Foot support systems include a fluid flow control system that facilitates movement of fluid into, out of, and/or within a sole structure and/or article of footwear, e.g., to change and/or control pressure in fluid filled bladder(s). Aspects of this technology may relate to one or more of: (a) footwear structures in which such systems are incorporated; (b) valve stem based fluid flow transfer systems; (c) solenoid based fluid flow transfer systems; (d) user input button features; (e) air filter features; (f) fluid tube to fluid distributor connection features; (g) fluid distributor to footwear connection features; (h) valve position sensor features; (i) valve transmission features; (j) pressure control algorithm features; (k) electronic communication features; (l) system sealing features; and/or (m) pressure sensor mounting features.