The effect of age on ankle joint position sense differs between contralateral matching and ipsilateral reproduction...

Ankle joint angle position sense (JPS) plays a crucial role in maintaining balance and coordinating movements, yet its changes across the lifespan remain unclear. This cross-sectional study aimed to investigate changes in ankle JPS across the lifespan using an ipsilateral reproduction task (IRT) and a contralateral concurrent matching task (CMT). One hundred and fifty eight individuals (6-92yrs) were allocated into 6 groups: Young-children (YC; n = 14) and Old-children (OC; n = 15), Young (Y: 19-39yrs; n = 33), Middle-aged (M: 40-59yrs; n = 41), Young-Old (YO: 60-5yrs; n = 24) and Old-Old (OO: >76yrs; n = 31) adults. The IRT consisted of reproducing a previously experienced ankle angle with the same limb. The CMT consisted of matching the passively held target ankle angle of one limb with the contralateral ankle. Both tests were performed blind-folded from 5° and 20° plantar flexion position to a 5° dorsiflexion target position. Error was expressed in absolute (AE) and constant (CE) values. In IRT, no difference was observed for AE and CE (p > 0.05) between groups, regardless of the initial position (5° or 20°). For the CMT, no age effect was observed for AE (p > 0.05), but children and older adults showed more positive (overestimation) and more negative (underestimation) CE, respectively, regardless of the initial position (p < 0.001). These results indicate that age affects the direction of the error (CE) rather than the magnitude of the error (AE), regardless of the angular range. They further suggest that CMT and CE could be more relevant when comparing ankle JPS between populations of different ages.