Minimum Detectable Difference and Learning Effects of Single-Leg Functional Performance Tests in Healthy Adults

OBJECTIVES Clinicians commonly compare the uninvolved limb to the involved limb to assess impairment and readiness for return to sport. However, measurement variability and learning effects may influence interpretation. This study aimed to determine the minimum detectable difference at the 95% confidence interval (MDD<sub>95</sub>) between limbs and evaluate learning effects across days and trials in three functional performance tests.METHODS Twenty-four healthy adults (12 males, 12 females; age = 22.3 ± 1.7 years) participated in a 3 × 3 × 2 (day × trial × leg) repeated-measures design. Participants performed vertical jump (VJ), triple hop (TH), and timed crossover hop (TCH) tests for three trials on each leg across three consecutive days. A repeated-measures analysis of variance (ANOVA) was conducted to examine the effects of day, trial, and leg. MDD<sub>95</sub> was calculated for each test.RESULTS No significant interactions involving leg were observed (<i>p</i> = 0.12-0.85), indicating no between-limb differences. Significant learning effects were found across days and trials for all tests (<i>p</i> < 0.05). Performance improved progressively across trials and days, with the greatest improvements observed in the TCH test. MDD<sub>95</sub> values ranged from 2.84-3.16 cm for VJ, 7.47-9.05 cm for TH, and 2.16-3.07 s for TCH.CONCLUSIONS Functional performance test outcomes are influenced by learning effects and should be considered in clinical interpretation. MDD<sub>95</sub> provides an objective benchmark for quantifying interlimb differences and monitoring rehabilitation-related recovery folllowing injury. Incorporating this threshold may improve the sensitivity of functional performance testing and support return-to-sport decision-making, where interlimb symmetry is considered an indicator of functional readiness for safe participation.