Ultrasound has quickly become one of the most practical tools for evaluating skeletal muscle in both clinical and research settings. Its portability, absence of radiation, and ability to capture real-time images make it ideal for older adults, individuals with chronic illness, and people with limited mobility. As interest grows in monitoring muscle health for aging, performance, and disease management, ultrasound offers an accessible way to assess both muscle mass and tissue quality.

Ultrasound measures of muscle mass typically focus on muscle thickness or cross-sectional area. Muscle thickness—commonly assessed in the quadriceps, biceps, or gastrocnemius—represents the distance between the superficial and deep fascia and closely mirrors measurements obtained through MRI. These values are sensitive to changes caused by aging, immobilization, resistance training, and disease progression. Cross-sectional imaging, which involves tracing the muscle’s borders in the transverse plane, provides an even more accurate estimate of muscle size, though it requires greater technical skill.

Importantly, ultrasound also provides insight into muscle quality through analysis of echogenicity, or the brightness of the muscle on B-mode images. Increased brightness generally indicates higher levels of intramuscular fat, fibrosis, or other degenerative changes—alterations that often appear before a measurable decline in muscle mass. This makes ultrasound especially useful for early detection of sarcopenia, neuromuscular disorders, or muscle wasting linked to chronic disease. Additional architectural measures, such as fascicle length and pennation angle, offer further insight into a muscle’s force-producing capacity and functional performance.

The versatility of ultrasound supports a wide range of applications. In geriatrics, it helps identify age-related muscle deterioration and track responses to exercise or nutrition interventions. In critical care, it allows clinicians to monitor the rapid muscle loss that accompanies immobilization. For individuals with neuromuscular conditions, ultrasound can detect subtle tissue changes before they manifest as weakness. Sports medicine professionals use it to assess training adaptations and guide rehabilitation, while clinicians managing chronic diseases rely on it to monitor muscle wasting associated with conditions like kidney disease or cancer.

Because ultrasound is noninvasive, accessible, and cost-effective, it is increasingly integrated into comprehensive muscle assessments. Its ability to detect both structural and textural changes gives it a unique role in understanding functional decline, evaluating treatment response, and supporting personalized care. However, obtaining high-quality images and accurate measurements requires consistent technique and standardized machine settings, underscoring the importance of proper training and protocol adherence.

Additional Reading

Pillen, S., Tak, R. O., Vegter, M., van der Laak, J. A., Hoogerbrugge, P. M., Verrijp, K. N., & Arts, I. M. (2009). Skeletal muscle ultrasound: Correlation between fibrous tissue and echo intensity. *Ultrasound in Medicine and Biology, 35*(3), 443–446. https://doi.org/10.1016/j.ultrasmedbio.2008.09.016

Reimers, K., Reimers, C. D., Wagner, S., Paetzke, I., & Pongratz, D. E. (1993). Skeletal muscle sonography: A correlative study of echogenicity and morphology. *Journal of the Neurological Sciences, 116*(1), 82–92. https://doi.org/10.1016/0022-510X(93)90322-U

Strasser, E. M., Draskovits, T., Praschak, M., Quittan, M., & Graf, A. (2013). Association between ultrasound muscle echogenicity and functional performance in older adults. *Aging Clinical and Experimental Research, 25*(5), 548–555. https://doi.org/10.1007/s40520-013-0112-9

Fukumoto, Y., Ikezoe, T., Yamada, Y., Tsukagoshi, R., Nakamura, M., Mori, N., Kimura, M., & Ichihashi, N. (2012). Skeletal muscle quality assessed from echo intensity is associated with muscle strength of middle-aged and elderly persons. *Clinical Interventions in Aging, 7*, 359–365. https://doi.org/10.2147/CIA.S32744

Tillquist, M., Kutsogiannis, D. J., Wischmeyer, P. E., Kummer, M., Kozar, R., Leong, K., & Dukes, G. (2014). Bedside ultrasound is a practical and reliable measurement tool for assessing quadriceps muscle layer thickness. *Critical Care Medicine, 42*(9), 2142–2148. https://doi.org/10.1097/CCM.0000000000000408

Young, H. J., Jenkins, N. T., Zhao, Q., & McCully, K. K. (2015). Measurement of intramuscular fat by muscle echo intensity. *Current Opinion in Clinical Nutrition and Metabolic Care, 18*(3), 225–229. https://doi.org/10.1097/MCO.0000000000000168

Arts, I. M., Pillen, S., Schelhaas, H. J., Overeem, S., & Zwarts, M. J. (2010). Normal values for quantitative muscle ultrasonography in adults. *Muscle & Nerve, 41*(1), 32–41. https://doi.org/10.1002/mus.21458