INFLUENCE OF STANCE WIDTH AND BINDING ANGLES ON TIBIAL ROTATION AND OLLIE JUMP HEIGHT IN SNOWBOARDING

The purpose of this study was to investigate the influence of stance width and binding angles on tibial rotation during a flat landing of a drop jump and Ollie jump height in snowboarders. Six binding conditions combined of three stance widths and two binding angle setups (forward and duck stance) were tested on 10 expert freestyle snowboarders. Relating to knee injury risk, tibial rotation was assessed using skin markers during the flat landing of a 51cm drop jump. The influence on the performance was investigated by the assessment of the Ollie jump height using a Quattro Jump force plate. An influence of the binding parameters on tibial rotation during a flat landing was found, whereas Ollie jump height didn’t differ significantly. A bigger angle of the front foot and a negative angle of the rear foot reduced the magnitude of internal tibial rotation

MOMENTS IN THE KNEE AND HIP DURING DESCENT AND ASCENT OF SQUATS

The aim of this study was to compare the moments in the knee and hip during the acceleration phases, namely the descent and the ascent phase of squats. 20 subjects executed barbell squats with zero, 25 %, and 50 % body weight (BW) extra load. Based on motion capture and force data, an inverse dynamic calculation of the load condition of knee and hip was performed. The free chosen time for one repetition was less than 2 s. According to Newton’s second law, it is expected that during the acceleration phases of the body and the extra load, the load conditions are higher. The experimental data shows only shows small differences in the range of a few percent during the acceleration and deceleration phases of the squat. Therefore, the main part of the loading during squatting is based on the body weight and the barbell and not due to the acceleration of the mass

LOAD CONDITION OF THE WRIST DURING THE FORWARD HANDSPRING, THE FORWARD HANDSPRING WITH ULNAR DEVIATED HAND POSITIONING AND THE BACKWARD HANDSPRING

The aim of this research was to deterime the loading conditions throughout the forward handspring, the forward handspring with ulnar deviated hand positioning and the backward handspring using an inverse dynamics approach based on simultaneously acquired kinetic and kinematic data. 14 gymnasts performed five of each movement. The range of motion (ROM) around the pronation/supination axis in the forward handspring with ulnar deviated hands was significantly higher than in the two other executions. The calculated moment acting on the wrist during backward handsprings exceeded the ones during the forward executions significantly. Due to the knowledge of the loading conditions, long-term damages can be estimated and minimized in such repetitively excessive motions

INFLUENCE OF THE STEP LENGTH AND POSITION OF THE FRONT KNEE ON THE LOAD CONDITIONS OF THE KNEE AND HIP DURING LUNGES

The aim of this study was to quantify the differences in the loading conditions of the lunge strength exercise at different step lengths and different tibia angles of the front leg. Eleven subjects performed lunges with 25 % body mass (BM) barbell extra load on two force plates. The movement was recorded with a motion capture system. The angles and the forces were calculated using inverse dynamics. A larger tibia angle led to a smaller ROM of the front knee, a larger ROM of the rear knee and hip, whereas a larger step length decreased the ROM of the rear knee and hip. A larger tibia angle resulted in a decreased moment in the front knee, front and rear hip and an increased moment in the rear knee. This possibility for varying the angles and corresponding moments allows coaches and therapists to adapt the lunge to an efficient exercise for strength training

How well can skin marker analysis detect the kinematics of a total ankle arthroplasty? - a comparison to videofluoroscopy

ISSN:1757-114

Restrictions in the ankle sagittal- and frontal-plane range of movement during simulated walking with different types of orthoses

Different types of orthoses are available to clinicians for non-surgical treatment of acute ankle sprains. The goal of this study was to scientifically compare the movement restrictions in the sagittal and frontal plane during simulated walking between one adaptable semi-rigid brace (OrthoTri-PhaseTM), four non-adaptable semi-rigid braces (OrthoStandardTM, MalleoLocTM, MalleoSprintTM, VACOankleTM), and one rigid cast. Predefined time sequences of rotational moments and axial loading during gait were applied via an ankle joint simulator, with the pneumatic pressure inside the orthoses kept constant to ensure the same condition for different trials and orthoses. The peak ranges of motion (RoMs) in the frontal and sagittal plane during gait were analyzed for statistically significant differences using single-factorial ANOVA with post-hoc Bonferroni analysis. Significant differences in peak plantar-/dorsiflexion and in-/eversion RoM during gait were found between different types of orthoses. In the sagittal plane, the rigid cast most significantly restricted overall RoM followed by the Ortho Tri-PhaseTM in Phase 1 and the Ortho StandardTM. The peak restriction in-/eversion RoM of the VACOankleTM came closest to the rigid cast, with a shift towards inversion. The VACOankleTM allowed for significantly larger dorsiflexion movement compared to all other orthoses. The present results may help clinicians in the decision-making process of finding the optimal orthosis for individual patients

Sling-based infant carrying affects lumbar and thoracic spine neuromechanics during standing and walking

Background Regular infant carrying might be a contributing factor for the development and progression of low back and pelvic girdle pain in mothers after childbirth. However, the neuromechanical adaptations of the spine due to different sling-based carrying techniques are not sufficiently well understood in order to provide evidence-based carrying recommendations. Research question What are the immediate effects of different sling-based infant carrying techniques on trunk neuromechanics? Methods Using a Vicon motion capture and a wireless surface electromyography system, three-dimensional pelvis and spinal kinematics as well as activation patterns of eight trunk muscles were derived from fifteen healthy young women during upright standing and level walking without carrying a load and while carrying a 6 kg-dummy with a sling in front and on either side. Data were analyzed using Statistical Parametric Mapping, allowing group comparisons of discrete parameters (standing) as well as continuous data (walking). To distinguish between clinically relevant and clinically not relevant kinematic findings, statistically significant differences were only considered in case of ≥5°. Results Compared to unloaded walking, carrying the dummy in front was mainly associated with increased lumbar lordosis (standing: (Δ8.8°, p = 0.006; walking: (Δ ≥ 8.2°, 1–100% of gait cycle [%GC], p < 0.001). When carrying the dummy on the preferred side, increased thoracic kyphosis (standing: ≥6.4°, p ≤ 0.003; walking: Δ ≥ 5.6°, 1–100%GC, p < 0.001) and axial rotation towards the ipsilateral side (standing: Δ5.3°, p = 0.003; walking: Δ ≥ 5.0°, 46–58%GC, p = 0.002) were observed. All three conditions entailed increased paraspinal muscle activity during walking, although only unilaterally in side carrying (lumbar, preferred condition: Δ ≥ 13.2%maxMVIC, 49–57%GC, p < 0.001; thoracic, non-preferred condition: Δ ≥ 5.3%maxMVIC, 47–58%GC, p < 0.001). Significance Carrying an infant alternating on both sides using a sling could be advantageous for preventing musculoskeletal pain resulting from excessive lumbar hyperextension and paraspinal muscle hyperactivation in women after childbirth. Keywords Trunk ; Kinematics ; Gait ; Electromyography ; Statistical parametric mappin

The effect of increasing heel height on lower limb symmetry during the back squat in trained and novice lifters

Background: Symmetry during lifting is considered critical for allowing balanced power production and avoidance of injury. This investigation assessed the influence of elevating the heels on bilateral lower limb symmetry during loaded (50% of body weight) high-bar back squats. Methods: Ten novice (mass 67.6 ± 12.4 kg, height 1.73 ± 0.10 m) and ten regular weight trainers (mass 66.0 ± 10.7 kg, height 1.71 ± 0.09 m) were assessed while standing on both the flat level floor and on an inclined board. Data collection used infra-red motion capture procedures and two force platforms to record bilateral vertical ground reaction force (GRFvert) and ankle, knee and hip joint kinematic and kinetic data. Paired t-tests and statistical parametric mapping (SPM1D) procedures were used to assess differences in discrete and continuous bilateral symmetry data across conditions. Results: Although discrete joint kinematic and joint moment symmetry data were largely unaffected by raising the heels, the regular weight trainers presented greater bilateral asymmetry in these data than the novices. The one significant finding in these discrete data showed that raising the heels significantly reduced maximum knee extension moment asymmetry (P = 0.02), but in the novice group only. Time-series analyses indicated significant bilateral asymmetries in both GRFvert and knee extension moments mid-way though the eccentric phase for the novice group, with the latter unaffected by heel lift condition. There were no significant bilateral asymmetries in time series data within the regular weight training group. Conclusions: This investigation highlights that although a degree of bilateral lower limb asymmetry is common in individuals performing back squats, the degree of this symmetry is largely unaffected by raising the heels. Differences in results for discrete and time-series symmetry analyses also highlight a key issue associated with relying solely on discrete data techniques to assess bilateral symmetry during tasks such as the back squat

SOFT TISSUE ARTEFACTS CAUSE AN UNDERESTIMATION IN KNEE FLEXION ANGLE IN SKINMARKER BASED SQUAT SIMULATIONS

Simulated muscle forces provide crucial knowledge for rehabilitation and training exercise design. To accurately simulate the internal loading conditions, input kinematics of the skeletal structures without soft tissue artefact (STA) are required. The aim of this study was to evaluate the ability of two numerical approaches to reduce STA for squat kinematics. Squat repetitions of 6 elderly subjects were examined using skin markers and video-fluoroscopy. Kinematic analysis was performed with a segmental and musculoskeletal simulation approach and compared to fluoroscopic data. The averaged RMS errors relative to the maximum knee range of motion were 8.8%, 32% and 49% for flexion/extension, ab-/adduction, and internal/external rotation, respectively. Skin marker based underestimation of the flexion angle could be corrected with a linear factor of 1.15

MUSCULOSKELETAL SQUAT SIMULATION EVALUATION BY MEANS OF AN INSTRUMENTED TOTAL KNEE ARTHROPLASTY

Knowledge of internal loading conditions based on validated musculoskeletal (MS) simulations can allow improved training and rehabilitation design and monitoring. The aim of this study was to evaluate the ability of individualised reference MS models, based on comprehensive motion analysis, to determine knee joint contact forces (JCFs), as measured in 6 subjects with instrumented total knee arthroplasties (TKA) during squat exercises. Maximum simulated JCFs reached approximately 100% higher than the in vivo measured values at high joint flexion angles; however, at knee flexion angles of below -l0 degree, the models underestimated the real forces by up to 50%. Improvements of reference MS models, even if they are individualised, are clearly required, especially at joint angles -50 degree