METHODS AND ANALYSIS: This is double-blind randomised controlled trial, with parallel group, concealed allocation, blinding of patients and assessors, and intention-to-treat analysis. 240 adult participants who had median sternotomy from eight hospitals in Malaysia will be recruited. Sample size calculations were based on the unsupported upper limb test. All participants will be randomised to receive either standard or early supervised incremental resistance training. The primary outcomes are upper limb function and pain. The secondary outcomes will be functional capacity, multidomain recovery (physical and psychological), length of hospital stay, incidence of respiratory complications and quality of life. Descriptive statistics will be used to summarise data. Data will be analysed using the intention-to-treat principle. The primary hypothesis will be examined by evaluating the change from baseline to the 4-week postoperative time point in the intervention arm compared with the usual care arm. For all tests to be conducted, a p value of <0.05 (two tailed) will be considered statistically significant, and CIs will be reported. The trial is currently recruiting participants.

ETHICS AND DISSEMINATION: The study was approved by a central ethical committee as well as the local Research Ethics Boards of the participating sites (UKM:JEP-2019-654; Ministry of Health: NMMR-50763; National Heart Centre: IJNREC/501/2021). Approval to start was given prior to the recruitment of participants commencing at any sites. Process evaluation findings will be published in peer-reviewed journals and presented at relevant academic conferences.