From muscle mass to muscle function: redefining recovery after cardiovascular surgery

This invited commentary refers to ‘Association between the rate of force development of quadriceps and physical performance in older patients undergoing cardiovascular surgery: a cross-sectional study’, by T. Adachi et al., https://doi.org/10.1093/eurjcn/zvaf183. Cardiac rehabilitation (CR) has long been recognized as a cornerstone of secondary prevention, yet the growing heterogeneity of the cardiac population, especially among older adults, demands that rehabilitation strategies evolve beyond traditional exercise prescription.1,2 The recent study by Adachi et al. provides an important contribution to this shift by examining the rate of force development (RFD) of the quadriceps as a determinant of functional performance in older patients after cardiovascular surgery.3 Their cross-sectional analysis identifies RFD as a potential marker that bridges the gap between pure muscle mass assessment and real-world physical capacity. The concept of recovery after cardiovascular surgery has historically emphasized the restoration of haemodynamic stability and muscle mass. However, the study by Adachi and colleagues shifts the focus towards how fast patients can generate muscular force rather than how much muscle they possess.3 This distinction is clinically meaningful. Early-phase RFD (within 100 ms of contraction) reflects neural activation and motor unit recruitment, while later phases are influenced by muscle size and tendon properties.4,5 Thus, RFD captures both neural and muscular integrity elements often overlooked in conventional rehabilitation metrics. From a nursing and rehabilitation perspective, this nuanced understanding of muscle function opens an avenue for more individualized recovery pathways. Bedside nurses and physiotherapists are uniquely positioned to detect early declines in functional velocity how rapidly a patient transitions from lying to sitting, or stands from a chair and to tailor interventions that address neuromuscular inefficiency before it translates into frailty or dependency.6 In Adachi et al.’s study, RFD values (RFD100 and RFD200) and maximal voluntary contraction (MVC) were significantly correlated with the Short Physical Performance Battery (SPPB), gait speed, and chair-stand test results.3 These associations persisted even after adjustment for confounders such as age, sex, and body composition, although they diminished once MVC was included as a covariate. Importantly, RFD retained its predictive strength in patients with low skeletal muscle mass suggesting that, in sarcopenic or frail populations, neural factors may play a more decisive role in physical performance than absolute strength. This finding aligns with emerging evidence that loss of motor unit connectivity and reduced firing rates precede measurable declines in muscle mass. The ability to assess RFD could therefore complement traditional indices such as MVC and muscle cross-sectional area, offering clinicians a more sensitive window into the early stages of neuromuscular impairment.7,8 The findings from Adachi et al. hold strong relevance for the entire spectrum of professionals within the Association of Cardiovascular Nursing and Allied Professions (ACNAP). Functional recovery after cardiovascular surgery is not the sole domain of physiotherapists or exercise specialists it is a shared, collaborative goal that integrates the expertise of nurses, dietitians, psychologists, and other allied health professionals.3 Nurses are often the first to detect functional decline or fatigue during hospitalization, enabling early referral for assessment of rate of force development (RFD). Physiotherapists can translate these findings into individualized exercise prescriptions focusing on power and velocity rather than endurance alone. Dietitians, beyond supporting muscle mass accretion, can enhance muscle function by optimizing nutrition to provide substrates for neuromuscular regeneration and energy metabolism, while psychologists can address motivation, fatigue, and fear of movement factors that profoundly affect participation in rehabilitation. This integrated approach aligns perfectly with ACNAP’s vision of person-centred, team-based cardiovascular care. Embedding RFD evaluation into multidisciplinary pathways could unify assessment and intervention strategies across nursing, nutrition, exercise, and psychosocial domains, ultimately enhancing patient recovery trajectories and long-term self-management capacity. Beyond individual care, the integration of RFD into rehabilitation paradigms has implications for health systems increasingly challenged by population ageing and multimorbidity. Hospital-acquired functional decline following cardiac surgery is a major contributor to readmissions and long-term dependency. Identifying early markers of impaired functional recovery such as low RFD could allow healthcare providers to allocate rehabilitation resources more efficiently and to design tiered, home-based interventions. Community cardiac rehabilitation programmes could, for instance, incorporate velocity-based resistance training or neuromuscular stimulation protocols tailored to RFD profiles. Such approaches have already demonstrated benefits in improving lower-limb power and mobility among older adults and may be particularly relevant for those unable to engage in high-intensity regimens.9–11 Importantly, nurse-led, multidisciplinary CR teams are ideally positioned to coordinate these interventions, ensuring continuity of care from hospital to home. While the findings by Adachi et al. are compelling, several practical challenges remain. Standardization of RFD measurement for clinical use is necessary, including simplified protocols and validated cut-off points for risk stratification.3 Larger multicentre studies are warranted to explore the prognostic value of RFD for mortality, rehospitalization, and quality-of-life outcomes. Moreover, longitudinal research could determine whether interventions specifically designed to enhance RFD lead to tangible improvements in independence and cardiovascular prognosis. From a research design standpoint, integrating RFD into multidomain assessments of frailty and recovery combining physical, cognitive, and psychosocial measures would reflect the complex reality of older cardiac patients. Nurses and allied health professionals can play a pivotal role in implementing such multidimensional frameworks, bridging the gap between laboratory metrics and patient-centred outcomes. Ultimately, the study by Adachi et al. challenges us to rethink what ‘recovery’ means after cardiovascular surgery. The emphasis on function rather than merely form mirrors the broader shift in cardiovascular care towards patient-centred, outcome-based medicine.12 In practice, this means recognizing that restoring muscle function, mobility, and confidence may be as crucial as optimizing ejection fraction or surgical success. Cardiac nurses, dietitians, and physiotherapists, as integral members of multidisciplinary teams, are uniquely positioned to operationalize this shift. By translating physiological markers like RFD into actionable interventions, they can help transform rehabilitation from a standardized sequence of exercises into a personalized journey of functional renewal. Ultimately, integrating RFD assessment into multidisciplinary cardiac rehabilitation could bridge the gap between muscle mass recovery and functional independence. For older adults undergoing cardiovascular surgery, measuring how quickly muscles respond not merely how strong they are may redefine the standards of postoperative care, inform interdisciplinary practice, and support a more person-centred model of cardiovascular recovery. Izabella Uchmanowicz (RN PhD MBAFESCFHFA (Conceptualization [lead]; Writing—original draft [equal]; Writing—review & editing [equal])), Arkadiusz Matras (Writing—original draft [equal]; Writing—review & editing [equal]), and Michał Czapla (PhD RD EMT-P FESC (Writing—original draft [equal]; Writing—review & editing [equal])) This study has no external funding. No new data were generated or analysed in support of this commentary.