As always, if you just want the take home message, scroll to
the bottom paragraph…
It is a well established fact that athletes need more
protein than non-athletes. It has been
shown that, depending on the sport, athletes need anywhere from 50-175% more
protein than the average person. This
post will be a bit of a continuation on the last one on nutrient timing. We’ll have a look at a couple of specific
substrates and what they do, namely essential amino acids (EAA), branched chain
amino acids (BCAA) and glutamine, and their effect on the strength training
athlete in particular.
EAA’s
The twenty basic amino acids can be broken up into two
groups, essential and non-essential.
Non-essential amino acids can be synthesised by the human body and we
therefore don’t need to obtain them from food.
Essential amino acids are just that, essential, as we can’t synthesis
them. There are 11 non-essential amino
acids and 9 essential AA’s. When looking
at the quality of a protein source, it is the EAA content that is the guiding
factor. In this regard, animal and dairy
proteins are higher quality as they contain more EAA than plant based proteins,
including supplements.
What’s interesting is that EAA supplements have been shown
to stimulate as much protein synthesis as whole protein sources containing the
same EAA content. The particular study found
that a 180 calorie supplement, containing 15 g of EAA, stimulated as much
protein synthesis as 850 calories of whole protein sources with the same EAA
content.
It pays to look athe amino acid profile of any supplement
you’re buying. Some are a bit dodgy and
while they might be marketed as a whole protein source, the fact is that
they’re really not that good as they have a lower content of EAA.
BCAA’s
We looked at BCAA in the last post regarding their timing
around training. However, BCAA are
unique among amino acids in their ability to regulate metabolism, neural
function and blood glucose and insulin levels.
The synthesis of BCAA in vivo is low however and they’re seen as the
rate limiting step of muscle protein synthesis.
This means that without them, protein synthesis can’t continue.
Orally ingested BCAA appear in the blood stream quickly
which allows them to be supplied to the working or damaged muscles to stimulate
protein synthesis. It is interesting to
note that BCAA have been shown to stimulate as much protein synthesis as EAA
with the same BCAA content. So, we can
say that it is the BCAA component of EAA that is stimulating protein
synthesis. However, only Leucine was
able to stimulate a comparable amount of muscle protein synthesis
independently.
Supplements that contain a sufficient amount of leucine have
been shown to shift the athletes net protein balance from negative to positive
to promote an anabolic environment. Additionally,
whey (which contains 36%more leucine
than soy protein) can stimulate 33% more protein synthesis after exercise than
soy. This is due to the increase leucine
content of whey protein compared to soy protein.
Therefore, we can say that an athlete’s protein requirements
should be based on leucine content first, then BCAA, then EAA content of the post
workout supplement. Again, this should
be dairy and animal based protein rather than plant based.
BCAA combined with resistance training were shown to
increase lean body mass, strength and decrease body fat. They also aid recovery by minimising DOMS and
increasing testosterone.
While leucine is the BCAA that is responsible for the
majority of the effects of protein supplements post workout, it is currently
thought that it achieves this via its metabolite β-hydroxy-β-methylbutyate
(HMB).
HMB
This metabolite of leucine, HMB, has been shown to speed
muscle repair, and hypertrophy after resistance training in both trained and
non-trained individuals. However, it is
most effective when the training stimulus is novel. Novel training stimuli cause more breakdown
of muscle tissue and hence HMB can stimulate more protein synthesis and a
larger adaptation.
HMB therefore is best taken during periods of training when
novel stimuli are introduced (crossfitters take heed!) rather than maintenance
or off season training.
If this was a novel training stimuli for her, she could benefit from HMB.
Glutamine
Glutamine is an amino acid, the synthesis of which, under
stressful conditions, is impaired.
Intense exercise decreases blood levels of glutamine, therefore limiting
its availability as a source of nitrogen for protein synthesis and for immune
cells, which use glutamine as a fuel.
Glutamine also has a role in whole body carbohydrate storage
in that it has been shown to induce net muscle glycogen synthesis. Further to this, when taken with glucose,
glutamine also promotes storage of glycogen in sites outside the skeletal
muscles (i.e. the liver), which is an important step in blood sugar regulation.
The take home message
In terms of amino acids, 8-10 g of EAA or 3g leucine combined
with 1.5 g of isoleucine and 1.5 g of valine taken before exercise is
sufficient to maximise protein synthesis to aid recovery and increase the
protein balance.
To further benefit the athlete in terms of decreasing muscle
damage from training, 3-6 g of HMB can be taken daily before exercise. Again, this is most effective when combined
with novel training stimuli.
Glutamine is best taken in 6-8 g doses consumed after
exercise when carbohydrates are being consumed to increase the muscle glycogen
and whole body glycogen stores.
So there you have it. If anyone is after any more specific information on what presented here, please don’t hesitate to message me or leave a comment.
