IN THE LAST DECADE sports scientists have made great strides in
understanding how muscles work during exercise, how muscles recover, and the
primary causes of fatigue. A result of this research has been the development
of nutritional formulas that are far more effective in improving muscle
performance. Protein is an excellent example. At one time carbohydrate was
considered the only macronutrient essential for improving exercise performance.
Research conducted at leading universities in the ‘90s clearly demonstrated
that protein could improve endurance, reduce muscle damage, and even enhance
rehydration.
Most of this research was
conducted with whey protein. Whey
protein has many advantages for use during aerobic exercise. It is rapidly
absorbed, fast-acting, and contains a high percentage of the specific amino
acids known to improve exercise performance. If I could choose only one protein
to use in sports recovery and energy products it would be whey. However, as we
learn more about the metabolic processes that affect endurance and recovery we
now understand that it is possible to get an enhanced effect using a
combination of proteins.
Each protein has a unique amino acid profile. In other words,
each protein is rich in certain amino acids and deficient in others. The key
amino acids involved in sports performance include branched-chain amino acids
(BCAAs), leucine, isoleucine, valine, arginine and glutamine. Neither whey
protein nor soy protein is equally rich in all of these amino acids, but the
amino acid profiles of the two proteins is complementary, so that when they are
combined they create a better sports protein.
BCAAs can be readily utilized as an energy source during
exercise. During extended exercise, almost 20% of a muscle’s energy comes from
protein, primarily BCAAs. When a sports drink containing protein is consumed
during exercise, the muscles use this protein instead of breaking down muscle
protein for energy. This is one reason why a protein-enhanced sports drink
reduces muscle damage and speeds muscle recovery.
Of the BCAAs, leucine plays a critical role in turning on both
protein and glycogen synthesis, which is why it is such a key player in the
recovery process. Recent research shows that valine prevents the release of
fatigue signals from the brain, which play a much bigger role in the onset of
fatigue than was previously known.
Two other amino acids, arginine and glutamine, have roles in
improving muscle performance. Argnine serves as a precursor to the formation of
a compound that increases nutrient and oxygen delivery to muscle cells and
glutamine is the primary amino acid found in muscles. During intense exercise,
muscle glutamine levels are depleted.
The ideal protein would
have high levels of all of these key amino acids. As a single protein, whey
comes closest to filling the bill. However, by combining proteins we can raise
the levels of these key amino acids in a subtle but important way. For example,
soy protein has higher levels of arginine, valine and glutamine than whey
protein. Thus the addition of soy protein to a predominantly whey formulation
enhances the overall effectiveness of the protein component by increasing
nutrient delivery to muscle cells, preventing glutamine depletion, and
inhibiting the release of brain fatigue signals.
When it comes to protein in sports energy and recovery product, two are definitely better than one.
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