John Milton's forth an interesting theory of effeminacy in his Paradise Regain'd. Satan tempts Christ in the wilderness to seize the Roman title of Emperor and rule the world. Christ rebuffs him, of course, and then lists the vices of Rome. Around line 140 in Book IV, Christ says:
Of triumph that insulting vanity;Here, the gladitorial games are said to be a "scene effeminate". Watching bloodshed not only moves one to bloodshed, it also makes one "effeminate".
Then cruel, by thir sports to blood enur'd
Of fighting beasts, and men to beasts expos'd,
Luxurious by thir wealth, and greedier still,
And from the daily Scene effeminate.
What wise and valiant man would seek to free
These thus degenerate, by themselves enslav'd,
Why is this? When men "daily" stir their passions, they become overcome by passions. Milton (who is often labeled as a misogynist) believed that women are moved more by their passions, while men are governed by reason. Bloodsport creates a need for passion in men and so Milton sees Roman debauchery and effeminacy deriving from their thirst for blood.
Perhaps, if Milton was so concerned with men becoming effeminate, he should have looked in the mirror. Check out the picture above for full details. All the same, I think it is an interesting theory.