So what is it all about, why is it so exciting and why should you be paying attention? ‘Cause if you want to get faster you should be paying attention.
Training with a power meter gives you a clear picture of what went on during a single ride or race. The downloadable data, when analyzed with CyclingPeaks creates a huge amount of information – average power, normalized power (Pn), intensity factor (IF) and more. Andrew Coggan, Ph.D designed a metric called Training Stress Score (TSS). CyclingPeaks will calculate a TSS for individual workouts using ride data and your current Functional Threshold (FT). TSS is a numeric measure of training stress which is determined by how hard and how long you were pedaling.
TSS = IF x IF x duration in hours x 100
IF = Pn/FT
A single ride TSS is like looking at a single tree in a forest. You get a nice picture of that tree but don’t know where it sits in the forest. The beauty of the PMC is it tallies up TSS over time to give a bird’s eye view of the forest – or your entire season. The PMC tallies up TSS data in two categories, Chronic Training Load (CTL) and Acute Training Load (ATL). CTL is an exponentially weighted average of TSS per day with a 42 day time constant. Or in other words it takes into account the last six weeks of training. ATL is the same but it has a time constant of seven days, so considers only very recent training.
CTL is a measure of fitness. A lot of training over a long time gives a high CTL or high fitness level. ATL is a measure of freshness. Following a big training week ATL will be high and you will be tired. Conversely a low volume week will produce a low ATL and you will be fresh or have
The final key metric the PMC tracks is Training Stress Balance (TSB).
FYI tidbit: the term TSB was coined by none other than LW Coaching coach Dave Harris during the development of the PMC tool.
TSB = CTL – ATL
TSB can be thought of as “form”. When you are really fit (high CTL) and really fresh (low ATL), TSB will be high. This is peak form and the type of scores you want to have on your “A” race day.
The PMC can be used retroactively to look at CTL, ATL and TSB scores during times you had personal best performances and during times you thought you should have but didn’t. It can be used for forward planning to target a specific CTL, ATL and TSB known to put you in peak form and to time it to land smack bang on race day. The PMC takes much of the guess
work out of training and peaking.