Trunk Movements Research Articles

Lumbopelvic rhythm analysis by quartiles: Identification of differences in lumbar and pelvic contribution during trunk flexion and extension in subjects with low back pain of different origin. A case-control study.

Low back pain (LBP) can alters spinal kinematics. However, for adequate clinical care, a better understanding of lumbopelvic biomechanical behaviour according to the type of LBP is required. Our objectives were to identify differences in lumbopelvic rhythm (LPR) between subjects with acute low back pain (aLBP), axial spondyloarthritis (axSpA) and healthy subjects. As well as to identify correlations between LPR and sociodemographic and clinical data. In each group of 39 subjects, LPR total and by quartiles (Q) and metrological and clinical data were evaluated. No differences were found in relation to total flexion and LPR extension. However, study by Q showed less movement in aLBP compared to axSpA and healthy subjects at the Lumbar level in Q2 (p=0.001), Pelvis in Q3 and Q4 and Trunk in Q3 (p=<0.001). In Q4 the aLBP moved the Trunk less than axSpA exclusively [-3,64°(95% confidence interval-6.53,-0.74), p=0.011]. For the extension movement, the Pelvic motion of Q2 was lower for the aLBP group compared to axSpA group [-3,11°(-6.00,-0.22), p=0.030], and Trunk motion of Q2 and Q3 (p=0.001, p=0.007, respectively), and Lumbar mobility of Q3 were also lower compared to axSpA and control groups (p=0.031). Specific correlations were found for each group. aLBP with BMI, axSpA with metrology and Healthy subjects with age. Subjects with aLBP showed less lumbar, pelvic or trunk movement in Q2 and Q3 of trunk flexion and extension movements than axSpA and controls. RPL and its interrelationships with sociodemographic and clinical variables depend on the lumbar condition.

Research on the promotion effect of personalized training program based on biomechanics on the physical health of college students

Biomechanics-based personalized training programs can significantly improve physical health among college students, but there is limited evidence on how these programs affect spinal twist stretch function and overall health, despite previous research demonstrating the potential benefits of such programs. In this study, the influence of a biomechanics-based personalized training program investigates the physical health of a college student population. This study involved 68 college students, divided into two groups: 34 participants undergoing a personalized biomechanics-based training program (Group A) and 34 participants following a standard exercise regimen (Group B). The training program included exercises designed to enhance spinal twist stretch activation and stability. The participants’ core muscle activation was recorded through EMG from rhomboids, latissimus dorsi, and external obliques, while kinematic data were obtained from a three-dimensional motion analysis system. The assessments were done pre and post-8-week structured nutrition and physical activity modification period. These data are stimulated using SPSS, to compare pre and post-test measurements within each group and to determine the differences between spinal twist stretch and global physical health gains using paired t-tests, analyze of variance (ANOVA) descriptive statistics, and correlation analysis. The result demonstrated that Group A significantly improved spinal twists, stretch, and physical health among college students. Exercises targeting specific biomechanical principles exhibited more pronounced spinal twist stretch activation. The program improved trunk stability and movement accuracy, with a moderate correlation between muscle activation and overall physical health improvements. This approach improved core stability and muscle function but also led to better overall health outcomes compared to standard exercise regimens.

Analysing trunk and arm motion in volleyball jump serve: a comparison of straight line and diagonal line techniques

ABSTRACT This study aimed to clarify the disparities in trunk rotation and attack arm movement and their effect on hand kinematics adjustments between straight-line (SL) and diagonal-line (DL) volleyball jump serves. Thirteen male professional volleyball players (age 21.53 ± 5.39 years, height 1.95 ± 0.06 m, body mass 86.48 ± 11.63 kg, experience 8.61 ± 3.47 years) performed SL and DL jump serve, with three-dimensional coordinate data captured using a motion capture system (200 hz). Paired t-test and statistical parametric mapping examined kinematic differences between the two serving directions. At ball contact (BC), the speed of the attack arm hand was significantly faster in DL (16.99 ± 1.36 m/s) compared to SL (16.37 ± 1.53 m/s), whereas the face angle was significantly smaller in DL (1.98 ± 11.75°) than in SL (17.60 ± 17.98°). Forward rotation angles of the pelvic and upper torso at BC were significantly greater in DL (28.47 ± 10.89°; 21.30 ± 10.25°) than in SL (18.27 ± 12.46°; 9.09 ± 14.41°). During the arm swing phase, the pelvic’s forward rotation angles in DL were significantly greater than in SL at 42–72% spiking motion, and the upper torso’s angles were significantly greater at 49–58% spiking motion. These findings underscore the importance of adjusting pelvic and upper torso rotations to control the hand’s face angle when serving in the diagonal line.

Investigation of muscle activation during kinetic chain based exercises in individuals with and without forward head posture.

The Band Pull-Apart (BPA) exercise is used to strengthen the periscapular muscles. It was recently stated that the lower extremity and trunk movements should be included in the shoulder rehabilitation programs to optimize an effective energy transfer throughout the kinetic chain. The aim of this study is to investigate the effects of kinetic chain based BPA exercise on the muscle activations of the sternocleidomasteideous (SCM) and the trapezius muscles in individuals with and without forward head posture (FHP). Eighteen individuals with FHP and 18 individuals without FHP were included. Photographic measurements were made to identify individuals with FHP. The muscle activations of SCM, Upper Trapezius (UT), Middle Trapezius (MT), and Lower Trapezius (LT) were measured with surface EMG. BPA exercise was performed in the standing, unipedal standing, squat, unipedal squat, and Bulgarian split squat (BSS). There was no Group × Exercise interaction for the SCM, UT, MT, LT muscle activations, or for the UT/MT and UT/LT ratios (p> 0.05). While there was a difference in the activation of all muscles between individuals with and without FHP (p< 0.05), both ratios were similar (p> 0.05). There was a statistically significant difference between exercises for SCM, MT, and LT muscle activations (p< 0.000 for these muscles), UT/MT (p< 0.000) and UT/LT ratios (p= 0.004). SCM muscle activation in squat was lower than activation in standing (Mean Difference (MD) = 2.5% Maximal Voluntary Isometric Contractions (MVIC); p= 0.004) and in unipedal standing (MD = 2.1% MVIC; p= 0.002). MT muscle activation in squat was higher than activation in standing (MD = 9.7% MVIC), unipedal standing (MD = 7.8% MVIC), unipedal squat (MD = 6.9% MVIC) and BSS (MD = 9.4% MVIC; p< 0.000 for these positions). LT muscle activation in the squat was higher than activation in the standing (MD = 8.5% MVIC) and unipedal squat (MD = 8.1% MVIC; p< 0.004 for these positions). UT/MT ratio in the squat was lower than standing (MD = 0.3), unipedal standing (MD = 0.2) and BSS (MD = 0.3; p< 0.000 for these positions). UT/LT ratio in squat was lower than unipedal squat (MD = 0.5) and BSS (MD = 0.6; p= 0.002; for these positions). Performing the BPA exercise in the squat position is suggested in cases where lower SCM and UT muscle activation, lower UT/MT, and UT/LT ratios and higher MT and LT muscle activations are needed for individuals with and without FHP.

Differences in spinal axial rotation angles during the lumbar-locked rotation test between hyper and normal thoracic rotation groups: A cross-sectional study.

Trunk rotation is important in many sporting activities The thoracic spine has reciprocal relationships with the lumbar and pelvic spines, such that reduced flexibility in the lumbar or thoracic spine can lead to abnormal patterns of trunk movement and pain. However, few studies have investigated the relative trunk rotation mobilities of the thorax, lumbar, and pelvis. To compare thoracic, lumbar, and pelvic rotation angles during the lumbar-locked rotation test between hyper and normal thoracic rotation groups. Thirty-two young, active participants were enrolled in this study. After the attachment of inertial measurement units at the T1, T7, T12, L3, and S2 levels, the participants were required to stand in a comfortable upright posture for 5s to allow postural measurements before performing the lumbar-locked rotation test. The participants were then divided into hyper thoracic rotation and normal thoracic rotation groups based on T1 angle measurements obtained during the lumbar-locked rotation test. The hyper thoracic rotation group had significantly higher thoracic rotation angles on both the right (p< 0.05) and left (p< 0.05) sides compared with the normal thoracic rotation group. Furthermore, we observed flat lumbar lordosis in the hyper thoracic rotation group compared with the normal thoracic rotation group, particularly in the lower lumbar region in standing posture. Our data suggest that evaluations of thoracic mobility should consider relative thoracic, lumbar, and pelvic motions, rather than the T1 angle alone. This study provides a basis for health professionals to evaluate movement dysfunctions associated with thoracic hypermobility.

Effect of a back-support exoskeleton on internal forces and lumbar spine stability during low load lifting task

This study assessed the effect of a small-torque generating passive back-support exoskeleton during a low demanding occupational task, namely a repetitive lifting/lowering of an empty crate between the knee and shoulder heights. A comprehensive set of outcomes was considered, ranging from the measured trunk muscle activation and trunk movement to the estimated muscle group forces/coordination, spine loading and spine stability, using a dynamic subject-specific EMG-assisted musculoskeletal model. The exoskeleton decreased back muscle activation and corresponding muscle forces in the lowering phase and reduced spinal loading at larger trunk flexion angles (decreased peak compression and shear forces by ∼ 15%). However, the effect sizes were small (ηG2 < .06), questioning the usefulness of this type of exoskeleton, even for light tasks. On the other hand, the unique results of the present study showed that coordination between the main muscle groups as well as spinal stability remained unchanged with low effect sizes, suggesting that the use of this exoskeleton is safe.

Evaluating functional ability in older adults’ object retrieval behavior from kitchen furniture using OpenPose and REBA

The purpose of this study is to evaluate, through analysis, the ability of older persons to retrieve items from kitchen cabinets. To achieve this goal, data were collected from 128 valid questionnaires and supplemented with field research and user interviews. The study revealed that the elderly’s behavior in retrieving items from kitchen spaces is characterized by both high frequency and difficulty. For this experiment, a total of 42 participants, comprising 21 males and 21 females from the self-care elderly population in the Yangtze River Delta region, were recruited. Two different experimental settings were arranged: one with kitchen utensils arranged in a straight line and another with a purpose-made chest of drawers with varying heights. Video recordings using the Logitech C930C were utilized to capture the gestures and behaviors of the elderly while retrieving objects from the kitchen cupboards (cabinets). By employing a combination of the OpenPose model and the Rapid Entire Body Assessment (REBA) method, which involves calculating human posture angles, REBA scores, and determining the risk level of Work-Related Musculoskeletal Disorders (WMSDs), a risk assessment framework for manual operations associated with WMSDs was developed. Using the angle data acquired from the user operation experiment as parameters, a gradient model of the elderly user’s operational capability was established. The findings indicated a significant impact of neck, trunk, and knee movements on the subjects (P < 0.001). The participants were able to distinguish between different levels of exertion, categorizing movements as ‘easy’, ‘moderate,’ or ‘strenuous.’ These results form the basis for a comfort gradient model for leaning over and retrieving items. Given the prevalent conditions of bone and joint degeneration and osteoporosis among the elderly population, it is evident that they face challenges when accessing items in the kitchen. Therefore, investigating the elderly’s execution abilities during the retrieval process becomes crucial. Understanding how different cabinet heights impact the joint angles of the elderly can be instrumental in optimizing cabinet designs for elderly users, thereby reducing their physical exertion in the kitchen and enhancing their comfort levels. This research holds significant value in improving the quality of life for the elderly population at home and fostering the advancement of elderly-friendly design principles.

Increasing trunk muscle strength improves trunk movement asymmetry during gait in subacute stroke patients

Increasing trunk muscle strength improves trunk movement asymmetry during gait in subacute stroke patients

Fall Risk Classification Using Trunk Movement Patterns from Inertial Measurement Units and Mini-BESTest in Community-Dwelling Older Adults: A Deep Learning Approach

Fall Risk Classification Using Trunk Movement Patterns from Inertial Measurement Units and Mini-BESTest in Community-Dwelling Older Adults: A Deep Learning Approach

The effect of trunk exercises with hip strategy training to maximize independence level and balance for patient with stroke: Randomized controlled study.

Balance while seated and the capacity to conduct selective trunk movements are significant predictors of functional outcomes following stroke. Patients with inappropriate muscle activation and inadequate movement control in the trunk muscles cause mobility and daily function difficulties. Stroke patients have weak leg muscles and decreased balance, resulting in compensatory changes. Functional postural strategy training is necessary to restore balance in these patients. Few studies have examined the effect of physical therapy trunk exercises with hip strategy training on improving balance and increasing independence after stroke. This study aimed to explore the effect of selective trunk exercises (STE) with hip strategy training in improving balance in patients with stroke as well as independence levels. A multicenter inpatient stroke treatment randomized pre- and post-test control trial. Forty-six stroke survivors were randomly allocated to experimental or control groups (n=23 each). The experimental group received hip strategy training and trunk exercises. All groups received Neuro-Developmental Treatment (NDT)-based physical therapy four times a week for 6weeks. Trunk impairment scale, Berg Balance Scale (BBS), and functional independence measure (FIM) measured static and dynamic seated balance, functional balance, and trunk movement coordination pre- and post-therapy. The experimental group's post-therapeutic measures were substantially higher than the control group. The experimental group's TIS score, and subscale improved more than the control group. The experimental group considerably increased the BBS score. The experimental group also showed greater FIM gains. This study demonstrated that adding STE in conjunction with hip strategy training to patients after has a positive impact on trunk control while maintaining static and dynamic sitting balance, functional balance, and independence levels which are effective in stroke rehabilitation.

Evaluation of the Movement and Play Opportunities and Constraints Associated With Containers for Infants.

Containers (eg, strollers, bouncers) are an important part of infants' environment but may negatively impact infant development and health. This study evaluated movement and play opportunities, constraints, and manufacturers' developmental claims for infant containers. Containers were identified through Amazon.com. A content analysis of identified products was conducted to identify movement and visual-manual play opportunities, constraints, and developmental claims. Content was analyzed for 460 containers. Containers varied in their movement and play opportunities; however, most did not incorporate toys and restricted trunk movement, self-directed locomotion, and independent head and trunk control. Containers, especially those with built-in toys, often had claims related to gross motor, sensory, and fine motor development. These findings demonstrate the variability of movement and play opportunities observed across and within categories of infant containers. General recommendations about container use may be less effective than more specific education to parents about selecting and implementing containers.

Immediate effects of thoracic mobilization versus soft tissue release on trunk motion, pain, and lumbar muscle activity in patients with chronic low back pain

IntroductionThoracic mobilization and tissue release are common manual techniques in clinical practice. However, the relative effects of these two treatments on chronic low back pain (CLBP) have not yet been explored. Thus, this study aimed to investigate and compare the immediate effects of thoracic mobilization with those of soft tissue release on trunk movement, pain sensation, and muscle activity in patients with CLBP. Methods28 participants were randomly assigned to two intervention groups. The mobilization group received mobilization treatment at the hypomobile joints of the trunk segment, while the soft tissue release group received thoracolumbar fascia release and massage in the lumbar region. The trunk range of motion (ROM), tissue hardness, pressure pain threshold (PPT), and erector spinae activity during light-weight lifting tasks were measured before and immediately after both interventions. FindingsAll measured outcomes in both groups improved after intervention (p < 0.05). The mobilization technique significantly improved side bending and rotation, PPT, and tissue hardness compared to soft tissue release. However, lumbar muscle activation reduced to a greater extent in the soft-tissue release group. ConclusionBoth techniques improved trunk ROM and PPT and reduced tissue hardness and muscle activation. Therefore, both these techniques are recommended for patients with CLBP. Trial registrationISRCTN75190733.

The effect of a soft active back support exosuit on trunk motion and thoracolumbar spine loading during squat and stoop lifts

Back support exosuits aim to reduce tissue demands and thereby risk of injury and pain. However, biomechanical analyses of soft active exosuit designs have been limited. The objective of this study was to evaluate the effect of a soft active back support exosuit on trunk motion and thoracolumbar spine loading in participants performing stoop and squat lifts of 6 and 10 kg crates, using participant-specific musculoskeletal models. The exosuit did not change overall trunk motion but affected lumbo-pelvic motion slightly, and reduced peak compressive and shear vertebral loads at some levels, although shear increased slightly at others. This study indicates that soft active exosuits have limited kinematic effects during lifting, and can reduce spinal loading depending on the vertebral level. These results support the hypothesis that a soft exosuit can assist without limiting trunk movement or negatively impacting skeletal loading and have implications for future design and ergonomic intervention efforts.

The cervico-ocular reflex changes following treatment in individuals with subclinical neck pain: a randomized control trial.

Individuals with subclinical neck pain (SCNP) exhibit altered cerebellar processing, likely due to disordered sensorimotor integration of inaccurate proprioceptive input. This association between proprioceptive feedback and SMI has been captured in cervico-ocular reflex (COR) differences where SCNP showed higher gain than healthy participants. Previous neurophysiological research demonstrated improved cerebellar processing in SCNP participants following a single treatment session, but it is unknown whether these neurophysiological changes transfer to cerebellar function. In a parallel group, randomized control trial conducted at Ontario Tech University, 27 right-hand dominant SCNP participants were allocated to the 8-week chiropractic care (n = 15; 7M & 8F) or 8-week control (n = 12; 6M & 6F) group. COR gain (ratio of eye movement to trunk movement) was assessed using an eye-tracking device at baseline and at post 8-weeks (treatment vs. no treatment). COR gain (10 trials): participants gazed at a circular target that disappeared after 3s, while a motorized chair rotated their trunk at a frequency of 0.04Hz, with an amplitude of 5º, for 2 minutes. A 2 × 2 repeated measures ANOVA was performed. COR gain was significantly reduced following 8-weeks of chiropractic care compared to the SCNP control (8-weeks of no treatment) group (p = 0.012, ηp2 = 0.237). The decrease in COR gain following treatment is likely due to normalized proprioceptive feedback from the neck, enabling improved processing and integration within the flocculonodular lobe of the cerebellum.

Visual Deprivation's Impact on Dynamic Posture Control of Trunk: A Comprehensive Sensing Information Analysis of Neurophysiological Mechanisms.

Visual information affects static postural control, but how it affects dynamic postural control still needs to be fully understood. This study investigated the effect of proprioception weighting, influenced by the presence or absence of visual information, on dynamic posture control during voluntary trunk movements. We recorded trunk movement angle and angular velocity, center of pressure (COP), electromyographic, and electroencephalography signals from 35 healthy young adults performing a standing trunk flexion-extension task under two conditions (Vision and No-Vision). A random forest analysis identified the 10 most important variables for classifying the conditions, followed by a Wilcoxon signed-rank test. The results showed lower maximum forward COP displacement and trunk flexion angle, and faster maximum flexion angular velocity in the No-Vision condition. Additionally, the alpha/beta ratio of the POz during the switch phase was higher in the No-Vision condition. These findings suggest that visual deprivation affects cognitive- and sensory-integration-related brain regions during movement phases, indicating that sensory re-weighting due to visual deprivation impacts motor control. The effects of visual deprivation on motor control may be used for evaluation and therapeutic interventions in the future.

Less Pain, but no changes in maximal inclination angles during an overhead reach task following local anesthetic in patients with ongoing shoulder pain

This multicenter observational study aimed to assess how pain reduction, induced by local anesthesia, affects the relative angular contributions of the shoulder girdle and trunk to the maximal angular performance during a semi-constrained overhead reach task in patients with ongoing shoulder pain. Twenty-nine individuals (age 59.0 SD 12.8 years;16-male) with symptomatic shoulders were administered corticosteroid and lidocaine injections by their attending orthopedic surgeon. Immediately before and after the injections, participants reached for a target on the ceiling ten times as high as possible while their pain levels, shoulder, and trunk movements were recorded. The analysis revealed that there was a significant reduction in pain following the injections. However, there were no significant differences in maximum shoulder and trunk inclination angles between the pre- and post-injection conditions. Notably, there were slight but statistically significant alterations in humeroscapular kinematics during the initial phase of arm elevation following the injections. In conclusion, acute pain relief following local anesthetics is not associated with immediate alterations in maximum shoulder girdle and trunk inclination angles during a semi-constrained overhead reach task in patients with ongoing shoulder pain. However, there are signs of small alterations in humeroscapular kinematics during the initial phase of arm elevation.

Compensatory trunk movements of transfemoral amputees when walking with different gait velocities

Compensatory trunk movements of transfemoral amputees when walking with different gait velocities

Utilizing machine learning to analyze trunk movement patterns in women with postpartum low back pain

This paper presents an analysis of trunk movement in women with postnatal low back pain using machine learning techniques. The study aims to identify the most important features related to low back pain and to develop accurate models for predicting low back pain. Machine learning approaches showed promise for analyzing biomechanical factors related to postnatal low back pain (LBP). This study applied regression and classification algorithms to the trunk movement proposed dataset from 100 postpartum women, 50 with LBP and 50 without. The Optimized optuna Regressor achieved the best regression performance with a mean squared error (MSE) of 0.000273, mean absolute error (MAE) of 0.0039, and R2 score of 0.9968. In classification, the Basic CNN and Random Forest Classifier both attained near-perfect accuracy of 1.0, the area under the receiver operating characteristic curve (AUC) of 1.0, precision of 1.0, recall of 1.0, and F1-score of 1.0, outperforming other models. Key predictive features included pain (correlation of -0.732 with flexion range of motion), range of motion measures (flexion and extension correlation of 0.662), and average movements (correlation of 0.957 with flexion). Feature selection consistently identified pain, flexion, extension, lateral flexion, and average movement as influential across methods. While limited to this initial dataset and constrained by generalizability, machine learning offered quantitative insight. Models accurately regressed (MSE < 0.01, R2 > 0.95) and classified (accuracy > 0.94) trunk biomechanics distinguishing LBP. Incorporating additional demographic, clinical, and patient-reported factors may enhance individualized risk prediction and treatment personalization. This preliminary application of advanced analytics supported machine learning's potential utility for both LBP risk determination and outcome improvement. This study provides valuable insights into the use of machine learning techniques for analyzing trunk movement in women with postnatal low back pain and can potentially inform the development of more effective treatments.Trial registration: The trial was designed as an observational and cross-section study. The study was approved by the Ethical Committee in Deraya University, Faculty of Pharmacy, (No: 10/2023). According to the ethical standards of the Declaration of Helsinki. This study complies with the principles of human research. Each patient signed a written consent form after being given a thorough description of the trial. The study was conducted at the outpatient clinic from February 2023 till June 30, 2023.

Precision of trunk movement in people with chronic low back pain

BackgroundMotor control exercise is commonly applied in people with chronic low back pain (CLBP), but possibly not all people with CLBP have motor control impairments. We suggest movement precision as measure to identify motor control impairments. Movement precision has been operationalized as trunk movement variability (TMV) and as trunk tracking error(s) (TTE). Objectives: To compare the known-group validity and the responsiveness of TMV and TTE. DesignWe used a case-control comparison (Healthy controls (n = 30) vs CLBP (n = 60)) to assess the known-group validity. A cohort study, (measurements in week 3 and week 12 of treatment), was used to assess responsiveness. MethodsTMV (temporal (CyclSD) and spatial (MeanSD)) was analyzed during standing, repetitive flexion and rotation tasks (35x). TTE was measured during movement target tracking tasks, again in flexion and rotation. Participants with CLBP followed a multidisciplinary intervention and both measures were assessed in week 3 and week 12 of treatment. 2-way MANOVA and 2-way ANOVA were used to assess the effect of Group (CLBP vs healthy controls) and direction (flexion vs rotation) on TMV and TTE. For responsiveness, 2-way MANOVA and 2-way ANOVA were used to assess the effect of treatment and direction on both measures. FindingsAt baseline, TMV was not different between groups, while TTE was higher in the people with CLBP (p = 0.005, np2 = 0.09). Treatment strongly decreased temporal TMV (p = 0.025, np2 = 0.33) and TTE (p < 0.001, np2 = 0.844). ConclusionsThese results demonstrate that TTE is more sensitive to CLBP and more responsive to treatment than TMV.

Increased force and elastic energy storage are not the mechanisms that improve jump performance with accentuated eccentric loading during a constrained vertical jump.

Accentuated eccentric loading (AEL) involves higher load applied during the eccentric phase of a stretch-shortening cycle movement, followed by a sudden removal of load before the concentric phase. Previous studies suggest that AEL enhances human countermovement jump performance, however the mechanism is not fully understood. Here we explore whether isolating additional load during the countermovement is sufficient to increase ground reaction force, and hence elastic energy stored, at the start of the upward movement and whether this leads to increased jump height or power generation. We conducted a trunk-constrained vertical jump test on a custom-built device to isolate the effect of additional load while controlling for effects of squat depth, arm swing, and coordination. Twelve healthy, recreationally active adults (7 males, 5 females) performed maximal jumps without AEL, followed by randomised AEL conditions prescribed as a percentage of body mass (10%, 20%, and 30%), before repeating jumps without AEL. No significant changes in vertical ground reaction force at the turning point were observed. High load AEL conditions (20% and 30% body weight) led to slight reductions in jump height, primarily due to decreased hip joint and centre of mass work. AEL conditions did not alter peak or integrated activation levels of the knee extensor muscles. The constrained movement task used here, which excluded potential contributions of trunk motion, arm swing, rate of descent, squat depth, and point of load application, allows the conclusion that increased elastic energy return is not the primary mechanism for potentiating effects of AEL on jump performance.