NP vs. AP (and road vs. trainer)

peterpen

I'm new to using a PM and Cycling Peaks and not sure about how to weight NP vs. average power. For instance, here's some numbers from my ride yesterday on my bread and butter training loop.
Entire ride (209w):
Duration: 2:43:09
Work: 2024 kJ
TSS: 251.8 (intensity factor 0.967)
Norm Power: 251
Distance: 48.574 mi
Min Max Avg
Power: 0 963 209 watts
Heart Rate: 85 229 153 bpm
Cadence: 29 120 82 rpm
Speed: 0 50.3 18 mph
Torque: 0 445 96 lb-in

This loop has 3000' of ascent and I did 4x 10' intervals at 250w but took it real easy on the four main climbs (excluding 15" sprints at the bottom and top of each climb.) So I'd say 7 out of 10 RPE. That is also reflected by my av. HR (that max of 229 is interferance, the real max was 10 bpm below my actual maxHR.) Now, I think (hope?) my threshold power has moved up since September (when it was tested at 260w @ OBLA) but yesterday's ride sure felt more like an 80% effort than a 96% effort.

Curious to hear how much attention people pay to NP? Other than RapDaddy - seems like NP is the name of the game for you. I sure like the bigger numbers it gives me, but the AP number seems often to correlate more closely to RPE.

My other question - how do your road watts compare to trainer watts? For the same RPE, I can usually get 25 - 40 extra watts during intervals >10' on the road vs. the trainer (same holds true for rollers vs. trainer.) I'm able to keep my temp. low indoors (big ol' fan, windows open, plenty of liquids) but damn it seems a lot harder. Thoughts?

RapDaddyo

Well, here's a quick way to find out whether NP or AP is more representative of the physiological demands of a variable power ride. If you think your FT is ~260w, do two 20 min rides. First, ride for 20 mins at 240w constant power. Then, ride for 10 mins at 200w and 10 mins at 280w. The AP of the 2nd ride is the same as the first ride, 240w. But, the NP is much higher for the 2nd ride. Did the first ride feel like the same effort as the first ride? I only have confidence in NP because I have done so many variable power rides and have studied the data. I didn't wake up one morning and say, "I believe in NP." My confidence in the statistic is the result of >4K miles of investigation. NP is nothing more of less than Andy represents it to be -- the physiologically equivalent CP effort of a VP ride. But, that turns out to be a statistic of enormous value for pacing strategies, training and racing. I am not trying to sell you on NP -- I am simply sharing with you why I trust the statistic.

frenchyge

Personally, I find NP to be a very accurate predictor of whether I will be able to complete an intended workout, and I pay more attention to NP for any outdoor ride, any interval workout, and any 'tempo' ride (highly variable by design). I might look at AP for any fairly steady trainer ride, but in that case NP would be very close to AP anyway. So, I suppose whenever NP and AP differ significantly, I feel NP more accurately portrays the difficulty of the workout.

rmur17

1st one: Trainer to road watts for me is 20-25W lower over an hour L4 effort. I don't drop my CPS FT indoors to account for this: I just accept the fact that poorer cooling etc. indoors makes the workouts less effective.

2nd one: NP versus AP. Well I've been using power and AC's toolkit for about three years. I did have some misgivings about NP --- not for hard rides --- but for what I'd call 'sloppy' rides with lots of short stops, easy coasting in the group, long downhills etc. But I have not been able to find any personal (or wider) evidence that NP isn't a better reflection of the average workout demands. I track AP and NP for all workouts & track my AP and NP power-duration curves (and PB's of course). No issues remain with NP for me.

3rd one: At IF=0.97 for 2.75hrs, I suspect your FT is higher than 260W

rmur

RapDaddyo

Agree. For me, my 3hr MP is ~92-95%FT.

peterpen

thanks for the feedback guys. that ride was almost a "no chain" ride where everything goes well, so that may certainly played a role in my RPE and subsequent surprise at the NP & IF #'s.

but here's another question: if my power is 25w lower on a trainer, how do I take this into account when I have my next LT test, which is done on a Computrainer? Obviously, I'll talk with my trainer about this (and check my PT against the Computrainer) but I'm curious about other's thoughts on this apparaent connundrum.

rmur17

are you taking a 'true' LT - ramped test at increasing power levels with lactate sampling and not necessarily to exhaustion??

For shortish efforts say up to around 20min, I don't find my indoor/outdoor power vary that much. When I spoke of 20-25W, that was for a full AC gold-standard 40k indoor TT effort on the Computrainer. After some time at threshold or thereabouts, I find myself overheating indoors no matter how much I try to cool off. I guess some of the wattage loss is due to motivation as well. Staring at the floor or ole CT screeen for a tough hour-session isn't really much fun.

I typically stick to shorter indoor tests that are not as certain as a 40k but, gven enough personal history, I feel are close enough. For example the CP-Monod tests with perhaps 5-min and 20-min efforts, the BCF style MAP test, or a 30-min TT effort.

I presume Andy's new book will cover all the permutations for establishing and tracking FT power

rmur

peterpen

yep, 30w every 3 minutes and the ol' earlobe prick, stopped prior to complete exhaustion - but at 8.5 mmol/l it probably wasn't far off
In addition to the heat factor, I think part of the difference may lie with my tendency to wiggle around a bit on the bike - the trainer tends to get wobbly when I'm putting down lots of power. I'm learning that there's a certain technique to riding the trainer - or maybe there's a certain lack of technique to my riding on the road + rollers. Plus, I definitely hear you on the motivation factor - while the not wanting to look like a chump can help in the lab setting, long trainer intervals at home lack the motivation provided by actually going somewhere.

AndROOb

My response is to do with the road vs. trainer issue.

A week ago I went out and did a session on the road which included 2x20's at approx 230 watts, and although it wasn't easy, I did complete the session and ride home. Frustratingly for me, the cpu deleted the ride data when I removed it from the bike mount, but hey, that's another story.
Two days ago I did the 2x20's @ 230watts on the turbo, and could only manage 10 minutes. I repeated the 10 minute intervals another 2 times, after which time I could not do any more.
The reason it is harder is because the trainer session is relentless resistance at whatever power you're riding at. If you're riding on even a fairly flat road, it is always slightly up or down and always a bumpier ride than a turbo trainer.

I think that for creating a physiological adaptation, interval work on a trainer are a more efficient method, although it is equally important to put the power down in a real situation, which is on the road.

frenchyge

Got my butt kicked on the trainer just last night. Apparently, the 2 weeks off over the holidays and the recent few days of nice weather which permitted riding outside have allowed me to 'forget' how to ride on the trainer again. There I was, punching the downstrokes with my eyes bulging and my wheel slipping like mad while the trainer and my PM just laughed at me. I guess it's going to take a couple rides to get used to it again.