Double threshold vs light 'special blocks'

Vin lananna does this stuff. Tempo in the am, 300s in the pm. I’m sure plenty of others do it too.

The two parts System A, one part System B, with a dash of System C usually doesn't work.

According to what I have read, the double threshold system typically includes one fast workout a week. Ingebrors usually do 200m hill repeats. Perhaps you might try swapping these for some work at mile pace.

this is actually a good post.

In my opinion, I got very fit (aerobically - 10k shape) by doing x2 (and even x3 on occasion) double thresholds weekly. Over a 3 week span, I did x5 somewhere between sub-threshold to threshold (let's call it 3/4th marathon pace), while the 6th would be fast 400s ~5k pace and the possible 7th would probably be a generic tinman CV workout.

However, for getting into optimal mile shape, I found it best to replace an evening session with 200s at 800 or 300s at mile once every 10 days. You need to teach your body to produce more lactate more, and you also need to be able to buffer it. So, doing something like 6-8x200 @ 800 effort off ~45s rest in the evening does that, and it also teaches you to run fast on tired legs.

I'm a sceptic of this double threshold fad. Schumacher has had the best non African 5K and 10k athletes recently and he doesn't use it. Salazar didn't use it for Farah and Rupp. I don't believe Ritzehein uses it for his crew, although it looks like they're going to try it based on a recent coffee club. The Kenyans don't do it, specifically Kipchoge. The Ehtiopians don't do it. Japanese marathoners don't do it. Just because one brother of a trio from Norway has had success and one 5K guy from Norway ran 13:06, are we supposed to buy into this? I'm honestly not convinced. Sure kids are running faster, but c'mon, it's the shoes and the BU track. Take those two things away and I'm just not seeing the progression. The stats at the elite level back this up as well. No harm in extra tempo work, in fact it's a great thing to do as a younger athlete, but I just don't believe it's the Holy Grail some of these Shaman are making it out to be.

"Just because one brother of a trio from Norway has had success and one 5K guy from Norway ran 13:06...."

^ I think you too readily dismiss the fastest times of Henrik (1500m = 3:31.46; 3000m = 7:36.85; 5000m = 13:15.38) and Filip (1500m = 3:30.01; 3000m = 7:34.00; 5000m = 13:11.75) Ingebrigtsen (to say nothing of their places in championship races).

Anyway, that's a small disagreement I have with your post. I suspect there's huge lot of good with the double (sub-)lactate threshold workouts, but as you indicate there might be something better.

How would you do this while avoiding injury/overtraining?
I do 1 tempo, one threshold and 1 LR each week, with EZ mileage (9:30-10:00) as a fill-in. True EZ pace. Consistent 35-42 mpw for the last 6-7 weeks and feeling strong.

Bowerman and Dillinger had us doing this back in the 70’s.

If you are only doing 35-42 miles per week I would strongly not consider any "double workout days"....especially double threshold days. Your volume/mileage (and Easy mileage pace) does not support it imo.

I think people seem to forget that the whole "double threshold" is a fairly advanced training concept and stimulus much like Canova's "Special Block" or even the Chinese "crash training system."

If you run moderately hard, moderately high volume and can get away with it, then yeah you can get super fit! But there is an injury and overtraining risk. There are probably some "pros" that train with all this kind of quality (big double Threshold and Canova workout types) but are probably also on PEDs...which would actually make sense as you'd want to push yourself harder and more often if you could recover faster and get bigger gains.

For people running under 60 miles a week....why would you even bother running twice a day?