Early and Longer Period?

[bathtub-koipond.livejournal.com]

So, usually my period comes about the 18th of each month and lasts about 3-5 days, but this month it came on the 7th at it lasted for about a week...Now I know the length isn't too bad or outrageous but I'm just curious as to why it came early...

Though I recently started fencing about a month ago, and I go for about 2 hours, twice a week (4 hours total, plus about an hour during the week I practice by myself), and let me just say now that fencing TEARS your legs to hell, well basically just your lower body....so I thought this might be the reason why it came early and was longer...

Is that possible? Can exercise affect your period like this? Thanks for all the help!