Well, I think it is difficult if not impossible to designate the measurables of as strictly positive effects (hematocrit, plasma volume, mitochondrial density, glycogen, etc.) because the question is whether exercise training will negatively impact these variables as well (i.e., via dehydration, RBC lysis, muscle damage, etc.). Hence, training could have both negative and positive consequences on these variables and their maintenance or increase could, in principle, be a result of less exercise and thus less negative influence. In any case, you raise good points and they deserves some more thought, discussion and/or research.

However, for the purposes of the OP, I think we ought to focus on providing information on optimal tapers for prolonged endurance performance. It would be very difficult to extrapolate the results of studies using subjects of different training levels and who followed a different training regimen than the OP. Hence the utility of the modeling approach from both a conceptual and practical standpoint.

As for research on shorter tapers (<7 d) on endurance sport performance, I suggest the OP inputs the following string into the PubMed search bar:
taper[tiab] AND ("running"[MeSH] OR running[tiab] OR "bicycling"[MeSH] OR "cycling"[tiab] OR "swimming"[tiab] OR "swimming"[MeSH] OR "triathlon"[tiab])

You get 100 abstracts from this search. I quickly glanced through and located the following abstracts that seemed relevant.
http://www.ncbi.nlm.nih.gov/pubmed/23707141 (observational study, half-IM athletes)
http://www.ncbi.nlm.nih.gov/pubmed/10029340 (triathlon, IM)

Here are some abstracts for a few studies involving tapers <7 d. The results appear equivocal with respect to performance.
http://www.ncbi.nlm.nih.gov/pubmed/8007812 (run, 5 km)
http://www.ncbi.nlm.nih.gov/pubmed/10950440 (run, half-marathon on treadmill)
http://www.ncbi.nlm.nih.gov/pubmed/1559951 (run, x-country)
http://www.ncbi.nlm.nih.gov/pubmed/2703282 (run, 10 d taper)

Cheers for that :) I have a 3hr ride with tempo work 7 days out and a 90min run 6 days out. Its a bit experimental at this stage. If i had a normal functioning pancreas i would prob reduce the run length, but i find it harder to deal with a changing need in insulin as that ruins a race quicker than a slightly overcooked body.

Here is how I "tend to do it"

All races, 14-12 days out really easy to "pre rest" and let my body absorb the previous block. No more long runs after this point, regardless of duration of race. For half IM and Olympic tri, run intervals pick up after that and end 6 days out, but for IM no run internvals. For half IM, keep biking and swimming longer the weekend before. For Olympic tri lots of short bike and swim intensity up till 3 days before (more rest). 2 weeks out for Olympic tri is very intensity oriented on bike and swim. For IM, I just remove all intensity on race week. Half IM, 4 days out remove intensity. Race week for half and full IM minimal running (20-40 min total spread over the week). For half IM B race, the taper would be more similar to an Olympic tri as I don't want to lose training progression for each B event. Friday is typically off. Saturday is generally 30 min of biking with 10x30 seconds hard. There may or may not be a short 15 min swim also with sprints...it depends on venue and water access.

It kind of depends on how much load you are carrying now. No need to do a 2 week taper if you are training 8 hours a week. In contrast, if you are putting in 25 hours a week then a longer taper might be in order.

I'm normally around 15-17 hours a week and I like to do a 10 day taper.

jaretj

A good quick read: http://www.jhse.ua.es/...article/view/219/329

I hadn't read that one before.

Here's another that I like:
http://alancouzens.blogspot.com/2012/09/tapering-part-ii-taper-weeks-by-sport.html

---

____________________________________________
Don Larkin
Reach For More
http://www.reachformore.fit/
USAT Lvl1 Coach, NSCA-CPT, NASM-CPT, BS Exercise Science

It sounds like you know what you need to do. Just try what you think is best given your condition - the worst case is that you learn something for next time.