The objective of this study was to investigate the modulation of the ankle muscle electromyographic (EMG) response as a function of mental set. Thirteen young healthy subjects underwent 40 unexpected and self-initiated drops from 30 cm above two separate force-plates. Following unexpected drops, reflex activities were observed in the medial gastrocnemius (MG) and tibialis anterior (TA) at mean latencies (±SD) of 83.59±10.1 and 99.43±21.82 ms, respectively. Following self-initiated drops, the response latency of the MG was significantly shortened (to 71.98±10 ms, P<0.05), and the TA was significantly lengthened (to 183.33±45 ms, P<0.05) when compared with unexpected drops. Such a modulation was associated with a significant reduction of the impact force on landing as compared with unexpected drops (by 17%, P<0.05). Interestingly, a negative correlation was found between the onset of the TA EMG response and the magnitude of the impact force on landing during expected (r=-0.66, P<0.05) but not unexpected drops.
- Electromyographic responses
- Impact force
- Mental set
- Unexpected and self-initiated drops
ASJC Scopus subject areas