Selective effect of static stretching, concentric contractions, and a one-leg balance task on ankle motion sense in young and older adults.

BACKGROUND: Being aware of ankle movement and motor control has a critical role in maintaining balance during functional activities such as standing, walking, and running. Since the somatosensory system declines with aging, this is even more important for older adults. RESEARCH QUESTION: How do different exercise modalities (static stretching, one-leg balance task, concentric contractions, and control) acutely influence ankle motion sense in young and older adults? METHODS: Seventeen young and fifteen older participants performed four different intervention protocols (static stretching, one-leg balance task, concentric contractions, and control) in random order. Each session comprised measurements of ankle motion sense in plantar flexion (PF) and dorsal flexion (DF) directions prior to and after an intervention protocol. Average threshold levels (in degrees) of motion sense detection were calculated from three trials in each direction (PF/DF). RESULTS: A lower threshold of motion ankle sense was observed for young adults compared to older adults regardless of the exercise modality and the direction of the movement (p < 0.001). However, the changes in PF and DF ankle motion senses followed a similar trend in both groups during the three exercise modalities: static stretching increased ankle motion sense threshold (PF: 14% and 5%; DF: 19% and 11% in young and older adults, respectively), concentric contractions decreased ankle motion sense threshold (PF: -24% and -14%; DF: -19% and -21% in young and older adults, respectively), and the one-leg balance task did not significantly influence the ankle motion sense threshold (PF: -1% and -2%; DF: 6% and 1% in young and older adults, respectively). SIGNIFICANCE: Based on these results, static stretching should not be performed before ankle activities that require a good balance, precision, and coordination. Concentric contractions could be recommended before activities that challenge our postural stability.