Setting up your HR zones is very similar to setting up your power zones. You'll need to know your resting HR, your max HR and your LTHR. You can get a good sense of your resting HR by taking measurements as you awaken every morning and averaging that number over a week. However, HR varies greatly based on illness, life stress, lack of sleep, a hard workout the day before, etc. So you should account for those things and take your resting HR on a "normal" week, whatever that means for you. To get your max HR and your LTHR, you will need to test. I recommend the same two references as I did above.
As with your CP, when you enter your LTHR, don't forget to backdate if you'll be importing data. This date should also be set to sometime before the first workout you plan to import. Now just one more thing before we dive into the good stuff.
Manually entering workouts
As I mentioned above, GC only provides you with as good of an indication of your stress balance as the data you put in. Sometimes you go on a ride and don't have your HR monitor, or ride without a powermeter, or you go to an indoor cycling class and can't upload the data to your computer. GC gives you an option to enter a workout manually.
Go to Ride -> Manual ride entry, and the window on the right should pop up. There is apparently a very minor coding glitch in GC, but when you first open this window, the fields next to "hours," "mins" and "secs" are tiny slivers. You need to expand the window by dragging one of the corners to expand the fields. Then just fill in as many fields as you have information for and click "OK." You notice that the number of fields in this window is rather limited, and you may have way more data at your disposal. Don't fear, you can enter all of that data in the next step.
Once you manually enter your ride and save it, go to your ride summary from the home screen and select the ride you just entered. Below your ride summary, you will see three tabs: workout, notes and metrics. Clicking on "metrics" gives you the option to fill in those fields that were lacking in the previous window. As an example, below is my 1.5 hour workout at M2. I know my time on the bike, my average watts for the workout, the KJs and my average HR. To enter those values, simply click the checkbox next to them and a field appears. Note that BikeScore and Daniels Points were filled in automatically, as those were the numbers automatically calculated in the previous step.
Now we're ready to dive into the good stuff!
BikeScore
BikeScore is a metric developed by Dr. Philip Friere Skiba and it gives a numeric value to your workout. A high score means a harder workout, a low score means an easier workout. Here's an explanation of how the number is calculated if you really want to get mathematical.
BikeScore gives you an indication of how hard you worked that day relative to your other workouts for a given time period. You can control that time period in Settings.
To set up the time period over which your score is calculated, go to Preferences and click on "Settings." In "Basic Settings" you want to change the value BikeScore uses to calculate your score. I have mine set on 28 days (4 weeks). In short, BikeScore numerically answers the question, "how hard did I ride today?"
Relative intensity
Similar to BikeScore, relative intensity numerically answer the question of "how hard did I work?" Unlike, BikeScore, however, RI is a simple mathematical formula I can wrap my mind around without getting the MEGO syndrome (my eyes glaze over). RI = xPower/CP(FTP). So RI is simply a proportion of your normalized power (discussed in Part I) to your FTP, or as I've been referring to it here, CP. As your fitness improves or declines, it's important to continue testing and update your CP to make sure this and other metrics are true representations what you're seeing.
Performance management metrics
Now, finally, we get to talk about stress scores and stress balance. GC offers three separate PM metrics you can use, Daniels, Skiba and TRIMP. I will go over all three in this blog, but my advice to you, pick one and stick with it. By the end of this section, you should be able to determine which metric will work best for you. All of them show similar data in slightly different ways and use different mathematical formulas to arrive at the numbers, but because all of that data is relative, as long as you don't try plotting Daniels STS vs. TRIPM LTS and making sense of it, you should be fine. I also find it very helpful to look at several metrics plotted on one graph, so I can see the relationship among them.
Looking at Daniels STS, Skiba STS and TRIMP STS plotted on one graph, you can see that the trend lines have a similarly trending slope even when the stress values are different due to the different formulas.

Let's look at this in detail. While the general similarities are visually obvious, it is more interesting to look at the differences. Note the difference in the first three plot points between TRIPM and Skiba. Namely, the second plot point is missing from TRIMP. Why is this? Well, the missing plot point on Nov. 2 is from my indoor workout and I didn't look at my average watts before I left. For TRIMP, if there are no watts, there is no plot point. Which may not make it the optimal metric for you if you sometimes ride without a power meter. While I try to do all of my training with a power meter, sometimes I race without one, or as above, I forget to record my average watts before leaving the cycling studio. Thanks to a comment by one of my readers, I realized I had this completely backwards. TRIMP uses HR primarily to calculate the intensity of the workout. BikeScore, on the other hand uses your xPower to calculate intensity. So why is that plot point missing? This appears to be a GC issue. I noticed that when I upload manually, there is no zone indicated in my ride summary, even if I enter my average watts and HR manually. I have a suspicion that TRIMP needs HR in zones to run the calculation, while BikeScore simply needs a watts entry. So unless you're uploading your ride from somewhere, you're not going to get a TRIMP calculation in GC. If anyone has any insight on this, I'd greatly appreciate it!
The next thing to pay attention to is the difference in trend lines among the three metrics. Despite some missing points, TRIMP and Skiba trend closely. They look identical, but because I eyeballed it, they are likely slightly different. However, Daniels is clearly a shallower slope. Why is this? Well, unlike TRIMP and Skiba, Daniels assigns difficulty to your workouts in a linear manner. Meaning that two one-hour workouts equal one two-hour workout, assuming the same intensity. Additionally, it was originally developed by Jack Daniels (no joke) for runners and has been adapted in GC to cycling.
The difference is clear if we examine TRIMP and Daniels side-by-side (the bars are TRIMP and lines are Daniels):
Let's look at the last three days on the graph and run some numbers. First let's compare the relative intensities for Nov. 18 and 19 for Daniels and TRIMP. On Nov. 18, I rode for 2:58 at 188 xPower, and on Nov. 19, I rode 5:13 at 191 xPower. The ratio of relative intensity for Daniels of Nov. 18 to Nov. 19 is .48. So my Friday ride was 52 percent less intense than my Saturday ride. However, according to TRIMP, the same ratio is .45, so the Friday ride was 55 percent less intense. That's pretty close. This gets even more interesting, however, as we compare Friday (18th) with Monday (20th). On Monday, I rode for 3:47 at xPower of 172.
The TRIMP score is higher on Monday, but the Daniels score is lower. The Daniels ratio for Monday as compared to Friday is 1.07. So Friday's ride was 7 percent harder than Monday's. The same calculation for TRIMP yields .94, making Friday's ride 6 percent easier. If you're keeping score, that's a 13 percent difference! So when did I work harder? I used BikeScore to settle the argument, and it appears that TRIMP and BikeScore are in agreement, 3:47 at 172 is in fact a harder workout than 2:58 at 188. Remember that BikeScore is the Skiba equivalent of TRIMP points and Daniels points.
[This paragraph was edited from the original version to coincide with the changes above.] From the above, you can probably guess which system I use primarily to track my stress - Skiba. From personal experience, I know that two hours at 200 watts are more than twice as hard than one hour at 200 watts, so Daniels just doesn't make sense from that standpoint. While I sometimes ride/race without my heavy Powertap wheel, I can use estimated watts to get a relatively close BikeScore. As mentioned above, due to an issue between GC and Garmin, TRIMP points don't calculate if you enter your ride manually, and I haven't yet been able to figure out how to resolve that issue. Again, any insight here would be very helpful.
Now let's check out the PM metrics that help track overall stress in all three systems.
Daniels metrics
Below is a plot of my Daniels LTS, STS and TSB.

As I mentioned above, you can see that STS rises more acutely than LTS, and the TSB line appears to be the exact opposite of STS. TSB is the difference of LTS and STS, so as you can see on the graph, when STS and LTS intersect, TSB equals zero - a point where you are neither fresh nor exhausted. I've selected the view of "This Month," but obviously there are a few days left this month and my last ride was on Nov. 20. GC projects STS, LTS and TSB to the end of the month as if I will do nothing for the remainder of the month. Extending the graph thusly, you can see that a few days off will have my TSB in positive numbers. In practice, after the build period(s), there will be a peak period where my training will be tapered and my STS will drop, but not as smoothly or acutely as in the graph because I will still ride, just at a lesser intensity or lower volume - it will be a jagged plot trending downward. How positive your TSB has to be for you to be refreshed yet maintain maximum fitness is extremely personal.
Skiba metrics
This is how the same data is represented when plotted with Skiba metrics.
As you can see, the lines of LTS and STS are similarly plotted in that they are lines, but the TSB is plotted as a bar graph. However, the metrics should be interpreted the same way. When LTS and STS intersect, TSB equals zero, and the remainder of my explanation in Daniels (above) applies equally here.
TRIMP metrics
TRIMP metrics, when plotted, look very similar to Skiba.
As you can see, I can just copy+paste the paragraph from the Skiba section, but I trust in your abilities to scroll up and substitute "TRIMP" for "Skiba."
Now what?
That is exactly the question I would be asking if I read the above post and it ended with the above paragraph. I've crunched some numbers, described some metrics and gave you a few how-to tips. But what you really want to know is how all of this can make you a better cyclists. In one paragraph below, I'm going to try to digest everything above into some advice you can take on and off the road as you gear up for season 2012.
Upload as much data as possible. If you have no data at all, but are experienced, you can probably estimate. Even if you estimate on the lower end, it will be better than having a rest day recorded if you record nothing at all. You now know how to upload from your Garmin and how to enter data manually, so there is no excuse. Monitor your training. As you go from week to week in base, you should see your STS rise acutely overall and your LTS rise gradually, with your TSB getting more negative. After a rest week, your TSB should be higher (a lower negative number) than it was at the end of your last training week. If it's not, you're working too hard during your recovery weeks and are not letting your body absorb all of the fitness you've gained. As you head into the build phase of your training, STS will rise even more acutely and LTS will continue to rise gradually, with TSB falling. You should see the same trends in your rest weeks in build as you did in base. Once you start peaking/tapering, your STS will gradually drop, and LTS will drop but even more gradually. Eventually, STS will catch LTS and your TSB will start trending into positive numbers. This is the point where you will likely have some of your best performances, but exactly how positive you have to be is up to you and your coach. Lastly, pick a metric that works best with the type of training you do and equipment you have and stick with it.
References and helpful links
Here are some references and helpful links to help you do further research, or go deeper where I merely gleaned over.