Frank Vandewiele

WHAT IS INTERVAL TRAINING?

Interval training is a training method that alternates periods of exertion with periods of passive or active rest and has been proven to have a positive impact on performance. After all, by using this method you can deliver more work than when you use the continuous form of training, especially when the intensity is quite high. This high intensity - an intensity that usually has to appeal to the anaerobic system - also ensures that the muscles are subjected to more strain and is therefore - in addition to the effect on the heart and blood circulation - also a kind of strength training for the muscles.

Initially, four variables determine the outcome: intensity and duration of the single effort and intensity and duration of rest. However, the final effect of such training also depends on the total volume - i.e. the number of repetitions per series and the number of series - and the duration and intensity of the rest between the series.

It goes without saying that if the mutual relationships of these variables change, the impact on the physiological response will be very different.

 Setting up an efficient interval training is therefore extremely complex.

TRAINING ZONES.

Effort zones arose from advancing scientific insights, but also from practical considerations specific to specific sports and disciplines. However, it is impossible to present here all the exercise zones used by trainers, athletes, sports doctors, exercise physiologists and others. Not only the number of zones can differ greatly, but also the variables on which they are based. For example, in the literature we find zones based on heart rate, on speed, on lactate concentration, on power, on oxygen consumption, even zones based on movement frequency.
However, as long as the duration of the single effort, the characteristics of the rest periods and the totality of the effort are not taken into account in addition to the intensity, the degree of strain of the zone in question cannot be mapped and therefore neither can the expected adjustment.

 Effort zones do have added value for the training method because they make us understand the need for different training levels, but they do not guarantee the training result.

LOAD INDEXES.

If we want to accurately calculate the “heaviness” of training and competitions, then “load indices” are necessary.
With the use of power meters in cycling, the term Training Stress Score was introduced about 15 years ago. This quantitative measurement gives a good picture of the external stimulus acting on the rider's body, but the physiological impact is far from clear. This is because TSS can have a comparable value despite the fact that completely different systems are activated so that the actual internal load on the body is incorrectly estimated.
Thanks to an update of the old Critical Power concept, Professor C. Dauwe was able to define not only zones but also load indices that calculate the “true physiological impact” of efforts.

 They are the basis for creating highly effective interval training.

BASIC PRINCIPLE.

As of the Recovery Threshold, comparable to the Maximum Lactate Steady State, the athlete has to call on his anaerobic energy reserve, but since the oxygen supply is not yet used 100% and can therefore still increase, the use of the anaerobic reserve will proceed “slowly”. We call it the zone of Slow Death. Once the VO2max is reached, with increasing intensity, all extra energy must come from the anaerobic system, so that the athlete quickly exhausts his anaerobic reserve. It is the zone of Fast Death.

 By definition, a score of 1 equals exhaustion of the anaerobic reserve once.

That depletion can therefore happen both slowly and quickly. If athletes train for better performance during long climbs or time trials, the interval training should focus on the score of the SD zone, if training for shorter explosive efforts, the attention should go to the score in the FD zone.

TRAINING MODULES FOR INTERVAL TRAINING.

Sportim developed modules that allow the athlete to set up the most efficient interval training based on the personal metabolic characteristics. This tool calculates on the basis of the chosen intensity (SD or FD zone) and the duration of the single interval what the contribution of the anaeobic system is, how quickly this reserve is used up and therefore how many repetitions are MINIMUM possible before it is exhausted (score = 1) (fig 1). Minimal, because depending on the chosen rest between the repetitions, the number of repetitions can be higher. This is the only unknown because the maximum possible number of repetitions does not only depend on the (rather fast) recovery of the anaerobic energy reserve, but is also determined by the recovery of other parameters such as PH, PCr, type of muscle fiber ... It is currently not possible to predict, depending on the chosen interval format, which system will most negatively influence the recovery and therefore the possible number of repetitions.

This imperfection is corrected in various ways in the modules.

• First of all, by calculating the total time the athlete trained at that particular intensity (number of repetitions per set and number of sets). These data are important for determining the size of the training effect (the bigger the load, the major adaptation we can expect) and for the interpretation of the athlete's current condition (fig 2).

• The load score (in the FD or SD zone) of the entire workout is calculated. This score can then be compared with the score of the competition for which one is training.

• Finally, the “exercise density” is also calculated. An FD score of 3 over a total exercise time of 36 minutes actually corresponds to an FD score of 10 over 2 hours.

• Both the load- and the density score are essential to compare the total load on the body during training with that of the intended competition (fig 3).

SUPERCYCLE AS “WEARABLE”

Wearable technology can no longer be ignored in the training supervision. They are getting "smarter" - at least if we are to believe the smartwatch manufacturers - but remember that "measuring” is not always “knowing".

Osborn Technologies and Charles Dauwe D.Sc. developed some widgets within the SuperCycle training app that do “measure to know”. Unique to this app is the possibility to display live the anaerobic energy balance and the corresponding load indices. Both the graphical and tabular summaries allow to evaluate the real load of training and competition (fig 4).

 It is therefore the ideal application to use together with the training modules.