we all know Glucocorticoids are very spread drugs on the doping-world!!they are use on cycling,football,climbing,cross country skier,thriathlon,rugby etc..in cycling "cortizon" is a drug with a tradition with more then 40 decades!!and many cyclers have reported after they have finish they carrier that they have win different races because of that drug(long time before EPO has come in).there are several Glucocorticoids that athletes are using:hidrocortizon,prednison,prednisolon,methylpr ednisolone,betamethazone,dexamethazone etc..
from my reasearch i know some good reasons why Glucocorticoids(GC) are good for endurence:
1)GC increase gluconeogenesis,which will release glucose in the blood,made out of the glicogen from the liver...the released glucose into the bloodstream will work as an energy supplier,but also will hit pancreatic receptors which will detect abnormal high levels of sugar in the blood and they will release INSULIN..HMMMM....INSULIN-A GREAT HORMONE INDEED!!BUT FOR RECOVERY ONLY!!not as pre-work out!!INSULIN it is counter productive to ATP production.INSULIN it is the hormone that after a work out will stop producing ATP levels,because the body needs to regenerate....
2)The metabolic effects of these compounds consolidate glycogen reserves in muscle tissue and accelerate lipolysis and glycolysis mechanisms induced by catecholamines and growth hormone;
3)Stimulation of fat breakdown in adipose tissue: The fatty acids released by lipolysis are used for production of energy in tissues like muscle, and the released glycerol provide another substrate for gluconeogenesis;
4)Inhibition of glucose uptake in muscle and adipose tissue: A mechanism to conserve glucose,which will be use later as a second for of energy;
5)neurostimulatory effects at cerebral GC receptors could attenuate central impressions of fatigue, and anti-inflammatory and analgesic effects could inhibit sensations of muscle pain on effort as well as raising the fatigue threshold;
6)They also increase users’ tolerance for pain and enable them to sustain efforts that would be unbearable under normal conditions;
7)GCs inhibit the production of prostaglandins!!this has 2 major benefits:
a)it will inhibit prostaglandines from the muscle cells which will allow muscle to contract forward and forward,because you know when you exercise your's body respond by releasing prostaglandines in every tissues,to the point you will almost can't move..not to mention to perform..this is what happenes when you have fever from exercise-it is from prostaglandines...you know that all the couch tell you to take an aspirin if you have fever & muscle cramps..and yes this is good because aspirin inhibit the production of PG,but remember that aspirin is a non-steroidal drug,much more weaker then GCs..so when you use GCs you will avoid any over-trained symptoms,and you will regenerate faster;
b)it will inhibit also the prostaglandines from the lungs which will cause Bronchoconstriction,with consequent coughing, wheezing, and shortness of breath.We all know that Exercise induced bronchoconstriction,and that's way after long exercise you will feel that you can not breathe anymore.GCs inhibit this effect.this is how GCs will give more AIR to you;
8)GCs blocks endogenous release of ACTH,so your's cortizol levels will be shut down by feed-back mechanism.Blood levels of ACTH,beta-endorphin, cortisol, and cortisol-binding globulin were lowered by GCs(Dexamethazone in this case) at rest and after exercise in one scientific study;
9)They possess pronounced anti-inflammatory activity and cause alteration of connective tissue in response to injuries. The anti-inflammatory and connective tissue effects of glucocorticoids might mask injuries;
10)it remove the lactic acid by converting the glucose via the Cori cycle in the liver(gluconeogenesis)
unfortunely GCs have some effects which are counter-productive to endurence also:
1)Glucocorticoid treatment is often linked to increased whole-body energy expenditure and hypermetabolism. Glucocorticoids affect mitochondrial energy production, notably in the liver, where they lead to mitochondrial uncoupling reducing the efficacy of oxidative phosphorylation.( a metabolic pathway that uses energy released by the oxidation of nutrients to produce adenosine triphosphate (ATP))
2)Glucocorticoids seem to reduce the effect of erythropoietin on these cells, most likely due to anti-inflammatory effects (the reduction of prostaglandin formation, since prostaglandin E2 has a stimulatory effect on erythropoietin action;
it seems that short-term administration of GCs(few days) before a competition has most of it's beneffits,and this 2 side-effects that i have mention don't have time to make serious problems!!
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Originally Posted by peachfuzz
why you think?because it decrease peformance?of course not 
