Training aided by power meters is the best. Much of this glossary defines power related terms. For a crash course in terminology/methodology, check out these articles:
- power 411 at cyclingpeakssoftware.com. Most of Andrew Coggan's power principles are described in detail.
- http://midweekclub.ca/powerFAQ.htm, the wattage forum FAQ. The nuts and bolts.
- http://www.pdqcleveland.org/power.htm for a collection of resources.
TSS - Training stress score. Invented by Andrew Coggan at the request of Hunter Allen, TSS puts a numeric score on workouts normalized such that 100 TSS points = 1 hour at threshold. It also considers the variability of efforts and weights them accordingly. Go to the power 411 link for more beta on this critical measure of cycling stress.
CTL - Chronic training load. This can be thought of in general terms as fitness, or you might even think of this as base. CTL trends upwards during building periods, and trends downwards during tapering periods. During a solid race period, it will be relatively steady unless you do long and/or multi-day races. It is quantified by different methods in the literature; the method I use was developed by Andrew Coggan and is currently available to only a handful of lucky beta-testers.
ATL - Acute training load. Similar to CTL, except that it reflects more recent training. ATL is much more reactive to big rides and days off; it fluctuates quickly.
TSB - Training Stress Balance. A measure of the balance between CTL and ATL. A highly positive TSB means that you are quite fresh, but losing CTL. A negative TSB, on the other hand, means you've been training consistently. Very negative values = the proverbial pain cave.
Headroom - A term I like to use to describe where your current CTL is in relation to it's recent historical max. Everyone has a CTL limit based on genetics, training experience, type of training performed, life stress that must also be balanced, and time available to train. If you are very close to this limit, you will find it difficult to recover from intense efforts, while if you have lots of headroom, you might be unfit. The trick is identifying the amount of headroom that is ideal for each type of training block to maximize the gains for your hard work.