TomBefore some my answer to your question you shall be aware of 2 points.One is that the António´s Summer isn´t my my main training method precisely. It contains some of my training principles, but it´s a peculiar aspect of my training that I did imagine for someone that wants to keep on training during the summer months.My Antonio´s summer training isn´t my main training method and it´s not target for cross runs or track runs whatever. It´s one special training,summer training with no specific event goal. On the first post of this thread I write “Just one my provocative training schedule for those of you that like this kind of Danny Henderson´s short rest interval training with the “Summer of Antonio” title, inspired in the name of Summer of Malmo”.Therefore if you want to know something more of my training details, you need to read something more,Another point you need to consider ad that I always try to advice, is the need of training individualization “persona-per-persona”. Here I just say what are training principles. Face to face with individual cases I might build different schedules. Some my runners, when they start to be coached by me they are surprised because early they read my training ideas and they did imagine what would be my training, the training I will put on them. Then they are surprised to what I prescribe, that despite doesn´t contradict my training method, by the need fo training individualization i prescribe something different they expect.Now the answer to your questions.
Normally I use to keep the same number of repetitions while longer each set, until the workout that the runner isn´t no more able to run faster than his distance event race pace. Normally with so short and active intervals like 100m ehead on track in about 40-45secs recovery I don´t prescribe more than 10 sets.
One example for your 5k runner example.
The workout sequence might be: 10X200m; followed by 10X250m; then 10X300m, then followed by 10X400m; followed by 10X500m….wait, my experience teach me that in very rare cases the 5k runner is able to run longer workout than 10X500m with 40-45secs recovery 100m ahead on track and keep on or faster his 5k pace. 10X600m ???? Hum…I doubt !
Then what´s the solution, continue to do the reverse sequence or why not introduce training by set groups like 5X600m+5X200m all with rec=100m/40-45secs. I guess that in this case he can resist because the 600s are just 5 times. Another example 5X500m+3X300m+2X200m.
Yes. If the improve of aerobic power does consider the continous tempo run and not the short intervals it would be a good idea to progress from longer to shorter and faster. From LT runs to fast LT (max lass) to hard tempo. In this case the logic it´s the opposite of short intervals that tend to be faster than race pace to race pace. In the case of tempos, it tends to be slower than race pace to race pace.
However if the tempo run is considered a merely aerobic condition workout it´s always good to run more (volume) and try keep the pace. To try to keep the pace because since the distance grows its imposiible to keep the same pace.
But again, all depends of what´s the workout target. If the workout target it´s merely aerobic condition then try more; but if the workout target it´s one tempo run closer to race pace, the goal is speed up the pace while reduce the total distance/duration.
Phase 3, would be what would be the target goal event, the major percent and the major workout frequency should be specific workouts, what means long reps with long stand recovery race pace distance event determined.
Eventually in each 3-4 workouts only one is special, all the other 2-3 shall be specific distance event long reps.
Also it´s a good thing to introduce some short reps aftere the long distance specific workouts BUT short reps WITH LONG STAND RECOVERY IN THIS CASE of Phase 3.
Of course that Phase 3 for one 800m runner might means 3X600m or 3X500+2X100m/800m race pace, as the might mean 8X600m+2X200m 6X1000m or 5k race pace, for the 10k road runner might mean 5xMile+3X300m or 3-4X2000m+3X200m/10k race pace and for the HM runner 3-5X3000m/Hm race pace or the marathon runner it might mean 4-5X4000m/maratjon pace. Just examples that you might undersatand the kind of specific workouts i think about when i say to you about the interest of doing long reps with long interval during the Phase 3.