Evaluation of the effects of a novel exercise program in the treatment of low back pain in women working in a seated position: A randomized trial.

BACKGROUND: Low back pain (LBP) in sedentary workers is an increasing problem. Hyperlordosis or hypolordosis of the lumbar spine may be one of the causes of LBP. Various exercise programs are used in the prevention of LBP, but they do not consider individualization for diagnosed hyperlordosis or hypolordosis of the lumbar spine. OBJECTIVE: The purpose of this study was to evaluate the effect of the authors' original exercise program aimed at reducing hyperlordosis or increasing hypolordosis. METHODS: Sixty women aged 26 to 40 working in a sedentary position participated in the study. The sagittal curvature and the range of motion of the lumbar spine flexion were measured with the Saunders inclinometer, and the level of LBP was evaluated using the VAS scale. Subjects were randomly divided into two groups that participated in a 3-month exercise program developed by the authors. The first group performed exercises adjusted to the diagnosed hyperlordosis or hypolordosis, and the second group performed the same exercises regardless of the lumbar lordosis angle. The study was conducted again after completing the exercises. RESULTS: There was a statistically significant difference between the groups (p< 0.0001) in the level of pain, with better results in the group where individualized exercise was used - 60% of the participants reported complete absence of LBP. The lumbar lordosis angle was within normal limits in 97% of the subjects in the first group, and in 47% of the subjects in the second group. CONCLUSION: The results of this study confirm the validity of using individualized exercises with regard to diagnosed hyperlordosis or hypolordosis of the lumbar spine in order to achieve better analgesic and postural correction effects.

Stabilometric profile of handstand technique in male gymnasts.

PURPOSE: This study aimed to determine the characteristic features of handstand posture control associated with a high level of ability among male gymnasts. METHODS: 8 acrobatic gymnasts (4 more and 4 less experienced) participated in the study. They performed a 10-second handstand five times with each hand positioned on one AccuSway (AMTI) force platform and the other hand on the second. Body sway changes were recorded in time series: centre of pressure (COP) and components of the ground reaction force (GRF) (vertical, medial-lateral and anterior-posterior). The COP amplitude and average of GRF components, the index of frequency (by Fast Fourier Transform) for the right and left hand were calculated. RESULTS: More experienced gymnasts performing a handstand concentrate mainly on minimizing anterior-posterior body sway with minimum medial-lateral body sway. Less experienced gymnasts' pressure exerted on a surface by the hands is irregular in a medial-lateral direction. More experienced gymnasts control body position in the handstand and show less variation of body sway compared to less experienced gymnasts. More experienced gymnasts revealed lower frequency of body sway in the handstand compared to less experienced gymnasts. CONCLUSION: The stabilometric profile of more experienced gymnasts means the better posture control in handstand. The minimizing of body sway is compensated by exerting more force on a floor surface and the less experienced athletes cannot do that even after several years of training. The gymnasts of both groups, during standing on their hands, put more load on the right hand.

Muscle Coactivation during Stability Exercises in Rhythmic Gymnastics: A Two-Case Study.

Balance exercises in rhythmic gymnastics are performed on tiptoes, which causes overload of foot joints. This study aimed to evaluate the engagement of muscles stabilizing ankle and knee joints in balance exercises and determine exercises which may lead to ankle and knee joint injuries. It was hypothesized that long-term training has an influence on balance control and efficient use of muscles in their stabilizing function. Two rhythmic gymnasts (8 and 21 years old) performed balances on tiptoes (side split with hand support, ring with hand support) and on a flat foot (back split without hand support exercise). Surface electromyography, ground reaction forces, and kinematic parameters of movement were measured. The measuring systems applied were synchronized with the BTS SMART system. The results show the necessity to limit balance exercises on tiptoes in children because gastrocnemius medialis (GM) and gastrocnemius lateralis (GL) activity significantly exceeds their activity. Ankle joint stabilizing activity of GM and GL muscles in the younger gymnast was more important than in the older one. Performing this exercise, the younger gymnast distributed load on the anterior side of the foot while the older one did so on its posterior. Gymnastics coaches should be advised to exclude ring with hand support exercise from the training of young gymnasts.

Symmetry of lower limb loading in healthy adults during normal and abnormal stance.

PURPOSE: The purpose of the research was twofold: (1) to describe the normal asymmetry in lower limb loading during a normal stance and during a stance with visual and vestibular disturbance relating to the lower limb dominance, (2) to assess relations of loading of both lower limbs with body weight and height (BMI) and leg functional dominance. METHODS: The subjects of this study were 95 students. Settings of the two Kistler platforms were used to register the time series of the vertical component of the ground reaction force while the subject was standing (45 seconds) in a normal position and next with eyes covered with a band and head tilted back position with one leg placed on one platform and the other on the second platform. The symmetry index (SI) was used to describe the asymmetry of the left or right loading. RESULTS: The greater loading of the left or right leg during standing was independent of the functional leg dominance. The distribution of left and right lower limb loading in both trials may suggest that a low asymmetry, less than 5%, is represented by about 30% of subjects in general. No significant correlation was found between the SI and BMI of subjects who had a normal body weight, but in the group of overweight subjects the correlation was very high (r = 0.9). CONCLUSION: The results show that in describing norms of asymmetry in posture control in healthy humans it is very important to compare the results to posture asymmetry in various injuries or diseases. The most important result is that the higher asymmetry of lower limb loading is associated with overweight, which implies greater risk to health of those people.

An Investigation into the Relation between the Technique of Movement and Overload in Step Aerobics.

The aim of this research was to determine the features of a step workout technique which may be related to motor system overloading in step aerobics. Subjects participating in the research were instructors (n = 15) and students (n = 15) without any prior experience in step aerobics. Kinematic and kinetic data was collected with the use of the BTS SMART system comprised of 6 calibrated video cameras and two Kistler force plates. The subjects' task was to perform basic steps. The following variables were analyzed: vertical, anteroposterior, and mediolateral ground reaction forces; foot flexion and abduction and adduction angles; knee joint flexion angle; and trunk flexion angle in the sagittal plane. The angle of a foot adduction recorded for the instructors was significantly smaller than that of the students. The knee joint angle while stepping up was significantly higher for the instructors compared to that for the students. Our research confirmed that foot dorsal flexion and adduction performed while stepping up increased load on the ankle joint. Both small and large angles of knee flexion while stepping up and down resulted in knee joint injuries. A small trunk flexion angle in the entire cycle of step workout shut down dorsal muscles, which stopped suppressing the load put on the spine.

The influence of sounds on posture control.

PURPOSE: It is still not clear which parameters of sound are the most significant for body reactions and whether the way of sound reception plays a role in body control. The purpose of this study was to determine the influence of frequency, spectrum and loudness of sounds on posture control in healthy women and men. METHODS: The study subjects were 29 young adults who were submitted to a 60-second standing test in the bipedal stance on the force platform (AMTI). During the tests, 3 sinusoidal sounds with various timing and 2 musical sounds (guitar and piano) of the frequency 225 Hz, 1000 Hz and 4000 Hz were applied through headphones. The centre of pressure (COP) amplitude was registered. The sway area and COP mean velocity were computed. RESULTS: It was found that high frequency sounds contributed to a significant decrease of sway area values. No significant influence of low frequency sounds on posture control was observed. The influence of the sound spectrum (timbre) on posture control is limited; only the crescendo spectrum improves the body stability in the bipedal stance and not the music spectrum as guitar and piano. The loudness of sound, although extremely high, is not the cause of postural control changing in relation to lower loudness. No effect of gender was found in terms of body stability under different sound conditions. CONCLUSION: Based on the results, it can be argued that, in general, in a bipedal stance in terms of stability high sound frequency improves posture control, whereas sound spectrum and intensity show a limited impact.

Posture control development in children aged 2-7 years old, based on the changes of repeatability of the stability indices.

One of the most common problems encountered in posture control studies is relatively poor repeatability of postural stability measures based on the COP (center of pressure) time-series which results from the inherent variability of postural control. The repeatability of the data reflecting the postural control mechanisms in young children is still not well enough explained. The differences between of the repeatability of the stability indices of left and right foot may reflect the lateralization development of legs in the support function. The aim of the present study was two-fold: the assessment of the repeatability of the stability indices in three consecutive trials in young children, aged 2-7 years old, during quiet bipedal stance and the description of process of lower limbs lateralization, based on the difference of repeatability of both feet stability the indices changing with years. The subjects were 272 young healthy children aged 2-7 years old separated in 6 groups for children of different age. Each child stood for around 90s on two AccuSway force platforms (AMTI). The shifts of COP beneath left and right legs were recorded onto a computer by using appropriate software compatible with platforms. The indices of the ellipse area and velocity COP shifts were calculated. For assessment of the repeatability the concordance correlation coefficient (CCC) of the indices was used between the 1st and 2nd, 2nd and 3rd, and 1st and 3rd trials. Young children of 2-4 years old exhibit low level of the stability indices repeatability which increases in 5-year-old children, 6-year-olds revealed both low and high and 7-year-olds good and high levels of repeatability. Youngest children showed higher repeatability of the ellipse area of the left leg, 3- and 4-year-olds the right leg, while 6-year-olds again the left leg. In 5- and 7-year-olds there were no differences in the repeatability of stability indices between the left and right foot. The comparisons of the repeatability of the velocity index between the left and right leg revealed the difference only in 3 years old children. Posture control development of children can be assessed on the basis of velocity index but the COP ellipse area index is better way to describe the lateralization process. The repeatability of the stability indices is poor from 2 to 4 year of life but increases significantly from 5 to 7 year of life. The comparisons of repeatability between the left and right foot indices reflect the developmental process of lateralization of lower limbs in the support function and reveal that the left lower leg is a dominant one in support function while standing position. The process of leg lateralization is finishing about 6th year of life.

Repeatability of frequency of corrective foot pressure during balance control in children aged between 2 and 7.

The frequency of corrective signal (the centre of corrective (COC) signal), which is the decomposition of COP (centre of pressure) and estimated COM (centre of mass) time series, is one of the indicators reflecting the quality of postural control during stance. Young children, in the period of intensive development, gradually improve the quality of postural control in a daily life. The purpose of this paper was to describe the time series of corrective centre of foot pressure repeatability in young children aged between 2 and 7 during body stability in natural stance position. 272 healthy children aged between 2 and 7 were divided into 6 age groups. Two AccuSway force platforms were used (one foot of the subject was on one platform, the second foot, on the other). The COP trajectories were the basis for the calculation of the frequency stability indices in frontal and sagittal planes for the left leg and right leg separately. The COC signals were collected by the method based on the Kuczynski viscoelastic model. In order to assess the repeatability, the concordance correlation coefficient (CCC) was used between the 1st and the 2nd trials, the 2nd and the 3rd trials, and the 1st and the 3rd trials. The maturation of postural control system goes rather slowly in two youngest groups which showed the poor repeatability in COC frequency between the 2nd and the 3rd years of life. From the 4th to the 7th year of life the inter-session repeatability rapidly increases in three consecutive trials. Poor difference of frequency concordance was found between the left and right lower limbs. It is concluded that the frequency of corrective foot pressure is the reliable indicator of postural control for children aged between 4 and 7, but not for younger ones.