Data was collected to study the usefulness of the thirty seconds sit-to-stand test as an alternative for estimating peak oxygen uptake and six-minutes walking distance in women with breast cancer, which is a cross-sectional study derived from the ONCORE project (Randomized controlled trial on comprehensive exercise-based cardiac rehabilitation program for the prevention of anthracyclines and/or anti-HER2 antibodies-induced cardiotoxicity in breast cancer), ClinicalTrials.gov Identifier: NCT03964142 DATASET FILE (xlsx) includes 4 sheets: - Dataset_variables: all variables collected pre-post intervention - Descriptive data (baseline): variables used for the descriptive analysis before the intervention (baseline) - Data_CPET-30STS(pre-post): pooled data from CPET-30STS pre-post intervention - Data_6MWD-30STS(pre-post): pooled data from 6MWD-30STS pre-post intervention

Funding: This work was supported by a competitive grant from the AECC Scientific Foundation – PRDLC21480DÍAZ -, and by a competitive grant of the Spanish Health Research Fund of the Carlos III Health Institute (ISCIII) - PI17/01687, co-funded FEDER, through Strategic Action in Healthcare, 2017.