Athletes generally make use of motor imagery (MI) as a part of their routines to visualise the perfect movement to perform and improve their physical performances. However, the lack of feedback during those cognitive trainings makes it difficult to know if they are done efficiently and if they enable an over-time progression. EEG-based neurofeedback (NF) training procedures could be used to fill this gap, but their lack of usability hampers their development outside laboratories [1]. One way to increase this usability, is to determine the most relevant feedback content to provide athletes with, in terms of NF performance (i.e., ability to self-regulate brain patterns), acceptability and cognitive load. Previous studies suggested that evaluative feedback is preferable for experts, whereas explanatory feedback should be used for novices [2, 3, 4, 5]. Still, most feedback used during NF trainings are evaluative. So far, only a few studies have compared these 2 kinds of feedback during NF trainings [6, 7], and none have assessed the relevance of combining them. Yet, this combination brings very important research questions. Indeed, we hypothesise that evaluative feedback will benefit NF performance, especially in participants who are used to practising MI, while explanatory feedback will be more usable by providing richer and meaningful information. Nonetheless, combining both might result in high cognitive load, which could be detrimental for NF performance [9, 10]. Thus, our study aims to assess the relevance of explanatory and evaluative feedback during MI-NF, in terms of NF performance, acceptability and cognitive load, in athletes. We will use a within-subject paradigm with a 2*2 design: Exp2 (explanatory feedback: yes vs. no) and Eval2 (evaluative feedback: yes vs. no). Thereby, each athlete will take part in two-sessions of MI-NF training during which their EEG activity will be recorded. They will also complete acceptability and cognitive-load questionnaires.< Réduire