The ß-agonist pathway may effect processes other than muscle sparing and fat loss. In fact in chickens ß-agonists were shown to be stronger growth promoting agents than steroids (believe it or not but poultry science folks are doing a lot of research trying to produce more muscular chickens since the muscle is the meat that we eat). In fact ß-agonists seem to produce muscle growth without the stimulus of exercise, something steroids have failed to do. However ß-agonists are not as effective in rats and the effects on humans is unknown. The ß-agonist clenbuterol can cause slow twitch muscle fibers to be converted to fast twitch fibers. It can also prevent muscle atrophy due to disuse. Other studies have shown that b-antagonists (agents that block b-receptors and prevent them from functioning) cause muscles to shift from fast twitch to slow twitch and cause muscle atrophy (muscle wasting or breakdown). These studies indicate that ß-agonists might play an important role in the maintenance of fast twitch muscle fibers and in maintaining and perhaps increasing muscle mass. It may be no coincidence then that large amounts of ß-agonists (adrenaline and noradrenaline) are produced during high intensity training sessions. Perhaps these ß-agonists are necessary in initiating the muscle growth stimulus.