{Reference Type}: Journal Article
{Title}: Effect of forward and backward sloped support surfaces on postural equilibrium and ankle muscles activity.
{Author}: Atsawakaewmongkhon S;Couillandre A;Hamaoui A;
{Journal}: PLoS One
{Volume}: 19
{Issue}: 6
{Year}: 2024
{Factor}: 3.752
{DOI}: 10.1371/journal.pone.0305840
{Abstract}: <B>BACKGROUND: </B>Although sloped surfaces are common in daily living, most studies of body balance are carried out on flat surfaces, and few data are available for sloping angles below 14°.<BR><B>OBJECTIVE: </B>The purpose of this study was to explore the effect of forward and backward sloping surfaces at 7° and 15° on postural equilibrium and the activity of flexor/extensor ankle muscles.<BR><B>METHODS: </B>Fifteen healthy subjects (8 males and 7 females) (27.67 ± 3.9 years) underwent a posturographic examination associated with a surface electromyogram (EMG) of tibialis anterior (TA), soleus (Sol) and gastrocnemius medialis (GasM) under five conditions of support inclination: 0° (H0), backward inclination at 7° and 15° (DF7 and DF15), forward inclination at 7° and 15° (PF7 and PF15).<BR><B>RESULTS: </B>Results showed that the center of pressure (CP) was shifted according to the surface slope, with a forward move in PF7 (p <0.001) and PF15 (p <0.001) and a backward move in DF7 (p <0.01) and in DF15 (p <0.001). The mean displacement of the CP along the anterior-posterior axis (Xm) was increased in DF15 (p <0.01) relative to the H0 condition but reduced in PF7 (p <0.01). The normalized EMG revealed higher values when the muscles were in a shortened position (PF7 for Sol, p <0.05; PF15 for GasM, p <0.01; DF15 for TA, p<0.01) and lower values of GasM and Sol when lengthened (DF15, p <0.05).<BR><B>CONCLUSIONS: </B>Our findings indicate that standing on a backward sloped surface impairs body balance, while low-angle forward sloped surfaces might improve postural stability. Muscular activity variations of the ankle flexors/extensors, which are stretched or shortened, also seem to be related to the length-tension relationship of skeletal muscles.