Sole‐ground contact and sitting leg position influence suprahyoid and sternocleidomastoid muscle activity during swallowing of liquids

Clinically, the stable sole‐ground contact in the diet is considered as important for achieving safe swallows in the dysphagic patients. However, the effects of varied sole‐ground contacts on swallow‐related muscles activities remain unclear. The aim of this study was to investigate the effects of sole‐ground contacts on the muscle activities during swallow for various materials; 26 healthy adult subjects participated in this study. Three different sole‐ground contact conditions were investigated; sole‐ground contact with knees bent to 90° (KB 90°), sole‐ground contact with knees bent to 135° (KB 135°), and sole‐ground off the floor (Off). Participants swallowed four bolus materials (saliva, 5‐ml water, 10‐ml water, and 5‐ml yogurt) in each sole‐ground contact condition. The muscular activities of the suprahyoid (SH) muscle and the sternocleidomastoid muscle during swallowing were detected and recorded using surface electromyography. The sole‐ground contact pressure was evaluated using the data acquisition system. Duration of SH during 10‐ml water swallow for Off was significantly longer than that for KB 90°. Duration of SH during 5‐ml yogurt swallow for Off was significantly longer than that for KB 90°. Integration of SH during 10‐ml water swallow for Off was significantly greater than that for KB 135°. Integration of SH during 5‐ml yogurt swallow for Off was significantly greater than that for KB 90°. No significant differences were found in peak of SH. Sole‐ground contact conditions had significant effect on swallow‐related muscles activities. The stable sitting positions might be more advantageous for performing effective swallows compared with less stable sitting positions.