Displaying data out from PHP

I have grabbed out the namedpair from php and the output from php is as follows:
[COLOR=Blue]MuscleDesc0=Bicep&Name0=Bench Press&ExID0=2&MuscleDesc1=Bicep&Name1=Bicep Curl&ExID1=1&MuscleDesc2=Bicep&Name2=Crunches&ExID2=20&MuscleDesc3=Bicep&Name3=Desmond&ExID3=21&MuscleDesc4=Bicep&Name4=Hill Climb&ExID4=5&MuscleDesc5=Bicep&Name5=Seated Row&ExID5=17&c=6[/COLOR]
And in Flash, I used the codes in Actionscript:
[COLOR=Blue]for(var x=0; x<Number(this.c); x++){
trace("Muscle Name: " + this.MuscleDesc[x])
trace("Exercise 1: " + this.Name[x]);
trace("Exercise 1 ID: " + this.ExID[x]);
}[/COLOR]
But when i run, the output windows shows undefined for all my variables.
I can display out my variables if I just use this.MuscleDesc0, this.Name0, this.ExID0 and output window will show the first set of variable which is Bicep, Bench Press, 2 respectively.

But when I used the for loop, its all undefined. Is it something wrong with my for loop declaration? Can someone tell me how i can amend my for loop to display it?