I'm experimenting for the next few months with a block of threshold work and I am doing two workouts per week with recovery in between along with SST & LSD.

I determine my LTHR by way of a standard 30min TT and record the avg HR for the last 20mins, which for my last test was 169bpm, from this I can calculate the rest of my training zones and by also using my RPE I like to think I can be pretty consistent.

My first session is a basic 2x20 (5minRBI) session, where, after a good 20-30min warm up I hold my cadence steady with my HR rising steadily through z4 til I ramp it up at the end tipping it into low z5. My first 20 is always a bit flaky but the second I find much easier and can be consistent throughout.

The other session I have been doing is a 3x12min (8min RBI) under/over session, where I start & build at z4 for 2mins and then ramp it up to low z5 during the next 2mins, back then to z4 and up again to z5 repeating for 12mins. Basically yo yo ing z4 to z5.

Both have similar TSS with the 3x12 being higher as I spend more time at z5 but with similar time spent at z4 for each. I also find the 3x12 much harder than the 2x20 and am totally cooked at the end of each interval.

Which one of these do you think is yielding the most benefit? Would I just be better sticking with the 2x20's twice per week or are there any other interval sessions I could throw in there to add a bit of variation.

Cheers.

Not sure which will yield the best results but very interested in the results.

I have just opened another thread about this before reading yours, have you ever done a real LT test? For me the 30min/average last 20 gives very different results from an actual test.

My goal is to get the 2x20min right. As per Friel et al http://velo-fit.com/new/pdf/intervals_vn_04_05_2004.pdf you should hit LT HR at the end of the first interval, and then have HR creep up a bit in the second interval. The article also states that many go harder than needed, oh if it just wasn't so much fun to give everything ...

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