Trunk Velocity Research Articles

Improvements in Forward Bending Are Related to Improvements in Pain and Disability During Cognitive Functional Therapy for People With Chronic Low Back Pain.

OBJECTIVE: To investigate whether improvements in forward bending were related to improvements in pain and disability in people with chronic low back pain (CLBP) who were undergoing Cognitive Functional Therapy (CFT). DESIGN: Longitudinal observational study. METHODS: Two hundred and sixty-one participants with CLBP received CFT. Forward bending was assessed at each treatment session over 13 weeks (an average of 4.3 timepoints per participant [range, 1-8]). Spinal range of motion (ROM) and velocity were recorded using 2 inertial measurement units located at T12 and S2. Participants reported (1) average pain intensity (0-10 scale) (pain) and (2) pain-related activity limitation (Roland Morris Disability Questionnaire [disability]) via online questionnaires at 0, 3, 6, and 13 weeks. Multivariate multilevel models were used to evaluate associations between individual rates of change over time for 3 spinal movement measures (trunk velocity, trunk ROM, lumbar ROM) and pain/disability. RESULTS: Strong correlations were observed for increased trunk velocity with reduced pain (r = -0.81; 95% CI: -0.98, -0.05) and with reduced disability (r = -0.77; 95% CI: -0.95, -0.22). Moderate correlations were observed between increased trunk ROM with reduced pain (r = -0.37; 95% CI: -0.67, 0.04) and with reduced disability (r = -0.32; 95% CI: -0.6, 0.03). There was no evidence of association between changes in lumbar ROM and pain (r = -0.46; 95% CI: -0.90, 0.44) or disability (r = -0.01; 95% CI: -0.56, 0.55). CONCLUSION: Reductions in pain and disability were strongly correlated with increased trunk velocity in people with CLBP who were undergoing CFT. These findings are consistent with CFT that explicitly trains "nonprotective" spinal movement. J Orthop Sports Phys Ther 2024;54(11):721-731. Epub 7 October 2024. doi:10.2519/jospt.2024.12727.

Within-subject time series angular velocity differences between in-game high and low velocity fastballs in college baseball pitchers

PurposeThe purpose of the current study is to investigate the within-pitcher differences in time series angular velocities of the pelvis, trunk, shoulder, and elbow for high and low velocity fastballs in college baseball pitchers. MethodsIn-game data were retrospectively analyzed from 82 NCAA Division 1 pitchers ([1.89 ​± ​0.06] m, [92.8 ​± ​9.5] kg). Kinematic data were collected using an in-game markerless motion capture system. Time series data of pelvis, trunk, shoulder, and elbow angular velocities for each pitcher's fastest and slowest fastball were extracted for the pitch cycle (foot contact to ball release) and used for analysis. Within-subject time series comparisons were conducted using statistical parametric mapping (SPM) paired samples t-tests (α ​= ​0.012 5). ResultsEach of the tested segments were significantly faster in the fastest fastball trial compared to the slowest fastball trial. The duration of significance in reference to the pitch cycle, test statistic, and p-value, for each segment are as follows: Pelvis: 0%–4%, t ​= ​3.54, p ​= ​0.012; Trunk: 30%–67%, t ​= ​5.62, p ​< ​0.001; Shoulder External Rotation: 3%–50%, t ​= ​−6.03, p ​< ​0.001; Shoulder Internal Rotation: 96%–100%, t ​= ​4.11, p ​= ​0.008; Elbow: 75%–86%, t ​= ​4.13, p ​< ​0.001. DiscussionWithin-subjects differences exist in time series angular velocities when comparing the fastest and slowest fastball. These time series differences provide additional information to distinguish fastball velocity beyond what discrete metrics can provide. Pitchers should look to rotate each segment faster, and optimize the sequencing of these movements, to increase pitch velocity.

The effects of soft vs. rigid back-support exoskeletons on trunk dynamic stability and trunk-pelvis coordination in young and old adults during repetitive lifting

While back-support exoskeletons are increasing in popularity as an ergonomic intervention for manual material handling, they may cause alterations to neuromuscular control required for maintaining spinal stability. This study evaluated the effects of soft and rigid passive exoskeletons on trunk local dynamic stability and trunk-pelvis coordination. Thiry-two young (18–30 years) and old (45–60 years) men and women completed repetitive lifting and lowering tasks using two different exoskeletons and in a control condition. Both exoskeletons significantly reduced the short-term maximum Lyapunov exponent (LyE) of the trunk (p < 0.01), suggesting improved local dynamic stability. There was also a significant main effect of age (p = 0.05): older adults exhibited lower short-term LyE that young adults. Use of the soft exoskeleton significantly increased, while the rigid exoskeleton significantly decreased, long-term LyE, and these changes were more pronounced in the young group compared to the old group. Additionally, exoskeleton use resulted in significant increase (p < 0.001) of mean absolute relative phase (MARP) and deviation phase (DP) by ∼30–60 %, with greater increases due to the rigid than the soft device. Thus, trunk-pelvic coordination and coordination variability were negatively impacted by exoskeleton use. Potential reasons for these findings may include exoskeleton-induced changes in lifting strategy, reduced peak trunk flexion velocity, and cycle-to-cycle variability of trunk velocity. Furthermore, although the soft and rigid devices caused comparable changes in trunk-extensor muscle activity, they exhibited differential effects on long-term maximum Lyapunov exponents as well as trunk-pelvic coordination, indicating that exoskeleton design features can have complex effects on trunk neuromuscular control.

Beyond Simple Tapping: Is Timed Body Movement Influenced When Balance Is Threatened?

The tapping paradigm offers valuable insights into movement timing; however, it simplifies mechanics by minimizing force, restricting motion, and relying on a clear contact endpoint. Thus, it may not fully capture the complexity of larger-scale multi-segmental (or single-segment) timed body movements. The aim of this study was to extend beyond the tapping paradigm by examining the timing of two large-scale movements commonly performed in physical fitness or rehabilitation modalities, with varying inherent balance threats: two-legged squatting (low balance threat) and standing hip abduction (higher balance threat) paced by a metronome set at the participants’ preferred tempo (N = 39, all physically active). In synchronization with the metronome audio signal, the trunk and shank angular velocities were also recorded to extract the entrainment, synchronization, and pace stability metrics. Paired t-tests indicated similar entrainment in both movements (p &gt; 0.05 for IRI match) but significant differences in timing metrics’ manifestations (p ≤ 0.05, standing hip abduction: 50% greater IRI error, 30% lower synchronization error, 2.6% units lower pace stability). The similar entrainment but different synchronization error and pace stability highlight a complex timing interplay between balance threat/challenges and movement complexity concerning the two large-scale movements employed in physical fitness and rehabilitation modalities.

Association between movement speed and instability catch kinematics and the differences between individuals with and without chronic low back pain

Studies reported the existence of instability catch (IC) during trunk flexion in patients with chronic low back pain (CLBP). However, different movement speeds can cause different neuromuscular demands resulting in altered kinematic patterns. In addition, kinematic characterization corresponding to clinical observation of IC is still limited. Therefore, this study aimed to determine (1) the association between movement speed and kinematic parameters representing IC during trunk flexion and (2) the differences in kinematic parameters between individuals with and without CLBP. Fifteen no low back pain (NoLBP) and 15 CLBP individuals were recruited. Inertial measurement units (IMU) were attached to T3, L1, and S2 spinous processes. Participants performed active trunk flexion while IMU data were simultaneously collected. Total trunk, lumbar, and pelvic mean angular velocity (T_MV, L_MV, and P_MV), as well as number of zero-crossings, peak-to-peak, and area of sudden deceleration and acceleration (Num, P2P, and Area), were derived. Pearson’s correlation tests were used to determine the association between T_MV and L_MV, P_MV, Num, P2P, and Area. An ANCOVA was performed to determine the difference in kinematic parameters between groups using movement speed as a covariate. Significant associations (P < 0.05) were found between movement speed and other kinematic parameters, except for Area. Results showed that L_MV significantly differed from the P_MV (P = 0.002) in the CLBP group, while a significant between-group difference (P = 0.037) was found in the P_MV. Additionally, significant between-group differences (P < 0.05) in P2P and Area were observed. The associations between movement speed and kinematic parameters suggest that movement speed changes can alter kinematic patterns. Therefore, clinicians may challenge lumbopelvic neuromuscular control by modifying movement speed to elicit greater change in kinematic patterns. In addition, the NoLBP group used shared lumbar and pelvic contributions, while the CLBP group used less pelvic contribution. Finally, P2P and Area appeared to offer the greatest sensitivity to differentiate between the groups. Overall, these findings may enhance the understanding of the mechanism underlying IC in CLBP.

The correlation between ball velocity with hip-shoulder rotation and separation during pitching process in baseball pitchers

&lt;p&gt;目的：本研究欲探討成棒選手肩髖的旋轉及肩髖分離程度與球速間的相關性，用以尋找提升球速的方法。方法：以 18 位大專公開一級棒球投手作為研究參與者，同時利用慣性感測 (IMU)、二維影像分析系統及測速槍測量研究參與者之投球運動學參數，包括肩與骨盆在各時間點的旋轉角度、肩髖分離的角度、旋轉峰值時機及球速等。以皮爾森積差相關係數分析肩與骨盆的旋轉情況及肩髖分離程度與球速之間是否具有相關性。結果：本研究顯示除了上軀幹在膝蓋最高點 (r =-.295, p =.441)外，其餘分別為上軀幹在前導腳落地時 (r = -.821, p &lt; .001)、上軀幹在球離手時 (r = .765, p = .016)、骨盆在膝蓋最高點時 (r = -.791, p = .011)、骨盆在前導腳落地時 (r = .906, p= .001)、骨盆在球離手時 (r = .951, p &lt; .001)，都與球速呈顯著相關；上軀幹與骨盆的旋轉速度峰值、時機與球速呈顯著相關 (r = .934, p &lt; .001)、(r = .969, p &lt; .001)、(r = .881, p = .002)、(r = -.749, p = .02)；肩髖分離程度與上軀幹和骨盆的旋轉及球速皆呈顯著相關。結論：本研究顯示不僅是上軀幹，骨盆的旋轉與球速也息息相關，因此在投球動作上應注重投球動作的整體性，而非強調單一肢段的發力，且若能同時妥善運用肩髖分離，則能提升運動表現。&lt;/p&gt; &lt;p&gt;&amp;nbsp;&lt;/p&gt;&lt;p&gt;Purpose: This study aims to investigate the correlation between hip-shoulder and separation degree with ball speed in skilled baseball pitchers to identify methods for enhancing pitching velocity. Methods: Eighteen collegiate level-Ⅰbaseball pitchers participated as research subjects. An inertial measurement unit (IMU), a two-dimensional motion analysis system, and a radar gun were employed to measure the kinematic parameters of the pitching motion. These parameters included rotational angles of the shoulder and pelvic at various time points, the degree of hip-shoulder separation, peak rotation timing, and ball velocity. Pearson correlation coefficients between ball velocity, hip shoulder separation, and all trunk and pelvic kinematic variables were computed, and the level of significance was set at &amp;alpha; = .05. Results: The results indicate that, except for the upper trunk at the maximum knee height(r = -.295, p = .441), the rest were significantly related with ball velocity: the upper trunk at the landing of the leading foot (r = -.821, p&lt; .001), the upper trunk at the ball off hand (r = .765, p = .016), the pelvic at the maximum knee height (r = -.791, p = .011), the pelvic at the landing of the leading foot (r = .906, p = .001), and the pelvic at the ball off hand (r = .951, p &lt; .001). The peak rotation velocity and the timing of the peak rotation velocity of the upper trunk and pelvic is also significantly related to ball velocity(r = .934, p &lt; .001)、(r = .969, p &lt; .001)、(r = .881, p = .002)、(r = -.749, p = .02). The degree of shoulder-hip separation is significantly correlated with the rotation of the upper trunk and pelvic and ball velocity. Conclusion: Based on the findings of this study, we know the significance of not only the upper trunk but also pelvic rotation with ball velocity. Therefore, a holistic approach to pitching mechanics, emphasizing overall motion rather than isolating individual segments, is crucial. Additionally, effectively utilizing hip-shoulder separation can enhance overall athletic performance in baseball pitching.&lt;/p&gt; &lt;p&gt;&amp;nbsp;&lt;/p&gt;

SYNLOCO‐VE: Synthesizing central pattern generator with reinforcement learning and velocity estimator for quadruped locomotion

AbstractIt is a challenging task to learn a robust and natural locomotion controller for quadruped robots at different terrains and velocities. In particular, the locomotion learning task will be even more difficult for the case with no exteroceptive sensors. In this article, the learning‐based locomotion control is, therefore, investigated for quadruped robots only using proprioceptive sensors. A new framework called SYNLOCO‐VE is proposed by synthesizing a feedforward gait planner, a trunk velocity estimator, and reinforcement learning (RL). The feedforward gait planner is developed based on the well‐known central pattern generator, but it can change the foot length for improved velocity tracking performance. The trunk velocity estimator is designed based on deep learning, which estimates the trunk velocity using historical data from proprioceptive sensors. The introduction of the trunk velocity estimator can mitigate the influence of the partial observation issue due to the lack of exteroceptive sensors. RL is employed to learn a feedback controller to regulate the robot gaits using feedback from proprioceptive sensors and the trunk velocity estimation. In the proposed framework, the feedforward gait planner can also guide the training process of RL, thus resulting in more stable and faster policy learning. Ablation studies are provided to demonstrate the efficiency of different modules in the proposed design. Extensive experiments are performed using a quadruped robot Go1, which only has proprioceptive sensors. The proposed framework is able to learn robust and stable locomotion at different terrains and tasks. Experimental comparisons are also conducted to illustrate the advantages of the proposed design over the state‐of‐the‐art methods.

Inferring glacier mass balance from Sentinel-1 derived ice thickness changes using geoinformatics: A case study of Gangotri glacier, Uttarakhand, India

All glaciers respond to climatic changes by fluctuating their mass. Investigations of glacier dynamics are necessary for glacier monitoring. Himalayan glaciers make ongoing glacier observations challenging due to their location in a severe topographic environment and inhospitable terrain. Glacier area contraction or extension, together with a corresponding snout shift, can be linked to oscillations in glacier mass. Sentinel-1 dual-polarized datasets were used in this investigation to retrieve glacier surface velocity. Estimates of ice thickness were enhanced by segmenting the glacier into 100-m height intervals. Also, ice thickness variations between 2017 and 2022 have been used to compute glacier mass balance, and the results for several glacier zones have been briefly analyzed. The study revealed that the maximum surface velocity above Gangotri Glacier was approximately 0.33 m/day, with an estimated average of 0.09 m/day. Surface velocities of the central trunk have been seen to range from 0.12 m/day to 0.23 m/day. Additionally, between 2017 and 2022, the surface velocity was spotted between 0.19 m/day to 0.35 m/day. For the glacier, an average ice thickness of 189 ± 17.01 m was calculated. In the central parts, where the drag was least noticeable, thicknesses up to 587 ± 52.83 m were estimated. In the lower accumulation zone and middle reaches, the thickness was found to be decreasing between 2017 and 2022, which can be attributed to increased melting and glacier slowdown. Due to the increased glacier movement throughout time, the lower accumulation reaches over the main glacier body, and its tributaries have experienced mass balancing rates ranging from −1.3 m.w.e./year to −0.5 m.w.e./year (thickness change between −3 m/year and −0.6 m/year). With the help of previous research and existing data, the results were compared and validated. The suggested algorithm and findings can serve as inputs for satellite-based ice thickness measurements and as fundamental research for the forthcoming NISAR mission (expected by mid-2024) which will carry L- and S-band antennas.

Pain Education and Virtual Reality Improves Pain, Pain-related Fear of Movement, and Trunk Kinematics in Individuals With Persistent Low Back Pain.

To evaluate the effect of combining pain education and virtual reality (VR) exposure therapy using a cognitive-behavioral therapy-informed approach (virtual reality-based cognitive behavioral therapy [VR-CBT]) on pain intensity, fear of movement, and trunk movement in individuals with persistent low back pain. Thirty-seven participants were recruited in a single cohort repeated measures study, attending 3 sessions 1 week apart. The VR-CBT intervention included standardized pain education (session 1) and virtual reality-based exposure therapy (VRET; session 2) incorporating gameplay with mixed reality video capture and reflective feedback of performance. Outcome measures (pain intensity, pain-related fear of movement (Tampa Scale of Kinesiophobia), and trunk kinematics during functional movements (maximum amplitude and peak velocity) were collected at baseline (session 1) and 1 week after education (session 2) and VRET (session 3). One-way repeated measures analysis of variances evaluated change in outcomes from baseline to completion. Post hoc contrasts evaluated effect sizes for the education and VR components of VR-CBT. Thirty-four participants completed all sessions. Significant ( P < 0.001) reductions were observed in mean (SD) pain (baseline 5.9 [1.5]; completion 4.3 [2.1]) and fear of movement (baseline 42.6 [6.4]; completion 34.3 [7.4]). Large effect sizes (Cohen d ) were observed for education (pain intensity: 0.85; fear of movement: 1.28), whereas the addition of VRET demonstrated very small insignificant effect sizes (pain intensity: 0.10; fear of movement: 0.18). Peak trunk velocity, but not amplitude, increased significantly ( P < 0.05) across trunk movement tasks. A VR-CBT intervention improved pain, pain-related fear of movement, and trunk kinematics. Further research should explore increased VR-CBT dosage and mechanisms underlying improvement.

Analysis of the impact of different branching angles on the coronary flow field based on fluid-structure interaction

The bifurcation angle of the coronary artery can have an impact on blood flow velocity, especially in the narrow region, where the flow velocity becomes more pronounced, leading to further deterioration of the stenosis in that area. In order to investigate the effect of bifurcation angle on the coronary blood flow field, four bifurcation angle models were established in Solidworks, and a bidirectional fluid-solid coupling method was used to numerically simulate the blood distribution. The changes in the blood flow field at different periods were analyzed. The results showed that the blood flow velocity distribution was similar in the same model at different periods, with high flow velocity mainly concentrated in the coronary artery trunk and smooth branching flow velocity. The flow velocity was different at various periods, resulting in a large difference in the WSS range, which was most obvious during the peak diastolic period. The bifurcation angle had the most significant effect on TAWSS, and as the bifurcation angle increased, the area of the high TAWSS region continued to expand. A small amount of vortex at the bifurcation ridge affected the shear stress direction, resulting in a high OSI (>0.3) region in that area. In conclusion, the bifurcation angle has a significant effect on TAWSS, with the most significant fluctuation in the 37.5° to 42.5° range, and there may be a critical angle causing the fluctuation in between.

A Biomechanical Evaluation of the Upper Limb Kinematic Parameters of the Throwing Action in Handball: A Case Study

Handball is a team sport that involves fourteen players who are attempting to score more goals than their opponent within two thirty-minute halves. A biomechanical analysis based on measuring the kinematics of jump throws could provide us with information on the ball’s velocity, the maximal internal rotation of the trunk, and the trunk’s flexion, as well as the angular velocity of the ball during shoulder rotation. The main aim of this study was to determine the wrist velocity during jump throws and standing throws without a run-up. The trunk, arm rotation, and wrist velocity will influence the speed of the ball during throwing. This case study included a senior-grade male handball player aged 18.75 years with a body mass index (BMI) of 25.5. The biomechanical evaluation was carried out using a three-dimensional Vicon system. The biomechanical analysis consisted of an evaluation of angular trunk velocity, angular arm rotation velocity, and wrist velocity during two types of throwing: jump throws and standing throws without a run-up. The data were recorded for standing throws without a run-up (S1) and jump throws (S2). For each situation, we measured two phases due to the great variation in the kinematic parameters. Phase 1 (F1) occurred when the elbow angle was 90°, up to the moment when the wrist had an inflection of its trajectory, and Phase 2 (F2) finished when the wrist’s velocity reached its maximum. The results regarding the angular velocity of the trunk torsion showed a high value of this parameter during Phase F2 compared to Phase F1 for both types of throws (S1 and S2). The angular velocity of the arm rotation achieved its maximum value in F2 during S2, and the wrist velocity was highest during Phases F2 and S2. The correlation analysis demonstrated that there was a good correlation between the angular velocity of the trunk torsion and the angular velocity of the arm rotation for S1 in Phase F1; however, in Phase F2, we found a good correlation between the angular velocity of the trunk torsion and wrist velocity. For S2, we found that in Phase F1, there was a good correlation between the angular velocity of the trunk torsion and wrist velocity; however, for Phase F2, there was a good correlation between the angular velocity of the arm’s rotation and wrist velocity. Therefore, the results from this case study indicate that the wrist velocity is influenced by the other two kinematic parameters, especially the angular velocity of the arm’s rotation. This means that the development of explosive force in the muscles of the trunk and arm could improve the wrist’s velocity and also increase the optimization of throwing in handball.

Comparison of sensitivity among dynamic balance measures during walking with different tasks.

Although various measures have been proposed to evaluate dynamic balance during walking, it is currently unclear which measures are most sensitive to dynamic balance. We aimed to investigate which dynamic balance measure is most sensitive to detecting differences in dynamic balance during walking across various gait parameters, including short- and long-term Lyapunov exponents (λs and λl), margin of stability (MOS), distance between the desired and measured centre of pressure (dCOP-mCOP) and whole-body angular momentum (WBAM). A total of 10 healthy young adults were asked to walk on a treadmill under three different conditions (normal walking, dual-task walking with a Stroop task as an unstable walking condition, and arm-restricted walking with arms restricted in front of the chest as another unstable walking condition) that were expected to have different dynamic balance properties. Overall, we found that λs of the centre of mass velocity, λs of the trunk velocity, λs of the hip joint angle, and the magnitude of the mediolateral dCOP-mCOP at heel contact can identify differences between tasks with a high sensitivity. Our findings provide new insights into the selection of sensitive dynamic balance measures during human walking.

Kinematic, Kinetic, and Temporal Metrics Associated With Golf Proficiency.

McHugh, MP, O'Mahoney, CA, Orishimo, KF, Kremenic, IJ, and Nicholas, SJ. Kinematic, kinetic, and temporal metrics associated with golf proficiency. J Strength Cond Res 38(3): 599-606, 2024-The biomechanics of the golf swing have been studied extensively, but the literature is unclear on which metrics are indicative of proficiency. The purpose of this study was to determine which metrics identified golf proficiency. It was hypothesized that discrete kinematic, kinetic, and temporal metrics would vary depending on proficiency and that combinations of metrics from each category would explain specific proficiency metrics. Kinematic, kinetic, and temporal metrics and their sequencing were collected for shots performed with a driver in 33 male golfers categorized as proficient, average, or unskilled (based on a combination of handicap, ball velocity, and driving distance). Kinematic data were collected with high-speed motion analysis, and ground reaction forces (GRF) were collected from dual force plates. Proficient golfers had greater x-factor at ball impact and greater trunk deceleration before ball impact compared with average ( p < 0.05) and unskilled ( p < 0.01) golfers. Unskilled golfers had lower x-factor at the top of the back swing and lower peak x-factor, and they took longer to reach peak trunk velocity and peak lead foot GRF compared with average ( p < 0.05) and proficient ( p < 0.05) golfers. A combination of 2 kinematic metrics (x-factor at ball impact and peak pelvis velocity), 1 kinetic metric (peak lead foot GRF), and 2 timing metrics (the timing of peak trunk and arm velocity) explained 85% of the variability in ball velocity. The finding that x-factor at ball impact and trunk deceleration identified golf proficiency points to the potential for axial trunk rotation training to improve performance.

The effects of trunk kinematics and EMG activity of wheelchair racing T54 athletes on wheelchair propulsion speeds.

The purpose of this study is to examine the impact of trunk kinematic characteristics and trunk muscle electromyography (EMG) activity on propulsion speeds in wheelchair racing T54 athletes. The Vicon infrared high-speed 3D motion capture system was utilized to acquire kinematic data of the shoulders, elbows, wrists, and trunk from twelve T54 athletes at four different speeds (5.55 m/s, 6.94 m/s, 8.33 m/s, and personal maximum speed). Additionally, the Trigno Wireless EMG system was employed to collect synchronous surface electromyography (EMG) data from the rectus abdominis and erector spinae muscles. The kinematics and EMG data of the trunk were compared across various wheelchair propulsion speeds while also examining the correlation coefficient between wheelchair propulsion speeds and: (1) the range of motion of upper limb joints as well as the trunk; (2) the maximum angular velocities of the upper limbs joints as well as the trunk; and (3) rectus abdominis and erector spinae EMG activity. Two multiple linear stepwise regression models were utilized to examine the impact of variables that had been identified as significant through correlation coefficient tests (1) and (2) on propulsion speed, respectively. There were significant differences in the range of motion (p<0.01) and angular velocity (p<0.01) of the athlete's trunk between different propulsion speeds. The range of motion (p<0.01, r=0.725) and angular speed (p<0.01, r=0.882) of the trunk showed a stronger correlation with propulsion speed than did upper limb joint movements. The multiple linear stepwise regression model revealed that the standardized β values of trunk motion range and angular velocity in athletes were greater than those of other independent variables in both models. In terms of the EMG variables, four of six variables from the rectus abdominis showed differences at different speeds (p<0.01), one of six variables from the erector spinae showed differences at different speeds (p<0.01). All six variables derived from the rectus abdominis exhibited a significant correlation with propulsion speed (p<0.05, r>0.3), while one variable derived from the erector spinae was found to be significantly correlated with propulsion speed (p<0.01, r=0.551). The movement of the trunk plays a pivotal role in determining the propulsion speed of wheelchair racing T54 athletes. Athletes are advised to utilize trunk movements to enhance their wheelchair's propulsion speed while also being mindful of the potential negative impact on sports performance resulting from excessive trunk elevation. The findings of this study indicate that it would be beneficial for wheelchair racing T54 athletes to incorporate trunk strength training into their overall strength training regimen, with a specific emphasis on enhancing the flexion and extension muscles of the trunk.

Proof of Concept Testing of Safe Patient Handling Intervention Using Wearable Sensor Technology

Background: Healthcare workers make up one of the occupations in the United States that experience the most musculoskeletal injuries. These injuries are often related to the movement and repositioning of patients. Despite previous injury prevention attempts, injury rates remain at an unsustainable level. The purpose of this proof-of-concept study is to provide preliminary testing of the impact of a lifting intervention on common biomechanical risk factors for injury during high-risk patient movements.; Methods: A before-and-after (quasi-experimental) design was utilized to compare biomechanical risk factors before and after a lifting intervention. Kinematic data were collected using the Xsens motion capture system, while muscle activations were collected with the Delsys Trigno EMG system. Results: Improvements were noted in the lever arm distance, trunk velocity, and muscle activations during the movements following the intervention; Conclusions: The contextual lifting intervention shows a positive impact on the biomechanical risk factors for musculoskeletal injury among healthcare workers without increasing the biomechanical risk. A larger, prospective study is needed to determine the intervention’s ability to reduce injuries among healthcare workers.

Key points of development of motor skills in childhood embodied in gait parameters

ObjectiveTo observe changes of correlations of gait parameters of four sets of body in children aged 3–6. DesignA cross-sectional observational study. SettingDong Gang kindergarten in Suzhou, China. ParticipantsA total of 89 children between 3 and 6 years old. Main outcome measuresA total of 37 three-dimensional (3-D) gait parameters assessed with a wearable gait analysis system in 2-min walking test, for 3 times. ResultsThere were significant differences in gait speed, stride length and sagittal range of motion (ROM) of trunk among children of 3–6 years old (P < 0.05). The left and right toe out angle, sagittal ROM of waist, coronal ROM of trunk and arm swing velocity of male were significantly greater than those of female children (P < 0.05). Most gait parameters were symmetrical (P < 0.01). Canonical correlations of Upper Limbs Set vs. Trunk and Waist Sets increased by ages (P < 0.05). Canonical correlation of Trunk Set vs. Waist Set decreased by ages. Canonical correlations of Lower Limbs Set to any other sets were not significant (P > 0.05). ConclusionsValues and symmetry of gait parameters cannot reflect the development of motor skill during ages of 3–6. Proper trunk movement coordinating with upper limbs and isolating from waist is the key point of development of motor skill in walking. It is built during preschool period and girls develop better. Before the preschool period, lower limbs’ isolating movements from the other segments have already developed well. These key points of motor skills in walking should be considered when motor tasks for segment isolation and coordination are given to children with motor dysfunction.

Trunk Velocity Changes in Response to Physical Perturbations Are Potential Indicators of Gait Stability.

Response to challenging situations is important to avoid falls, especially after medial perturbations, which require active control. There is a lack of evidence on the relationship between the trunk's motion in response to perturbations and gait stability. Eighteen healthy adults walked on a treadmill at three speeds while receiving perturbations of three magnitudes. Medial perturbations were applied by translating the walking platform to the right at left heel contact. Trunk velocity changes in response to the perturbation were calculated and divided into the initial and the recovery phases. Gait stability after a perturbation was assessed using the margin of stability (MOS) at the first heel contact, MOS mean, and standard deviation for the first five strides after the perturbation onset. Faster speed and smaller perturbations led to a lower deviation of trunk velocity from the steady state, which can be interpreted as an improvement in response to the perturbation. Recovery was quicker after small perturbations. The MOS mean was associated with the trunk's motion in response to perturbations during the initial phase. Increasing walking speed may increase resistance to perturbations, while increasing the magnitude of perturbation leads to greater trunk motions. MOS is a useful marker of resistance to perturbations.

Fall Prevention Training for Service Members With an Amputation or Limb Salvage Following Lower Extremity Trauma.

Recent military conflicts have resulted in a significant number of lower extremity injuries to U.S. service members that result in amputation or limb preservation (LP) procedures. Service members receiving these procedures report a high prevalence and deleterious consequences of falls. Very little research exists to improve balance and reduce falls, especially among young active populations such as service members with LP or limb loss. To address this research gap, we evaluated the success of a fall prevention training program for service members with lower extremity trauma by (1) measuring fall rates, (2) quantifying improvements in trunk control, and (3) determining skill retention at 3 and 6 months after training. Forty-five participants (40 males, mean [±SD] age, 34 ± 8 years) with lower extremity trauma (20 with unilateral transtibial amputation, 6 with unilateral transfemoral amputation, 5 with bilateral transtibial amputation, and 14 with unilateral LP procedures) were enrolled. A microprocessor-controlled treadmill was used to produce task-specific postural perturbations which simulated a trip. The training was conducted over a 2-week period and consisted of six 30-minute sessions. The task difficulty was increased as the participant's ability progressed. The effectiveness of the training program was assessed by collecting data before training (baseline; repeated twice), immediately after training (0 month), and at 3 and 6 months post-training. Training effectiveness was quantified by participant-reported falls in the free-living environment before and after training. Perturbation-induced recovery step trunk flexion angle and velocity was also collected. Participants reported reduced falls and improved balance confidence in the free-living environment following the training. Repeated testing before training revealed that there were no pre-training differences in trunk control. The training program improved trunk control following training, and these skills were retained at 3 and 6 months after training. This study showed that task-specific fall prevention training reduced falls across a cohort of service members with diverse types of amputations and LP procedures following lower extremity trauma. Importantly, the clinical outcome of this effort (i.e., reduced falls and improved balance confidence) can lead to increased participation in occupational, recreational, and social activities and thus improved quality of life.

Rating of perceived difficulty scale for measuring intensity of standing balance exercises in individuals with vestibular disorders.

A method for prescribing the difficulty or intensity of standing balance exercises has been validated in a healthy population, but requires additional validation in individuals with vestibular disorders. This study validated the use of ratings of perceived difficulty for estimation of balance exercise intensity in individuals with vestibular disorders. Eight participants with a confirmed diagnosis of a vestibular disorder and 16 healthy participants performed two sets of 16 randomized static standing exercises across varying levels of difficulty. Root Mean Square (RMS) of trunk angular velocity was recorded using an inertial measurement unit. In addition, participants rated the perceived difficulty of each exercise using a numerical scale ranging from 0 (very easy) to 10 (very difficult). To explore the concurrent validity of rating of perceived difficulty scale, the relationship between ratings of perceived difficulty and sway velocity was assessed using multiple linear regression for each group. The rating of perceived difficulty scale demonstrated moderate positive correlations RMS of trunk velocity in the pitch (r = 0.51, p < 0.001) and roll (r = 0.73, p < 0.001) directions in participants with vestibular disorders demonstrating acceptable concurrent validity. Ratings of perceived difficulty can be used to estimate the intensity of standing balance exercises in individuals with vestibular disorders.

Role of Pelvis and Trunk Biomechanics in Generating Ball Velocity in Baseball Pitching.

Orishimo, KF, Kremenic, IJ, Mullaney, MJ, Fukunaga, T, Serio, N, and McHugh, MP. Role of pelvis and trunk biomechanics in generating ball velocity in baseball pitching. J Strength Cond Res 37(3): 623-628, 2023-The purpose of this study was to determine the impact of pelvis rotation velocity, trunk rotation velocity, and hip-shoulder separation on ball velocity during baseball pitching. Fastball pitching kinematics were recorded in 29 male pitchers (age 17 ± 2 years, 23 high school, 6 college). Pelvis and trunk angular velocities and hip-shoulder separation were calculated and averaged for the 3 fastest pitches. Associations between peak pelvis velocity, peak trunk velocity, hip-shoulder separation at foot contact, and ball velocity were assessed using Pearson correlation coefficients and multiple regression. The average ball velocity was 33.5 ± 2.8 m·s -1 . The average hip-shoulder separation at foot contact was 50 ± 12°. The peak pelvis velocity (596 ± 88°·s -1 ) occurred at 12 ± 11% of the time from stride foot contact to ball release, with the peak trunk velocity (959 ± 120°·s -1 ) occurring at 36 ± 11%. Peak trunk velocity was predictive of ball velocity ( p = 0.002), with 25% of the variability in ball velocity explained. No combination of factors further explained ball velocity. Hip-shoulder separation at foot contact (17%, p = 0.027), peak pelvis velocity (23%, p = 0.008), and the timing of peak pelvis velocity (16%, p = 0.031) individually predicted peak trunk velocity. The combination of peak pelvis velocity, hip-shoulder separation at foot contact, and the timing of peak trunk velocity explained 55% of the variability in trunk rotation velocity ( p < 0.001). These data highlight the importance of interactions between pelvis and trunk for maximizing velocity in pitching. Training to improve pelvis-trunk axial dissociation may increase maximal trunk rotation velocity and thereby increase ball velocity without increasing training load on the shoulder and elbow.