How trainable is it do be able to do a 20 min threshold effort after 3000, 4000, or 5000 KJ? Is there a point where a threshold effort is just not going to happen, or does this sticky come down to the amount of training you’ve dome.
Great question! I will address this from the fatigue resistance and MSP maximal sustained power point of view. First, we need to acknowledge that threshold is a moving target and tho we use it to identify and set training zones and we look for increases and perforamcne gains at threshold it technically moves constantly. For example if you do a threshold effort at the start of a long 4hr ride you will produce "X’ watts, then do same effort at very end of that ride and the watts will be “x”, often lower because of the fatige. This said, I would say your MSP is more citical at those kjs you state which is also an indication of your fatige resistance which is highly trainable. If those are the specific kjs, then di some sub threshold MSP efforts in order to increase your fatige resistance and MSP which often is more beneficial vs threshold anyways. Both MSP and fatigue resistance are about going harder for longer durations of time. Software like WKO5 can also help with all of these metrics after certain kj as well. Thanks!
This will have a lot to do with your ability to spare carbohydrate during the long endurance piece between the efforts.
This can be improve with endurance, tempo and diet manipulation.
There is no question raising your endurance and tempo ability will allow for a closer repeatable power after the long endurance section.
It is very possible to do a 20 min threshold effort after any number of Kj’s, as long as those Kj’s were expanded using your type I fibers. Put in another way, if those are ‘fat kilojoules’ you should have the CHO left to fuel your type II fibers for the threshold effort.
If you have been riding at a power level which requires utilisation of your type II fibers, you have been burning CHO which may lead to the situation where you have insufficient fuel left for the 20 minute effort.
I think this is a great question the OP is asking. Dr. San-Millán mentions in this video (@~7:00min) that the high intensity efforts are better done at the end of endurance training. I’d love to learn more about the “whys” and whether this is significant or not.
It seems logical to me to either perform HIT at the beginning or both beginning and end of a ride. The thinking being that one gets 1. higher quality HIT when fresh (better load to stress ratio) 2. depleting the high intensity energy system at the outset would force the (well fueled) aerobic system to perform for the remainder of the ride (and maybe even allow recovery for a 2nd round of HIT). Racing is often this way anyways, but this might not be best practice for training.
Maybe this gets to specificity to the event/goals, and to the comments already (@steveneal and @Fpike ) about fatigue resistance, base fitness and fueling.
As you pointed out, this becomes quality vs specificity. When I am wanting more power or more time at power I might prescribe intervals after a good warm up when an athlete is “more fresh”. I love intervals mid ride and at the end because it really is more race/event specific. Once I see what I want or we have progression with power and duration, I willl move intervals to end of rides. This also helps train fueling on the bike as you need to eat in order to get thru intervals at the end vs begining when often glycogen stores are already full or enough to fuel the efforts. From a fatige resiatnce perspective I love intervals of 4-6 min at 85-92ish% FTP, I will include these in a ride when I have prescribed HIIT intervals in the beginning of the ride, sometimes I want these done on low glycogen storage to teach the ability to produce solid power when low on fuel and teach body to use fat as fuel in these situations.
@Fpike awesome comments as always, I agree totally.
I also think of the mental side of these efforts when at the beginning and the end. This can really be specific to races as well, and also work on mental toughness in the athlete.
I have even used hill repeats after B races to try and simulate higher level races the athlete will be faced with.