The training calendar, as everyone knows, has three periods:
Fall/Winter: Endurance + Strength = BASE
Winter/Spring: Intervals and speed work = BUILD
Summer: Race = KICK ASS!
This is an oversimplification, but it gets at the issue of when to do MST and plyo: when we lift really heavy weights and jump around, are we building battleships in the drydocks, or are we already at sea and simply greasing up our barrels? It's no use lifting weights for 12 weeks in January if those gains we make disappear by the 16th week.
Unfortunately, as far as I'm aware, there are no studies out there which would answer this question for us. So we'll have to use what we know and try to guess. I bring this up because it's important to note that any answer I give to the question of "when to do MST" is going to be speculative.
Training for improvement > 12 weeks
Suppose I begin a maximal strength training (MST) in January and see 10% gains by March 1. This would be consistent with the results of what we've learned in the exercise studies examined in previous posts. What we don't know is what the effect will be in April: we don't know what will happen if I continue MST through April, or if I drop the MST entirely and just ride the bike.
This crappy chart shows a number of possible results: if you continue MST after 12 weeks, you could continue seeing growth, you could plateau, or you could lose ground.
In fact, most improvements in the MST study done on the Danish national cycling team occurred in the first eight weeks of the training. Their FTPs looked something like this:
This means, unfortunately, that we probably won't see continuous improvement if start now and lift through May. We'll probably see improvement through December or January, and then level off.
On the other hand, it means that just as the Danish cyclists maintained their improvements over the last four weeks of the study by continuing to lift, we can probably maintain strength we gain in January by continuing to lift through April, or later.
In fact, lifting in the middle of the season is not out of the question, especially if you're targeting a late-season race.
I'm sorry that I haven't given any real answer to the question of when to start MST. There's no evidence that it works over 20 weeks, that its effects linger, so I can't say do it in November. On the other hand, I can't say it's the best use of your time in the Spring, when you're trying to build high-end power: interval training has been shown, again and again, to be incredibly beneficial--moreso even than MST.
All I can say is try it out, probably during your base phase, and certainly during your build phase. And if you're daring, give it a whirl in the weeks before a big race. And let me know the results!