The prevalence of ICU-acquired weakness (ICU-AW) among critically ill patients was found to be approximately 48 %, with an average loss of nearly 2 % of skeletal muscle per day during the initial week of ICU admission (Fazzini et al., 2023). ICU-AW has been shown to have detrimental effects on the long-term outcomes of ICU patients, including increased morbidity and mortality rates, decreased cognitive and functional abilities at the time of discharge, and diminished quality of life (Vanhorebeek et al., 2020). Furthermore, many of these functional impairments can persist for up to 5 years following ICU discharge (Wieske et al., 2015).

Early mobilization and nutritional therapy constitute two pivotal strategies for enhancing muscle synthesis and fostering the recovery of physical function in critically ill adults (Balke et al., 2022, Nakano et al., 2021, Wang et al., 2020). Despite being recommended by various guidelines (Devlin et al., 2018, Hodgson et al., 2014), the translation of expert consensus recommendations for early mobilization into clinical practice was poor (Black et al., 2023, Capell et al., 2019), primarily hindered by patient-related factors and constraints in terms of staffing, resources, and equipment availability (Parry et al., 2017, Rai et al., 2020). In light of their inherent advantages, including portability, affordability, adjustable resistance, controllable intensity, and versatility across diverse environments such as in-bed and bedside, elastic bands based resistance training (RT) has garnered significant utilization in clinical research, particularly among populations such as those with COPD (Cai et al., 2021, Lima et al., 2020) and elderly (de Oliveira et al., 2017, Martins et al., 2013). Multiple meta-analyses have demonstrated the significant benefits of elastic band RT in improving patients' physical function (Cai et al., 2021, de Oliveira et al., 2017, Lima et al., 2020, Martins et al., 2013), reducing inflammatory markers such as interleukins and C-reactive protein (Liu et al., 2022). However, the application of elastic band RT remains relatively limited in ICU patients. Additionally, beta-hydroxy beta-methylbutyrate (HMB) is hypothesized to have these effects by increasing protein synthesis, and inhibiting protein breakdown, reducing muscle cell apoptosis (Kaczka et al., 2019). Nonetheless, several studies have investigated critically ill patients, yielding inconclusive findings (Nakamura et al., 2020, Supinski et al., 2021, Viana et al., 2021).

The research agenda regarding the prevention or treatment of ICU-AW indicates that (Latronico et al., 2017), the most important research priority is to investigate the interaction between early rehabilitation and nutritional therapy. A systematic review (Silva et al., 2017) indicated that in conjunction with RT and HMB has the potential to mitigate markers of muscle damage and optimize gains in muscle mass and strength resulting from training. Limited research has been conducted to examine the combined intervention’s synergistic effects within the context of ICU. Recognizing the pivotal role played by nurses in the rehabilitation of critically ill patients (Mukpradab et al., 2022), the predominant mode of program delivery has been nurse-led, complemented by intermittent multidisciplinary collaboration (Chen et al., 2021, Jensen et al., 2016). Consequently, employing an exhaustive literature review and expert consultations, we have formulated a nurse-directed, low-intensity, hierarchical strategy that integrates RT with elastic bands and/or HMB nutritional intervention for critically ill patients.

Prior to a definitive Randomized Controlled Trial (RCT), a crucial step is the design of a feasibility study assessing predefined progression criteria for either the evaluation design or the intervention itself (Skivington et al., 2021). Prioritizing considerations such as recruitment and retention rates, compliance, acceptability, and safety, rather than solely concentrating on effectiveness or efficacy (Eldridge et al., 2016). However, the term “acceptability” often lacks clarity, being conflated with satisfaction, participant experience, and engagement, and is inadequately defined, under-theorized, and poorly assessed (Sekhon et al., 2018). To address this, Sekhon et al. proposed the Theoretical Framework of Acceptability (TFA), covering affective attitude, burden, perceived effectiveness, ethicality, intervention coherence, opportunity cost, and self-efficacy (Sekhon et al., 2017). Accordingly, we conducted a four-arm, mixed-methods, feasibility randomized controlled trial to explore the feasibility, safety, acceptability, and potential efficacy of implementing elastic bands-based RT and/or HMB administration in critically ill patients.