The TRP ion channels TRPA1 and TRPV1 have a complicated & interesting relationship with neural activation and pain.
TRPV1 is partly responsible for the pain we feel from eating hot peppers. Capsaicin (or some capsaicinoids or even ginger) bind to this receptor, and we can FEEL IT. The nerves on which TRP ion channels reside become hyperexcited, which has the theoretical effect of feedback inhibition on other afferent nerves in the spinal cord. As far as the TRP-muscle cramp theory goes, this dampens hyperexcited muscle cramp-inducing nerves. So basically, instant resolution of painful muscle cramps.
Effects on body recomposition, more on spices, and my personal experience!