I have used papain with some marinades for goat meat. Personally I do not care much for marinades any more, at least not long ones. For example, I used to marinate chicken overnight with spices and yogurt when making chicken tikka or tandoori chicken.
1 Pain at the base of the spine causes the psoas muscle to shorten and weaken(1,2,3,). 2  80% of Western people will suffer from debilitating backpain some time in their lives(5).  Western style walking (comfortable shoes & flat ground) fails to trigger muscles that stabilize hip joints & lower back.
The lattisimus dorsi is a large muscle with a very broad origin on the vertebrae and ribs of the mid to low back, tapering into a narrow insertion on the anterior (front) of the head of the humerus bone of the arm.