A few thoughts…
There is a clear definition, its the dividing line between:
- stable oxygen consumption vs increasing until you hit max oxygen consumption (vo2max)
- stable heart rate vs increasing to HRmax
- stable blood lactate generation vs increasing blood lactate
Once you’ve estimated that “line” then you have an estimate for ability to do a “long” effort without explicitly defining “how long.” And using a multiplier of say 65-80% to estimate your lower aerobic threshold (LT1). Then you can do some additional field testing to estimate anaerobic capacity. And now you can also predict how long you can hold an effort above that line / threshold.
Now instead of lab testing, we have mathematical models that only require efforts. Or you can be even more basic, and if you have enough hard efforts from short to long, simply look at your power duration curve to estimate your functional threshold power.
Lets compare two mathematical models that use actual efforts to estimate that dividing line:
|
Critical Power (CP) |
mFTP in WKO |
protocol: |
2-4 max efforts between 2-20 minutes |
3 max efforts short/med/long |
practically it estimates: |
best power you can hold 20-40 minutes |
best power you can hold 30-70 minutes |
Notes:
- critical power info from Dr Skiba’s latest book
- mFTP info from WKO docs
I’ll also note that some of the more practical sports science studies that report performance improvements use time trials rather than Critical Power. Either way, you can document a performance increase or decrease if the athlete gave a max effort(s).
But how many max efforts are you going to ask someone to do in a study?
Using CP to properly fit your data to a line (linear equation: Power = W’/time + CP) you really need 3 max efforts - the Skiba book has an example with 3-min effort, 5-min effort, and 13-min effort. Over on the HighNorth blog they would like 4 efforts: 3-min, 5-min, 12-min, 20-min.
Using a time trial it is one effort.
What about vo2max estimates? They are a very popular metric in studies. Similar to using TT as performance metric, a vo2max estimate only requires one max effort (a ramp test), which as we know, doesn’t heavily rely on good pacing and therefore is far easier to administer when using untrained study participants.
Lets go back to the clear definition - a dividing line - between stable and unstable:
- oxygen consumption
- lactate in blood
- heart rate
No matter if you pick the functional “long effort” effort (hopefully without 20-min fudge factor), or “the more science-y CP” model, or the “proprietary” mFTP model, you end up with an estimate that can be held for “a range of time” and not a specific duration. There is no 60 minutes.
Clear definition, and then it comes down to the type of participants in the study. Regardless, different athletes will walk away with a CP or FTP (TT or mFTP) that merely estimates what they can hold for “a long time” without a precise estimate of how long. Which brings me back to Coggan’s the best prediction of performance is performance itself, and my own “go long” protocol (adapted from Friel’s 30-min test) which looks just like Kolie Moore’s last protocol in that article on TP blog.
Well before Zwift and TR came along, it was well documented by physiologists that different ramp protocols produce different “FTP estimates” and to be more precise they documented different max aerobic powers (MAP) because thats actually what a ramp test is designed to estimate. Applying an exact %, like TR’s 75% (Zwift too?), has also been documented to produce results that may or may not make sense. Because as Coach Chad has explained, and many others explained decades before him, not everyone has the same FTP as % MAP.