Lower Limb Kinematics Research Articles

Effect of fatigue on neuromuscular and biomechanical variables after anterior cruciate ligament reconstruction: a systematic review.

This systematic review is aimed to evaluate the outcomes of published studies on the topic of fatigue-induced neuromuscular and biomechanical changes after anterior cruciate ligament (ACL) reconstruction. The identification of studies involved a search across three databases - PubMed, Scopus, and Sportdiscus - until July 2023. The key terms utilized were fatigue, anterior cruciate ligament, biomechanics, electromyography, and landing. Included in the analysis were studies that examined the impact of fatigue on neuromuscular or biomechanical variables in individuals with ACLR, with comparisons drawn to either the contralateral side or healthy controls. Fourteen studies, involving 396 athletes (245 males, 151 females; mean age 23.43 years) met the inclusion criteria. Among these studies, eleven employed general fatigue protocols, and three used peripheral protocols. The tasks varied across the studies, including single-leg landing tasks, maximum voluntary isometric contraction tests, forward jump, and squat. Despite differing tasks, the findings regarding the impact of fatigue on lower limb kinematics, kinetics, and surface electromyography muscle activation patterns were inconsistent. However, in the majority of cases, the response to fatigue was similar between individuals who had undergone ACL reconstruction (ACLR) and healthy. The main finding of this systematic review was that fatigue changed things sometimes, however, fatigue did not change biomechanics and activity patterns differently in patients after ACLR vs. controls. General fatigue protocols did not produce enough stimulation to show deference between ACLRs and controls. Future studies should focus on different fatigue protocols (such as sport-specific protocols) and more challenging landing tasks.

High-frequency epidural electrical stimulation reduces spasticity and facilitates walking recovery in patients with spinal cord injury.

Spinal cord injury (SCI) causes severe motor and sensory deficits, and there are currently no approved treatments for recovery. Nearly 70% of patients with SCI experience pathological muscle cocontraction and spasticity, accompanied by clinical signs such as patellar hyperreflexia and ankle clonus. The integration of epidural electrical stimulation (EES) of the spinal cord with rehabilitation has substantial potential to improve recovery of motor functions; however, abnormal muscle cocontraction and spasticity may limit the benefit of these interventions and hinder the effectiveness of EES in promoting functional movements. High-frequency excitation block introduced in peripheral nerve stimulation could reduce abnormal activity and lead to more physiological activation patterns. Here, we evaluated the application of high-frequency EES (HF-EES) in alleviating undesired muscular cocontraction and spasticity in two patients with motor incomplete SCI implanted with a commercial 32-channel EES paddle commonly used for pain therapy. To design custom HF-EES protocols, we first mapped the muscles targeted by different EES configurations. Our results showed that HF-EES substantially reduced patellar reflex in one participant and eliminated both patellar reflex and ankle clonus in the other participant. By combining HF-EES and low-frequency EES (LF-EES) to enhance functional movements with intensive rehabilitation, we observed notable improvements in lower limb kinematics, muscle strength, and clinical lower limb motor assessments over the trial period. This study suggests that HF-EES could be an important supplementary tool in SCI treatment, emphasizing the importance of personalized rehabilitation approaches and advanced tools to optimize EES treatments and offering hope for individuals with SCI-related motor deficits.

Gait pattern differences in unilaterally affected children with cerebral palsy and children with acquired brain insult.

Children with cerebral palsy (CP) or acquired brain insult (ABI) present with motor disorders affecting movement, muscle tone, and posture. While CP is commonly a consequence of perinatal brain insult (PBI), pediatric ABI can occur between birth and adolescence, with movement patterns that may not be consistent with CP. Are gait patterns associated with CP different from those with pediatric ABI? Children with unilateral motor impairment and history of ABI at ≥18 months of age were identified from gait lab records and matched with children with CP having a history of PBI at ≤ 1 year old. Matching was by GMFM-D, age at Instrumented Gait Analysis (IGA), and sex. Kinematic and temporospatial data from the earliest IGA were analyzed. The primary outcome measurement was average knee flexion in stance, as children with CP tend to walk with a more flexed knee and individuals with a brain insult as older children, youth and adults tend to walk with a more extended knee. Secondary variables were temporospatial parameters and lower limb kinematics in stance and swing. Wilcoxon or T-Tests were used. Twenty-six unilaterally affected children with CP (age: 10.8±3.3 years; f:6/m:20; GMFCS I:14, II:38), and 26 unilateral children with ABI (age:11.1±4.3 years; f:6/m:20) were included in each group. Significantly lower knee flexion angles during stance and swing, and shorter single support duration on the affected side were found in the ABI group as compared to CP (p<0.05). In children with ABI, there was a negative correlation between age of insult and severity of internal hip rotation (p<0.05). Children with ABI tend to walk with less stability on the affected side as reflected by the more extended knee and reduced single support compared with children with CP. The age at which the brain insult occurs has a significant effect on the hip rotational profile in children with ABI. Further studies on muscle activation patterns, kinetic data and response to treatment are warranted to gain insight on how the stage of brain and musculoskeletal system development at the time of injury affect gait patterns.

Treadmill belt accelerations may not accurately replicate kinematic responses to tripping on an obstacle in older people.

Treadmill belt perturbations have high clinical feasibility for use in perturbation-based training in older people, but their kinematic validity is unclear. This study examined the kinematic validity of treadmill belt accelerations as a surrogate for overground walkway trips during gait in older people. Thirty-eight community-dwelling older people were exposed to two unilateral belt accelerations (8 m s-2) whilst walking on a split-belt treadmill and two trips induced by a 14 cm trip-board whilst walking on a walkway with condition presentation randomised. Anteroposterior margin of stability (MoS), number of falls, and trunk and lower limb kinematics were quantified for the step prior and five recovery steps following the treadmill perturbations and the walkway trips which elicited elevating and lowering strategies. Rates of falls following the treadmill accelerations and walkway trips were 0% and 13.1%, respectively. MoS was similar during the first recovery step (P>0.05) but less negative during subsequent recovery steps following treadmill belt accelerations than walkway trips (P<0.01) regardless of recovery strategy. Excluding the first recovery step in the lowering strategy, recovery step lengths, toe clearance, maximum trunk, hip and knee angles (P<0.05) were smaller during recovery on the treadmill compared to the walkway. Destabilisation by treadmill belt accelerations quickly dissipated after only one recovery step but continued for multiple recovery steps following walkway trips. Smaller trunk displacement, step lengths, toe clearance and no falls on the treadmill indicate treadmill belt accelerations may not accurately simulate the biomechanical challenge of obstacle-induced trips in older people.

Research on gait recognition by using 1DCNN based on lower limb kinematic posture data

Research on gait recognition by using 1DCNN based on lower limb kinematic posture data

Establishing thresholds for swing transparency at the knee during gait to inform exoskeleton design.

Knee exoskeletons have been developed to assist, stabilize, or improve human movement or recovery. However, exoskeleton designers must implement transparency (i.e., get out of the way) modes during the swing phase of locomotor tasks to avoid impeding movement. The problem is that it is not understood how sensitive people are to small knee torques or what level of knee impedance is acceptable (sufficiently transparent) during swing phase. Here, we (i) characterized the biomechanical consequences of knee stiffness and damping during swing, and (ii) leveraged user perceptions of being impeded and toe clearance to define transparency thresholds, below which the participants were sufficiently unimpeded during the swing phase of gait. We conducted a series of human subject experiments that involved walking and stair ascent/descent while wearing a modified knee brace with five stiffness values ranging from 0 to 4 Nm/rad and five damping values ranging from 0 to 0.77 Nm/rad/s. We measured changes to lower limb kinematics, knee flexor muscle activity, and participants' perception of being impeded during swing. Kinematics, muscle activity, and perceived impedance all changed in response to added stiffness and damping. For stiffness, we found the median transparency thresholds for walking and stairs to be 1.76 Nm/rad and 2.95 Nm/rad, respectively, which corresponds to peak knee moments during swing of around 2.3 and 5 Nm. For damping, we found the median transparency threshold for walking and stairs to be about the same, 0.29 Nm/rad/s, which corresponds to peak knee moments during swing of around 2.3 Nm. These values provide useful benchmarks for defining quantitative design requirements for knee exoskeletons intended for locomotor activities.

Evaluation of a smartphone-based markerless system to measure lower-limb kinematics in patients with knee osteoarthritis

Evaluation of a smartphone-based markerless system to measure lower-limb kinematics in patients with knee osteoarthritis

Trunk fatigue effect on lower limb kinematic and electromyographic patterns during the single-leg drop-landing test in female novice runners

Trunk muscle fatigue could influence the dynamic control of the lower limbs in runners, and the single-leg drop-landing (SLDL) test could simulate the landing and reveal those changes. This study compared the effect of trunk muscle fatigue on the kinematic and electromyographic patterns of the lower limb during SLDL in female novice runners. The kinematics of the main joints and electromyographic (EMG) of the main muscles of the lower limb during SLDL pre- and post-fatigue muscle trunk were registered in 18 female novice runners. The integrated EMG (iEMG) was calculated into 3 phases (F1, before movement starts; F2, eccentric; and F3, concentric). There was an increase in the tibialis anterior and soleus mean iEMG in F1, a reduction in tibialis anterior (TA) and gastrocnemius medialis (GM) maximum iEMG in F2, and an increase in the biceps femoris (BF) minimal iEMG in F2. Also, we found a reduced ankle angle, increased hip angle in the sagittal plane, and a reduced knee angle in the frontal plane post-intervention. The induction of trunk muscle fatigue in female novice runners influenced the TA, SO, GM, and BF EMG changes, the kinematic pattern of the ankle and hip in the sagittal plane, and the knee in the frontal plane during the SDLD.

Medial and lateral knee contact forces and muscle forces during sit-to-stand in patients one year after unilateral total knee arthroplasty

Understanding how forces are transmitted through the knee after TKA is essential, as it may explain why many patients experience pain or functional limitations during various activities. This study compared knee muscle forces and knee contact forces (KCF) during sit-to-stand in patients one year after unilateral total knee arthroplasty (TKA) with either a medial ball-and-socket (MBS) or posterior stabilized (PS) implant and compared them to a group of similarly healthy aged controls (CTRL). A musculoskeletal model and static optimization estimated lower limb kinematics, knee kinetics, muscle forces, and KCFs. The normalized sit-to-stand cycle was compared among the groups using statistical nonparametric mapping, and peak between-limb differences were compared using discrete statistics. The PS group required greater forward lean during the sit-to-stand task, causing greater spine flexion, posterior pelvic tilt, and decreased hip flexion on the operated limb. PS and MBS groups favoured their non-operated limb, resulting in less range of motion throughout the lower limb, lower knee kinetics, muscle forces, and KCFs on the operated limb. Compared to the controls, the MBS and PS groups had reduced medial compartment KCF. The control group did favour their dominant limb over their non-dominant limb. Post-operative rehabilitation should continue to promote greater use of the operated knee to have more symmetrical loading between operated and non-operated limbs and improve strength and mobility at the hip and ankle joints. One year after surgery, TKA patients remain with reduced muscle forces and KCF on their operated limb during a sit-to-stand task, regardless whether they received an MBS or PS implant.

IMU Calibration Effect on Lower Limbs Kinematics Against Optical Motion Capture in Post-Stroke Gait

BackgroundStroke is the most common cause of disabilities worldwide. Rehabilitation is central to restore functions. Inertial measurement units (IMU) can be used to ease goal settings and monitor progression. Contrary to optical motion capture (OMC), IMU are less expensive, portable, and allow large scale data collections in ambulatory settings. Although Xsens MVN system validity has been demonstrated in healthy participants, its validity among post-stroke (PS) patients is yet to be proven. Research questionComputation methods being affected by the calibration type; the goal of this study is to compare lower limbs kinematics from Xsens system, after two calibrations against OMC in slow PS walkers exhibiting reduced ranges of movements. MethodsData was collected for six PS patients. They were equipped with 29 reflective markers and seven IMU. A minimum of two walks with a dynamic calibration and four walks with a static calibration were performed. All trials were accomplished at a self-selected walking speed and PS used their usual walking aids. ResultsFew interactions between the calibration type and side were found for the ankle abduction/adduction (A/A) bias, root mean square error (RMSE), and range of motion difference (ROMd) (p = 0.011, p = 0.048, p = 0.039). Few effects of the side on errors' values were found. We noticed some effects of the calibration type on errors' values, the dynamic calibration showing better results. In the sagittal plane, we reported RMSE values from 3.6 to 4.8°, 5.2 to 6.5°, and 5.0 to 5.9° for the hip, knee, and ankle dynamic calibration. SignificanceThe calibration type, reduced range of movement, and slow walking speed does not seem to impact Xsens' accuracy to a great extent. Nevertheless, dynamic calibration provides slightly better results. Considering the patient's walking ability, we recommend using this calibration.

Validity of an inertial measurement system to measure lower-limb kinematics in patients with hip and knee pathology

Gait analysis for patients with orthopedic joint diseases is crucial to understand their functional status. Inertial measurement unit (IMU) systems, as alternatives to optical motion capture (OMC) systems, enable gait analysis outside the laboratory. However, their accuracy requires validated before widespread clinical use. Therefore, this study evaluated the validity of the Xsens IMU system for lower-limb joint angle measurements during walking in patients with hip and knee pathology and compared the error metrics among patients with hip pathology, patients with knee pathology and healthy controls. We used OMC system and Xsens IMU systems to simultaneously collect lower-limb kinematic data of 130 patients with knee pathology, 110 patients with hip pathology and 25 healthy individuals during walking at self-selected speed. Validity was assessed using root mean square error (RMSE), amplitude difference and coefficient of determination (R2). The RMSEs for the patient groups ranged from 2.5° to 8.8°, with half of the joint angles showing acceptable accuracy and the rest tolerable accuracy. The joint angles measured by both systems were more consistent in the sagittal plane (R2: 0.62–0.96), with lower consistency in the frontal and transverse planes (R2: 0.44–0.63). Compared to the control group, both patient groups had higher RMSEs and lower R2 across most joint angles. Our results suggest that the Xsens IMU system offers highly comparable sagittal plane kinematic waveforms in patients with hip and knee pathology. Caution should be taken when interpreting the frontal and transverse plane kinematics and assessing patients with severe joint deformities.

Data should be made as simple as possible but not simpler: The method chosen for dimensionality reduction and its parameters can affect the clustering of runners based on their kinematics

Dimensionality reduction is a critical step for the efficacy and efficiency of clustering analysis. Despite the multiple available methods, biomechanists have often defaulted to Principal Component Analysis (PCA). We evaluated two PCA- and one autoencoder-based dimensionality reduction methods for their data compression and reconstruction capability, assessed their effect on the output of clustering runners’ based on kinematics, and discussed their implications for the biomechanical assessment of running technique. Eighty-four participants completed a 4-minute run at 12 km/h while trunk and lower-limb kinematics were collected. Data reconstruction quality was assessed for Direct PCA (PCA directly on original variables) and Fourier PCA (modelling time series as Fourier series and then applying PCA) using popular variance explained criteria; and a feedforward autoencoder (AE). Agglomerative hierarchical clustering was then applied and the agreement between the resulting partitions was assessed. Meaningful errors in the reconstructed signals were found when applying popular variance explained criteria, suggesting reconstruction error should be assessed to make a more informed decision about how many components to retain for further analysis. Direct PCA, Fourier PCA and AE yielded different clusters, warranting caution when comparing outcomes from studies that use different dimensionality reduction techniques: each method may be sensitive to different data features. Direct PCA retaining 99 % of the original variance emerged as the best compromise of data compression, reconstruction quality and cluster separability in our dataset. We encourage biomechanists to experiment with diverse dimensionality reduction methods to optimise clustering outcomes and enhance the real-world applicability of their findings.

Effect of experimental knee pain location on gait kinematics.

In this study, we investigated whether experimental knee pain alters lower limb kinematics and knee arthrokinematics during gait, and if this motor adaptation depends on the spatial characteristics of the painful stimulus. Twenty-one participants walked on a treadmill for 60-s trials, either without stimulation or while experiencing painful electrical stimulation in the medial, lateral or anterior region of the knee. Perceived pain location was analyzed using pain drawing. Gait spatiotemporal parameters, lower limb kinematics, and dispersion of the knee helical axes on the sagittal plane were quantified for each trial and compared between conditions using ANOVAs with repeated measures or Friedman tests. Pain perception was localized in the area the stimulation was applied to. Compared to walking without pain, participants demonstrated reduced knee extension (1.5 ± 1.5 degrees, p = 0.002) and reduced hip extension (0.8 ± 1.1 degrees, p = 0.037) when pain was induced in the anterior region, but not medially or laterally. Anterior knee pain increased the mean distance of the helical axes during late stance (0.7 [0.3, 1.4], p = 0.010), while medial pain increased both mean distance (0.3 [0.1, 0.5], p = 0.037) and mean angle (1.2 ± 1.4, p = 0.010) during early swing. Acute, experimental knee pain alters gait kinematics and increases the dispersion of the helical axis. These adaptations depend on the spatial characteristics of the painful stimulus. These adaptations may reflect an attempt of the central nervous system to protect the painful tissue while searching for a less painful movement strategy.

Ankle Taping Does Not Affect Running Kinematics During a Treadmill Protocol in Well-Trained Runners: A Secondary Analysis from a Randomized Cross-Over Controlled Trial.

Background: The purpose of this randomized cross-over controlled trial was to evaluate the biomechanical effects of ankle taping using rigid tape (RT) or kinesiotape (KT) compared to no taping during treadmill running in well-trained amateur runners. Methods: A total of 22 participants (15 men and 7 women) completed three running sessions on a treadmill, each lasting 30 min, under different conditions: no taping (CG), RT, and KT. Sagittal and frontal plane kinematics were analyzed using the Kinovea software to assess the ankle dorsiflexion, knee flexion, hip extension, tibial angle, foot strike pattern, heel eversion, and pelvic drop across three intervals (0-10, 10-20, and 20-30 min). Results: The results demonstrated no significant differences in sagittal plane variables (ankle dorsiflexion, knee flexion, hip extension, and cadence) or frontal plane variables (heel eversion and pelvic drop) between the CG, RT and KT groups at any time point. Although heel eversion significantly increased over time due to fatigue, the taping conditions did not affect running kinematics. Conclusions: These findings suggest that neither RT nor KT alters running biomechanics in well-trained runners over prolonged treadmill running. The study highlights that taping, commonly used to prevent ankle injuries, does not significantly modify lower limb kinematics in the absence of injury. Further research is needed to evaluate the effects of taping in novice or injured runners and under more demanding conditions, such as overground running.

Necessity of Gyroscopes and Accelerometers in Angle Estimation for Quantitative Physiotherapy Evaluation of Lower Limb Kinematics During Walking

Necessity of Gyroscopes and Accelerometers in Angle Estimation for Quantitative Physiotherapy Evaluation of Lower Limb Kinematics During Walking

Greater squat stance width alters three-dimensional hip moment demands

Barbell squat exercise may be performed with different stance widths, which will influence lower limb kinematics and joint reaction forces. Consequently, three-dimensional hip moments may vary with stance width, influencing muscle loading, and the muscles trained when performing squat exercise. To examine how squat stance width affects hip moments, males (n = 11) and females (n = 13) performed barbell squats at narrow, medium, and wide stance widths. Motion capture and force platform data were used to calculate three-dimensional hip net joint moments (NJM) as indicators of the muscular moments required. Hip extensor NJM was greater for wide than medium (P < 0.001) and narrow (P < 0.001) stance squats. Hip adductor NJM was not different between squat stance widths (P = 0.414). Hip lateral rotator NJM was greater in medium versus narrow squats (P < 0.001), and in wide versus medium (P < 0.001) and narrow (P < 0.001) squats. Taken together, the rotational demands at the hip increase as stance width increases, due to higher hip extensor and lateral rotator NJM. In contrast hip adductor NJM is invariant. These data provide insight into the three-dimensional requirements that muscles must meet at the hip when squat exercise is performed at different stance widths.

Comparison of gait deviation index (GDI) and gait variability index (GVI) measured by marker-based and markerless motion capture systems in children with cerebral palsy (CP)

BackgroundThe Gait Deviation Index (GDI) is a metric clinicians use to assess overall gait pathology in children with cerebral palsy (CP) by comparing kinematic data to a normative sample. The Gait Variability Index (GVI) is a related metric that quantifies the variability in spatio-temporal variables during gait. The GDI and GVI have been verified using marker-based motion capture approaches, but video-based markerless motion capture has not been compared using these tools in children with CP. Research questionDo GDI and GVI scores differ when measured using markerlessTheia3D and a marker-based approach between the more and less affected legs in children with CP? MethodsFifteen children with CP (GMFCS levels I-IV) and 24 typically developing children aged 6–18 years were recruited for this study. Overground walking was performed at a self-selected pace while the pelvis and lower limb kinematics were simultaneously recorded using both motion capture systems. Differences in GDI and GVI scores when considering the effect of system and limb impairment were analyzed using two-way repeated-measures ANOVAs. ResultsGDI scores were 6.9 points lower (p < 0.05) when measured using Theia3D compared to the marker-based approach and 6.8 points lower (p < 0.05) in the more affected limbs than in the less affected limbs. These GDI score differences are considered clinically significant. No differences were identified in GVI scores between systems or limb impairment. Differences in kinematic measurements were found in children with CP, including pelvic tilt, hip flexion/extension, hip rotation, and foot progression angle, where root mean square differences between systems exceeded 10°. SignificanceTheia3D can adequately measure variability in spatio-temporal gait parameters for quantifying GVI scores in children with CP compared to the marker-based approach. However, caution is needed when quantifying lower limb kinematics and interpreting GDI and GVI scores using Theia3D in children with CP.

Validity and reliability of trunk and lower-limb kinematics during squatting, hopping, jumping and side-stepping using OpenCap markerless motion capture application

ABSTRACT OpenCap is a web-based markerless motion capture platform that estimates 3D kinematics from videos recorded from at least two iOS devices. This study aimed to determine the concurrent validity and inter-session reliability of OpenCap for measuring trunk and lower-limb kinematics during squatting, hopping, countermovement jumping, and cutting. Nineteen participants (10 males, 9 females; age 27.7 ± 4.1 years) were included. Countermovement jump, single-leg triple vertical hop, single-leg squat, sidestep cutting and side hop tasks were assessed. For validity, OpenCap was compared to a marker-based motion capture system using root-mean-square error. Test–retest reliability of OpenCap was determined using intraclass correlations and minimum detectable change (MDC) from two testing sessions. The squat had the lowest RMSE across joint angles (mean = 7.0°, range = 2.9° to 13.6°). For peak angles, the countermovement jump (jump phase) (ICC = 0.62–0.93) and the squat (ICC = 0.60–0.92) had the best reliability across all joints. For initial contact, the side hop had the best inter-session reliability (ICC = 0.70–0.94) across all joint angles. As such, OpenCap validity and reliability are joint and task specific.

Analysis of the interplay between proximal lower limb and foot joint structures as a mechanical predictor of neuropathic ulceration

BackgroundDiabetes-related foot ulcers are a leading cause of morbidity and mortality globally, in which the most significant contributing factor is peripheral neuropathy. The purpose of this research was to evaluate the influence of diabetic peripheral neuropathy and ulceration on lower limb and foot joint kinematics during gait. Research questionAre there any significant alterations lower limb and foot joint kinematics during gait in the presence of active and history of diabetic neuropathic ulceration? MethodsA prospective, cross-sectional study was conducted, recruiting eighty adult participants who were equally divided into four groups, namely, the diabetes (DM), diabetic peripheral neuropathy (DPN), active diabetic neuropathic ulceration (DNU) and history of diabetic neuropathic ulceration (DHNU) groups. Three-dimensional gait analysis was performed, and participants were instructed to walk barefoot over a 10-m walkway at self-selected speed. The acquired pelvic, hip, knee, ankle and foot joint segmental kinematic data was compared between individuals with and without active neuropathic ulceration. ResultsMean scores between the four independent groups was performed using the Kruskal-Wallis test. Participants within the DNU and DHNU groups demonstrated significantly reduced knee flexion, ankle dorsiflexion and first metatarsal dorsiflexion kinematics with resultant increased anterior pelvic tilt, hip flexion and midtarsal kinematics (all values p<0.01) when compared to participants within the DM and DPN groups. SignificanceThrough the integration of a more individualised, biomechanical approach, the findings in this study may provide improved preventative and management strategies of ulceration amongst the diabetic population.

Effect of External Work Magnitude on Mechanical Efficiency of Sledge Jumping.

The mechanical efficiency of human locomotion has been studied extensively. The mechanical efficiency of the whole body occasionally exceeds muscle efficiency during bouncing type gaits. It is thought to occur due to elasticity and stiffness of the tendinomuscular system and neuromuscular functions, especially stretch reflexes. In addition, the lower limb joint kinetics affect mechanical efficiency. We investigated the impact of varying external work on mechanical efficiency and lower limb kinetics during repeated sledge jumping. Fifteen male runners performed sledge jumping for 4minutes at 3 different sledge inclinations. Lower limb kinematics, ground reaction forces, and expired gases were analyzed. Mechanical efficiency did not differ according to sledge inclination. Mechanical efficiency correlated positively with the positive mechanical work of the knee and hip joints and the negative contribution of the hip joints. Conversely, it correlated negatively with both the positive and negative contributions of the ankle joint. This may be attributable to the greater workload in this study versus previous studies. To achieve greater external work, producing more mechanical energy at the proximal joint and transferring it to the distal joint could be an effective strategy for improving mechanical efficiency because of the greater force-generating capability of distal joint muscles.