Global proteomics reveals distinct muscle adaptations to menstrual cycle phase-based sprint interval training in endurance-trained females.

Advances in mass-spectrometry (MS)-based technologies have leveraged our understanding of protein-wide adaptations in human skeletal muscle in response to exercise. However, there is a lack of such data in females, particularly pertaining to already trained females and menstrual cycle phase-based sprint interval training (SIT) despite its efficacy and popularity. Here, we present a comprehensive global proteome analysis of skeletal muscle adaptations to high-frequency SIT during different menstrual cycle phases in endurance-trained females. We randomized 49 eumenorrheic females to either high-frequency SIT in the follicular (FB) or luteal phase (LB) over one menstrual cycle comprising eight sessions of 6×30-s all-out efforts. MS-proteomics, covering 4155 proteins after filtering, revealed notable differences in muscle adaptations to phase-based SIT. LB suppressed mitochondrial pathways of the tricarboxylic acid cycle and electron transport chain while enriching ribosomal complexes. Conversely, FB enriched filament organization and skeletal system development. Mitochondrial repression during LB was linked to reduced V˙O, whereas exercise capacity improved in FB only. Our findings show that menstrual cycle phase-based high-frequency SIT induces distinct protein-wide muscle adaptations and affects phenotype in endurance-trained eumenorrheic females. CLINICAL TRIAL REGISTRATION NUMBER: NCT04136457.