It has a huge effect when you are in a weakened state (like AF). as your adrenals get excited and release adrenaline during the deed. then have to work harder to replenish lost hormones. It can definitely wear your energy down and help tire the adrenals - especially when they are week.
If you must do it, I recommend not doing it to completion - until you are stronger. you'll "know" when you can handle it and it doesn't cause such a draining effect anymore.
You might want to into the Aneros line of prostate massagers. They can be deeplysoothing and relaxing and less draining than spanking the money traditionally.