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Objective : The way how individual bars of sensorimotor insoles influence the gait kinematics is not fully understood yet. Therefore, this study aimed to explore the effect of three sensorimotor orthotic conditions (the medial calcaneal and retrocapital lateral bars and their combination) on the gait parameters in healthy adults during the stance phase of gait cycle. Materials and methods : Twenty-six young adults performed 20 gait cycles in each condition using their self-selected cadence and provided standardised shoes with the base-sole and the three types of orthotics. A three-dimensional motion analysis system (8 cameras; 200 Hz) was used and a six-degrees of freedom model was applied. The cadence, the stride length, the first peaks of foot external rotation, eversion and dorsal flexion as well as the first peak of hip adduction were analysed. Results : Significant differences ( p  < 0.05) were found for all parameters between the orthotic conditions, except the cadence. Significant difference in the first peak of hip adduction ( p  = 0.008) was found between the dominant and non-dominant leg. There were no significant interactions between the factors of condition and leg dominance ( p  > 0.05). Conclusions : There seems to be overall tendencies in immediate changes in ankle joint kinematics caused by all three sensorimotor orthotic conditions and besides the mechanical principles, also 'proprioceptive mechanism' seems to play a role. However, maximum observed average angular change was 2° and some variability in reactions to each orthotic condition exists among the individuals. Therefore, clinical relevance of such changes remains unclear and careful analysis of expected outcomes should be the common part of every orthotic intervention.

Background and Aim: Previous studies have supported the advantages of an external focus of attention (EFA) relative to an internal focus of attention (IFA) in healthly adults. However, effects of attentional focus instructions on skill performance and acquisition in children are equivocal. The aim of this study was to examine the effects of attentional focus instructions on performance of a whole body coordination task in children with and without developmental coordination disorder (DCD)., Methods: Children with DCD (n = 18) and typically developing (TD) children (n = 21) (9-10 years) were asked to perform 3 countermovement vertical jumps in the IFA (Concentrate on the swing of your arms), EFA (Concentrate on getting as close to the ceiling as possible), and control conditions., Results: The results showed that regardless of children's motor development proficiency, the jump height and vertical take-off velocity (V TO ) were higher in EFA relative to both IFA and Con conditions. In addition, V TO was significantly higher in the Con relative to IFA condition., Conclusion: The results of the current study showed that EFA relative to IFA instructions could enhance the neuromuscular activation of dynamic contractions of the leg muscles in both children with and without DCD. The findings suggest that the beneficial effects of EFA relative to IFA instructions on children's motor performance is identical across children with different levels of motor proficiency., Competing Interests: Declaration of Competing Interest None., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

PURPOSE OF THE STUDY The number of patients with total hip arthroplasty (THA) has been growing. In addition to traumatic indication, the patients manifest abnormalities in kinematics and kinetics of gait preoperatively. The aim of the study was to assess kinematics of the pelvis and lower limbs during walking in patients with unilateral primary and revision THA. MATERIAL AND METHODS A total of 18 patients (10 females, 8 males) with primary THA (pTHA) as well as 18 patients (9 males, 9 females) with revision THA (rTHA) participated in the study. The control group (CON) comprised 19 healthy subjects (11 females, 8 males). Kinematic data were collected using the optoelectronic motion system Vicon MX. Kinematic parameters were obtained by means of 16 reflective markers placed on the patient's body in correspondence with the Plug-in Gait model. All the patients also underwent a clinical examination (evaluation of the surgery result, patient's satisfaction assessment, Harris score evaluation) and a specific X-ray evaluation of both hips. RESULTS The analysis brought the following results: - non-operated limb (NL) in pTHA vs. rTHA: significantly smaller total range of motion (ROM) in the hip joint (36.4° vs 41.7°) in the sagittal plane, - operated limb (OL) in pTHA vs. rTHA: significantly greater values of maximum knee flexion (14.2° vs. 9.8°) and extension (7.9° vs. 4.0°), - NL in pTHA vs. CON: significantly smaller ROM in the knee (51.0° vs. 57.9°) and hip (36.4° vs. 43.6°) joints in the sagittal plane, - OL in pTHA vs. CON: significantly smaller knee flexion (52.9° vs. 57.6°), hip extension (-0.6° vs. -10.4°), and the total ROM in the knee (51.5° vs. 57.9°) and hip (34.5° vs. 43.6°) joints in the sagittal plane, - NL in rTHA vs. CON: significantly greater pelvis ROM in both the sagittal (5.6° vs. 3.1°) and transverse (12.1° vs. 9.9°) planes, - OL in rTHA vs. CON: significantly smaller total ROM in the knee (48.9° vs. 57.9°) and hip (31.4° vs. 43.6°) joints in the sagittal plane. DISCUSSION After THA surgery, various gait pathologies as well as compensatory mechanisms can develop and chain; therefore, a complex approach to physical therapy in THA patients is needed. The number of significant differences found in kinematic parameters between pTHA and rTHA was low a year after the surgery. Compared to CON, both the THA groups exhibited similar mechanisms causing worsening their gait dynamics. CONCLUSIONS Gait in both the THA groups was characterized by a decreased ROM in the knee and hip joints in the sagittal plane, compensated by increased pelvic anteversion. Approximately one year after THA surgery, the NL is still noticeably dominant in gait. The changes in lower limb mechanics after revision THA persist even after a considerable time since the surgery. Key words: primary total hip arthroplasty, revision total hip arthroplasty, gait, range of motion, pelvic kinematics, biomechanics.

Objective: Pregnant women are at elevated risk for functional and structural changes in the movement system. Common problems are loss of foot arch height and low back pain which can have strong influence on the decrease in quality of life., Aims: The aim of the study was to assess effect of physiotherapy intervention for preventing and treating changes in foot structure as well as low back pain during pregnancy., Design: Parallel intervention study., Setting: Department of Midwifery, Faculty of Health Sciences, Palacký University Olomouc., Methods: Twelve healthy pregnant women were randomly divided into the experimental and control groups. The women in the experimental group performed daily exercises aimed at the foot arch. The McGill Pain Questionnaire and the Pregnancy Mobility Index were used to measure level of pain and its impact on quality of life. The Foot Posture Index, Navicular Drop test, Chippaux-&#352;mirák index, and a podoscope were used to evaluate load and anthropometry of the foot. The data were collected at the turn of the first and second trimester and in the third trimester of pregnancy., Results: Statistically significant differences between the baseline and post-intervention were found only in the control group. Pain score obtained from the visual analogue scale as well as the Pregnancy Mobility Index score increased significantly (p = 0.04, p = 0.03 resp.). The Foot Posture Index results increased significantly on both the right (p = 0.04) and left (p = 0.04) lower limb. Chippaux-&#352;mirák index significantly increased on the right lower limb (p = 0.03)., Conclusions: The intervention prevented or reduced the changes in the foot structure and low back pain. This intervention can be recommended in primary or secondary prevention to increase quality of life in pregnant women.

Ballet training has been reported to positively influence balance ability. It is not entirely clear how improved balance ability manifests under standing conditions with different demands on postural control. The aim of the study was to compare balance of ballet dancers and non-dancers in a unipedal stance under different conditions. Twenty-five professional ballet dancers and twenty-five controls completed four unipedal standing balance tests: firm surface with eyes open and closed; foam mat surface with eyes open; and firm surface with eyes open immediately after performing ten 360° whole-body turns. The centre of pressure (COP) data were obtained with a force platform and the direction-specific standard deviations, velocities, and sample entropy of the COP displacement were computed. A three-way analysis of variance was used to compare groups, genders, and conditions. For standing immediately after performing ten turns, the postural sway parameters were significantly larger in the control group compared to the ballet dancers in both men and women. In this stance condition the values of postural sway and COP velocities in the control group were larger in the men compared to the women. For both genders in the control group all postural sway and COP velocity parameters were larger in standing with eyes closed and standing after performing 10 turns compared to standing with eyes open on both firm and foam surface. In the ballet dancers all COP velocity parameters were larger in standing with eyes closed compared to all other conditions. The results from the present study indicate that professional ballet dancers do not have a better general balance ability than untrained subjects., Competing Interests: The authors have declared that no competing interests exist.

The aim of our study was to compare gait in terms of foot loading and temporal variables after 2 different operative approaches (the extended lateral approach [ELA] and sinus tarsi approach). Twenty-two patients who sustained an intra-articular calcaneal fracture underwent plantar pressure distribution measurements 6 months after surgery. Measurements were performed while patients walked on the pedobarography platform. The values of dynamic variables were significantly lower on the operated limb in the ELA. In the sinus tarsi approach, no differences were observed between the operated and uninjured limbs (UIN) at peak pressure and at maximal vertical force. The values of temporal variables (contact time of the foot and of the heel) between the operated and UIN differed in the ELA. The hypothesis that differences in foot load between operated and UIN will be more significant in the ELA was confirmed. Our results showed that the differences in loading and temporal variables between the operated and the UIN persisted 6 months after surgery in both methods. The operated limb was less loaded, with the tendency to shift the load toward the midfoot and forefoot. After the less invasive sinus tarsi approach, the dynamic and temporal variables on the operated limb were nearly the same as those on the healthy one. The sinus tarsi surgical approach can be recommended for treatment of displaced calcaneal fractures., (Copyright © 2018 the American College of Foot and Ankle Surgeons. Published by Elsevier Inc. All rights reserved.)

Purpose: It is well known that postural stability is influenced by visual stimuli. The influence of saccadic eye movement on postural control has been described, however, a specific response of different body segments has not been studied yet. Therefore, the aim of this study was to assess the effect of horizontal and vertical saccadic eye movements on postural stability with specific focus on upper trunk, lower trunk and lower limbs movement variability and complexity., Methods: Eighteen elderly participants (age 70.3 ± 7.7 years) stood in bipedal stance in three visual conditions - horizontal saccades, vertical saccades and fixation. Accelerometers were attached to their lower back, sternum and shanks. Movement variability of each body segment was described by root-mean-square and sample entropy of acceleration., Results: The results of the present study revealed significant influence of saccadic eye movements on anterior-posterior and vertical shanks, and vertical lower trunk movement variability described by root-mean-square., Conclusions: The correlations between results of the observed segments showed segment-specific variability patterns but generalised complexity pattern.

Purpose: Vertical jump height is recognised as a determinant factor in elite volleyball performance. In previous studies there are different opinions on whether vertical jump height performance improves during maturation or not. The aim of this study was to assess the differences in jumping abilities in two different age groups of female volleyball players and to determine the take-off efficiency during repeated jumps., Methods: Seventeen female volleyball players from two different age categories - adults and under 16 years - participated in this study. Quattro Jump 9290BA force platform (Kistler, Winterthur, Switzerland) was used to assess the jumping performance during squat jumps, counter movement jumps, and 45-second continuous jumps., Results: Jumping performance did not differ significantly between the two groups. The main efficiency of the conversion of mechanical work into mechanical energy was only 24% and it decreased during the test., Conclusions: The influence of age on the jumping performance in a group of female volleyball players was not confirmed. Take-off efficiency was in both groups quite low and it did not improve during the test.

Objectives: The aims of the study were to assess the kinematics of the lower limbs and pelvis during normal walking in professional ballet dancers and to investigate relationships between movements of segments of the lower limbs and pelvis., Methods: Thirty one professional ballet dancers and twenty eight controls completed five walking trials at their preferred speed. Kinematic data in the basic anatomical planes for ankle, knee, and hip joints as well as for the pelvis were collected with an optoelectronic motion system., Results: The female ballet dancers had in comparison with the controls significantly larger (p < 0.01) knee flexion in the swing phase and hip abduction in the preswing phase. Compared to the control group, the male ballet dancers had significantly larger dorsiflexion in the final stance and the total pelvic tilt range of motion. The number of significant correlations between kinematic parameters was higher in the female ballet dancers., Conclusions: It can be concluded that specific movement techniques and compensatory strategies used in ballet dance can alter relationships between movements of segments of the lower limbs during normal walking. The relationships between movements in the joints of the lower limbs and pelvis are stronger in women.

Computing the local dynamic stability using accelerometer data from inertial sensors has recently been proposed as a gait measure which may be able to identify elderly people at fall risk. However, the assumptions supporting this potential were concluded as most studies implement a retrospective fall history observation. The aim of this study was to evaluate the potential of local dynamic stability for fall risk prediction in a cohort of subjects over the age of 60 years using a prospective fall occurrence observation. A total of 131 elderly subjects voluntarily participated in this study. The baseline measurement included gait stability assessment using inertial sensors and clinical examination by Tinetti Balance Assessment Tool. After the baseline measurement, subjects were observed for a period of one year for fall occurrence. Our results demonstrated poor multiple falls predictive ability of trunk local dynamic stability (AUC = 0.673). The predictive ability improved when the local dynamic stability was combined with clinical measures, a combination of trunk medial-lateral local dynamic stability and Tinetti total score being the best predictor (AUC = 0.755). Together, the present findings suggest that the medial-lateral local dynamic stability during gait combined with a clinical score is a potential fall risk assessment measure in the elderly population.

Objective: Pulmonary rehabilitation is mainly focused on exercise training and breathing retraining in children with asthma. Conversely, balance training is not usually recommended for the treatment, although postural deficits were found in these patients. Therefore, this study assessed the effect of balance training intervention on postural stability in children with asthma., Methods: Nineteen children with mild intermittent asthma (age 11.1 ± 2.1 years, height 147.6 ± 13.9 cm, weight 41.8 ± 13.3 kg) were randomly assigned to an experimental group or a control group and completed a four-week physiotherapy program including breathing exercises and aerobic physical training (six times/week, 45 minutes). Both groups performed the same training, but only the experimental group underwent exercises on balance devices. The center of pressure (CoP) velocity in the anteroposterior (V y ) and mediolateral (V x ) directions, and total CoP velocity (V tot ) were recorded before and after training in the preferred and the adjusted stances under eyes open (EO) and eyes closed (EC) conditions., Results: The addition of balance intervention led to significant improvements of V tot (p = 0.02, p = 0.04) in both types of stance, V x in the preferred stance (p = 0.03) and V y in the adjusted stance (p = 0.01) under EO conditions. Significant improvements were also found in V y in the adjusted stance (p = 0.01) under EC conditions., Conclusions: Results of this study support the effectiveness of balance training as a part of physiotherapy treatment for improving balance performance, predominantly under EO conditions, in children with mild asthma.

Psurny, M, Svoboda, Z, Janura, M, Kubonova, E, Bizovska, L, Martinez Lemos, RI, and Abrantes, J. The effects of Nordic walking and slope of the ground on lower limb muscle activity. J Strength Cond Res 32(1): 217-222, 2018-Nordic walking (NW) has proven to be a simple and safe mode of exercise that can be used in various types of sport, recreation, and rehabilitation activities. The aim of this study was to assess the effect of Nordic walking and slope of the ground on lower limb muscle activity. The experimental group consisted of 22 healthy men (aged 22.8 ± 1.4 years). The subjects walked on a treadmill at a self-selected speed. Two walking conditions (NW and walking) and 2 ground slopes (level ground and uphill walking at an 8% incline) were used. The surface electromyographic signals of the gastrocnemius lateralis, tibialis anterior, vastus medialis, rectus femoris, biceps femoris and gluteus medius were recorded. Nordic walking resulted in increased activity of some lower limb muscles, particularly during the first half of the stance phase, and decreased muscle activity during the first half of the swing phase. Uphill walking elicited increased muscle activity compared with level walking, particularly during the stance phase and the second half of the swing phase during both walking and NW, and the change was more pronounced during walking. We concluded that NW increased muscle activity in the lower extremities compared with walking, particularly on level ground. Increasing the ground slope enhanced the muscle activity to a much greater extent than NW.

Purpose: The aim of this study was to compare gait stability and variability between walking conditions and age groups., Methods: Twenty-six healthy younger and older females participated. Trunk acceleration in the vertical (V), medial-lateral (ML) and anteriorposterior (AP) directions during 5 minutes walking overground and 3 minutes walking on the treadmill at self-selected speed were recorded. Root mean square and standard deviations of acceleration, stride time and its variability, Lyapunov exponents (LE), multiscale entropy (MSE) and harmonic ratios (HR) were computed., Results: Both age groups showed significantly higher stride time variability and short-term LE in all directions during overground walking. For the older group, overground walking showed higher V and AP standard deviation. Significantly lower values for overground walking were observed for long-term LE (V and ML for the younger group, ML for the older group), HR (ML for the older group) and MSE (V for the older group). Significant age-related differences were found for V long-term LE for overground walking., Conclusions: The present findings suggest that both linear and advanced computational techniques for gait stability and variability assessment in older adults are sensitive to walking conditions.

A wobble board (WB) is a balance rehabilitation tool that is used in physiotherapy to improve strength and stability. The WB tested in this study includes a sensory module for measuring patients' tilt and rotation during stance. The aim of this study was to assess the reliability and validity of a balance measurement using a WB. Thirty healthy young adults participated in this study. The participants stood on the WB to simultaneously record the tilt of the WB and the center of pressure data using a force plate. The data were recorded during five measurement sessions on various days, with four trials each. Sways, velocities and indexes of complexity (CI) were computed. For reliability assessment, we used intra-class correlation coefficients within and between sessions; for validity, we computed Spearman correlation coefficients. The velocities and CI showed good intra-session reliability, and the sways showed mostly poor intra-session reliability. The results of inter-session reliability showed good to excellent reliability for CI, poor reliability for sways and poor to good reliability for velocities. The Spearman correlation coefficient showed excellent agreement between the mean velocities computed from the force plate and the WB. Our results confirm that the WB tested is suitable for stability assessment in young adults., (Copyright © 2017 IPEM. Published by Elsevier Ltd. All rights reserved.)

The authors investigate the ways in which varied postural responses to translating platform perturbations are associated with the variables of strength and power. Twenty-four physically active and 27 sedentary young adults were exposed to a set of postural perturbations at varied velocities (10 and 20 cm/s) and the respective accelerations (6.4 and 6.9 m/s 2 ), constant distance (6 cm), and 4 directions of platform motion (forward, backward, left-lateral, and right-lateral). They also performed maximum voluntary isometric contraction (MVC) and chair rising/chair jumping tests. The analysis of variance revealed significant interaction effect for peak center of pressure displacement, direction by velocity: F 3,129 = 24.43, p = .002; and direction by acceleration: F 3,129 = 34.18, p = .001. There were no significant correlations between peak center of pressure displacements and peak force and peak rate of force development measured during MVC in either standing (r = .27-57) or sitting positions (r = .12-51) and peak power during chair jumping (r = .47-.59) in all participants. As such, only a small proportion of variance was explained (9-39%, 3-23%, and 23-41%, respectively). In conclusion, interaction effects indicate that the composition of stimuli strongly influences compensatory responses and this effect is more pronounced in sedentary than in physically active young adults. Nevertheless, the dynamic balance is not associated with muscle strength and power in either group.

The aim of this study was to determine whether respiration would be altered during visual biofeedback condition while standing on a foam surface. Fifty young, healthy subjects (24 men, 26 women) were divided into a spirometry group, in which additional spirometry analysis was performed, and a control group. All subjects were tested in two conditions: 1) standing on a foam surface and 2) standing on a foam surface with visual biofeedback (VF) based on the centre of pressure (CoP). CoP amplitude and velocity in anterior-posterior (Aap, Vap) and medial-lateral (Aml, Vml) directions were measured by the force platform. Breathing movements were recorded by two pairs of 3D accelerometers attached on the upper chest (upper chest breathing - UCB) and the lower chest (lower chest breathing - LCB). Results showed that significant decreases of CoP amplitude and velocity in both directions were accompanied by a significant decrease of lower chest breathing, and an increase of LCB frequency was seen during VF condition compared to control condition in both groups. Moreover, a significant decrease in tidal volume and increased breathing frequency during VF condition were confirmed by spirometric analysis. Reduced breathing movements and volumes as well as increased breathing frequency are probably part of an involuntary strategy activated to maximize balance improvement during VF condition., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Considering that most of the falls in elderly population arise during walking, tests derived from walking performance would be desirable for comprehensive fall risk assessment. The analysis of spatial temporal parameters and the center of pressure displacement, which represents the interaction between the human body and the ground, would be beneficial. The aim of this study was to compare spatial temporal gait parameters and their variability and the variability of the center of pressure displacement between elderly fallers and nonfallers during gait at self-selected, defined and fast speeds. A prospective study design was used. At the baseline, measurements of ground reaction force during gait at self-selected, defined and fast walking speeds by two force plates were performed. In addition, the Tinetti balance assessment tool, the Falls Efficacy Scale-International and the Activities-Specific Balance Confidence Scale were used. Mean and coefficient of variation of spatial temporal gait parameters and standard deviations of center of pressure displacement during loading response, midstance, terminal stance and preswing phases were calculated. Comparison of the fallers and nonfallers exhibited no significant difference in clinical tool, scales or spatial temporal parameters. Compared to nonfallers' increased variability of walking speed at self-selected and defined speed, step width at fast walking speed and center of pressure displacement during preswing phase in medial-lateral directions at defined walking speed was found in fallers. However, application of the Holm-Bonferroni procedure for multiple comparisons exhibited no significant effect of group in any of the gait parameters. In general, our study did not observe an effect of group (fallers vs. nonfallers) on variability of spatial temporal parameters and center of pressure movement during gait. However, walking speed, step width as well as standard deviation of COP displacement in the medial-lateral direction during preswing exhibited a certain potential for distinguishing between elderly fallers and nonfallers.

Although entropy-based measurements of gait dynamics are becoming widely used tools for fall risk assessment, their relationship to fall occurrence is still unclear. The aim of this study was hence to compare fallers and non-fallers in terms of gait dynamics assessed by the multiscale and Shannon entropy. This study included 139 participants, aged 60-80 years, divided into two groups according to fall occurrence during a 6-month prospective observation (38 fallers, 101 non-fallers). The methodology involved the use of the Tinetti balance assessment tool (TBAT) and 5min of overground walking with 3D accelerometers located near the L5 vertebra and shanks. We analyzed 150 strides for gait complexity, an index of complexity (CI), computed from multiscale entropy (MSE) and Shannon entropy (ShE) derived from the recurrence quantification analysis. We found no significant differences between groups in MSE and CI. The TBAT total score was significantly higher in non-fallers (P=0.033), however, both groups showed low risk of falls. ShE in the anterior-posterior direction from trunk and in the medial-lateral direction from the shanks were both significantly higher in fallers (P=0.020; P=0.024). ShE was negatively correlated with CI, the shank ShE in the vertical direction was positively correlated with TBAT. Taken together, our findings suggest that MSE is not able to distinguish between highly functional groups, whereas Shannon entropy seems to be sufficient in fall risk prediction., (Copyright © 2016 Elsevier B.V. All rights reserved.)

Purpose: The aim of the study was to determine whether it is possible to assess static balance on an unstable surface using center of pressure velocities obtained with a force platform when standing on a wobble board., Methods: The center of pressure velocities were recorded with a force platform within three days (four trials per day) in thirty young adults in three conditions: standing on a rigid surface, compliant surface, and on a wobble board. Reliability of mean velocities of the center of pressure was examined using intraclass correlation coefficients. Relationships between the three conditions were assessed with Pearson correlation coefficients., Results: Intra-session reliability was excellent for standing on a rigid surface and on a compliant surface and good for standing on a wobble board. Inter-session reliability was good for all parameters in all conditions, except for poor reliability in the anterior-posterior direction in standing on a wobble board. All correlations between the same parameter in different conditions were statistically significant (P < 0.05), except for velocity of the center of pressure in the anterior-posterior direction between stance on a rigid surface and stance on a wobble board., Conclusions: Centre of pressure velocity parameters obtained with a force plate when standing on a wobble board can provide valuable information about postural stability in unstable conditions.

Background: The aim of our study was to compare spatiotemporal parameters and lower limb and pelvis kinematics during the walking in patients with hallux valgus before and after surgery and in relation to a control group., Methods: Seventeen females with hallux valgus, who underwent first metatarsal osteotomy, constituted our experimental group. The control group consisted of thirteen females. Kinematic data during walking were obtained using the Vicon MX system., Findings: Our results showed that hallux valgus before surgery affects spatiotemporal parameters and lower limb and pelvis kinematics during walking. Hallux valgus surgery further increased the differences that were present before surgery. Specifically after hallux valgus surgery, the walking speed decreased even more (p=0.09, η 2 =0.19) while step time increased (p=0.002, η 2 =0.44) on both legs. The maximum ankle plantar flexion of the operated leg during toe-off decreased to a greater extend (p=0.03, η 2 =0.26). The asymmetry in the hip and the pelvis movements in the frontal plane (present preoperatively) persisted after surgery., Interpretation: Hallux valgus is not an isolated problem of the first ray, which could be just surgically addressed by correcting the foot's alignment. It is a long-term progressive malfunction of the foot affecting the entire kinematic chain of the lower extremity., (Copyright © 2016 Elsevier Ltd. All rights reserved.)

Lots of athletic skills performed during practice or competition are initiated by the legs, where athletes either walk or run prior to executing specific skills. Kinematic chains are used to describe the relationships between body segments and joints during movement. The aim of this study was to determine the relationships between movements of lower limb segments and the pelvis in open and closed kinematic chains while walking. The experimental group consisted of 32 males (age 23.3 ± 2.5 years, body mass 78.1 ± 8.7 kg, body height 182 ± 6 cm). For 3D analysis, an optoelectronic system Vicon MX (7 cameras, frequency 200 Hz) was used. Positioning of the segments was determined by the PlugInGait Model. Each participant executed five trials at speeds ranging from 1.38 to 1.52 m·s -1 . The relationships between angle variables of the lower limbs and the pelvis in selected gait cycle phases were evaluated using STATISTICA software (version 10.0) and the Spearman correlation. The highest numbers of moderate and large correlations were found at opposite toe off, heel rise and initial contact for the sagittal and transversal planes in comparison to the frontal plane. The closed kinematic chain had a stronger impact on determining the movement pattern. The instructions or interventions focusing on closed kinematic chain alternation are more effective for changes in a movement pattern. The preferred limb initiates kinematics in the direction of propulsion, while the non-preferred limb in internal and external rotation.

Objective: This study assessed the postural stability in children with asthma using balance tests under conditions of a comfortable foot placement and with a foot placement provoking instability., Methods: A group of 10 school children from 8 to 10 years old with mild intermittent asthma and 10 healthy children of the same age range performed four balance tests in a randomized order: preferred stance, adjusted stance, and tandem stance each under both conditions of eyes opened (EO) and eyes closed (EC), as well as a one-legged stance with eyes-opened conditions. To determine postural stability, the center of pressure (CoP) movement was recorded. Basic stabilographic parameters were calculated: CoP velocity in the anterior-posterior direction, CoP velocity in the medial-lateral direction, and the total CoP velocity., Results: Statistically significant differences between the groups were found only for the one-legged stance. Significantly greater anterior-posterior CoP velocity (p = 0.05) and total CoP velocity (p = 0.03) were found in children with asthma when standing on the preferred foot. A significantly greater medial-lateral velocity (p = 0.02) was also found in the non-preferred foot of children with asthma., Conclusions: We can conclude that standing on one leg might be an appropriate test with which to identify balance differences between young children with mild intermittent asthma and healthy children.

Between 1992 and 2010, a total of 334 males participated in this study that assessed the differences and relationships between anthropometric variables and lower limb muscle strength in young and adult ski jumpers (n = 207) and Nordic combined (NC, n = 127) athletes. All athletes completed a maximal vertical jump from an in-run position and a maximal relative isometric force (MRIF) of the knee extensor measurement in a laboratory setting. The body mass index (BMI) in young competitors was lower than in adult groups (NC: p < 0.001; ski jumping [SJ]: p < 0.001). Similarly, the MRIF in both limbs was lower for both disciplines in the groups of young competitors. The vertical jump height (VJH) was lower for young competitors than for adults (NC: p ≤ 0.05; SJ: p < 0.001). When comparing SJ and NC athletes, BMI was lower in SJ athletes. In addition, the adult SJ competitors exhibited greater values of bilateral MRIF (p ≤ 0.05) and VJH (p < 0.01). There was a strong positive correlation in MRIF between the left and right lower limbs (p < 0.001) for all groups of SJ and NC athletes; therefore, it was determined to be sufficient to measure the MRIF on a single limb. Application of the new training methods (e.g., less emphasis on maximum resistance exercises) resulted in improved explosive power in ski jumpers even at lower-body weights. These changes are in accordance with the change in ski jump techniques.

The aim of the study was to assess lower limb loading during walking after unilateral total hip arthroplasty (THA) revision. Twenty-three THA revision subjects (12 men, 11 women) were divided into three groups according to time since surgery as 1 to 6 years, 6 to 11 years, and over 11 years. Two force plates were used to measure the ground reaction force during the stance phase. On the operated limb, compared to nonoperated limb, we found lower first vertical peak in the group of 1 to 6 years after revision and lower propulsion peak in the group of 6 to 11 years since revision. In the group of 11 years since THA revision, no significant difference was found. With advancing years after surgery, the stance phase duration got reduced and propulsion peak increased in the operated limb; minimal vertical force decreased and the time of minimal vertical force increased in the nonoperated limb. The study findings suggest the tendency to a more gradual and safer weight acceptance on the operated limb during the first years after THA revision, followed by limitation of foot propulsion. Despite this fact, lower limb loading can be considered as symmetrical across the whole measured period.

Aims: The objectives of this pilot study were to assess the potential use of 3D videography for analyzing the motion of the body center of mass (COM) in newborns and to determine differences in spontaneous movements between preterm and full-term infants., Methods: The group comprised 10 preterm newborns (gestational age at birth between 26 and 37 weeks; birth weight 800 to 2960 g; gestational age at the time of examination 34 to 39 weeks) and 10 full-term infants (gestational week 38 to 41; birth weight 2810 to 4360 g). To determine the range of motion of the COM, 3D videography was used (2 cameras, 25 Hz). When recording their movements, the infants were in the supine position, calm and awake. The recordings were processed using the APAS software. Selected points on the body were marked to obtain data for calculating the basic parameters of COM trajectories., Results: The range of motion of the COM in both craniocaudal and anteroposterior directions was significantly greater in premature infants (P < 0.05 and P < 0.01, respectively) than in full-term babies. The variability of motion of the COM was significantly greater in the craniocaudal (P < 0.01) and anteroposterior (P < 0.05) directions in preterm babies. This was also valid for the velocity of motion of the COM in the craniocaudal direction (P < 0.05)., Conclusions: 3D videography can be used for experimental assessment of motor behavior in preterm infants. Basic kinematic characteristics of the motion of the COM (range, variability, velocity) are greater in preterm infants.

Objective: Postural control is a complex skill based on the interaction of dynamic sensorimotor processes. This study assessed the effect of lateral perturbations on postural re-stabilization regarding lower limb preference., Methods: A group of 14 physically active individuals (9 male, 5 female) randomly underwent postural perturbations in lateral-left and lateral-right directions at a velocity of 0.2 m.s-1 and a platform shift of 6 cm. Perturbation to the preferred limb side (PS) was noted when the contralateral body movement was primarily controlled by the preferred limb and perturbation to the non-preferred limb side (NS) was noted when the contralateral body movement was primarily controlled by the non-preferred (stabilizing) limb. Prior to, during and after the perturbation centre of pressure (CoP) was registered using a computerized motor driven FiTRO Dynamic Posturography System based on force plate (Fitro Sway Check) with a sampling rate of 100 Hz. The basic stabilographic parameters of peak displacement (Peak 1), peak-to-peak displacement (Peak 2), time to peak displacement (Time 1), time to peak-to-peak displacement (Time 2) and re-stabilization time (Time 3) were analyzed., Results: Results showed significantly larger Time 3 on PS than on NS (2.81 ± 1.32 s and 1.73 ± 1.10 s; p=0.02). However, there were no significant differences in other parameters between PS and NS., Conclusion: It may be concluded that the observed shorter re-stabilization time at NS was due to the stabilization role of the non-preferred limb.

Objective: To assess the rider's movement during walking the horse in repeated therapeutic horse riding sessions and to determine the relationship between movements of the horse's back and the rider's trunk., Method: A total of 12 healthy females (age: 23.3±2.8 years; height: 167.3±4.2 cm; weight: 59.2±5.3 kg) participated in 10 therapeutic horse riding sessions. Two English Thoroughbreds with similar body constitution (aged 19 and 14 years) were used in the experiment. Nine markers were placed on the rider's body and the horse's back, and four video cameras with a 25 Hz frequency were used. Collected data were processed with APAS software., Results: The mediolateral displacements of C7, Th12, and L5 were gradually decreasing in each of the first three sessions. Statistically significant differences (p<0.05) were found between individual sessions in the displacement of C7, Th12 and L5 in the mediolateral and vertical directions as well as in the shoulder and pelvic lateral tilt and rotation. These differences did not show any general tendencies regarding the riders' increasing experiences with riding. The relationships between the displacement of C7, Th12, and L5 and the sacral tuber on the horse's back in the vertical direction were statistically significant (p<0.01) during all sessions., Conclusions: The displacement of C7, Th12 and L5 in the mediolateral direction decreased during riding sessions. A significant relationship was found between the vertical movement of the horse's back and the rider's trunk. These relationships differed between the horses.

This study assesses the longitudinal changes in anthropometric and motor parameters of ski jumpers. Male ski jumpers (n = 329) at various competitive levels participated in this study. These competitors were divided into two groups by age (18 years and younger, and over 18 years), and then divided into seven even intervals within those groups. Basic anthropometric parameters, maximal relative isometric knee extensor force, reaction time, knee extension time, and vertical jump height were measured. The conditions, instruments, and systems of measurement were consistent throughout the study. A reduced body mass index (BMI) in the adult jumpers was significant (P < .01) in the first three (1982-1993) and in the last three (1998-2010) intervals. Adults had an increase of maximal relative isometric knee extensor force (P < .01) in the last three intervals (1998-2010). They had greater maximal relative isometric knee extensor force (with exception of the first interval, 1982-1985) and vertical jump height than younger competitors (P < .01). Both young and adult jumpers exhibited the increase of strength and power in the lower limbs and a decrease in BMI during the whole observed period.

The variability of the centre of pressure (COP) movement is a tool that is often used for stability assessments during standing; however, this variable can provide relevant findings during dynamic conditions, which are more related to fall risks. The aim of this study was to investigate age-related differences in the variability of COP movement. Healthy young (younger group - 25 subjects, age 22.2 ± 1.8 years) and middle-aged (elder group - 25 subjects, age 56.6 ± 4.9 years) females participated in this study. The ground reaction forces and COP movement during walking at a self-selected speed were recorded using two force platforms. Each stance phase was divided into four subphases: loading response (LR), mid-stance (MSt), terminal stance (TSt) and preswing (PS). Standard deviations of the medial-lateral, anterior-posterior and total COP displacements were assessed. For statistical comparisons, one-way ANOVA and the Bonferroni post-hoc test were used. These results showed significantly higher COP movement variability in selected variables in the PS, LR and MSt subphases in the elder group (p < 0.05) compared with the younger group; no differences were found in the TSt subphase. A comparison of the subphases within the groups revealed significant differences (p < 0.001 for all cases and both groups) between the parameters in the LR × MSt, LR × TSt, MSt × PS and TSt×PS subphases. The LR and PS subphases showed significantly higher values for the variability parameters., (Copyright © 2014 Elsevier B.V. All rights reserved.)

Background: A symmetrical gait affords the most efficient walking pattern. Bionic prostheses should provide better gait symmetry than mechanically passive prostheses with respect to a nonpathological gait., Objectives: To compare the basic temporal-spatial parameters of gait in transfemoral amputees fitted with bionic or mechanically passive prosthetic knees with those of subjects with a nonpathological gait., Study Design: Three-dimensional gait analysis using an optoelectronic device., Methods: Eight transfemoral amputees participated in the study. Subjects walked across two dynamometric platforms a total of 15 times. Movement kinematics were measured using optoelectronic stereophotogrammetry., Results: The swing time of the affected limb in patients fitted with a mechanically passive knee joint was longer than that of the nonaffected limb by 0.055 s (effect size = 1.57). Compared with the control group, the swing time of the prosthetic limb in patients fitted with a mechanically passive knee was longer by 0.042 s (effect size = 2.1). Similarly, the stance time of the nonaffected limb was longer by 0.047 s (effect size = 1.07)., Conclusions: Compared with a mechanically passive knee joint, a bionic knee joint evinced gait symmetry. Both the stance time and the swing time for amputees with a bionic knee were similar to those of nonamputees., Clinical Relevance: Prosthetists aim to design prostheses that achieve a good symmetry between the healthy and affected limbs. The use of bionic technology achieves a level of symmetry approaching that observed in nonamputees., (© The International Society for Prosthetics and Orthotics 2013.)

Ballet is an art that puts extreme demands on the dancer's musculoskeletal system and therefore significantly affects motor behavior of the dancers. The aim of our research was to compare plantar pressure distribution during stance phase of gait between a group of professional ballet dancers and non-dancers. Thirteen professional dancers (5 men, 8 women; mean age of 24.1 ± 3.8 years) and 13 nondancers (5 men, 8 women; mean age of 26.1 ± 5.3 years) participated in this study. Foot pressure analysis during gait was collected using a 2 m pressure plate. The participants were instructed to walk across the platform at a self-selected pace barefoot. Three gait cycles were necessary for the data analysis. The results revealed higher (p < 0.05) pressure peaks in medial edge of forefoot during gait for dancers in comparison with nondancers. Furthermore, differences in total foot loading and foot loading duration of rearfoot was higher (p < 0.05) in dancers as well. We can attribute these differences to long-term and intensive dancing exercises that can change the dancer's gait stereotype.

Deformities of the feet in children can influence not only optimal foot development but also the development of other body segments. The aim of the study was to compare the hip and pelvis kinematics in groups of children with and without valgus deformity of the hindfoot. Three groups of children participated in the study: bilateral hindfoot valgosity (11 children, age 5.4 ± 1.4 years), unilateral hindfoot valgosity (14 children, age 5.6 ± 1.6 years) and the control group (8 children, 4.8 ± 1.2). Hindfoot valgus angle was measured clinically during standing. Hindfoot valgosity was considered in the range of 6 to 20 degrees. Kinematic data from five trials for each child was obtained using the Vicon MX system (six infrared cameras, frequency 200 Hz, Vicon Motion Systems, Oxford, UK). The results of our study showed significantly higher pelvic anteversion during the whole gait cycle for both unilateral and bilateral hindfoot valgosity children and significantly higher hip external rotation during the first half of the stance phase in bilateral deformity. The differences in the hip and pelvis kinematics, when compared to the control group, are higher for the group with bilateral deformity than in the group with unilateral deformity.

The concept of kinematic chains has been systematically applied to biological systems since the 1950s. The course of a ski jump can be characterized as a change between closed and open kinematic chains. The purpose of this study was to determine a relationship between adjacent segments within the ski jumper's body's kinematic chain during the in-run phase of the ski jump. The in-run positions of 267 elite male ski jumpers who participated in the FIS World Cup events in Innsbruck, Austria, between 1992 and 2001 were analyzed (656 jumps). Two-dimensional (2-D) kinematic data were collected from the bodies of the subjects. Relationships between adjacent segments of the kinematic chain in the ski jumper's body at the in-run position are greater nearer the chain's ground contact. The coefficient of determination between the ankle and knee joint angles is 0.67. Changes in the segments' positions in the kinematic chain of the ski jumper's body are stable during longitudinal assessment. Changes in shank and thigh positions, in the sense of increase or decrease, are the same.

Objectives: To evaluate the limits of stability (LOS) in persons with transtibial amputation (TTA), and to determine the effects of prosthetic alignment alterations on motor control strategies., Design: Before-and-after trial., Setting: A kinesiology laboratory at a university hospital., Participants: Male patients with TTA (n=10) and controls (n=17)., Interventions: Prosthetic alignment., Main Outcome Measures: For the LOS test, the maximum excursion, endpoint excursion, direction control, movement velocity, and reaction time with inclination in the forward direction, toward the amputated leg/right leg, and in the backward direction, and toward the nonamputated leg/left leg. Measurements were performed using the following 5 prosthetic alignments: the optimal alignment, with the prosthesis shorter by 1cm, with the prosthesis longer by 1cm, and with the prosthetic foot in 5° of extra plantar flexion and 5° of extra dorsiflexion., Results: Compared with the control group, maximum excursion and direction control were lower (P<.05) in patients with TTA with backward body inclination for all tested prosthetic alignments. Direction control in backward inclination was reduced (P<.05) compared with other tested directions for all assessed prosthetic alignments. Differences between the tested alignments were not significant in any of the tested directions., Conclusions: Patients with TTA have decreased voluntary body inclination backward within the LOS for all tested prosthetic alignments. Compared with controls, changes in prosthetic foot settings by means of rotation in the sagittal plane had a larger impact on movement strategy in patients with TTA than did changes to the length of the prosthesis., (Copyright © 2013 American Congress of Rehabilitation Medicine. Published by Elsevier Inc. All rights reserved.)

Elderly adults should perform exercises that maintain or improve balance to reduce risk of injury from falls. Bone fractures secondary to falls in the elderly, particularly sedentary females, continue to pose a major health and economic problem. A greater understanding of the processes that contribute to the propensity for falling may be obtained by considering changes in gait biodynamics with age and activity level. Therefore, the purpose of this study was to quantify the relationships between age/activity level and selected biodynamic parameters of the lower extremity during normal gait. Seventeen healthy women, 9 young and 8 elderly, were divided into groups of 9 active and 8 sedentary subjects. Three-dimensional (3D) video motion and force platform kinematic and kinetic data were collected from the hip, knee, and ankle of the right lower extremity as the subjects walked at self-selected speeds. Data were analyzed as functions of age and activity level by using a 2-way analysis of variance. As expected, our results show that the elderly group had significantly greater (p < 0.05) functional and mobility limitations in their lower extremity joints than did the younger group. Significant, age-related lower-limb gait alterations were manifested primarily at the ankle, whereas activity-related alterations were manifested most prominently at the hip. The knee showed the fewest changes accompanying age or activity level. Thus, age and activity level affect gait, which may have a role in the subsequent development of a predisposition to gait-related imbalances and resultant falling and increased hip fracture risk. Strength and conditioning professionals may consider these factors related to age and activity level when individualizing exercise regimens for their older, or sedentary, clients. Prophylactic physical activities involving specific, controlled 3D body movements may help prevent abnormal lower-limb joint kinematics (and their hypothetically coupled, intrinsic postural control strategies), thereby reducing fall and fracture propensity.

The purpose of the study was to evaluate marked postural asymmetry and gross joint mobility in elite female volleyball athletes. Sixty-two Czech and Slovak elite female volleyball athletes (age 20.7±2.03 years, body mass 71.1±6.18 kg, body height 1.804±.0618 m, BMI 21.8±1.78) were examined by an experienced rehabilitation physician. The set of tests included the frontal posture gross examination, the forward bending test from the standing position and the deep squat test. The spiking hand and the presence of any lower extremity injury were estimated by interview. The proportion test, Mann-Whitney test and t-test were used to evaluate statistical significance (p<0.05). Fifty subjects (80.6%) exhibited "typical" frontal plane posture in which the acromion, scapula and the iliac crest were in a higher position on the left side than on the right, significantly more frequently than all the other patterns (proportion test, p<0.0001). Ninety-eight percent of the subjects with the "LLL pattern" preferred the right arm for spiking (proportion test, p<0.0001). Forty-one subjects (66%) exhibited hypermobility in the forward bending test, significantly more frequently than twenty-one subjects (34%) with normal results (proportion test, p=0.0003). Thirty-four subjects (55%) did not succeed in the deep squat test and hypermobility in the forward bending test paradoxically prevailed in them significantly (proportion test, p=0.004). Restriction in the deep squat test was not linked to obesity, age (t-test, p=0.081) nor knee (proportion test, p=0.85) and ankle injury (Mann-Whitney test, p=0.36) in the past. Significant prevalence of hypermobility in the forward bending test was not surprising because of general body composition and the performance of regular stretching exercises in elite female volleyball athletes. On the other hand, surprisingly, more than half of the subjects did not succeed in the deep squat test. The cause of poor results in the deep squat test could be due to the tightness of the soleus muscle suffering from chronic overloading and/or an inappropriate stretching methods. An inappropriate and/or insufficient compensatory exercise and stretching method or system could be the cause of their marked postural asymmetry as well. A detailed examination of posture and muscle imbalance performed by an experienced physician or physiotherapist as well as individually tailored compensatory exercises and a stretching system can be strongly recommended to all elite athletes, not only to volleyball players.

The purpose of this study was to assess the execution of the flight phase in the Nordic combined (NC) among three groups of competitors, representing different skill levels, and to compare them with three groups of ski jumpers (SJs). Thirty NC and thirty SJ competitors, who performed ski jumps on an HS-134 m jumping hill, were divided into three subgroups based on jump length execution. Two-dimensional (2-D) kinematic data were collected from the lower extremities, trunks, and skis of the competitors. The SJ group had a smaller lower extremity angle ( p < 0.05), which results in the larger center of mass anterior movement ( p < 0.05) in comparison to the NC competitors. The NC competitors achieved jump lengths comparable to those of the SJ competitors by having significantly higher in-run velocities.

The athlete's inrun position affects the outcome for take-off in ski jumping. The purpose of this study was to examine the kinematic parameters between skiers' adjacent body segments during their first straight path of the inrun. Elite ski jumpers participated in the study at the World Cup events in Innsbruck, Austria, during the years 1992 through 2001. A video image was taken at a right angle to the tracks of the K-110 (meter) jumping hill. Kinematic data were collected from the lower extremities and trunk of the athletes. Findings indicated that jumpers had diminished ankle and knee joint angles and increased trunk and hip angles over the 10 years. In recent years, the best athletes achieved a further length of their jumps, while they experienced slower inrun average velocity. These results are perhaps explained by several possible contributing factors, such as new technique of the jumper's body kinematics, advancements in equipment technology, and somatotype of the jumpers.

Objective: To investigate the effects of mirror feedback on upright stance control in elderly transfemoral amputees., Design: Before and after intervention trials., Setting: University medical bioengineering laboratory., Participants: Elderly transfemoral amputees (N=12)., Interventions: Participants were asked to stand upright, as immobile as possible, in 2 Eyes-open and Mirror-feedback experimental conditions. The latter experimental condition consisted of supplying the participants with their frontal reflection by positioning a mirror in front of them., Main Outcome Measures: Weight-bearing symmetry and the displacements of the center of foot pressure under the nonaffected limb and the prosthetic limb., Results: Mirror feedback did not modify weight-bearing symmetry and had different effects on the center of foot pressure displacements under the nonaffected limb and prosthetic limb: a decreased center of foot pressure surface area was observed in the Mirror-feedback condition relative to the Eyes-open condition under the nonaffected limb, whereas no significant difference between the Eyes-open condition and the Mirror-feedback condition was observed under the prosthetic limb., Conclusions: Results suggest that elderly transfemoral amputees were able to integrate augmented visual biofeedback through the use of mirror-reflected body image to improve their upright stance control. The present findings could have implications for clinical practice and rehabilitation.

Hippotherapy employs locomotion impulses that are emitted from the back of a horse while the horse is walking. These impulses stimulate the rider's postural reflex mechanisms, resulting in training of balance and coordination. The aim of the present study was to assess the changes in magnitude and distribution of the contact pressure between the rider and the horse during a series of hippotherapy lessons. The monitored group, consisting of four healthy women (mean age 22.75 years, mean body weight 59.75 kg, mean height 167.25 cm) without any previous horse riding experience, received five 20 minute-lessons lessons in a three-week period. Hippotherapy was given on a 15-year-old thoroughbred mare. An elastic pad (Novel Pliance System, 30 Hz, 224 sensors) was used for pressure magnitude evaluation. The maximum pressure value was increased (p<.05) in the event of a second measurement (5th lesson). The pressure exerted on the rider upon contact of the rear limbs was higher than upon contact of the front limbs (p<.01). The size of the center of pressure (COP) deviations in the anteroposterior direction reduced (p<.05) with the number of lessons received. With the growing experience of the participant, an increase in pressure occurred on contact of her body and the horse's back as well as in the stability of the COP movement.

The morphologic variations of the shoulder blade have not yet been evaluated in clinical medicine. We observed that subjects with less standard shapes of the shoulder blade often suffer from musculo-skeletal shoulder syndromes with concurrent intrinsic impingement syndromes or, more precisely, partial-thickness rotator cuff tears. This experience became a basis for an experiment, in which we categorized individual phenotypes of the shoulder blade. A clinically useful finding of the presented study is a tool for predicting patients at risk for manifestations of impingement syndrome and also for prediction of easy or complicated restoration of neuromuscular stabilization of the shoulder. Lower functional potential of the external rotator muscles of the shoulder is in close relation to the individual shape of the shoulder blade, for the most part with the cranio-caudal dimension of the infraspinous fossa.