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.
Transversospinalis: The Deep Muscles of the Spine. There are three layers of muscle on the back of the body that are associated with the spine and stretch from the pelvis to the head. These deep muscles of the spine are largely responsible for maintaining posture and moving the spine. From my humble perspective few of these muscles are being accessed successfully. If you are familiar with what I am on about, my take is that everyone habitually leans backwards through life.