Question: What are the features and failings of the "software" brains must use to control muscles?

My hypothesis: Controlling muscles and skeletons in 3-D space requires motor maps which ideally estimate current configurations in continuous space and extrapolate them into new configurations nearby in space and time. Mis-learning caused by inadequate or bad data results in maps with unaddressable muscles (sensorimotor dark-space) and spatio-temporal discontinuities, which appear as the crackling or snapping inside joints during continuous motion. See Continuous Models.

Summary: Most muscular pain and motion limits are data problems, not tissue problems, and suffer from the same feedback traps as data does.

Testable sub-predictions:

1. "Inflexibility" and "blockages" are control properties of motor maps, so during general anaesthesia flexibility will increase.

2. Muscle tightness and soreness will be co-localized with proprioceptive ambiguity, as on bony prominences.

3. Muscle hypo-activity will be co-localized with proprioceptive hypo-sensitivity, as in the "core" muscles so necessary to balance and coordination.

4. Because many muscle pops and cracks result from discontinuous changes in muscle activity (due to discontinuous motor maps), their occurence will decrease under general anaesthesia and/or after localized sensorimotor training.

5. Many felt injuries (like sprains) are due not to tissue damage but to muscles whose proprioceptive sensations are suddenly (but temporarily) out of context and hence uncomfortable.

Refutation: Reproduce the popping, snapping, and inflexibilty of joints when cortical control and/or sensation is disabled.

(My personal experience and second-hand knowledge from conversing with credentialled bodyworkers so far agree with all these tenets)