Background <p>Given the limitations of gait speed tests for sarcopenia assessment, this study evaluated the Elbow Performance Test (EPT), a simple upper-extremity alternative.</p> Aims <p>This study aimed to evaluate the test-retest reliability of the EPT and its ability to distinguish between older adults with sarcopenia and healthy young controls.</p> Methods <p>This cross-sectional study included 96 male participants: 43 older adults with sarcopenia (≥60 years) and 53 healthy young controls (≤40 years). Assessments covered muscle strength, mass, and physical performance, including 4-meter gait speed, the Short Physical Performance Battery (SPPB), and Timed Up and Go (TUG). The EPT required 30 self-paced elbow flexion-extension repetitions with a 1-kg weight. Test-retest reliability was assessed after 7–10 days using intraclass correlation coefficients (ICCs).</p> Results <p>All performance test scores differed significantly between the sarcopenia and control groups (<i>p</i> &lt; 0.01). The EPT showed excellent test–retest reliability in both the control (ICC = 0.932; 95% CI:0.885–0.960) and sarcopenia (ICC = 0.905; 95% CI:0.831–0.947) groups. In terms of reliability, the EPT outperformed gait speed and SPPB in both groups and was comparable to the TUG test in the sarcopenic group.</p> Conclusions <p>The EPT demonstrated excellent reliability and effectively distinguished between older adults with sarcopenia and healthy controls. Given its simplicity, high repeatability, and minimal equipment needs, the EPT may serve as a practical tool for assessing upper-extremity muscle performance, particularly in settings where traditional lower-extremity-based tests are less feasible. Further studies are warranted to confirm its broader clinical utility across diverse populations.</p> Clinical trial registration <p>This trial was retrospectively registered at ClinicalTrials.gov (Identifier: NCT07065448) on July 03, 2025.</p>