The Influence of Knee Proprioception and Strength on Lower-Limb Functional Symmetry in Healthy Adults

This study examined the association between knee proprioception, strength, and functional symmetry in healthy individuals using isokinetic strength tests, proprioception assessments, and hop tests. Twenty young, healthy adults (mean age 26.5 ± 4.1 years, 85% right-limb dominant) participated. Knee extensor and flexor strength were measured at 60°·s^-1 and 240°·s^-1. Proprioception was assessed by measuring passive joint position sense (JPS1: position recognition; JPS2: repositioning) and kinesthesia (threshold to detection of passive motion, TTDPM). Functional performance was evaluated using the single-leg hop test (SLH), triple-hop test (TH), and crossover hop test (COH). Symmetry was calculated using the limb symmetry index (LSI) as the ratio of non-dominant to dominant limb values. The results showed that THT (p = 0.011) and COH (p = 0.032) performance was superior on the dominant limb. A correlation analysis revealed strong positive correlations between hop test distances and knee extensor strength (r = 0.56-0.70, p < 0.001). JPS symmetry was negatively correlated with hop test symmetry (JPS1: SLH, r = -0.53; THT, r = -0.49; COH, r = -0.70). The participants with poorer position sense on the non-dominant leg were 2.7 times more likely to show LSI < 90% (p = 0.035). In conclusion, proprioception-particularly joint position sense-is associated with functional symmetry during dynamic tasks, highlighting the importance of proprioceptive assessments in rehabilitation and injury prevention.