This is probably a little nerdy for some of you. You've been warned. I'm trying to keep this as basic as possible.
I'm sure there are write-ups way better than this. If you already use a PMC, you probably know as much or more than I do.
Performance Management Charts are pretty cool. They show your fitness, short term fatigue, and can predict if whether or not you'll have good form at a race. Most of the "big name" cycling apps have them. Strava, Training Peaks WKO, Golden Cheetah, etc. Here's what you need to get started.
A powermeter. Technically, you could estimate training stress for each workout, but it won't be very accurate, therefor it wouldn't be of much value. So lets just say that you need a powermeter. Quarq, Powertap, Stages, etc. They'll all work. A powercal may or may not.
You need to know your FTP. You'll need to enter that into your app of choice.
At least 6 weeks of data in order to get any data, but 12 or more weeks are preferable.
Strava Premium ($), WKO ($$), Golden Cheetah (FREE). I use Golden Cheetah
Some quick definitions - way more detail is here, but I'm trying to keep this simple: http://home.trainingpeaks.com/blog/article/what-is-the-performance-management-chart
Training Stress Score (TSS) - This is calculated for each ride. It's based off your FTP, so a 100 point ride for a pro and a 100 point ride for an amateur would create the same level of fatigue, but the distance or time could be way different. IF you say your FTP is higher than it actually is, all of the stats on your PMC will be low. If you sandbag your FTP and put in a low number, all the lines on the PMC will be too high. I'll just copy some TSS info from the training peaks site, since it gives a better explanation than I can.
You earn 100 TSS for an all out, 100%, 60-minute workout. Of course most workouts are not completed at 100%, so most workouts will accumulate less than 100 TSS per hour.
You can earn more than 100 TSS within a single workout (as long as it is longer than an hour), but never more than 100 TSS per hour.
Think of intensity as an RPE value on a scale of 1-10, 10 being the hardest. If you exercised at a level 5 for two hours, then you would accumulate 50 TSS/hour or 100 total points. It wouldn’t matter if you were training for the Tour de France or to simply complete your first triathlon.
Chronic Training Load (CTL) - Basically, this is your long-term fatigue, but we will all it fitness. It his weighted average of you TSS over the last 6 weeks. The more you workout and harder you work out, the higher your CTL gets. The higher your CTL, the more fit you are.
Acute Training Load (ATL) - This is your short term fatigue, but we will just call it fatigue. It's a weighted average of your TSS over the last 7 days. I think you can adjust the number of days, but I think 7 is a good default.
Training Stress Balance (TSB) - This is your "form." It's a combo of training stress and rest. This is a predictor of how you will do on race day. When the line is going up, you'll perform better than when the line is going down. A positive number shows good form. IF the number is negative, you'll be too tired to have great form.
Blah Blah Blah. Let's look at my PMC from last year and see if we can draw some conclusions.
I took some time off after my ironman in August, so all my numbers started pretty low. You can see the blue (CTL) and pink (ATL) start increasing once I started training again. This means that my fitness is increasing, but so is my fatigue. That's why my green (TSB) line is going down. You can see that in general the TSB is exactly opposite of ATL.
My goal is to try and get the blue line as high as possible before the season starts (without cheating and sandbagging my FTP). This means riding lots and lots of miles as a moderate intensity. On Feb 3 it starts to level out a bit. A week before that was our training camp, and that's why my pink line (ATL) jumped up so high. You can see that my green line is at an all time low around training camp. If I was to race the day after camp, I would have been really tired and had bad form. After camp I took a recovery week. You can see that the pink line (ATL) drops a bit and the green line goes up. As the green line was going up, I raced at Cedar Hill and won. The PMC predicted a good race, and it was.
At this point on my chart, the blue line is pretty high. That means I'm carrying maximum fitness. Since I was focusing on mostly the spring races, it was time to "withdraw some fitness from the bank." Since I was racing every weekend and recovering during the week, the pink line started to slowly decline and the green line was slowly increasing. This meant that I more or less carried good form all the way until mid-to-late April. The weekend of Joe Martin I was actually at my highest TSB. Unfortunately, I didn't go race. Bummer. I did a TT the following week and set my all-time PR on that course. I think that the fact that I wasn't racing Joe Martin was a reason for me to take some extra rest, which is what caused my TSB to rise so much. Unfortunately, these easy weeks also dropped my CTL a bit.
I felt great during that whole February - April stretch. I had pretty consistent results. No wins after Cedar Hill, but some results I'm proud of. After that stretch, it was time to try and raise my CTL a bit and get ready for crit season. You can see that I had a good 3 week build going into May. Then I probably took too much time off. I should have kept training a few more weeks in order to peak again for pro-am and tulsa tough. My TSB was really high at Tulsa Tough, but my fitness level (blue line) had already dropped some. I had some decent races, but nothing great to speak of.
So there are some ways that I think a person could "trick" the PMC but not get good results. For example, if I took a full week completely off from riding, the TSB would jump way up; however, I don't think that means I would race good. I never feel good after a full week off. If I took two full weeks off, it would even be higher, but I think I would race even worse.
TSB also doesn't know your strengths and weaknesses as a racer. If you are a poor climber with a high TSB going into a climbing race, it doesn't mean you'll win. You'll probably climb better than you would have with a lower TSB, but it doesn't turn you into a guy named Alberto. It also can't predict what will happen in a race. IF you miss the winning breakaway, you still lose the race, no matter what your TSB is.
So the PMC isn't perfect, but it does seem to line up pretty well with how I felt last season. By having this data, I'm able to perform small tweaks to my training this season to figure out how to bring better form to the races I really care about...hopefully.