Training load based on intensity zones

The most common method of training load (Volume x Intensity) is not suitable for workouts that have changes in intensity (ie. interval session, hilly run, cross-country skiiing). For example an easy run on aerobic threshold at heart rate of 131 for 58 minutes results in training load of 7598. Similarly, an interval session of 4 x 3 minutes maximal run with jogging for recovery may result in 58 min sesion with average heart rate of 131 which lead to exactly the same training load, but the second session is much harder and has a greater impact on organism.

To overcome this limitartion, Foster et al (2001) split the intensity scale into 5 zones.

Using intensity zones like above training load is calculated as the cumulative total of the time spent in each training zone. Coming back to the example above, an aerobic threshold run was done in Zone 1 that results in 1 x 58 min = 58. The interval session resulted 4 times 4 minutes at maximal speed (4 x 3 =12 min and for the jogging then 58 min – 12 min = 46 min). Intervals, maximum speed result in Zone 5, therfore 5 x 12 = 60 and jogginin Zone 1, 1 x 48 = 48, resulting in cumulative load of the training 60 + 48 = 108. We now see that the interval training session results in approximaltely 2 times higher load compared to simple volume x intensity method. Training zone based load calculation helps quite easitly to distinguish between hard and easy days in training program. An example is given below.

Table 1. An example of the trainings during a typical week. Training volume is given in minutes. Training zones are the corresponding zone numbers.

Figure 1. The resulted training loads of the example week given in Table 1.

There are limitations of this method, as strength training and technical sessions are difficult to evaluate according this scale.

See also Session RPE method for training load    Training stress score   Polar exertion index     Training effect