An alternative to training fasted?
Another cold snap is sweeping across the U.K. and with it the uncomfortable side effects of cold weather and short days. This can make your pre-season foundation training quite unpleasant. You have a choice of either going outside and freezing (and possibly slipping on ice). Or produce a puddle of sweat during hours of indoor training? In order to train the fat metabolism and thus our "foundation" in addition to the short and intensive work, riders have been looking for alternative training strategies. The “fasted training”, i.e. a training session without prior food intake, which promotes increased fat burning. However, few have the time and inclination to drag themselves out of bed in the morning to sit on the roller for an hour or more. So what are the alternatives that still achieve high fat burning?
The afterburn effect of physical activity
The initial idea comes from the "afterburn effect". It has already been shown many times that after a workout there is increased fat burning. This “afterburn effect” is characterised by an increased oxygen uptake after the end of training, the so-called EPOC (excess postexercise oxygen consumption). The extent of this effect depends on the intensity of the previous exposure. For example, a continuous 30-minute exercise of medium intensity (85% of VO2max) causes less oxygen uptake at the end of the exercise than four repeated 30-second "all-out" sprints (Fig 1).
Fig. 1 Afterburn effect (so-called EPOC) after various forms of training
Can this effect be used to make fat metabolism training even more effective in the evening. If no fasting training is possible, this would be an exciting alternative. For this reason, we compared different training sessions with each other that started with a more intensive interval at the beginning.
Classic fat burning training
As a base value, we first did a classic fasting training session in the morning (no breakfast, last meal 8-10 hours before the workout). During training on an empty stomach, the fat metabolism rate was 32 g/h at the beginning and increased to 37 g/h over the course of the hour (Fig.2). A super effective workout for burning fat, but we already knew that. To make things a little easier for my clients rather than do these rides fasted, i'd rather they were carb depleted but had consumed a high protein meal the evening before and on the morning of the session.
Fig. 2 One hour “endurance” riding on an empty stomach
Next we did the same continuous exercise (a few days later), this time only with well-filled carbohydrate stores (last meal 2-3 hours before exercise). Here the whole result looked very different. Especially at the beginning of the session, the fat metabolism is much lower (11 g / h) compared to the training on an empty stomach. Although it increases to 18 g / h over the course of the hour, it is still significantly lower than with an empty stomach (Fig. 3).
Fig. 3 Driving for one hour after eating beforehand
Fat metabolism training with an initial interval
With an almost “all out” interval at the beginning of the workout, we wanted to activate the energy expenditure first, in order to then intensify the basis with the “afterburn effect”.
This third workout was also completed with well-filled carbohydrate stores (last meal again 2-3 hours before exercise). At the beginning the lipid metabolism of 17 g/h was again in the similar range as in the previous unit (differences of approx. 5 g/h are in the range of the usual measurement deviation). After 15 minutes, an "All Out" effort in the form of a ramp (20W every 30 seconds until the max load was reached) was completed and then another 200W continuous load for 30 minutes. At the end of this load, the fat metabolism was over 30 g/h and thus increased by almost 50% compared to the beginning (Fig. 4).
Fig. 4 Increased fat burning in the base after an initial ramp interval
It is therefore clear that a high level of stress at the beginning of a unit leads to a significantly higher fat metabolism in the further course of the unit. So it seems to be possible to stimulate fat burning with an intensive interval and the resulting “afterburn effect”. This would mean a significant optimisation of the fat metabolism training, even if these units do not come close to the level of fasting training.
Incidentally, other tests with a wide variety of interval shapes gave similar results. It is important that the input exposure is required in order to enter into a so-called "oxygen debt". Here using the example of a 5 + 3 minute interval (Fig. 5).
Fig. 5 Increased fat burning in the base after an initial 5 + 3 minute interval
Why is that?
The reasons for this have not yet been researched in this specific context (afterburning effect in combination with fat metabolism training), but parallels can certainly be drawn with EPOC studies. It is important to note that the results presented here are based on a spirometric measurement methodology, which is known to be influenced by intensive intervals *.
Several reasons for the effect seen are discussed in the EPOC studies. In addition to the consumption of readily available carbohydrates, the higher input exposure primarily leads to changes in hormone regulation. After high-intensity units, increased concentrations of the hormones adrenaline and noradrenaline were detected, which have a stimulating effect on lipid metabolism. In addition, an already proven, higher concentration of free fatty acids and glycerol after intervals is also an indicator of a more active lipid metabolism.
It can therefore be summarised that in order to effectively train the fat metabolism, diet and so-called fasting training are still the best means. However, if this is not feasible, an “All Out” load at the beginning of a unit leads to a significantly increased fat metabolism rate and can be used as a “trick” to intensify a basic training that is too short.
This does not mean that from now on you should start all fat metabolism training with an intensive interval. The body adapts very specifically to certain loads. This type of training will be a different stimulus for the organism due to the changed hormone regulation and the resulting oxygen debt and consequently address other cellular mechanisms. As always, the "dose makes the poison".
Have fun burning fat!
The lipid metabolism rate, determined spirometrically, is ultimately based on a calculation from the ratio of oxygen consumed to CO2 produced and is not a direct representation of the processes within the muscle cell. The initially significantly higher lipid metabolism in the first few minutes of intense exercise is known to be due to a reduced CO2 release due to the restoration of the blood buffer system. However, we also tested very long periods of time (plus 2 hours) and saw the same effects.
Do you want to play it safe and find out your individual maximum fat burning zone? In our INSCYD PPD endurance performance diagnostics, we determine your “Fatmax” using a specific procedure. With this you can effectively find out where and how much fat you metabolise and thus control your training to the point.