Choosing protein shakes as a means of getting well-defined muscles has become an increasingly common practice. There are different protein supplements on the market, many in the form of powders that you can make into shakes for use before or after workouts or use as meal replacements. Sources of protein powders include whey, casein and soy.
Protein Sources
Whey protein is easily digested and absorbed by the body and is often taken after an intense workout to aid in muscle recovery. Casein protein, on the other hand, is effective for allowing slow, extended release of the protein into your system. This is often used before bed or in the mornings and is absorbed into your body over a longer time frame than whey. Soy protein is a plant-based alternative for those who prefer protein that is not from an animal source.
Whey Absorbed Faster Than Soy or Casein
The "Journal of Applied Physiology" published a study in September 2009 reporting on the effects of different protein sources on young men's muscles. Healthy subjects were given whey, casein or soy protein isolates and tested both at rest and after exercise. The researchers observed that muscle protein synthesis was 93-percent greater after taking whey protein than casein and 18 percent greater than after taking soy. The conclusion was that while both soy and whey are quickly-digested proteins, whey is faster, but both whey and soy are more quickly absorbed than casein.
Other Ingredients
Many protein powders contain other ingredients. Creatine may be added to improve muscle size and boost strength. Glutamine is an amino acid used up quickly by the body that may be added to a supplement to enhance muscle building. Branch-chain amino acids, or BCAAs, which include leucine, isoleucine and valine, are sometimes included for muscle growth and improved endurance. Some brands will have additional vitamins and minerals or carbohydrates.
Choosing a Protein Shake
The amount of nitrogen replaced by 100 g of protein powder is a measure of the biological value, or BV, of the shake. Whey has the highest BV at about 104, casein measures 77 and soy comes in at 74.
If you suffer from milk allergies, you should avoid casein and whey proteins, both of which are derived from milk. Be careful not to consume more protein than your body can use. The excess has to be eliminated from the body and can cause discomfort such as gas, cramps and lethargy. One gram of protein per pound of body weight meets the muscle-building demand.
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