Trunk In Individuals Research Articles

Effects of a plank-based strength training programme on muscle activation in patients with long COVID: a case series.

This study aimed to analyse the effects of a plank-based strength training programme on muscle activation in patients with long COVID. Case series study that included patients with long COVID who participated in a 12-week trunk and pelvic muscle strength training programme. Clinical variables and the modified fatigue impact scale (MFIS) were used to assess fatigue levels. Percentage of muscle activation during a core muscle plank was measured via surface electromyography. Pre- and post-intervention results were compared using the Wilcoxon signed-rank test and evaluated with Cohen's D effect size (ES). Twenty-one subjects participated in the study; 81% female, mean age 47.5 years (range: 28-55 years), and median duration of symptoms 21 months (range: 5-24 months); 90.5% of the participants experienced fatigue (MFIS score = 38). Muscle activation during plank exercises improved across all muscles after the intervention, with significant increases in the left (p = 0.011, medium ES) and right external oblique (p =0.039, small ES) muscles and the right latissimus dorsi muscle (p = 0.039, small ES). Additionally, significant reductions in fatigue were observed in the total MFIS score (p = 0.004, medium ES) and in the physical (p < 0.001, large ES) and psychosocial subscales (p = 0.033, small ES). Results suggest that a plank-based strength training programme may be effective in enhancing trunk and pelvic muscle activation in individuals with long COVID.

Validation of Pelvis and Trunk Range of Motion as Assessed Using Inertial Measurement Units.

Trunk and pelvis range of motion (ROM) is essential to perform activities of daily living. The ROM may become limited with aging or with neuromusculoskeletal disorders. Inertial measurement units (IMU) with out-of-the box software solutions are increasingly being used to assess motion. We hypothesize that the accuracy (validity) and reliability (consistency) of the trunk and pelvis ROM during steady-state gait in normal individuals as measured using the Opal APDM 6 sensor IMU system and calculated using Mobility Lab version 4 software will be comparable to a gold-standard optoelectric motion capture system. Thirteen healthy young adults participated in the study. Trunk ROM, measured using the IMU was within 5-7 degrees of the motion capture system for all three planes and within 10 degrees for pelvis ROM. We also used a triad of markers mounted on the sternum and sacrum IMU for a head-to-head comparison of trunk and pelvis ROM. The IMU measurements were within 5-10 degrees of the triad. A greater variability of ROM measurements was seen for the pelvis in the transverse plane. IMUs and their custom software provide a valid and reliable measurement for trunk and pelvis ROM in normal individuals, and important considerations for future applications are discussed.

Biomechanical analysis of trunk and lower limbs during stair activity in patients with scoliosis

Staircases are a frequently encountered obstacle in daily life, requiring individuals to navigate ascending and descending movements that place additional demands on the trunk and lower limbs compared to walking on level surfaces. Therefore, it is crucial to examine the biomechanical characteristics of the trunk and lower limbs in individuals with scoliosis during stair activity. The aim of this study was to investigate the biomechanical differences in trunk and lower limbs during daily stair activities between patients with scoliosis and a healthy population. Additionally, the study aimed to explore the relationship between trunk abnormalities and lower limb biomechanics, providing a clinical and objective assessment basis for scoliosis. The Qualisys system, based in Gothenburg, Sweden, was employed for data collection in this study, with a sampling frequency of 150 Hz. It captured the kinematics of the trunk and lower limbs, as well as the kinetics of the lower limbs during stair ascent and descent for both the 28 individuals with scoliosis and the 28 control participants. The results indicate that scoliosis patients demonstrated significantly higher asymmetry compared to the control group in various measures during ascent and decent. These include different parts of kinematics and kinetics. Scoliosis patients demonstrate noticeable variations in their movement patterns compared to the healthy population when engaging in stair activities. Specifically, during stair ascent, scoliosis patients exhibit a seemingly more rigid movement pattern, whereas descent is characterized by an unstable pattern.

The immediate effect of unilaterally applied lumbar mobilisations on the passive straight leg raise and ninety-ninety test in asymptomatic adults: A randomised crossover trial

ObjectivesThis study assessed the immediate effect of unilateral posterior-anterior lumbar mobilisations on trunk and lower limb flexibility in asymptomatic individuals. Study designRandomised cross-over trial. ParticipantsTwenty-seven participants (age = 26.0 years ±6.4) with no current or recent history of lower back or leg pain/surgery completed the study. Main outcome measuresParticipants attended two sessions, receiving either grade 3 (‘treatment’) or grade 1 (‘sham’) unilateral spinal mobilisations. Outcome measures (modified-modified Schober's test [MMST], ninety-ninety test [NNT], and passive straight-leg raise [PSLR]) were assessed immediately before and after (post-1 and post-2) the intervention. An instrumented hand-held dynamometer was used to measure the change in NNT and PSLR joint angle (deg) and passive stiffness (Nm/deg) pre- and post-intervention. ResultsThe mean change in PSLR angle at the first (P1) and maximal (P2) point of discomfort following the treatment was 4.8° and 5.5°, and 5.6° and 5.7°, larger than the sham at post-1 and post-2, respectively. There was no effect of the treatment on the PSLR at P1 or P2 for the contralateral limb at either timepoint. There was no effect of the treatment on MMST distance, NNT angle or passive stiffness, or PSLR passive stiffness, for either limb. ConclusionsImmediate effects of unilateral posterior-anterior lumbar mobilisations in asymptomatic individuals are isolated to treatment side and limited to a small increase in PSLR range, with no change in lumbar motion or the NNT test.

Postural control of the trunk in individuals with and without low back pain during unstable sitting: A protocol for a systematic review with an individual participant data meta-analysis.

IntroductionPostural control of the trunk is critical for performance of everyday activities and the health of spinal tissues. Although some studies report that individuals with low back pain (LBP) have poorer/compromised postural control than pain-free individuals when sitting on an unstable surface, others do not. Analyses commonly lack the statistical power to evaluate the relevance of features that could impact the performance of postural control, such as sex, age, anthropometrics, pain intensity or disability. This paper outlines a protocol for a systematic review with an individual participant data (IPD) meta-analysis that aims to synthesise the evidence and evaluate differences of postural control measures between individuals with and without LBP during unstable sitting.Methods and analysisA systematic review with IPD meta-analysis will be conducted according to PRISMA-IPD guidelines. To identify relevant studies, electronic databases and the reference lists of included articles will be screened. Unstable seat movements are derived from centre of pressure (CoP) data using a force plate or angle of the seat using motion systems/sensors. The comprehensiveness of reporting and methodological quality of included studies will be assessed. Analysis will involve a descriptive analysis to synthesise the findings of all included studies and a quantitative synthesis using two-stage IPD meta-analysis of studies that include both individuals with and without LBP for which IPD set can be obtained from authors. Analyses will include consideration of confounding variables.EthicsExemption from ethical approval was obtained for this review (University of Queensland, ID: 2019003026).Systematic review registrationPROSPERO ID: CRD42021124658.

Carpal Tunnel Syndrome and Diabetes-A Comprehensive Review.

Carpal tunnel syndrome (CTS) is the most common compression neuropathy in the general population and is frequently encountered among individuals with type 1 and 2 diabetes. The reason(s) why a peripheral nerve trunk in individuals with diabetes is more susceptible to nerve compression is still not completely clarified, but both biochemical and structural changes in the peripheral nerve are probably implicated. In particular, individuals with neuropathy, irrespective of aetiology, have a higher risk of peripheral nerve compression disorders, as reflected among individuals with diabetic neuropathy. Diagnosis of CTS in individuals with diabetes should be carefully evaluated; detailed case history, thorough clinical examination, and electrophysiological examination is recommended. Individuals with diabetes and CTS benefit from surgery to the same extent as otherwise healthy individuals with CTS. In the present review, we describe pathophysiological aspects of the nerve compression disorder CTS in relation to diabetes, current data contributing to the explanation of the increased risk for CTS in individuals with diabetes, as well as diagnostic methods, treatment options, and prognosis of CTS in diabetes.

Altered trunk and lower extremity movement coordination after neuromuscular training with and without external focus instruction: a randomized controlled trial

BackgroundThis study sought to determine the effects of a 6-week neuromuscular training (NMT) and NMT plus external focus (NMT plus EF) programs on trunk and lower extremity inter-segmental movement coordination in active individuals at risk of injury.MethodsForty-six active male athletes (controls = 15, NMT = 16, NMT plus EF = 15) participated (age = 23.26 ± 2.31 years) in this controlled, laboratory study. Three-dimensional kinematics were collected during a drop vertical jump (DVJ). A continuous relative phase (CRP) analysis quantified inter-segmental coordination of the: (1) thigh (flexion/extension)—shank (flexion/extension), (2) thigh (abduction/adduction)—shank (flexion/extension), (3) thigh (abduction/adduction)—trunk (flexion/extension), and (4) trunk (flexion/extension)—pelvis (posterior tilt/anterior tilt). Analysis of covariance compared biomechanical data between groups.ResultsAfter 6 weeks, inter-segmental coordination patterns were significantly different between the NMT and NMT plus EF groups (p < 0.05). No significant differences were observed in CRP for trunk-pelvis coupling comparing between NMT and NMT plus EF groups (p = 0.134), while significant differences were observed CRP angle of the thigh-shank, thigh-trunk couplings (p < 0.05).ConclusionsTrunk and lower extremity movement coordination were more in-phase during DVJ in the NMT plus EF compared to NMT in active individuals at risk of anterior cruciate ligament injury.Trial registration: The protocol was prospectively registered at UMIN_RCT website with ID number: UMIN000035050, Date of provisional registration 2018/11/27.

Coordination Variability During Walking and Running in Individuals With and Without Patellofemoral Pain Part 2: Proximal Segments Coordination Variability

There is a scarcity of studies evaluating the variability of couplings between proximal segments (trunk, pelvis, and thigh) in individuals with patellofemoral pain (PFP) while emerging evidence has suggested that aberrant motions of trunk and pelvis can have a contributory role in the etiology of PFP. The purpose of this study was, therefore, to evaluate the trunk, pelvis, and thigh intersegmental coordination variability in PFP compared with healthy individuals. Thirty-four participants (17 with PFP and 17 healthy controls) walked (at preferred speed) and ran (at preferred and fixed speed) on a treadmill each trial for 30 seconds. Three-dimensional kinematics were recorded using a motion capture system. Continuous Relative Phase was used to calculate the coordination variability of couplings between trunk, pelvis, and thigh. The PFP group was significantly less variable at trunk-thigh and pelvis-thigh in frontal plane during stance at preferred speed running and trunk-pelvis in sagittal plane during swing irrespective of trial. The variability differences of the following couplings among study groups tended to be significant with the PFP group showing lesser values: trunk-thigh and pelvis-thigh in frontal plane during stance at fixed speed running, trunk-pelvis in frontal plane during swing at preferred speed running and trunk-thigh in sagittal plane during swing. Lower variability in coordination of trunk, pelvis, and thigh in individuals with PFP indicates the system’s reduced ability to transit between movement patterns and to respond to different perturbations which could result in the progression of the patellofemoral joint injury.

Intersegmentar orientation between trunk and lower limbs in individuals after stroke: a pilot study

Introduction: Postural control, which involves stability and intersegmental orientation against gravity, is considered a prerequisite for movement to occur efficiently and in different contexts [1]. After central nervous system damage, individuals tend to demonstrate motor impairments, which can affect their functional ability in different activities, such as standing and walking [2]. These altered motor behaviours restrict voluntary, well-coordinated and effective movements, which in turn limit a person’s ability to perform everyday tasks [2]. Therefore, this study aimed at analysing the correlation between the orientation of the trunk and lower limbs of individuals after stroke during standing. Materials and methods: This was a pilot cross-sectional study. Were included individuals at the chronic stage post-stroke, who had a single unilateral ischemic event involving the medial cerebral artery; as exclusion criteria were considered inability of autonomous standing, presence of other pathologies that could interfere with postural control, and cognitive impairment. Trunk linear extension and lower limb segmental orientation were assessed using the postural assessment software SAPo. The correlation between the variables was analysed through the Pearson correlation coefficient, with a significance of 0.05. This project was approved by an Ethics Committee and an informed consent was signed by each participant. Results: From 236 individuals that were contacted, only 11 fulfilled the criteria to participate, 5 female and 6 male, aged between 45 and 84 years old. The lesion was located at the right hemisphere in 5 individuals and in 6 individuals at the left. All participants were overweight, nevertheless none had morbid obesity. Results showed a significant moderate correlation (r = 0.642; p = 0.03)) between the trunk orientation and the knee angle of contralesional side. Other correlations were almost null or weak, and with no statistical significance. Discussion and conclusions: These preliminary results suggest that the vertical trunk orientation and the knee angle of contralesional side might present a positive moderate correlation in post-stroke individuals, which might be of interest for the physiotherapy clinical reasoning. This finding deserves, however, further analysis.

Trunk, pelvis and hip biomechanics in individuals with femoroacetabular impingement syndrome: Strategies for step ascent

BackgroundFemoroacetabular impingment (FAI) syndrome is common among young active adults and a proposed risk factor for the future development of hip osteoarthritis. Pain is dominant and drives clinical decision-making. Evidence for altered hip joint function in this patient population is inconsistent, making the identification of treatment targets challenging. A broader assessment, considering adjacent body segments (i.e. pelvis, trunk) and individual movement strategies, may better inform treatment programs. This exploratory study aimed to compare trunk, pelvis, and hip biomechanics during step ascent between individuals with and without FAI syndrome. MethodsFifteen participants diagnosed with symptomatic cam-type or combined (cam plus pincer) FAI who were scheduled for arthroscopic surgery, and 11 age-, and sex-comparable pain- and disease-free individuals, underwent three-dimensional motion analysis during a step ascent task. Trunk, pelvis and hip biomechanics were compared between groups. ResultsParticipants with FAI syndrome exhibited altered ipsilateral trunk lean and pelvic rise towards the symptomatic side during single-leg support compared to controls. Alterations were not uniformly adopted across all individuals with FAI syndrome; those who exhibited more pronounced alterations to frontal plane pelvis control tended to report pain during the task. There were minimal between-group differences for hip biomechanics. ConclusionExploratory data suggest biomechanics at the trunk and pelvis during step ascent differ between individuals with and without FAI syndrome. Those with FAI syndrome implement a range of proximal strategies for task completion, some of which may have relevance for rehabilitation. Longitudinal investigations of larger cohorts are required to evaluate hypothesized clinical and structural consequences.

Biomechanical compensations of the trunk and lower extremities during stepping tasks after unilateral transtibial amputation

BackgroundLower extremity movement compensations following transtibial amputation are well-documented and are likely influenced by trunk posture and movement. However, the biomechanical compensations of the trunk and lower extremities, especially during high-demand tasks such as step ascent and descent, remain unclear. MethodsKinematic and kinetic data were collected during step ascent and descent tasks for three groups of individuals: diabetic/transtibial amputation, diabetic, and healthy. An ANCOVA was used to compare peak trunk, hip and knee joint angles and moments in the sagittal and frontal planes between groups. Paired t-tests were used to compare peak joint angles and moments between amputated and intact limbs of the diabetic/transtibial amputation group. FindingsDuring step ascent and descent, the transtibial amputation group exhibited greater trunk forward flexion and lateral flexion compared to the other two groups (P<0.016), which resulted in greater low back moments and asymmetric loading patterns in the lower extremity joints. The diabetic group exhibited similar knee joint loading patterns compared to the amputation group (P<0.016), during step descent. InterpretationThis study highlights the biomechanical compensations of the trunk and lower extremities in individuals with dysvascular transtibial amputation, by identifying low back, hip, and knee joint moment patterns unique to transtibial amputation during stepping tasks. In addition, the results suggest that some movement compensations may be confounded by the presence of diabetes and precede limb amputation. The increased and asymmetrical loading patterns identified may predispose individuals with transtibial amputation to the development of secondary pain conditions, such as low back pain or osteoarthritis.

Effects of performing hip abduction and adduction during bridging exercise on trunk and lower extremity muscle activity in healthy individuals

Effects of performing hip abduction and adduction during bridging exercise on trunk and lower extremity muscle activity in healthy individuals

Diaphragm Contractility in Individuals with Chronic Ankle Instability.

Previous investigations have identified impaired trunk and postural stability in individuals with chronic ankle instability (CAI). The diaphragm muscle contributes to trunk and postural stability by modulating the intra-abdominal pressure. A potential mechanism that could help to explain trunk and postural stability deficits may be related to altered diaphragm function due to supraspinal sensorimotor changes with CAI. The purpose of this study was to examine the diaphragm contractility in individuals with CAI and healthy controls. Twenty-seven participants with self-reported CAI and 28 healthy control participants volunteered. A portable ultrasound unit was used to visualize and measure the right and left hemidiaphragm thickness at the end of resting inspiration and expiration in supine while breathing quietly. The diaphragm movement was imaged and recorded on B-mode ultrasonography. The degree of diaphragm contractility was calculated from the mean of three images from the end of resting inspiration and expiration. Independent t-tests were used to compare the degree of diaphragm thickness of right and left sides between the CAI and the control groups. The CAI group had a smaller degree of left hemidiaphragm contractility compared with the control group (P = 0.03). There was no between-group difference in other diaphragm variables. Individuals with CAI appear to have altered diaphragm contractility, which may be an illustration of diaphragm dysfunction and central nervous system changes in CAI population. The association between CAI and altered diaphragm contractility provides clinicians a more comprehensive awareness of proximal impairments associated with CAI. Future investigation is needed to determine whether altered contractility of the diaphragm contributes to functional impairments, activity limitations, and participant restrictions commonly observed in patients with CAI.

The effects of movement speed on kinematic variability and dynamic stability of the trunk in healthy individuals and low back pain patients

BackgroundComparison of the kinematic variability and dynamic stability of the trunk between healthy and low back pain patient groups can contribute to gaining valuable information about the movement patterns and neuromotor strategies involved in various movement tasks. MethodsFourteen chronic low back pain patients with mild symptoms and twelve healthy male volunteers performed repeated trunk flexion–extension movements in the sagittal plane at three different speeds: 20cycles/min, self-selected, and 40cycles/min. Mean standard deviations, coefficient of variation and variance ratio as variability measures; maximum finite-time Lyapunov exponents and maximum Floquet multipliers as stability measures were computed from trunk kinematics. FindingsHigher speed significantly reduced the kinematic variability, while it increased short-term Lyapunov exponents. Long-term Lyapunov exponents were higher at self-selected speed and lower in low back pain patients as compared to control volunteers. Floquet multipliers were larger at self-selected speed and during higher pace trunk movements. InterpretationOur findings suggest that slower pace flexion–extension trunk movements are associated with more motor variation as well as local and orbital stability, implying less potential risk of injury for the trunk. Individuals with and without low back pain consistently recruited a closed-loop control strategy towards achieving trunk stability. Chronic low back pain patients exhibited more stable trunk movements over long-term periods, indicating probable temporary pain relief functional adaption strategies. These results may be used towards the development of more effective personalized rehabilitation strategies and quantitative spinal analysis tools for low back pain detection, diagnosis and treatment, as well as improvement of workspace and occupational settings.

Methods for the assessment of neuromotor capacity in non-specific low back pain: Validity and applicability in everyday clinical practice.

Physiotherapists and clinicians require methods that can be used in everyday practice for measuring proprioception of the trunk in individuals with non-specific low back pain (NSLBP). Our objective was to conduct a systematic literature review of methods used for assessment of proprioception of the trunk in individuals with non-specific low back pain. Data were obtained from MEDLINE, CINAHL, Embase, PEDro and CENTRAL databases from their inception to December 2011. Reference lists of the selected reviews were hand searched for other potentially relevant studies. Randomized and nonrandomized controlled studies proprioception of the trunk in individuals with low back pain were selected. Thirty-six studies satisfied the selection criteria and were included in this review. Two reviewers independently selected the studies, conducted the quality assessment, and extracted data from each study. The Strobe scale was used to evaluate the scientific rigor of each selected study. This systematic review covered all the relevant literature, but none of the included studies offered a valid, reliable and feasible method to assess neuromotor capacity in everyday physiotherapy clinical practice.

Muscle perfusion of posterior trunk and lower-limb muscles at rest and during upper-limb exercise in spinal cord-injured and able-bodied individuals

Nonrandomized-controlled trial. To assess muscle perfusion at rest and during arm-cranking exercise (ACE) in upper and lower posterior trunk and vastus lateralis (VL) muscles in individuals with spinal cord injury (SCI) and controls (C). Exercise Physiology-Biochemistry Laboratory. Eight SCI with thoracic lesion and eight C received injections of radioactive tracer to trapezius (TRAP), latissimus dorsi (LAT) and VL. Radioactive counts were recorded with a γ-camera for 10 min at rest and during ACE (60% VO(2max) for 20 min). Time-count curves were generated and the isotope clearance rate, expressed as half-life time (T(1/2),min), was calculated to assess muscle perfusion. Resting T(1/2) was lower in TRAP and LAT vs VL (P<0.05) in SCI, however, there were no differences among muscles in C. Arm-cranking increased (P<0.001) the isotope clearance in TRAP and LAT in SCI and C, whereas no effect was found on T(1/2) in VL in both groups. T(1/2) was longer (P<0.05) in SCI vs C in VL at rest and during ACE, whereas there were no differences between groups in posterior trunk muscles. Resting muscle perfusion was reduced in the paralyzed limbs of SCI compared with C, whereas there was no evidence of impaired microcirculation in upper and lower back muscles in SCI. Although ACE did not induce a hyperemic response in VL, it increased hyperemia in upper and lower posterior trunk muscles in SCI, suggesting beneficial effects of this type of activity on muscle microvasculature in this region.

Coordination of trunk and pelvis in young and elderly individuals during axial trunk rotation

It has been well known that complex tasks such as walking and arm reaching can be achieved by the coordination of the trunk and pelvis. However, understanding of the effect of aging on the coordination of the trunk and pelvis during axial trunk rotation is still lacking. The present study examined relative phase of the trunk and pelvis during axial trunk rotation, and compared it between young and older groups. 22 healthy young (age: 23.9±4.6, gender: 11 male and 11 female) and 22 healthy elderly (age: 68.4±4.9, gender: 11 male and 11 female) individuals participated in the experiment and performed axial trunk rotation. Relative phase between the trunk and pelvis was calculated based on the angular displacements of the two segments. The results demonstrated age-related changes in coordination pattern of the trunk and pelvis during axial trunk rotation.

Trunk, Pelvis, Hip, and Knee Kinematics, Hip Strength, and Gluteal Muscle Activation During a Single-Leg Squat in Males and Females With and Without Patellofemoral Pain Syndrome

Controlled laboratory study using a cross-sectional design. To determine whether there are any differences between the sexes in trunk, pelvis, hip, and knee kinematics, hip strength, and gluteal muscle activation during the performance of a single-leg squat in individuals with patellofemoral pain syndrome (PFPS) and control participants. Though there is a greater incidence of PFPS in females, PFPS is also quite common in males. Trunk kinematics may affect hip and knee function; however, there is a lack of studies of the influence of the trunk in individuals with PFPS. Eighty subjects were distributed into 4 groups: females with PFPS, female controls, males with PFPS, and male controls. Trunk, pelvis, hip, and knee kinematics and gluteal muscle activation were evaluated during a single-leg squat. Hip abduction and external rotation eccentric strength was measured on an isokinetic dynamometer. Group differences were assessed using a 2-way multivariate analysis of variance (sex by PFPS status). Compared to controls, subjects with PFPS had greater ipsilateral trunk lean (mean ± SD, 9.3° ± 5.3° versus 6.7° ± 3.0°; P = .012), contralateral pelvic drop (10.3° ± 4.7° versus 7.4° ± 3.8°; P = .003), hip adduction (14.8° ± 7.8° versus 10.8° ± 5.6°; P<.0001), and knee abduction (9.2° ± 5.0° versus 5.8° ± 3.4°; P<.0001) when performing a single-leg squat. Subjects with PFPS also had 18% less hip abduction and 17% less hip external rotation strength. Compared to female controls, females with PFPS had more hip internal rotation (P<.05) and less muscle activation of the gluteus medius (P = .017) during the single-leg squat. Despite many similarities in findings for males and females with PFPS, there may be specific sex differences that warrant consideration in future studies and when clinically evaluating and treating females with PFPS.

Responses of the Trunk to Multidirectional Perturbations during Unsupported Sitting in Normal Adults

Understanding how the human body responds to unexpected force perturbations during quiet sitting is important to the science of motor behavior and the design of neuroprostheses for sitting posture. In this study, the performance characteristics of the neck and trunk in healthy individuals were assessed by measuring the kinematic responses to sudden, unexpected force perturbations applied to the thorax. Perturbations were applied in eight horizontal directions. It was hypothesized that displacement of the trunk, settling time and steady-state error would increase when the perturbation direction was diagonal (i.e., anterior-lateral or posterior-lateral) due to the increased complexity of asymmetrical muscle responses. Perturbation forces were applied manually. The neck and trunk responded in a synchronized manner in which all joints achieved peak displacement simultaneously then returned directly to equilibrium. Displacement in the direction of perturbation and perpendicular to the direction of perturbation were both significantly greater in response to diagonal perturbations (p<.001). The center of mass returned to equilibrium in 3.64±1.42 s after the onset of perturbation. Our results suggest that the trunk sometimes behaves like an underdamped oscillator and is not controlled by simple stiffness when subjected to loads of approximately 200 N. The results of this study are intended to be used to develop a neuroprosthesis for artificial control of trunk stability in individuals with spinal cord injury.

Threatened fishes of the world: Triplophysa siluroides (Herzenstein 1888) (Balitoridae)

Common name: Catfish-like loach. Conservation status: Vulnerable, China Red Data Book of Endangered Animals (Yue and Chen 1998), and China Species Red List (Wang and Xie 2004). Identification: Body scaleless but densely covered with wart-like epidermal tubercles. Predorsal trunk depressed (SL≥ 200 mm) or laterally compressed (SL≤150 mm). Head depressed and tapering. D: iii, 8–9; P: i, 12–14; V: i, 7–8; A: ii, 5; C: 15–16 (branched rays). Irregular cloud-like bars present on the trunk in large individuals (SL>250 mm), while 8–15 regular bars in small ones (SL=104–191 mm) (Herzenstein 1888). Distribution: Endemic to the upper reaches of the Yellow River drainage in Qinghai, Sichuan and Gansu provinces in China (Zhu 1989; Ding 1994). Abundance: It is a commercial species in its distribution regions, with its populations declining dramatically in recent decades. Habitat and ecology: Inhabits bottom of the plateau rivers with gravel bottom, deep and swift current, or stays in slow current and static water with alluvial silt and lots of aquatic plants. It is a carnivorous fish with strong swimming ability. Reproduction: Spawning from June to August in the brooks with gravel bottom and slow flowing water, eggs are yellow and 2–3 mm in diameter. Larvae prefer to the riverside or adjacent small pools. Threats: Illegal fishing methods including poisoning, electrification and bombing. Overfishing resulted from tourists’ favorite of eating wild fishes has become one of the most harmful threats in recent decade. Conservation action: The lack of proper protection for this species has created some concern. The lack of protection has been related to poor public awareness and a lack of financial resources. Conservation recommendations: Strict fishing controls should be put into place and a natural reserve for this species created. Artificial propagation should be strengthened along with the release of artificial reared young fishes into the wild.