Context: I've got a pulley strain and following my usual routine I've been climbing fairly lightly without crimping. Still the strain is taking a long time to heal which has got me thinking about the mechanics of open-handing vs crimping.
When I use an open hand grip on an edge or sloper and if I want to get my pinky on, there's a bend in the hand/fingers at the metacarpophalangeal (MCP) joint. Thinking about diagrams I've seen about how the pulleys work, this would suggest that the a2 is under strain despite the fact I'm not crimping. Basically I'm interested in people's knowledge or opinion on whether level of stress on the a2 defined by the angle at the MCP joint, irrespective of a bend in the PIP joint?
This would contrast with suggestions (e.g. in Dave Mac's injury book) that when you have a pulley strain you should splint the PIP joint to stop yourself crimping, but not worry about the MCP. It would also mean that a chisel/drag type grip, where the MCP is not bent but the PIP is, would involve less strain on the pulley than open-handing with pinky on or pulling on slopers.
I'm aware this post would be a lot better with pictures in to illustrate my points, but I've never got the hang of embedding them anyway.