Depends on the steroid; mine (prednisolone) just used to make me absolutely manic, eat enormous amounts of food and sleep only 4-5 hours a night. I used to go into work and get there at 5.30am. Very aggressive too. Had I been cycling then it would have suited me doing audaxes. Also made me very big up top as the body was secreting fat in my upper torso.
Hope it's nothing serious. It never used to help my rugby training any as I was generally too sick to go and when I did I was absolutely exhausted (from being permanently semi-anaemic).
You should be okay Jonathan. A short course won't have that much effect.
I used to take 45mg straight off for a week then 35mg for a week, etc. then taper down to 5mg, 2.5 mg, 0.5mg to ween myself off. I took it off and on for 8 years and eventually when I stopped I ended up dragging myself around for a whole year being steroid deficient (permanently tired) as my body wouldn't produce the natural equivalent. It eventually kicked in but took a while.