I was spurred to post this after reading Which fingers to use in a 2 finger pocket when rock climbing?
Last year I injured myself training on a shallow three finger pocket with an open hand grip and my pinky dropped. While hanging with maximum effort I felt a popping sensation in the palm of my hand and heard a brief but audible ripping-paper sound. Pain and swelling followed.
I never received a professional diagnosis, but seeing as I would not be climbing for a while I had time to read fairly extensively on the subject, and I concluded that in all likelihood I had suffered a partial tear of the fourth palmar lumbrical. This is a small muscle that runs between the flexor tendons of the fourth and fifth digits, seen below:
When some of the digits are nearly fully extended and others maximally flexed a shearing force is created in the lumbricals, which can lead to a tear.
Reference this illustration from Lumbrical Tears in Rock Climbers – A. SCHWEIZER [PDF]
Since this injury I am shy to commit to any pockets. I can baby the fourth lumbrical by avoiding splitting the fourth and fifth (ring and pinky) fingers, but that does not protect the third lumbrical from shear as shown in the illustration above.
As I have become more aware of the interconnection between digits I have noted that none of them are independent, not even the index and middle fingers which do not share a lumbrical.
For example if I:
- with my wrist extended or at least straight
- hold the 3rd, 4th, & 5th digits straight (in line with the palm) using the other hand
- and flex my index finger down toward my wrist as far as possible
I feel a sharp and almost painful tension in my forearm. I did not feel even this much discomfort in my palm before the tear so it seems probable that this is another source of potential injury.
It seems that not flexing the dropped fingers from the lowest joint (MCP) greatly reduces shearing stresses. This works OK when I can prop the fingers against the face of the rock, e.g.:
However on protruding plastic gym holds or overhanging routes when I cannot prop my fingers I don't seem to be able to hold them back like that and still truly exert. Is this something I just need to practice?
Contrarily I see plenty of strong climbers bending the dropped fingers at the palm like this:
Did I injure myself only because I was trying too hard? It happened at near 100% exertion, and afterward someone told me to train at no more than 60-70% intensity. If that is true (is it?) an injury could still happen on a hard route unless I intentionally limit myself, right?
How can I minimize the possibility of (re)injury while training for and climbing hard on pockets?