I decided to post for the first time to your thread because your question struck a chord with me because I have been interested in height research for a while now.
Mind you, I'm talking about actual scientific research - not the
horrible scams and lies that are spread all over the internet. Believe
me when I say that I've searched through all of what's to be found out
there and there's just not much to be found as far as true, scientific
evidence.
First and foremost, pills and injections, unless prescribed by and
taken under the strict guidance of a medical professional, should be
avoided at all costs. If you are talking about ordering substances like
these online, please reconsider for your own safety.
The fact of the matter is that you are limited by your genetics - and
the fact that your natural growth process has completed. As you may
already know, adolescent children that are in the midst of their
natural growth cycles can undergo a series of hormone treatments that
have shown success at helping them grow taller than their natural
growth cycles have allowed.
However, since you say you are 21 years old, this is naturally not an
option for you, as your natural growth phase is coming to a close.
However, what is an option is what is known as optimizing your current
height through a series of stretching and exercise as well as
nutritional regimens. What these focused exercises (among other things)
do for you is take advantage, in large part, of the naturally-pliable
cartilage that binds the vertebrae in your spine together. While this
may sound a little scary, its really not. What happens is that through
proper nutrition that strengthens your cartilage and stretching
exercises that help strengthen the muscles in your back that surround
your spine, you are able to actually gain an inch or even a little more
in height after a few months of effort.
Add in specific yoga and Pilates exercises that have been proven to
remedy any and all posture issues that you may have (and almost
everyone has, even if they cannot tell), there have been people that
have gained up to 3 inches in height naturally and safely.
Even something seemingly as simple as sleeping on your back (in a
proper manner and definitely if you don't have any medical conditions
that prevent you from doing so) without a pillow. What this does is
gradually and safely straighten some of the natural arch in your spine
and neck. While some arch is perfectly normal (and necessary) many
people develop more of an arch than necessary simply due to habits such
as staring at a computer screen for hours per day or sitting improperly.
All of these small factors add up.
I've found a few videos on YouTube that give you an example of the
exercises that I'm referring to and the only website that I trust on
the subject since it demonstrates nothing but natural, safe methods to
go about gaining height in this manner.
Personally, I believe that any kind of pills, lotions, or false shoe
lifts are not to be messed with. Faking your height with shoe lifts, in
my opinion, is kind of like living a lie. Sooner or later you may be
"found out." Also, popping strange pills or rubbing strange lotions on
your legs to "help you grow taller" is just junk science. If that stuff
worked, a major pharmaceutical company would have patented it and made
billions by now. Finally, scary surgery such as leg-lengthening surgery
costs a fortune ($50,000+), is extremely painful, and takes months or
even longer to heal. Added to that, if you make only your legs longer,
it seems to me that your body may look a little out-of-proportion.
I do feel for you since I was a relatively short man at 28 years old at
5'7" but after dedicating myself to a few months of stretching
exercises and diet I can honestly say that I am now 5'9". Certainly not
a basketball player by any means, but I am happier now that I am of the
"average height" for a man in the United States. I still do the
stretching exercises once a day (the videos I posted recommend twice a
day - which I did at first as well as the other recommended things that
the poster of the videos recommends at his website that you can find on
the YouTube page) and I have kept the same height for over a year now.
Good luck, SAR-21 and I hope this helps!