Every time you push off and hyperextend the toe, which happens when doing something as simple as taking a step or more strenuous like cutting and jumping, the MTP joint is involved. 2022 June 20, Virginia Zakas, “The 5 injuries that can derail a fantasy season — and what they mean for your team”, in The New York Times:
(abbreviation, alt-of, countable, initialism, uncountable) Initialism of microsomal triglyceride transfer protein.
An important feature of MTP is its capability to relay mail from one transport environment to another. 1981 May, Suzanne Sluizer, Jonathan B. Postel, “Mail Transfer Protocol”, in RFC Editor, →ISSN, RFC 780:
(abbreviation, alt-of, initialism) Initialism of Media Transfer Protocol, a generalization of PTP (Picture Transfer Protocol).