"Tender" is a seriously loaded term. You can have 'tender' meat by confining your roosters in cages so they don't get exercise. Commercially raised chicken is confined and 'marinated' in salt water prior to packaging, so it is 'juicy and tender'.
What we have come to recognize as 'tender' chicken is really artificial. Animals with exercise will have more muscle with a stringier, stronger texture. I've learned to love it and can't go back to grocery store chicken at all. It just tastes wet and flacid to me.