How to Quantify Training

posted Jan 3, 2011, 7:33 AM by Donald Vescio   [ updated Sep 12, 2011, 8:12 AM ]

Athletes interested in improving their performances always look for ways to quantify the quality and volume of their training sessions.   The ability to quantify training not only is a prerequisite for developing a structured training program, it also provides valuable data for the predictive forecasting of future performance.  While quantifying training might seem easy to do on first consideration, it actually is a remarkably complex function that requires a strong understanding of the various factors that impact performance.

Cyclists, for instance, used to track mileage as a way to quantify training.  While it is very easy to gather mileage data—in its most simplest form, all that is needed is a reasonably accurate map—tracking mileage alone does not give a true profile of the stresses associated with a training session, let alone the stresses that accumulate over the course of weeks and months.    Mileage alone does not factor in such variables as terrain (was the loop hilly or flat), temperature, or wind; riding ten flat miles on a warm spring day is very different than riding ten hilly miles in the middle of a January freeze.  And while one could draw a very rough equation between total miles ridden and overall physiological impact, such correlations will be extremely rough and non-predictive of future performance.

The next step for cyclists, then, was to track both mileage and time per session.  By adding in the variable of time, a rough approximation of intensity could be determined.  As heart rate monitors became common, a third variable was added to the calculus, and today power data promises to provide a fuller, more detailed overview of athletic performance.

The key concept to take away from the example of cyclists is that a variety of data need to be used in order to develop, assess, and predict individual athletic performance.


TRIMPS is an abbreviation of TRaining IMPulse, which was an early method of quantifying training volume and its overall physiological impact.  The concept of TRIMP was developed by Eric Bannister in the mid-1970s and represents the product of training volume and training intensity.    In its most elementary form, TRIMP scores could be based on the product of average heart rate and time spent training:

Avg HR *  Minutes Training

Example: 120 average HR for a training session of 60 minutes would yield a TRIMP score of 7,200


The problem with this simple form of calculation is that it is possible to register a 120 average heart rate for 60 minutes in a number of ways, such as performing at a HR of 120 for the entire session (a steady effort), or by doing a series of high HR efforts of 190, followed by recovery at lower HRs (an interval session, for instance).  While the TRIMP scores for both the steady effort session and the interval session are the same in this implementation,  we know from experience that an interval session is more physiologically stressful than a steady ride at a conversational pace.

To better quantify training stress, it is possible to factor in time spent in specific heart rate zones, which provides a much more granular record of a workout session.  In this slightly more advanced model, a TRIMP score could be calculated as the sum of a series of time in specific HR zones:


Workout A
5min Zone One  *  112  avg HR  = 160   (beginning of ride)
25min Zone Two  * 128 avg HR = 3,200 (warm-up and warm-down)
15min Zone Three * 136 avg HR = 2,040 (partial recovery from intervals)
15min Zone Four * 159 avg HR = 2,385 (intervals)

Total Training Stress = 7,785


Workout B:
60min Zone Two * 124 avg HR = 7,440

Total Training Stress = 7,440

The advantage of this more detailed calculation is that it factors in different levels of intensity that might comprise a workout, but it still is problematic in that heart rate is not necessarily an accurate predictor of work actually performed.  Heart rate can drift upward during the course of a session due to environmental factors (temperature, etc.), or heart rate can be depressed by fatigue, over-training, or cold temperatures.  With the advent of cycling power meters, watts were added to training stress calculations, which provide an even more accurate accommodation of actual work performed.  Power meters work great for quantifying training stresses for cyclists, but their data does not accommodate training stresses associated with swimming, running, and other athletic activities.



Enter Perceived Exertion
While most of today’s emphasis is on power values when monitoring performance, there is a significant body of research that suggests that perceived exertion still is a valuable and potentially accurate tool that an athlete can use to govern pacing during endurance events.    There are a number of perceived exertion scales available.  Gunnar Borg’s original scale ran from values of 6 (20% effort) to 20 (exhaustion); more intuitive are scales based on a simple ten point spread:

  • 0 - Nothing at all
  • 1 - Very light
  • 2 - Fairly light
  • 3 - Moderate
  • 4 - Somewhat hard
  • 5 - Hard
  • 6
  • 7 - Very hard
  • 8
  • 9
  • 10 - Very, very hard

By carefully monitoring performance values such as heart rate and power, an athlete can quickly normalize their sense of perceived effort with actual field metrics.  Incorporating perceived exertion can involve little more than adding an overlay to TRIMP scores like those calculated above:

TRIMP * PE = Total Training Score

Example of a Hard Interval Session:  TRIMP of 7,785 *  PE of 8 = 62,280/100 =  623
(Note: I divided the final Total Training Score by 100 and then rounded up to the next whole digit to establish a more manageable value)


Acute and Chronic Training Stress
While factoring in perceived exertion into TRIMP calculations (whether the TRIMP calculations are based on HR values or wattage values) does a pretty good job in getting an accurate sense of the intensity of a specific training session, it only provides insight into a specific point in time.  Athletes tend to forget that the effect of training is cumulative, which can lead to exhaustion and over-training. 

There are two different types of training stresses that we need to consider: acute and chronic.  Think of acute training stress as the short-term impact of a training session.  For instance, we know from practical experience that we will be tired the day after an interval session, so we try to build in easier workouts between intense workouts to facilitate recovery.  Similarly, chronic training stress should be regarded as the cumulative effect that training has on use over an extended period of time.  For instance, most good training programs will be based on a pattern of relatively intense of training cycles that might extend over a period of a month or two, followed by one to two weeks of light activity, again to facilitate recovery.


Putting It All Together
Successful coaches and athletes consider the following variables when developing and updating weekly, monthly, and annual training plans:

·         The duration of training sessions

·         The physiological stresses of training sessions

·         The short-term (seven day rolling average) acute physiological stresses of a training program

·         The long-term (say, forty day rolling average) chronic physiological stresses of a training program


For multisport athletes, it is critical that metrics are used to do like-kind assessment within specific sport sessions, as well as metrics that can assess the overall impact of multiple sport training session.  What is important to keep in mind is that whatever method being used to calculate session stress  should be considered over short and long-term horizons and that individual session scores have value only when taken in aggregate.   The easiest way to see emerging patterns is to graph acute and chronic training stress over time:

The chart above tracks both my acute (blue) and chronic (red) training stress for the months of November and December, 2010.  Note the significant variations in intensity as signified by the peaks and valleys described by the blue line; this line is marking a pattern of intense workouts, followed by recovery sessions, on a weekly basis. 

What is more informative is the pattern described by the red—the chronic—line in that accumulated training stress has been gradually increasing since the beginning of November.  Based on my annual plan, I would anticipate that the red/chronic line will continue to rise for the months of January and February, after which I have scheduled two weeks of easy to moderate training to prepare for my next macrocycle.  As I accumulate more data as the season progresses, the peaks and valleys of these initial curves will flatten, making it even easier to track long-term trends.


A good coach will help you collect and interpret data associated with your training sessions.  It is not enough to gather lots of information; it is important to both collect data that will be useful, and carefully analyze the data on a regular basis within the context of your short and long-term goals.