If you’re the sort of person who
just likes to see the result of something, feel free to scroll down to the last
paragraph for the take home message of this post.
Nutrient timing is all about
focusing on when to eat, not only what to eat and there are four main
principles that we, as coaches and athletes need to be aware of:
1.
Enhancing
the performance of individual training sessions.
2.
Enhancing
recovery following training
3.
Enhancing
net protein balance (providing an anabolic environment), and
4.
Enhancing
the adaptations to training programs over the long term.
I’m going to use this blog in
the context of the strength/power training athlete (weightlifter, powerlifter,
strongman, discus/shotput/javelin, sprinter etc). However the principles are applicable to
longer duration training with some adjustments.
Strength/power training is
primarily anaerobic. The athlete will
use ATP-PC and stored glycogen for fuel during the workout, as well as small
amounts of fat. Fat is generally not
utilised during the workout as an energy source as beta oxidation is too slow
of a process to generate the amounts of ATP necessary for high intensity
anaerobic training.
With this in mind, there really
hasn’t been any conclusive evidence that supplementing with carbohydrates (CHO) or
protein BEFORE an individual training session has much benefit FOR THAT
SESSION. However, this is not to say
that it isn’t a good idea, as supplementation with both protein and
carbohydrates has benefits in the longer term and in recovery.
Longer term effects of supplementation and timing of
nutrients
An intense resistance training
session can reduce muscle glycogen by 25-40%, depending on the session.
If this isn't replenished, subsequent workouts will suffer. It is
therefore important to replenish you muscle glycogen, especially if you're
doing more than one workout a day, or workouts clustered together (you crazy
crossfitters you!)
However, this is not to say that
you can go and scoff down three kilos of sweet potato as there is a limit on
the rate of muscle glycogen synthesis of about 1g/kg/hour. This level has been shown to replace up to
90% of muscle glycogen. This seems like a lot, however, remember that
your body is primed after exercise to use whatever you put in it for recovery
and adaptation to training, not storage.
It does get better however, as studies has shown that ingesting both
protein and CHO directly following a workout will replenish muscle glycogen
faster than CHO alone and do so with less CHO, around 0.67g/kg/hr. This leads to faster recovery and the ability
to hit high intensity workouts sooner and do so with more energy.
Protein/amino acids and muscle damage
A well as replacing lost glycogen, efficient recovery also
includes reducing muscle damage. Even a
small amount of protein (10g essential amino acids) ingested after physical
exertion has been shown to be enough to stimulate muscle recovery and reduce
muscle damage, as shown by the blood levels of creatine kinase.
Of the essential amino acids, three have been shown to
significantly reduce muscle damage, as much as a full dose of EAA’s. These are the branched chain amino acids
leucine, isoleucine and valine. An equivalent
dose of BCAA’s was shown to be more effective than whole protein sources at
reducing muscle damage and aiding recovery.
This study also investigated the effect of supplementing with BCAA’s on
DOMS and found that they caused a significant reduction in subjective levels of
DOMS compared to the whole protein and control groups.
In summary, taking a CHO /protein supplement immediately
following training will replenish muscle glycogen and BCAA’s will reduced
muscle damage and DOMS. This would be
especially important for people competing in multiple workout events, hint
hint.
Net protein
balance
The central focus of resistance training is maximising the
anabolic response. This includes having
a positive protein balance and an anabolic environment (building, not breaking
down). There are three ways we can do
this, increase protein synthesis, decrease protein breakdown, or a combination
of both.
EAA’s have, when ingested after training have been shown to
cause an improvement in net protein balance and stimulate an anabolic
environment with whey protein being shown to be superior to both casein and soy
proteins.
Not surprisingly, when both CHO and protein are ingested
directly after exercise, there is a significant increase in muscle protein
synthesis which is greater than only taking a protein supplement. It appears that EAAs/protein taken directly
after a strength/power training session enhances protein synthesis and supplementing
this with CHO inhibit protein breakdown.
The take
home message…
To maximise any training program, you need the right
nutrition. This isn’t only a case of
what to eat but also when to eat it.
We’ve seen in this post that supplementing your training with both CHO
and protein directly after exercise will enhance muscle glycogen synthesis,
inhibit protein breakdown and enhance protein synthesis. Additionally, supplementing with BCAA’s will
decrease muscle damage and hence improve recovery and decrease DOMS. This has the effect over the course of a training
program and enhances recovery and adaptation to the stimulus.
