International Biomechanics最新文献

In this pilot randomized controlled trial, we assessed the effects of a core-lower limb coordinated Pilates exercise on gait and postural balance in women with bilateral flexible pes planus. Twenty-two women aged 34.64 ± 9.59 years with bilateral navicular drop ≥10 mm assessed by the navicular drop test (NDT) were randomly assigned to either a Pilates training group or a control group. Gait parameters - including foot off, step time, stride time, walking speed, and cadence - were assessed using a validated three-dimensional motion analysis system. Postural balance was quantified as center of pressure (COP) sway in both anterior - posterior (AP) and mediolateral (ML) directions, including range, velocity, and root mean square (RMS), using a force plate. Gait and balance were evaluated at baseline and after the 8-week intervention. Significant improvements were observed in step-time (p = .014), stride-time (p = .045), and cadence (p = .033), as well as postural balance variables, particularly in ML-RMS (p = .003), for the Pilates group compared to the control group. These results suggest that Pilates exercise may benefit gait and postural balance in individuals with flexible pes planus.

Total wrist fusion is a surgical procedure used to manage pain in late-stage arthritis, though it results in a complete loss of wrist mobility. This loss can lead to compensatory movement patterns in other upper limb joints, which may increase the risk of secondary musculoskeletal disorders. This study investigated scapular kinematics in wrist fusion patients compared to healthy controls. Eighteen participants (nine wrist fusion patients, nine age- and sex-matched controls) were recruited. Scapular motion was tracked using motion capture during seven functional tasks. Bilateral scapular kinematics (upward rotation, internal rotation and anterior tilt) were analyzed at 30° increments of humeral elevation. Kinematic outcomes were assessed using linear mixed models with group and side (fusion or non-fusion) as independent factors. Participants with wrist fusion demonstrated greater scapular internal rotation, upward rotation, and anterior tilt for both arms as compared with the control group. Upward rotation was greater on the fusion side than the non-fusion side in the surgery group. These findings suggest that scapular kinematics are altered to compensate for wrist immobility during daily living and functional tasks. Understanding these compensatory patterns is important to guide post-surgical rehabilitation strategies and help prevent secondary upper limb injuries.

Achilles tendinopathy (AT) is common among runners and typically presents with Achilles tendon pain. Neuromotor alterations have been reported in AT during demanding tasks such as running; however, alterations during functional tasks such as walking remain poorly understood. Such information may be relevant and inform rehabilitation targets. Therefore, this exploratory study investigated lower limb neuromotor control during walking and running in people with AT compared with healthy controls (CO). Twenty-four male runners participated (AT = 12, CO = 12) and completed walking (WALK), perturbed walking (PERTWALK), running (RUN), and perturbed running (PERTRUN) on a custom split-belt treadmill. Lower limb muscle activity was recorded using electromyography to assess activity onset, offset, and duration during unperturbed tasks, and reflex latency and amplitude during perturbed tasks. A MANOVA (α = 0.05) examined group effects (AT/CO). During WALK, AT showed delayed onset of tibialis anterior, peroneus longus, and vastus medialis (p < 0.05). During RUN, gastrocnemius medialis duration was longer, while gluteus maximus onset was delayed and shorter in AT (p < 0.05). During PERTWALK, tibialis anterior reflex latency was delayed in AT (p < 0.05), whereas reflex amplitudes and all PERTRUN outcomes were not significant. These findings indicate potential neuromotor differences in AT.

The determination of the optimal prosthesis alignment for maximum patient comfort is an important rehabilitation goal, especially for lower limb amputees, where the assessment of biomechanics is complex. Despite this, quantitative gait analysis is rarely used in clinical practice, and the influence of prosthesis alignment on gait kinematics remains unclear. This study explores the use of an IMU-based motion capture system to assess the impact of prosthesis alignment on gait biomechanics. A transtibial amputee's gait was analyzed with various prosthetic foot alignments in the sagittal and frontal planes. Key gait parameters were measured, including joint flexion/extension angles, body tilt and center of mass (COM) oscillation. Deviations in joint angles from reference values reached 30°, and gait speed varied by up to 0.5 m/s depending on alignment. Notably, prosthesis alignment had minimal impact on the healthy leg's kinematics but significantly influenced gait asymmetry, also reflected in COM movement. The study confirms that prosthesis alignment can markedly affect amputee gait biomechanics. The proposed method enables clinicians to evaluate alignment suitability and make data-driven adjustments.

The head-mounted laser is commonly used in clinical proprioceptive tests, but its ability to measure movement across three planes of motion has not been investigated. Therefore, this study evaluated the head-mounted laser against a validated gold standard multi-sensor inertial measurement unit (IMU) (Xsens^TM) in measuring cervicocephalic movement across three planes. Fourteen healthy adults (seven males and seven females) performed six repetitions each of active cervical flexion, extension, lateral flexion and rotation, whilst instructed to maintain the laser beam within a bullseye corresponding to 4.5° of movement. Primary plane means Xsens^TM range of motion (ROM) was used to evaluate if movement remained less than 4.5°. During flexion, extension and rotation movements, mean ROM in the primary plane using Xsens^TM remained within the 4.5° threshold (2.97°-3.57°), indicating that the head-mounted laser corresponded with the IMU (p ≤ 0.01). However, Xsens^TM mean lateral flexion movement reached 11.34° and 12.10° for left and right lateral flexion, indicating poor correspondence (p = 0.95 and 0.97). The head-mounted laser is appropriate for clinical movement assessment in the sagittal and transverse planes but not recommended for the coronal plane. Other devices should be considered for complete clinical assessment of cervical position sense.

Intervertebral disc (IVD) degeneration is a potential contributor to low-back pain. While experimental IVD injury models have demonstrated IVD structural changes, the early mechanical consequences remain unclear. This study aims to assess and compare the effects of two IVD injury models on lumbar spine instability and assess back musculature adaptations to IVD injury. Thirty-one adult male Wistar rats were assigned to three groups: IVD knife stab lesion (knife), IVD needle puncture (needle), and sham surgery control (control). In the knife and needle groups, L4/L5 IVDs were injured at 14 weeks of age. One to two weeks post-intervention, lumbar multifidus (MF) and medial longissimus (ML) muscles were excised, L4-L5 spinal segments were harvested for mechanical testing, and IVDs were collected for histology. The needle group exhibited lower peak stiffness, peak moment and hysteresis than controls in flexion, with no difference in lateral bending. IVD height and area did not differ between groups, but the needle group had a smaller nucleus relative to the annulus area compared to controls. Morphological changes were observed in both injury groups. The needle group showed a higher normalized ML mass, while the normalized MF mass was unchanged. In conclusion, lumbar spine instability was successfully established via IVD needle injury in the rat.

Maximum voluntary contractions (MVCs) are the standard normalization method for muscle activity, but can be hindered by pain and injury. Submaximal normalization may be a viable option. The study objective was to compare muscle activation between symptomatic and asymptomatic groups with MVC and submaximal normalization to determine if similar relative between-groups differences could be detected. Eighteen participants, divided into symptomatic and asymptomatic groups, performed isometric MVCs and six dynamic functional tasks. EMG data were normalized using MVC and submaximal values from a weighted overhead lift. MVCs achieved higher activation levels for most muscles, but submaximal normalization provided comparable values for serratus anterior. Significant between-group differences were observed during the Comb Hair, with higher activation in the symptomatic group for the upper trapezius, middle trapezius, and supraspinatus across both normalizations. The serratus anterior during the Overhead Reach and lower trapezius in the Tie Apron were also different between groups with both normalizations. There were some significant findings that emerged from only one normalization method. Submaximal normalization may be a viable alternative to MVC normalization for select muscles and upper limb pathological populations. Submaximal normalization allowed for meaningful comparisons of muscle activation patterns during functional tasks without the need for maximum force exertion.

The purpose of the present study was to examine differences in inter-limb asymmetries between countermovement vertical jump (CMJ) and single-leg jump (SLJ) performed on an innovative portable force plate system. Seventy professional athletes competing in top-tier international leagues (e.g. NBA, Super League) participated in this investigation. Following the completion of a standardized warm-up, athletes stepped on a uni-axial dual-force plate system and performed three CMJs and six SLJs without an arm swing in randomized order. Peak takeoff and landing forces were recorded for each limb, from which asymmetry percentages were derived. Wilcoxon signed-rank test was used to make statistical comparisons (p < 0.05). Significant differences were found in all asymmetry-related metrics, overall (CMJ vs. SLJ; takeoff: 7.2 vs. 1.0%; landing: 3.3 vs. 6.8%) and within each sport. Peak takeoff force asymmetry was considerably greater in CMJ than in SLJ, while peak landing force asymmetry displayed a reverse trend, with notably greater inter-limb asymmetries being detected within SLJ than CMJ. While both tests can offer useful information to sports practitioners, these results suggest that CMJ and SLJ should not be used interchangeably but rather in conjunction with one another to obtain a better insight into athletes' performance capabilities and inter-limb asymmetry magnitudes.

Traumatic brain injuries frequently occur in the construction industry when workers are struck with their heads in a forward-flexed position. Hard hats, the primary form of protection against such events, may not be optimized for these forward-flexed impacts since certification testing is performed with a head form in an upright configuration. In response, this study assesses the impact mitigation of six commercially available hard hats when subjected to impacts in different head orientations - upright and with 30° of forward flexion. Impactors with a mass of 3.6 kg were dropped vertically onto a Hybrid III 50^th percentile head/neck form. Kinematic outcomes related to TBI (e.g. accelerations) were compared across impact conditions. Results indicated that impacts to the forward-flexed head resulted in the largest angular accelerations, and hard hats were the least effective at mitigating angular accelerations in this head position. Furthermore, correlation analysis indicated that hard hats that performed well in upright testing often performed poorly in forward-flexed conditions (or vice versa). Taken together, these results suggest consumers/employers are not equipped with the necessary information to select the safest products for all impact conditions based on safety certification results using upright testing alone.

Patella fractures are relatively rare, though effective treatment of these fractures is essential. Screws and cerclage cable have been proposed to treat displaced patellar fractures to overcome the disadvantages of the modified tension band technique. The aim of the present study was to compare the in vitro biomechanical behaviour of a surgical construct consisting of screws and cable cerclage figure-of-eight tension band against the classic tension band technique using a specifically designed 3-D printed model of patella fracture. The patellar-fracture fixation systems tested in the current study consisted of screws and cerclage cable tension band compared to a conventional modified AO (Association of Osteosynthesis) tension band. Each system was tested in ten 3D- printed patella - fracture models. Two trials were designed to reproduce the forces the patella withstands throughout the range of knee motion. Differences between forces and displacement were explored with the Student t test. In the extension test, the between-group difference of the force required for failure was 1455,9 N greater in the screw cerclage cable setup in the flexion test, the screw cerclage group showed lower fracture displacement (1,42 mm less displacement) at higher forces (more than 244,9 N) compared to the Modified AO tension band. Differences were found to be statistically significant. Screws and cerclage cable are an alternative to conventional surgical procedures for transverse patellar fractures. Further research must establish if this setup and new non metallic materials should become the surgical treatment gold standard.