Just about everyone will have a higher peak heart rate and maintain a higher heart rate for longer when running compared to cycling. That is because you are using more muscle groups when running. Those working muscle groups also need oxygen, and oxygen demand is a significant driver in heart rate. During long max sustained effort cycling, you hit a point where your leg muscles are using all the oxygen associated with your heart rate. The same is true when running. However, your upper-body and core require oxygen too. Your heart rate must increase to cover the demands of both your legs and upper body.
Utilizing more muscle groups is why the highest VO2 max results ever recorded are in cross-country skiers. They are using their upper and lower bodies at maximal capacity. Meaning a cross country skier would have a higher VO2 max when xc-skiing compared to riding a bike.
There are other drivers to increase heart rate such as blood acidity and CO2 concentration. These impacts can be seen in some riders when doing maximal out of the saddle 45-90sec efforts. These riders can hit heart rates 5-15 beats higher than during a 5-20min max sustained effort. YOu can get a better sense for where you are on this spectrum based on where you hit your peak heart rate during Full Frontal. Hitting your max heart rate after the 1-minute max-effort usually indicates you are one of these riders.
Thank you for pointing that out, I should have expanded that to be closer to 25%.
I would also note that when you consider MAP to be your Max RPM, and FTP to be your redline, then with your values, your FTP is 80.7% of MAP (222/275 *100). Though the way you phrased it, MAP = 124% of FTP is how we usually refer to these relationships.
That being said, 124% is right on the balancing point for focusing on sustained efforts or MAP efforts (for Attackers at least). Given your AC strength, the best MAP sessions for you would be ones with longer intervals (Nine Hammers, AVDP, some of the NoVid MAP sessions ( 3 x 3, 6 x 2 etc). Shorter interval MAP sessions will play in favor of your AC strength, so you’ll get slightly less MAP stimulus.
Honesty is the best policy!
That sounds like a threshold effort to me. Tempo might be a bit lower wattage, or maybe upper tempo. How long before you blow up?
The engine I want is a Cummins Diesel, currently have the two stroke out of a Trabant
Hi Sir Mac, I was thinking today does the percentage of MAP where a rider’s FTP becomes limited change for different rider types?
For me I have always been at about 127 - 135% MAP/FTP with my biggest strength being around 90 second efforts and my biggest area for improvement is sustained efforts. How does it change for a slow twitch muscle TT type rider who has no sprinting ability? Maybe someone like my friend who has a MAP/FTP ratio just under 120% and can’t sprint to save themselves? Would my FTP become limited by MAP at a higher percent than my friend?
How do you identify when FTP is being limited by MAP? Is this the sort of detail the app can detect or would I need to talk with a coach directly? I’m not sure how it can tell the difference between a rider with a naturally strong FTP compared to a natural sprinter without also having some information about the rider’s training history.
Sir Brian, M thank you for your reply. I recently did The Way out and stopped at 32 mins, I never recovered from this and had 6 more stops after 32 mins .I did not feel I was riding hard, but my legs lost strength and energy. I can ride all day, and do multi day 100 milers so endurance should not be an issue
@alchurch That does sound unusual. I agree that your outdoor activities seem incongruent with the struggles you are experiencing indoors. I’d contact the minions to see if they can help figure out what is going on.
You are spot on about other attributes impacting when a given area becomes a limiter. For someone with a high AC, the ratio where MAP becomes a limiter for your FTP is higher than someone with less anaerobic ability.
This ratio is impacted not only by the relative ratios between the different metrics. Absolute power for each given metric has an impact on where the cutoffs exist to determine a weakness. For those riders with really high FTP values, MAP has to be much closer to FTP for us to consider it a limiter.
Knowing your past ratios (and previous training) can also impact how we determine what areas are holding you back. However, the app (currently) does not consider this. At this point, you still need a qualified coach to get that deep into the details for an individual rider.
Beyond those things, we know that age, weight, and gender also play a roll in the cutoff points. This graph gives a good representation of the impact age and gender have on the 4 metrics.
I dream of the day when MAP is the limiter of my FTP. My map just leads me to cheese. Which possibly explains the dreams. 
My AC has been abysmal since starting Suff. It improves every test but I always finish thinking there was another 200 watts there that I cannot get out.MAP is my current strong point. I did thin air today and found it easier than the way out. There was so many micro breaks in TA I recovered between efforts
Awesome. Thanks for the info. I’ll check out the custom plans for my next training block.
That engine’s got to take me to work and back tomorrow 
Hi Mac!
Thank you for an excellent post.
During previous and this year I have currently felt see FTP has was plateuing a bit and think i need to “raise the roof” using VO2-max intervals. I switched from high volume polarized training (a lot of junk miles in zone 2) to low volume using SUF with more recovery and feel that my numbers go up and more importantly I feel I have more energy for everyday life.
One question regarding VO2 max and cross country skiing, as a former cross country skier would it make sense for me to do VO2-max intervals using cross country skiing or running up ski slopes, which is the workouts I have the highest heart rate and feel I get this forced-labour breathing. If this is a sign of being at 100% VO2-max, which some consider is a requirement for adaptations to VO2-max.
In cycling I only get a significant time of heavy breathing using “peak-and-fade” intervals. Which one of the sufferfest videos gets one the most amount of time at the highest % of VO2-max?
My 4DP:
FTP:343W
MAP:419W
AC:509W
NM:899W
@Coach.Mac.C Using the graph that you attached, my other two categories NM & AC are on the backside (higher percentage) of the curve but my MAP is not, percentage wise it is almost at the apex of that curve. As we talked previously, graphically and theoretically I suppose, does this mean that my MAP should be on the backside as well since the others are; is this why the App is telling me I have VO2 weakness rather than a sustained weakness. Am I understanding this graph clearly or at least the idea of it?
Hi @repstege thanks for your question! I’ll let @Coach.Mac.C chime in as well, but here are some of my thoughts.
First off, while your heart rate, breathing rate, and VO2 max values will be higher as absolutes when XC skiing or running compared to cycling (for individuals trained in all 3 sports) you can still achieve a cycling-specific VO2 max associated effort and associated adaptations on the bike. Your heart rate and breathing rate will be lower on the bike but you can still achieve appropriate training adaptations to VO2 training on the bike since there are some cycling specific adaptations that you could miss out on by switching over too much of your VO2 max/MAP intensity work to other exercise modalities.
Regarding MAP workouts with the highest amount of time at VO2 max, this is not an exact most to least list (because longer sessions like Kitchen Sink and Blender can skew things just because they’re so long), and also because there are different ways to achieve VO2 max - short micro intervals in sets, moderate length MAP target efforts, and even sustained just above FTP efforts can also get you to your VO2 max. Each of these different types of session can result in different types of adaptations that in sum can help increase your VO2 max.
Micro Intervals:
The Chores
Revolver & Revolver is Easy
The Shovel
The Cure
NoVids including: MAP Micro Intervals 3 sets 40/20s and Micro Intervals 3 sets 10 X 20s
MAP Intervals:
9 Hammers
14 Vise Grips
GCN VO2 Max Intervals
Butter
Joyride
Novids MAP 10 X 2 and MAP: 2 sets 5 X 2 and MAP 3 X 3
Above FTP Intervals:
The Omnium
A Very Dark Place
There is No Try
The Best Thing in the World
Blender
Happy training & racing!
i have the same “problem”. an easy fix is: race crits instead of the hills 
You are interpreting the graph and your values correctly. If you are on the right sight of the Bell Curve for both NM and AC, then your MAP should also be one the right side of the bell curve. The fact you are at the top of the bell curve for MAP is why your weakness is showing up as MAP, instead of Sustained.
Just some follow up questions that’ll give me a better idea of what might be going on.
- When you train indoors, do you normally train in the morning, afternoon, or evening?
- In the app, your current 4DP metrics are based on which test (Half Monty or Full Frontal) and when did you do your most recent test?
- Does the app record power for indoor rides from the trainer directly? Or from a power meter on your bike? What’s the make/model?
- Do you use power on outdoor rides? If so what’s the make and model?
- When riding outside, do you know what cadence you generally prefer to ride at? Or during something like Full Frontal, on the 20minute test, do you know what you tend to average for cadence?
- Lastly (to keep this from going down too many potential rabbit holes). When you say your legs go dead, are you referring to feeling a lack of energy? Muscular fatigue? Meaning you feel like if you were on a leg press in the gym you just wouldn’t be able to push another rep. A burning sensation that comes from shorter high-intensity efforts that lingers even when you reduce the effort?
Ouch. Now I’m depressed. AVDP doesn’t even make it in to MAP … and I tried that instead of NH this week and blew the whole lot. Must try harder.
Thanks for this explanation - dead good.