Traditional research states that runners need carbohydrate to train
effectively, but new studies show the benefits of fasted training. A
nutritionist explains the 'train low, compete high' concept.
With fasted training, carbohydrate fuelling is completed after exercise
rather than before.
You
need energy to fuel you on a run, right? Not always. Fasted training,
in certain circumstances, can help boost your performance. It has been a
highly researched topic by many top sports science institutions around
the world over the past few years, with my colleague, fellow
nutritionist Dr James Morton, leading the way at Liverpool John Moores University.
For many, fasted training has proven to be an effective technique. It
is not a fad diet or a method to reduce calorie intake by skipping
meals – it is simply a strategic training method where carbohydrate
fuelling is completed after training rather than before, to enhance
adaptation and performance.
This new strategy is in contrast to traditional research that states
carbohydrate availability and muscle glycogen stores should be high for
every single training session and race. The importance of carbohydrate
for performance is well documented, so this new training technique has
been described as the "train low, compete high" model. This means
choosing a number of running sessions to complete in a fasted state to
optimise training adaptations, while actually racing with high
carbohydrate stores and availability to maximise performance.
The most practical way to complete fasted training is to train in the
morning, before having breakfast. Hydration is still important, so
water or a low-calorie electrolyte drink should be consumed. Fasted
training is best completed at an intensity and duration that does not
require a great input from metabolism: typically training for around 60
minutes at a moderate intensity is recommended.
The reasoning behind fasted training is that it further enhances the
mitochondrial adaptations that occur as a result of aerobic training.
This improves the body's ability to use fat as a fuel source during
exercise, sparing muscle glycogen for when it is most needed – during
the tough parts of a race. However, on race day the body must also be
able to use carbohydrate as a fuel source. This is why it is best to
select certain shorter training sessions to complete fasted, while
others should be completed in a carbohydrate-loaded state. This will
ensure the body is well adapted to using both fat and carbohydrate for
fuel during exercise.
Although this train low, compete high approach produces great
adaptations to training, there are limitations. The main drawback is
that during these sessions, exercise intensity may be compromised. When
training in a fasted state in the morning, liver glycogen is low after a
period of sleep. This can lead to reduced blood glucose, making
exercise seem more difficult. Muscle glycogen may also be low depending
on your activities and nutrition the evening before, so this can make
high-intensity sessions particularly hard to complete. Training with low
muscle glycogen levels can also lead to a hormonal and metabolic
environment that increases muscle protein breakdown and can impair
immune function.
So repetitive fasted training can actually have negative effects, if
performed over a long-term period. This again emphasises the importance
of splitting your training programme, so certain sessions are completed
fasted to promote adaptations, while others are completed with
carbohydrate intake.
Often people struggle with the concept of training fasted just
because of their habit of consuming breakfast beforehand. So another
option is to consume a protein-only breakfast (no carbohydrate) and
moderate doses of caffeine (about 100-150mg), as this helps prevent
protein breakdown and reduces the risk of fasted training affecting
exercise intensity. For example, this could be three scrambled eggs and a
cup of strong coffee. As previously mentioned, hydration is also
important, so a low-calorie electrolyte drink consumed before and during
fasted training can optimise hydration without compromising adaptation.
