Hi Pierrehalmet,
That is a hell of a workout. There are many different workouts and schedules. This looks like descending pyramid training, not because of the time but because of your energy levels.
So, your question is a good one and, in this case, provides you with the answer. It isn’t. Obviously, this schedule wears you out.
There are a few different solutions. You proposed to change from a 3/1 to a 2/1 schedule. That is an option, but I think the simplest solution is to make the training easier.
It is okay if you feel tired after one training. It is okay if you feel tired after a training period, but if it wears you out, then you have taken on too much.
You could try 3 minute blocks and see what your energy levels are in week 3. Personally I always choose shorter intervals, like 30/15’s or 1/1.
I only use the longer blocks for competition or steep mountain sections that progress for a longer period of time.
When I use these blocks it is only for a couple of weeks during peak period.
Research shows that athletes can maintain the shorter blocks better. The result is more quality time at the desired power.
Like you said: 5x4 min gives you 12 min of solid time near VO2max. That also means that you are hammering yourself 8 minutes for nothing.
My advice would be to try the shorter blocks and vary more in the time you use them.
To give you an idea. Let’s take a 12 week period. Since you are an experienced cyclist you start with 2 sets of 3x 1/1. Next week you’d do 3 sets of 3x 1/1. In the 3rd week 3 sets of 4x 1/1 and in the 4th week you could do 3 sets of 5x 1/1.
In the next 4 weeks you choose another set-up. Let’s do 40/20’s. Start your first week with 2 sets of 6x 40/20’s. Next week do 3 sets of 8x 40/20’s. The 3rd week you’d do 3 sets of 9x 40/20’s and the 4th week you’d do 3 sets of 10x 40/20’s.
For the last block you could use your 4m blocks. Build the workouts up, so start with 1 block of 4 minutes in week one and ad on or two blocks every week, not exceeding the limit of 4 blocks.
But I would challenge you to do another workout. Try a pyramid workout. Start with 30/30, 1/1, 1:30/1:30, 1/1, 30/30 in your 1ste week.
Next week you do the same until 2:30. 3rd and 4th Week until 3:00. Again, if you are very fit you can do a 2nd set.
What you see in my schedule is that, during rest week I still use intervals, but these are more for play. They are not meant to tire you. Get acquainted with the new workout, maybe find an on- or offline route that fits the workout.
The most important thing is not what you can do, but what you must do.
Most cyclists take their training to extremes and attempt workouts at the limit of what they can, far beyond the ideal training load.
Taking yourself to the limit every training, takes you over the limit during a training period.
Take it easy and just push yourself occasionally. You will recover better and give your body better opportunities to grow.
Have fun, Coach Robert