The phenomenon of language contact is more noticeable in today's globalized society than ever before, and this is especially evident in the dominance and inevitable influence of the English language. The economic, political and military power of the United States, as well as its leading role in the development of information and communication technology, caused the spread of American culture, lifestyle, and thus language. In this regard, there is almost no world or European language that is not permeated with loanwords from English, i.e., Anglicisms. Words of English origin are found in all spheres of life and interests of other languages and peoples, such as information technology, but also economics, politics, fashion, tourism, music, advertising, and the fitness industry, which is the focus of this paper. The focus of this thesis will be the adaptation of Anglicisms in the Croatian language in the field of the fitness industry, one of the fastest-growing and developing industries in the world. More precisely, this paper aims to present, show and describe how Anglicisms are adapted in the Croatian fitness terminology. The analysis will be based on the methodological framework proposed by Croatian linguist Rudolf Filipović (1986, 1990) meaning that the changes and the process of adaptation are to be demonstrated on four levels: orthographic, phonological, morphological, and semantic. In this way, the paper also aims to provide insight and raise awareness of the enormous number of Anglicisms in the Croatian language and draw attention to the huge dominance and influence of the English language, on the example of fitness terminology.