Sentence:  The foot abduction is smaller (out-toeing is smaller) in the <WSD>high-heeled</WSD> gait (Adrian and Karpovich, 1966; Snow and Williams, 1994; Stefanyshyn et al., 2000), or no significant difference exists between the flat-heeled and the <WSD>high-heeled</WSD> gait (Merrifield, 1971). 
Meaning of the word marked with <WSD> tags:  Wearing high heels.