Influence of unstable footwear on lower leg muscle activity, volume change and subjective discomfort during prolonged standing

The present study was an attempt to investigate the effect of unstable footwear on lower leg
muscle activity, volume change and subjective discomfort during prolonged standing.
Methods: Ten healthy subjects were recruited to stand for 2 h in three footwear conditions: barefoot, flatbottomed
shoe and unstable shoe. During standing, lower leg discomfort and EMG activity of medial
gastrocnemius (MG) and tibialis anterior (TA) muscles were continuously monitored. Changes in lower
leg volume over standing time also were measured.
Results: Lower leg discomfort rating reduced significantly while subjects standing on unstable shoe
compared to the flat-bottomed shoe and barefoot condition. For lower leg volume, less changes also were
observed with unstable shoe. The activity level and variation of right MG muscle was greater with unstable
shoe compared to the other footwear conditions; however regarding the left MG muscle, significant
difference was found between unstable shoe and flat-bottomed shoe only for activity level.
Furthermore no significant differences were observed for the activity level and variation of TA muscles
(right/left) among all footwear conditions.
Conclusions: The findings suggested that prolonged standing with unstable footwear produces changes
in lower leg muscles activity and leads to less volume changes. Perceived discomfort also was lower for
this type of footwear and this might mean that unstable footwear can be used as ergonomic solution for
employees whose work requires prolonged standing