this a good workout.
Total duration can be 2-3hrs, go at least 2hr unless you are just completely wreaked. It's okay to ride with some fatigue.
Efforts should include 2-5 x 10-20min efforts in Zone 4. Longer efforts can be lower in the range (95% of FTP), while shorter efforts should be higher in the range (100-105% FTP).
Full recovery between efforts -- 10-20 mins.
Like Monday, this day is for recovery. If you went hard the last 2 days you should be ready for a little rest.
Ride at a mellow pace, Zone 1 - 2, for 60-90 minutes. Don't assume every week will be the same. Some weeks you'll feel like you need to take it super-easy and others you won't be so tired. But, even if you feel good, you will probably pay for it on the weekend if you "train" today.
Rest is critical to get the benefits of the hard work you've put in. You also need to consider that you'll be doing a lot of quality training and racing over the next several weeks. You MUST get rest during the block to be able to maintain consistency from week-to-week.
Short duration is 45 secs to 2 mins. These intervals tax and develop your anaerobic energy systems. These efforts are typically referred to as Zone 6.
Like other duration intervals, the goal is to have the effort be relatively steady for the full duration. You don't want to sprint at maximum the first 20 seconds and then fade away over the remaining time. Similarly, if you are targeting 400W for 60 seconds, don't ride 500W for 30 seconds and then 300W for 30 seconds (averaging 400W).
For this workout do 8-12 x 45 seconds at high Zone 6 effort. Recover in Zone 1 for 3 minutes between efforts.
Find trails that challenge you from a skills perspective. Use this day to ride and re-ride sections you find challenging or hitting up trails that you normally avoid because of their technical difficulty.
You can also work on basic skills like line selection and visual focus. Do this by directing your focus to these elements during the ride or while on a specific section of trail.
Push your edge gently and don't risk injury. The goal for the day is to become an incrementally better bike rider.
You can also work on "race skills" like starts. Do 10-15 starts with foot down and work on getting clipped in and up to speed as fast as possible. Do this drill with friends for extra challenge.
Overall effort on the ride should be fairly moderate. It's okay to work on sections that require a little physical effort, but don't end the workout completely hammered.
"Tempo" is equivalent to Zone 3. This is a moderately-hard effort but one that you could sustain for quite a long time. Endurance MTB races are often completed at this average effort level, up to even 6 hours.
In this workout you'll do 2 x 30min efforts in Zone 3. Every 5 mins up the effort to Zone 5 for 30 secs. Take 10-15 minute of Zone 2 recovery between efforts.
No structure for this workout. Find some friends and do something fun and maybe even adventurous or epic.