I'll cover some of the different benefits of wearing compression gear. I encourage you to read this page before making a decision on which compression garment is best for you. All brands have there own strengths, weaknesses and the most expensive does not always mean its the best garment for your bodies needs.
Increased Circulation:Faster delivery of blood to the muscle and quicker removal of waste; grandpa had it right.
The main benefit advertised are claims around the performance if you wear the garments. The next time you are on a longer flight wear some compression socks under your jeans. See how you feel. The reason is that increased circulation is claimed to give you benefits in performance. Speeding up blood flow, you get nutrients to your muscles faster and remove waste products such as lactic acid more efficiently. This means that you should experience a higher level of performance with faster recovery times when wearing garments post exercise. This in turn will let you train harder in your next session. I have felt this at training camps in the past.
In Arizona at a Coach Troy training camp, I put on compression tights and a compression top after a very cold swim and 80 mile bike ride when it SNOWED in Arizona. I was so cold that when I returned even a hot shower didn't warm me up. I put everything I had (that was clean) on. The next day I felt fresh and ready to go. The difference in my entire body from one day to the next was night and day. Notably, my compression top made my tired arms feel awesome. This same top is gettin' a bit ratty. What I learned from my favorite triathlon store is that compression tops don't sell. Interesting but not surprising. Most amateurs don't swim enough either so why would they buy compression tops? Swimming is a topic for another day.
It is worth pointing out that in this case often you are getting better performance from garments that have a higher price tag as more money has been put into the research and design of the product. Some garments have features like graduated compression (tighter in extremities) and compartmental compression (meaning = tighter in certain areas), there are both positive and negative outcomes form these features. Remember, its not always science that determines the designs.
Reduced Muscle Oscillation:Every time you move your muscles move too. Watch the "slo-mo" of the running in Kona. It looks violent. When muscles move small tears appear within the muscle tissue. The presence of these tears along with the build up of lactic acid is what causes muscle pain both during and post exercise. Reducing the rate at which this damage takes place allows the athlete to work longer and experience less pain following training. The principles behind stopping body shake are very old and probably the best example is the wearing of appropriate sports bras in female athletes or the jock in male athletes. Imagine having the wrong type of jock as a dude? Ouch. Squish. In the last NBC coverage of the 2010 Ironman World Championship, one female athlete very obviously didn't have enough support (or coverage for that matter). These are the reasons that your garments must be firm fitting and appropriate for your sporting activity.
Thermoregulation:Your body will operate best when at the right temperature, muscles must be kept warm for optimal performance and to avoid injury, but overheating is just as bad, it puts stress on your heart and slows your reactions. Thermoregulation may be one of the most beneficial features of wearing compression garments. Often it is overlooked. It is important to consider where you will be wearing your compression wear because the brands all use different but similar fabrics.
Increased Proprioception:Having a garment that is effectively a second skin you are heightening these senses. This is achieved through the contact with the skin and the elastic properties of the fabric. These are heavily used in the NBA. Watch any game and you'll see at least two or three in use any night.
Increased Muscle Power Output:There are claims that the stretch in the fabric will help with power output aiding the reflex and the movement in general. The suits that were tested are the ones worn by elite Olympic athletes. These so-called "super suits" are not available in your local sports store and are much heavier and over larger amounts of compression. The jury is still out.
So... what do you need? I own a compression top. Soon to be two as one may turn into a bike rag soon. Compression shorts - not sure the comfort loss is worth it. Perhaps in a bike time trial and certainly not in a long distance triathlon without some design changes. Compression tights - really quite awesome except for one thing they chafe in odd areas and would not recommend them for long runs. Lastly, compression socks and sleeves - I have never raced with them. I have worn them for long flights to Kona and the west coast as well as for recovery. For a long day like Ironman
Before the last paragraph... I am not sponsored by these companies and have never received any free product from these companies or their subsidiaries.
I really like the Zoot compression tights and top. 2XU makes a very good compression top. For socks, I like the CEP socks a lot. CEP are notably better than the Zensah in that after many wearings and washings. The Zensah lost shape after a lot of washings. They did still work though. I'm convinced they work for recovery. Racing? Not sure personally. My personal results for the last four years have been awful. Maybe I'll give it a go - although if you aren't training much it will affect your results more than any compression gear.
Credit to my friend Fernando in New Zealand and Jon at the Australian Olympic Committee for giving me the "science content" of this blog entry. Friendships forged in the lava fields go far beyond "normal" friendships.