The aim of the study was to investigate age-related changes in postural responses to platform translation with 3 various velocities. We focused on the influence of linear velocity using the smoothed profile of platform acceleration (till 100 cm.s−2 ). Eleven healthy young (20-31 years) and eleven healthy elderly (65-76 years) subjects were examined. The subjects stood on the force platform with their eyes closed. Each trial (lasting for 8 sec) with different velocity (10, 15, 20 cm.s−1 ) of 20 cm backward platform translation was repeated 4 times. We have recorded displacements of the centre of pressure (CoP) and the EMG activity of gastrocnemius muscle (GS) and tibialis anterior muscle (TA). The results showed increased maximal values of CoP responses to the platform translation. There was also observed a scaling delay of CoP responses to platform translation with different velocities in elderly. The EMG activity of GS muscle during backward platform translation was of about similar shape in both groups during the slowest platform velocity, but it increased depending on rising velocity. EMG activity of TA was not related to the platform velocity. Early parts of postural responses showed significant co-activation of TA and GS muscles of elderly. It is likely that elderly increased body stiffening in order to help their further balance control., Z. Halická ... [et al.]., and Obsahuje seznam literatury
The study is aimed to examine balance control of slightly obese young adults during quiet stance and during gait initiation with and without crossing an obstacle. Forty-four young subjects were divided in two groups: control (BMI<25 kg/m2 ) and slightly obese (BMI from 25 to 35 kg/m2 ). Center of foot pressure (CoP) and kinematics of fifth lumbar vertebra (L5) were evaluated using a force plate and a motion capture system. During quiet stance with eyes open slightly obese group showed increased mean amplitude and velocity of CoP in anterior-posterior direction compared to normal weight subjects. During unloading phase of gait initiation significantly greater and faster lateral CoP shift was observed in slightly obese group compared to normal weight peers. Presence of an obstacle increased amplitude and velocity of the lateral CoP shift similarly in both groups. No BMI-related differences were found on L5 segment during gait initiation, which may indicate that postural control was already successfully performed in feet (CoP). We have shown that increased CoP parameters values and thus increased postural instability during quiet stance and during unloading phase of gait initiation is present not only in morbidly obese, but already in slightly obese subjects.
The aim of the study was to evaluate the effect of surgical reconstruction of anterior cruciate ligament (ACL) on postural stability and responses to lower limb (LL) muscles vibrations.Centre of pressure (CoP) was measured in 17 subjects during stance on firm/foam surface with eyes open/closed and during unilateral vibrations of LL muscles (
m. triceps surae – TS, m. quadriceps femoris – Q, m. quadriceps femoris and hamstrings simultaneously – QH). The measurements were performed: 1) preoperatively, 2) six weeks and 3) three months
after the reconstruction. Decreased postural stability was documented six weeks after the reconstruction compared to preoperative measurement. Three months after the reconstruction significant improvement was observed during stance on foam surface with eyes closed. Preoperatively, altered reactions of LL with ACL lesion compar
ed to intact LL were manifested by slower response in first 3 s of TS vibration and by increased CoP shift in last 5 s of QH vibration. After the reconstruction, we observed slower CoP reaction and decreased
CoP shift during TS vibration of LL with ACL lesion compared to
preoperative level. Posturography during quiet stance and during TS vibration reliably detect postural changes due to ACL reconstruction and can be potentially useful in clinical practice.