The study, published in European Geriatric Medicine by Junghyeon Hyeon of the Department of Family Medicine at Busan Paik Hospital, Inje University College of Medicine, examined data from the 2024 Korea National Health and Nutrition Examination Survey (KNHANES). Among 1,178 adults aged 65 and older who underwent both DXA and BIA scans on the same survey cycle—the survey-weighted mean age was 72.1 years and 54.3 percent were women—the agreement between the two devices proved far weaker than many clinicians might assume. Under the combined height-or-body-mass-index criterion adopted by the Asian Working Group for Sarcopenia (AWGS) in its 2025 consensus update, 83.0 percent of participants were classified as having low muscle mass by DXA, compared with just 55.5 percent by BIA. Observed agreement between the two modalities was only 65.4 percent, and Cohen’s kappa—a statistic that corrects for chance agreement—was a mere 0.246, a level conventionally interpreted as fair at best.

The technical heart of the problem lies in how each device estimates skeletal muscle and how the resulting values are adjusted for body size. DXA directly quantifies lean soft tissue by distinguishing X-ray attenuation at two energy levels, providing a regional partition of appendicular lean mass in the arms and legs. BIA, by contrast, does not measure muscle at all; it infers total body water from the resistance of tissues to a weak alternating electrical current and then applies population-specific prediction equations to estimate appendicular lean mass. Because fat and muscle conduct electricity differently, and because hydration status, body geometry and the equations themselves all influence the estimate, BIA values can diverge systematically from DXA references. When those estimates are then normalized—either by height squared, as in the traditional appendicular lean mass index, or by body mass index (BMI), a newer adjustment intended to account for adiposity—the divergence cascades into large differences in who crosses the diagnostic threshold.

The choice of adjustment criterion turned out to be decisive. Agreement was best under the BMI-adjusted criterion, where 50.6 percent of participants met the low-muscle-mass threshold by DXA and 41.1 percent by BIA, yielding 79.8 percent observed agreement and a kappa of 0.598—moderate, though still short of interchangeability. Agreement was worst under the height-adjusted criterion: 70.8 percent of older Koreans were flagged as having low muscle mass by DXA versus only 28.8 percent by BIA, with 56.5 percent observed agreement and a kappa of 0.258. The combined height-or-BMI definition, which classifies a person as having low muscle mass if either threshold is crossed, did not reconcile the two devices; instead, it widened the gap, because DXA’s height-adjusted flag swept large numbers of people into the low-muscle-mass category that BIA never reached.

The implications sharpen considerably when muscle strength enters the equation, since sarcopenia under AWGS 2025 requires not only low muscle mass but also low physical performance or low muscle strength—most commonly assessed by handgrip dynamometry. Among the 1,121 participants with handgrip-strength data, 131 had low handgrip strength. Within this clinically consequential subgroup, combined-criterion low muscle mass was found in 93.1 percent by DXA and 80.3 percent by BIA, but the devices disagreed in 22 individuals: 18 were classified as having low muscle mass by DXA but not BIA, and 4 by BIA but not DXA. In other words, for the very patients in whom a sarcopenia diagnosis would actually be made, the choice of device could change the answer.

The headline sarcopenia figures, by contrast, looked deceptively harmonious. Prevalence was 10.0 percent by DXA and 8.7 percent by BIA, with a kappa of 0.895—almost perfect agreement. But the study reveals why that harmony is partly illusory: 990 of the participants had normal handgrip strength and were therefore concordantly classified as non-sarcopenic regardless of what their muscle scans showed. The apparent consensus between the devices was driven overwhelmingly by the shared strength gate rather than by genuine agreement about muscle mass. Strip away the strength requirement, and the discordance re-emerges in full force among those who fail it.

These findings arrive at a pivotal moment. The AWGS 2025 consensus update, published in Nature Aging, marked a deliberate shift in framing—from sarcopenia as a discrete disease toward a broader concept of muscle health—and introduced more flexible body-size adjustments, including the BMI-based option, in recognition of the peculiarities of Asian populations, among whom high adiposity at lower BMI values can mask or distort muscle assessments. The 2019 AWGS criteria, like their European counterparts, had anchored low muscle mass primarily to the height-adjusted appendicular lean mass index, a metric that the new analysis suggests is especially vulnerable to device-dependent classification: it produced the largest DXA–BIA gap of any definition tested.

Prior research has already hinted at this fragility. The Bunkyo Health Study in Japan, which compared BIA and DXA for appendicular lean mass in more than 1,600 community-dwelling older adults, documented systematic differences between the modalities, and a 2024 systematic review and meta-analysis of muscle-measurement techniques concluded that agreement varies substantially depending on the device, the derived variable, and the cutoffs applied. Work from hospital cohorts has similarly found that multifrequency BIA can overestimate or underestimate muscle mass relative to DXA depending on patient characteristics. What the new Korean analysis adds is a nationally representative test of the newest AWGS 2025 criteria themselves—including the combined height-or-BMI definition—showing that even the updated framework does not erase modality dependence.

For clinicians and researchers, the practical message is one of precision and transparency. A statement that a patient “has low muscle mass” is incomplete, and potentially misleading, unless it specifies the measurement device, the derived muscle variable—height-adjusted or BMI-adjusted appendicular lean mass—and the adjustment criterion used to apply the cutoff. In screening and epidemiological surveys, where portable BIA dominates because it is inexpensive, radiation-free and quick, prevalence estimates of low muscle mass may be substantially lower than what DXA-based studies of the same population would report. In clinical practice, a patient flagged by DXA but cleared by BIA may miss an opportunity for early resistance training and nutritional intervention, while the reverse discordance could prompt unnecessary concern. The study’s author argues that interpretation should always be integrated with muscle-strength assessment, since strength data—handgrip in this case—anchor the diagnosis in functional terms that matter to patients.

The analysis is not without limits inherent to its design. Cross-sectional survey data capture agreement at a single point in time and cannot address whether one device better predicts falls, fractures, disability or mortality—the outcomes that give sarcopenia its clinical meaning. The KNHANES 2024 protocol was approved by the Institutional Review Board of the Korea Disease Control and Prevention Agency, and the study used de-identified public data with survey weights applied to prevalence estimates while agreement statistics were computed unweighted. Still, with populations across Asia and beyond aging rapidly, and with sarcopenia prevalence projected to climb, the findings sound a timely warning: before the field can agree on how many older adults have sarcopenia, it must first agree on how to measure the muscle they have lost. Until then, DXA and BIA should be treated as complementary tools with distinct biases—not as interchangeable windows onto the aging body.

Muscle ultrasound, while not universally adopted, offers precise real-time imaging capabilities. This advanced technique utilizes high-frequency sound waves to create images of muscle structure and composition. It can measure muscle thickness, detect abnormalities, and assess muscle quality—all key factors in diagnosing sarcopenia. The fundamental advantage of ultrasound over other imaging modalities, such as MRI or CT scans, lies in its portability, cost-effectiveness, and ease of use. These attributes position muscle ultrasound as a potentially revolutionary tool in the ongoing fight against sarcopenia.

However, despite its promise, the journey of muscle ultrasound towards broader clinical application is not devoid of hurdles. One of the primary challenges is the lack of standardized protocols and the variability in ultrasound equipment quality across different settings. This inconsistency complicates the interpretation of results, leading to ambiguous diagnoses that could hinder timely intervention. Furthermore, the expertise required to operate ultrasound machines and interpret their findings can be a barrier in many geriatric care settings. The rapid advancement of technology in this field demands that practitioners stay informed and adequately trained to harness the full potential of muscle ultrasound.

Research exploring the efficacy of muscle ultrasound in assessing sarcopenia is gathering pace, with numerous studies investigating its feasibility and reliability. A significant aspect of this research focuses on establishing normative data for muscle characteristics, which is crucial for accurate diagnosis. These baseline measurements will help clinicians distinguish between normal age-related changes in muscle and pathological loss associated with sarcopenia. As studies accumulate, the hope is that robust guidelines will emerge to streamline the clinical utilization of muscle ultrasound, transforming it into a standard assessment tool for older adults.

Furthermore, the role of muscle ultrasound extends beyond mere diagnostics; it may also play a pivotal role in the management and monitoring of sarcopenia. By providing objective measurements, clinicians can tailor interventions more precisely. For instance, tracking changes in muscle mass and function over time can inform rehabilitation strategies, guide nutritional interventions, and assess the effectiveness of therapeutic exercises. Consequently, muscle ultrasound could serve not only as a diagnostic instrument but also as a valuable tool in personalized geriatrics, where treatments are individualized based on precise measurements and outcomes.

In parallel with advancements in muscle ultrasound, the broader context of sarcopenia management is evolving. Ongoing research underscores the importance of a multidisciplinary approach to managing this condition. Comprehensive strategies that incorporate strength training, nutritional support, and lifestyle changes are paramount. Evidence increasingly indicates that interventions combining these elements yield the best outcomes for older adults at risk of or already experiencing sarcopenia. However, the challenge remains in effectively communicating these combined strategies to both patients and healthcare providers, ensuring that interventions are adopted and sustained.

In the landscape of healthcare, building awareness around sarcopenia and its consequences is critical. Public health campaigns aimed at educating older adults and their caregivers about the signs of sarcopenia could encourage proactive measures. Educating stakeholders on the benefits of early detection and intervention can foster a culture of awareness that prioritizes muscle health. Simplifying the process of testing and diagnosis through accessible technologies like muscle ultrasound can empower older adults in taking charge of their muscle health.

Moreover, there is a growing recognition that sarcopenia and its management must be approached from a global perspective. As societies across the globe grapple with aging populations, the burden of sarcopenia will strain healthcare systems. Collaborative efforts are essential in addressing this issue, pooling resources, and sharing best practices. International guidelines and standards concerning sarcopenia diagnosis and treatment will require collaboration among researchers, healthcare professionals, and governing bodies dedicated to geriatric care.

In conclusion, muscle ultrasound stands at the crossroads of innovation and necessity in the battle against sarcopenia. While it faces challenges in standardization, training, and wider acceptance, the potential it holds as a diagnostic and monitoring tool is profound. As research continues to evolve, the vision of integrating muscle ultrasound into routine geriatric assessments could soon become a reality. In our quest to preserve the dignity and quality of life for our aging population, harnessing innovative technologies and fostering a proactive approach toward muscle health remains imperative.

The future of muscle ultrasound in combating the sarcopenia conundrum remains uncertain but filled with promise. As we deepen our understanding of the interplay between aging and muscle health, it becomes increasingly clear that the tools we employ will shape the landscape of geriatric medicine. Embracing advancements in muscle ultrasound technology not only facilitates timely diagnosis but could also forge pathways toward more effective treatments and management strategies, ultimately transforming the way we approach sarcopenia in aging populations.

This multifaceted approach—where diagnostic innovations, lifestyle adaptations, and comprehensive care converge—could redefine our response to sarcopenia. As we stand on the brink of unprecedented possibilities in geriatric healthcare, the implications of adopting muscle ultrasound could reverberate across disciplines, encouraging a paradigm shift toward a more proactive, informed, and empowered elderly population.

In a world where the population continues to age at an accelerating pace, the implications of sarcopenia cannot be underestimated. Stakeholders across the healthcare spectrum must unite in their efforts to heighten awareness, endorse innovation, and implement effective care strategies to combat the deleterious effects of muscle loss. As we reflect on the strides made thus far and anticipate the next steps on this journey, it is essential to keep in mind that the efficacy of muscle ultrasound and a comprehensive approach to managing sarcopenia could very well shape the future of geriatric wellbeing.

Ultimately, the pursuit of knowledge and improvement in muscle health transcends individual efforts. It is a collective endeavor that invites clinicians, researchers, patients, and advocates alike to share in the responsibility of addressing the looming challenge of sarcopenia. Through continued research, dialogue, and collaboration, we can work toward an era of enlightened geriatric care, ensuring that our aging population enjoys the vitality and independence they deserve.

Subject of Research: Sarcopenia Diagnosis and Management through Muscle Ultrasound

Article Title: The sarcopenia conundrum: why muscle ultrasound does (or does not) have a future.

Article References:

Perkisas, S., Welch, C. & Soulis, G. The sarcopenia conundrum: why muscle ultrasound does (or does not) have a future. Eur Geriatr Med (2025). https://doi.org/10.1007/s41999-025-01335-4

Image Credits: AI Generated

DOI:

Keywords: Sarcopenia, Muscle Ultrasound, Aging, Geriatrics, Diagnosis, Health Care, Musculoskeletal Health, Rehabilitation, Public Health, Nutritional Support.