The aim of the study was to identify differences in ankle kinaesthetic sense between young and older adults and to identify how different exercise modalities acutely influence ankle kinaesthetic sense in both groups. Initial and final measurements of ankle kinaesthetic sense were taken from seventeen younger (23.5 ± 1.9 years) and fifteen older (67 ± 1.7 years) adults who performed one of the following intervention protocols: static stretching, concentric contractions, balance task and control intervention. Before and after each intervention protocol we measured ankle motion sense detection (plantar flexion (PF) and dorsal flexion (DF) direction), passive and active ankle repositioning (positions: PF 5°, PF 15°, DF 5°, DF 10°) and ankle torque sense (10% and 30% of maximal voluntary contraction in PF and DF direction). We found significant differences between the younger and older group in motion sense detection, passive and active repositioning and ankle torque sense. The older group exhibited higher motion sense threshold, greater absolute errors (AE) in all positions of passive repositioning, greater AE in PF 5° and DF 5° in active repositioning and greater AE in torque sense test (greater relative AE in PF 10%, PF_POVPR and PF-DF_POVPR). Static stretching had a negative influence on ankle motion sense detection in DF direction, greater AE in active repositioning (PF 15°) and greater AE in ankle torque sense (DF 10%, DF_POVPR, PF_SUM, PF-DF_SUM) in the younger group, while in the older group there was only a tendency for similar differences. Concentric contractions improved ankle motion sense in both groups and had a negative influence on active repositioning (PF 5°, PF 15° and DF 10°) in the younger group, while similar, but smaller differences were observed in the older group. Only the older group showed greater AE in ankle torque sense after concentric contractions (DF_POVPR, PF-DF_POVPR). No significant differences were found in either group after the balance task. Our findings show that static stretching had a negative influence on ankle motion sense, active repositioning and torque sense in the younger group. Greater influence of static stretching on ankle kinaesthetic sense of younger adults compared to older can be explained with impaired gamma loop function as a consequence of aging. We also identified positive influence of concentric contractions on ankle motion sense in both groups, while negative influence was noticed on active ankle repositioning in young and on torque reproduction in older adults. This information could be useful for appropriate sequence planning during same exercise unit and to predict possible negative consequences with similar exercise modalities, especially in older adults.
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