I started to use power as my main data through power meters for the bike and the run at the very beginning of my IronMan journey, and there is no doubt I would not have made so much improvements in such a short period of time without them. I'm pretty much aware that even though prices have dropped off significantly the past few years, it still an investment. But if you've made it to that line, there is a good chance you want to make progress. That's why I'm always amazed by triathletes being around for years and chasing time with just heart rate and pace as a reference. It's like using horses when you could get a car.

As for me I'm using :

• Favero Assioma Duo for the bike. Nowadays the bike power meter can be placed on the rear wheel hub, the bottom bracket, the chainrings, the crank arm or the pedals. I went for that last option for convenience as I was often switching from my road bike to time trial bike, so I would always have one power meter and the same reference. I started with Garmin Vector 3 but quickly had various reliability problems — shared by many — that pushed me to drop them for the Favero which turned out to be absolutely perfect.
• Stryd for the run. Power in running is something fairly new, but as useful as it's on the bike. The major actor — and only serious one so far — is Stryd. It comes in a small footpod linked directly to your GPS watch.
  

  Without Stryd power meter on the run, no salvation !

  As for Garmin, you have plenty of custom data fields to display the power the way you want on your watch. After trying some, I found my happiness in the DataRun Premium metrics custom fields which are able to display a wide range of data. That may also be useful, but the latest version of Stryd released in September 2019 now accounts for the wind, a major upgrade. If you're not familiar with this technology yet and considering using it, please check the awesome Stryd review from DC Rainmaker, and read the even more awesome book of Ron van Megen and Hans van Dijk : The Secret of Running !

In both cases, you need to perform an FTP — functional threshold Power, the maximum power you can sustain for an hour — test to have accurate zones. I was trying to update the numbers at the beginning of every new training block. FTP tests are slightly different as run is more demanding than bike; you can find the process of each easily on the net. For the bike I found an innovative alternative through Xert, that I would define as a pretty nerdy cyclist thing. Among other things, it can actually calculate your FTP automatically based on your previous bike rides. As IronMan training is more about endurance, it doesn't really give the opportunity to breakthrough every day, so I was doing a Zwift race from time to time to update the FTP that way.

Please note that you just can't translate your bike FTP to your run FTP : it's just two different things. The only common point is the limitation of the human body :

• 6.4 watts/kg FTP and 88 ml/kg/min VO2 max for the men.
• 5.7 watts/kg FTP and 79 ml/kg/min VO2 max for the women.

These two are interconnected, and for the record you can accurately estimate your VO2 max knowing your FTP with this simple formula(fn) :

FTP = 0.072*VO2 max

As for the record and to be more exhaustive, swim now starts to offer power as a way of training through the SmartPaddle product, but the actual price makes it something very exclusive. That's a shame, because I'm 100% sure I would have been a way better swimmer if I used power in the water.

TrainingPeaks

When starting to prepare my IronMan journey, I quickly heard about TrainingPeaks a website and app allowing you to track all your workouts and fitness form in-depth. Registering and opening it for the first time, I was truly like a kid entering a candy shop. It was awesome : data, data everywhere. I'm sometimes wondering if the founder was not a hardcore fan of the American statistician William Edwards Demming and his famous phrase : « In God we trust. All others bring data. » It took me quite some time to truly understand how the whole thing was done and how the data fields were linked together. TrainingPeaks has been the baseline of my training, as you will notice throughout the next chapters. I will give the data fields and numbers i was looking at the most below, along with some tips.

PMC — Performance Management Chart

You can clearly see how my fitness slowly but surely improved throughout the year, along with the dedicated tapering blocks featured on the yellow line !

The PMC — Performance Management Chart — is the core tool of TrainingPeaks. It displays your overall fitness picture over a chosen period of time in a very accurate way, helping to build sustainable training blocks over a long period of time. Maybe more valuable, it allows to schedule a flawless tapering ahead of your race. The PMC is built using your TSS.

TSS — Training Stress Score

The TSS — Training Stress Score — is the basis of the data of calculations for TrainingPeaks training. Understanding how it works is absolutely mandatory to getting through proper training blocks and avoiding injuries. Working with swimming, cycling, and running, it provides the ability to quantify any workout based on intensity and duration. To make it short and simple, a 60 minutes all-out effort equals 100 TSS. It's an equal value between every athlete, whatever their level, because it's calculated according to the individual threshold of each discipline. Whenever I was building my training block, I was not aiming for duration or mileage, but for weekly TSS.

CTL — Chronic Training Load

Okay, here comes the hotstepper. The CTL — Chronic Training Load — is basically your current fitness form. It accounts for your past 6 weeks of TSS workouts, the more recent ones weighting obviously more than the older ones. This number doesn't reflect the outcome result of any race, some people with a 90 CTL can be a lot faster than some people with 130 CTL. However, and in general, the more the CTL, the more you're building power, strength and speed in the long term.

ATL — Acute Training Load

The ATL — Acute Training Load — is one of the data I was looking for the most. It's basically the fatigue you've built up over the last 7 days of training. Before using TrainingPeaks, I was already a runner and had to go through a various range of injuries due to overtraining. Once I understood correctly how to work with this data, I never had to deal with any serious injuries related to training, and preventing me from training.

This can turn highly individual, but here the zones I was looking for :

The 3 key numbers of any serious triathlete looking to avoid injuries and perform at its best !

• 20 / 30. Day race numbers depending on the distance. 20 for an IronMan 70.3, 25 for a marathon, and 28 for an IronMan 140.6.
• -10 / -25. Training block numbers. TrainingPeaks will remind you to take a break beyond -20, but with time it turned out that my injury risk limit was around -25. It happened quite frequently to be around that number, but never for more than 2 days apart some very specific cases to avoid injuries.
• -25 / -40. I went to that zone for more than 2 days only 3 times during the season, and it was for some calculated reasons : either bike boot camp or a last fitness form push before the #SUB10 attempt after my right foot second-degree burn. I could feel though that I was risking injury at any moment, so I was even more extra cautious about sleep and nutrition.

That being said, ATL can only work correctly while you're in a constant training effort during the season. Your form can be 50 if you had a 2 week break, but it doesn't mean your body is ready to cope with a straight 25 kilometre run. Same thing if you just ran a marathon at 100% and your ATL is at 0; it doesn't mean that your legs are ready to go for another 150 kilometres on the bike. But if you're in a middle of a training block, with well-rounded daily TSS, then ATL is a fantastic tool.

IF — Intensity Factor

This is the first data of a long list you will find directly in the workout dedicated tab. The IF — Intensity Factor — is the key to fitness. This data is the reason I made progress over the charts compared to the vast majority of my fellow athletes. Most of them are just cycling for cycling, or running for running. As long as the volume intended is done, they feel gucci. I can confidently say they are wrong. Training effectively and efficiently is not about how much or how far you train. It's about how hard you go, and if for the run some rules must be observed, there is no reason for not going frequently ham on the bike.

When it comes to racing, if your FTPs are set well either for bike and run, here are the IF zones to aim for in most of the age group athletes out there :

• IronMan 140.6 bike : 0.70 to 0.75 — 0.73 as personal best
• IronMan 70.3 bike : 0.80 to 0.83 — 0.81 as personal best
• IronMan 140.6 run : 0.70 to 0.85 — 0.81 as personal best
• IronMan 70.3 run : 0.83 to 0.87 — 0.95 as personal best
• Open marathon : 0.88 to 0.94 — 0.93 as personal best

Obviously, the faster you go, the higher your IF can be on a race as you make it shorter. That's why a professional triathlete can sustain a 0.78 to 0.82 IF on an IronMan 140.6 for a bike leg of around 4:15:00 !

W/KG

In theory, any watt is equal to another watt. The reality is a bit more complex as the speed linked to your power output relies as well on your weight. Let's say two athletes are pushing a steady 250 watts on the pedals, one with an 80 kg weight, the other one with an 85 kg weight. If the bike course is flat, their speed should be relatively close. But if we go on an ascending one, there is absolutely no doubt the 80kg athlete will ride much faster than the one weighing 85 kg. That's why the W/KG is an important data to look at especially throughout a whole season where your weight can vary by a wide margin.

What your W/KG ratio should be for a successful #SUB10 ? Well, it's difficult to say for the bike leg because it depends a lot on your bike course, but i'd say that for a flat race 2.8 W/KG and 3.0 W/KG on a hilly course should get you close to a #SUB5. As a point of comparison, a professional triathlete can nail the bike leg of an IronMan 140.6 with an average of 3.8 W/KG to 4.0 W/KG... Loco !

For the run it's more easier as the course is always more or less flat, so expect to hit a #SUB3 with 4.0 W/KG while 3.7 W/KG should carry you through a SUB3H30¹Considering you're using Stryd as your power meter for running.. (fn)

NP — Normalized Power

You can find all these numbers we're talking about in the TrainingPeaks workout summary.

When I was talking about the importance of power in my training earlier in the chapter, I was not joking ! Of all the power data available, this one is one of the most important to me when it comes to any training workout number. The NP — Normalized Power — is a metric created by TrainingPeaks; by their definition it's an estimate of the power that you could have maintained for the same physiological “cost” if your power had been perfectly constant, such as on an ergometer, instead of variable power output. In other words, if you do a harsh 10 x 2 minute VO2 intervals session of 60 minutes, the fatigue generated could be equal to an endurance ride of maybe 90 minutes. Despite this, the average power of both ride could be almost equal, and thus not reflecting the perceived effort. NP has been created to depict this reality, and is the data power you should account while going through your various training block workouts. Even more knowing that it's the NP that is used to calculate your TSS workout, instead of your average power.