Question: where does Threshold fit into a training plan?
It doesn’t fit well into a Polarized training protocol, where training intensity is either very low, or very high – way under threshold, or way above. Nor does it fit exactly in a Sweet Spot training plan, increasingly the go-to protocol for time-crunched cyclists, where you work just under your threshold for longer durations to push FTP up from below.
For me (and others), Threshold work is far more of a mental challenge than anything else – it’s not much higher intensity than Sweet Spot (88-95% FTP) but actually holding the full 100% power for any length of time feels significantly more difficult. Dropping the power by 5% doesn’t sound like much, but when you’re working at the edge of your physiological limit those few watts can be the difference between finishing or failing the prescribed workload.
“Intervals only work if you finish them”
I wish I could properly attribute that quote. It’s harsh, but true.
The whole point of any interval training is to accumulate more volume at higher intensity than you would be able to sustain in a single effort. This applies physiologically and mentally.
The physical application is obvious; work at an intensity just above your sustainable capacity and allow your body brief recoveries to replenish energy reserves before going again to eventually accumulate the prescribed workload.
The mental aspect is no different and I would argue becomes more critical the longer the work intervals become. Your brain is very good at coming up with excuses why you should stop anything so foolishly painful as riding up a 9% climb at 365 W. You can ignore that voice in the back of your head only for so long before it seizes control and hits the emergency shut-down button for your legs…
Adaptive Overreaching and Optimal vs Achievable
Your body adapts from being pushed beyond it’s limits, by definition. If that shut-down button gets hit before the required workload is complete, the adaptive benefit is sharply diminished. Therefore it is often less optimal, but more achievable to prescribe workloads at 95% – ie. Sweet Spot – where the full workload will be finished, rather than failing at 100%.
This applies to shorter durations and other energy systems as well – WKO4’s Optimized Intervals protocol suggests power targets at 95% of your performance-proven capacity across the range of time durations, to focus adaptation for each particular energy system.
For instance, from a previous point in my current training cycle, WKO4 recommended either long sustained (Extensive) work at 95% FTP, or significantly shorter, Intensive but still sub-threshold Aerobic work at 97% FTP.
So, where does Threshold fit into a training plan
My thought is that Threshold work should be done sparingly within most training blocks. Where it shines is as part of a Peak phase for pushing more race-specific efforts to bring you to the top of your fitness and race-readiness. The mental focus should already be primed as you approach a key race or target event, and physically you should be reaching the top of your capacity.
Most of us already do Threshold intervals throughout our Base and Build training phases: Each 20-minute Test we do – usually one every 4-6 weeks – is almost by definition a single max Threshold effort. Speaking for myself, I find I am able to summon a similar level of mental focus for Testing, as for racing. Those Test efforts are like little mental challenges that I can work up the focus for, if only occasionally.
So save the Threshold work for special occasions, where you’re particularly focused on hitting a new PR, or getting ready for a specific near-term event. Otherwise the benefits don’t outweigh the cost, in my opinion…
But maybe I’m just soft and need to do more 2×20’s