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Most hormones are proteins, which are chains of amino acids. Just like the proteins you find in your eggs and meat that you may be eating on a daily basis, especially for you lot of athletes out there. Don't forget though, hormones can be classified as steroids too, which typically aren't allowed in sports!
Those marketers for growth hormones tried to market something that incites the production of amino acids. Bovine somatotropin, also known as bovine growth hormone (BGH) are for cows, like other hormones, it is produced in small quantities and is used in regulating metabolic processes. Porcine somatotropin are for pigs, which provides more rapid growth and a greater proportion of muscle to fat on less feed. Again, don't even think about trying this for yourself! They definitely will not work and it won't be a surprise that they will be harmful.
There are many other hormones out there and they control many different things, like thyroid controls metabolism. So this is absolutely essential for athletes to be aware of their metabolism. You would want a higher metabolism if you want your body to process things at a faster pace, and lower metabolism for a slower pace.