There are a few very good reasons to keep track of your triathlon training, whether you are simply taking notes in a notebook, following a training plan written out for you, or using some kind of online training plan system:
Triathlon training is pretty complicated, with three sports to think about, and it can be very tricky to try and manage it all "on the fly"
Perhaps after a few weeks, or certainly after a few months, you should start feeling some real differences in your training, but that will be hard (maybe impossible) to measure accurately, if you don't keep track of things as you go along
It is very easy to feel overwhelmed, no matter what your level of experience is, in triathlon training, and writing it all down can be tremendously helpful if and when you do feel overwhelmed and want to make changes to your training
Full disclosure: in case you haven't noticed yet, I am a Level 3 Triathlon Coach and I make a substantial part of my living writing training plans for endurance athletes, so it might seem very self-serving for me to sing the praises of writing down your training plans and notes from your training. But, I think I can also be very objective when I talk about this as a triathlete, rather than as a professional coach, and tell you how valuable I personally find it to keep track of training sessions, as you go along.
Plan out your training in advance
I wrote another blog, about setting goals for next year, that talks about the fundamental ideas behind planning out your training, so you should probably read through that one before proceeding.
If this is your first time training for a triathlon, or your first time following a training plan, or you are not training for any particular race and just want to start enjoying and having fun with you training, then you do not need to be too strict or rigorous with planning out your training in advance. Here are a few basic guidelines that you can start with:
Rest at least one day a week and one week each month. Rest and recovery is important and you may not think it is a problem to remember to take some rest days or rest weeks, but you might be one of those people who gets caught up in the excitement of triathlon training, especially if you join a club. Rest is an important part of the training cycle, allowing for your body to rebuild itself after you overload it with consistent training.
Of course, this guideline should not be misconstrued as an excuse to take rest days or rest weeks whenever you feel like it. Please notice that I said, above, that rest allows your body to rebuild itself after consistent training, so you first have to do the consistent training, then you get to rest. Which leads me to...
Be consistent in your training. This is where writing things down and planning things out, even just a little bit at first, can really help. You certainly want to avoid being all over the place with your training - doing one bunch of things one week and then something very different the next week. Generally, you will want to practice each discipline at least twice a week, to allow your body to grow and adapt. If, for example, you only swim once a week, it will be too long between sessions for your body (and brain) to remember what it did last time, and you will struggle to make progress.
Build distances gradually and moderately. For people new to triathlon (and even for some very experienced triathletes), distance is the biggest worry. My other blog about "Distances of triathlons" was written to answer this very first question most people ask me, so I understand only too well that distance is what occupies much of people's concerns when it comes to triathlon training.
The rule of thumb here is that you can safely increase your distances by about 10-15% each week, and that is why it is good to give yourself plenty of time when planning out your training plans. And, remember, when you first get started with your training and you start building your distances, you should do it at an easy-to-moderate effort level, not be too worried about speed. For example, if you look at your first block of training and you want to build your running capabilities from 2 miles to 6 miles (3.2k to 10k), you could do it in 12 weeks, as follows (with numbers rounded to nearest 0.25 mile or 0.5k, to make things easy, even if it is not an exactly perfect set of numbers):
As you can see, it is very achievable, and actually kind of surprising, when you think of the possibility of tripling your mileage with 3 months of straightforward but consistent training. And, so, if you write down your plans in advance, it will be easier to remember what you are supposed to be doing and when you are supposed to be doing it. It will also be easier to make adjustments if something goes awry, along the way.
You can also follow a prepared training plan, without having to write one of your own. These days, there are several web sites, magazine articles, and books available to provide you with some fairly generic (but potentially useful) training plans that you might want to follow.
Take notes as you go along
Arguably, the most important aspect of taking notes as you go along is your ability to measure progress accurately and objectively. Both of these things can be very important motivational factors as you go along. Sometimes, you might feel like you have "lost your mojo" for training, or like you are doing loads and loads of work, but not getting anywhere. And, sometimes, going back and looking at your notes can be extremely useful in addressing that. For example, let's say you were following the example given above for increasing running distance from 2 miles to 6 miles, and you hit a rough patch somewhere around week 6. You might be struggling to do these runs, wondering how on Earth you are ever going to make it to 10k. If you took some pretty good notes, you might see that you are now running more than 3 miles each week pretty comfortably, at about the same pace you used to run 2 miles, which is more than 50% greater than you were ever able to run before, and you are actually sticking to the plan. If you keep sticking to the plan, you will be at your target distance in another 6 weeks. Maybe you think back to where you were 6 weeks ago and it feels like the time has passed very quickly. So, maybe the next 6 weeks will pass just as quickly and, before you know it, you will hit your target for this phase of training! There are loads of other things that you can record (more about that in the next blog about "Recording qualitative as well as quantitative information in your notes") that will help you with a little motivation and encouragement. For example, if you use a GPS-enabled Heart Rate Monitor, and you take notes that include some of that data, perhaps you will also be able to show yourself that you are doing each run a little longer, at the same average heart rate, with perhaps some increase in average pace, as you progress through your plans, week after week. Perhaps that will help you "get your mojo back."
By the same token, you might be able to go back through your notes from the past 6 weeks and see where you may have made some mistakes in your training or some glaring errors and inconsistencies start to show themselves. For example, I recommend (as does pretty much every coach or author who has ever written on the subject) to everyone I work with that they do a decent warm-up before each training session, and a decent amount of stretching after each session. If you go back and look at your notes, and see that you were not so consistent in your warm-ups and stretches, then you may find an answer to why you have been experiencing so much lower back pain lately, to the point that you have been advised to take a week or two off from training until it subsided. And, maybe you will correct that when you get back into training again.
Whatever you might discover when you look back at your notes from your training plans, for good or for bad, you will only discover it if you actually take some notes. So, please don't leave it to guesswork, and please take my word for it that taking notes can be one of the most valuable tools you will have in gauging progress as you go along.
Software tools for training plans and notes
The biggest name in this sector is TrainingPeaks, by far. I personally use it for my own training plans, as well as in writing training plans for my clients. I find it to be a very useful program, as a triathlete and as a coach, with a lot of built-in tools that are relatively easy to use (putting together an Annual Training Plan, as well as weekly plans and writing individual sessions). It also comes with an app you can download on your phone so you can check planned sessions on the go, and take notes after each session straight onto your phone. Since TrainingPeaks has a near-monopoly on this market, it also means that pretty much anyone who is creating and tracking training plans online is using this program, and that means you can share workouts, get some really good pointers from other people using the program, and generally find a lot of useful ways to incorporate the software into your training.
There is another program that has come on the scene in recent years, called Xhale, that offers a free trial, so it may be worth checking that out, too, as a comparison.