Journal Of Applied Biomechanics[JOURNAL]
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200 papers
Form and Function: Stronger Toes and Shorter Heels Associate With Better Gait Performance.
Smith RE, Gray A, Gomez-Palacios S … +3 more , Kashefsky H, Takahashi KZ, Franz JR
J Appl Biomech · 2026 Apr · PMID 41569817 · Publisher ↗
The human foot's unique structure is believed to facilitate our adoption of habitual bipedal locomotion. The foot is particularly important in enabling economical forward propulsion through plantar intrinsic force output...
The human foot's unique structure is believed to facilitate our adoption of habitual bipedal locomotion. The foot is particularly important in enabling economical forward propulsion through plantar intrinsic force output and ankle plantar flexor force transfer. An increased capacity for economical forward propulsion would enhance walking performance, that is, faster preferred walking speed (PWS) and improved walking endurance (WE). However, the association between the foot's unique features and walking performance remains unclear. This study investigated whether neuromechanical (flexor digitorum brevis muscle activity and thickness, toe flexor strength) and anthropometric (heel and toe length) foot features associated with PWS and WE (ie, 6-min walk test distance) in younger adults. Stronger toe flexors associated with greater WE (r = .641, P = .010), whereas shorter heels (ie, calcaneus length) associated with faster PWS (r = -.527, P = .044). Stronger toe flexors enhance WE by increasing net propulsion capacity, whereas shorter heels may enable optimal muscle-tendon operating conditions. These insights highlight potential targets for rehabilitation and assistive devices designed to improve walking performance in individuals with gait impairments.
Effects of a Pneumatic Knee-Actuated Exoskeleton on Gait Stability During Prolonged Walking With Load Carriage.
Johnson CD, Sarantos LC, Fohrmann D … +4 more , Hollander K, Zeppetelli DJ, Dempsey CA, Nagai T
J Appl Biomech · 2026 Apr · PMID 41468233 · Publisher ↗
Lower-extremity exoskeletons (EXOs) may be able to assist with performance and injury risk reduction for military-relevant activities, like walking with loads. However, the effects of EXOs on local dynamic stability (LDS...
Lower-extremity exoskeletons (EXOs) may be able to assist with performance and injury risk reduction for military-relevant activities, like walking with loads. However, the effects of EXOs on local dynamic stability (LDS), a measure of motor control, have not been established. Eleven active duty Army Soldiers (9 males, aged 22 [4] y) completed a familiarization session, followed by 2 testing sessions where they did (EXO) or did not (NoEXO) wear a pneumatic powered, knee-actuated EXO. Inertial measurement units were attached bilaterally to the shank and posterior pelvis. Participants completed a 2-mile ruck march on a treadmill at a self-selected pace (1.34 [0.10] m/s), carrying a load equal to 30% of body weight and an additional 9.07 kg for the EXO during that session. LDS was calculated using gyroscope data for 100 strides at the 0.25- (Start) and 2-mile (End) marks of the march. For the right shank, LDS was found to be significantly lower for EXO versus NoEXO (mean difference = 0.28, P < .01, partial η2 = .75). A similar effect was found for the left shank, and while not significant, the effect size was large (P = .07, partial η2 = .29). Finally, LDS was higher at the pelvis in the EXO versus NoEXO, and with a large effect size, although the results were not significant (P = .07, partial η2 = .29). Our results suggest that lower-extremity EXOs reduce distal LDS, which may point to the need for habituation periods for new users of EXOs.
Are There Cumulative Changes in Lumbar Spine Passive Stiffness Throughout a Week of Prolonged Seated Work?
Davidson JM, Callaghan JP
J Appl Biomech · 2026 Feb · PMID 41468231 · Publisher ↗
This study assessed daily and weekly changes in spine mechanical properties, specifically range of motion and passive stiffness, in those with and without sitting-induced low back pain to determine if time-dependent chan...
This study assessed daily and weekly changes in spine mechanical properties, specifically range of motion and passive stiffness, in those with and without sitting-induced low back pain to determine if time-dependent changes in mechanical properties were related to pain development in prolonged sitting. Over 1 week, 20 participants performed their seated office work and attended 5 laboratory sessions (Monday morning and evening, Tuesday morning, Friday evening, and the following Monday morning) to measure lumbar spine stiffness in passive flexion. Accelerometers measured seated lumbar flexion-extension each workday. In the morning and evening, participants provided low back pain ratings and performed maximum voluntary flexion. Statistical tests compared over time and between pain statuses (nonpain < 10 of 100 mm). There were increases in maximum flexion from morning to evening (2.0°; P = .003) and decreases in angular breakpoints on Monday evening and Tuesday morning (4.6% and 6.8% of passive flexion; P ≥ .056). Classification of seated spine flexion-extension into the transition and high stiffness zones of the passive curve (ie, moderate-high flexion) revealed that sitting strained the posterior passive tissues, likely contributing to the changes in range of motion and stiffness. Nevertheless, alterations in spine properties did not accumulate throughout the week and were not different by pain status.
Repeatability of Knee Kinematic Gait Outcomes Using a Novel Hospital Hallway Setup of a Markerless Motion Capture System.
Civiero SM, Laudanski AF, Legere HR … +3 more , Richardson CG, Dunbar MJ, Astephen Wilson JL
J Appl Biomech · 2026 Apr · PMID 41468215 · Publisher ↗
Instrumented gait analysis has traditionally been isolated to laboratory, marker-based optoelectronic motion capture systems, which limits clinical uptake. Markerless motion capture (MMC) systems driven by trained machin...
Instrumented gait analysis has traditionally been isolated to laboratory, marker-based optoelectronic motion capture systems, which limits clinical uptake. Markerless motion capture (MMC) systems driven by trained machine learning algorithms offer high-throughput solutions for translational clinical opportunities. The aim of this study was to examine the day-to-day repeatability of discrete knee kinematic gait metrics in a healthy population using an MMC system uniquely installed in a hospital hallway. Twenty healthy adults (13 females, 7 males) participated in 3 overground hallway gait sessions, on average 11 days apart, using a novel MMC system setup. Intraclass correlation coefficients, standard errors of measurement, and minimal detectable changes were examined for each gait outcome. Results indicated good-to-excellent repeatability, with most (7/8) outcomes having intraclass correlation coefficient values over .86. Standard error of measurement values for all kinematic outcomes were less than 2.0°, and minimal detectable change values were less than 4.7°. Our novel setup of a hospital hallway MMC system produced highly repeatable gait kinematic metrics in a population of healthy adults. Repeatability errors from this study can be used as a healthy reference for future applications of this system.
Impact of Alignment Strategies on Knee Biomechanics and Muscle Activation During Squatting After Total Knee Arthroplasty.
Li Z, Van Criekinge T, Winnock de Grave P … +2 more , Luyckx T, Claeys K
J Appl Biomech · 2026 Feb · PMID 41468204 · Publisher ↗
Inverse kinematic alignment (iKA), which preserves the natural knee oblique joint line in total knee arthroplasty, has been shown to produce lower-limb kinematics similar to healthy controls during gait. However, its abi...
Inverse kinematic alignment (iKA), which preserves the natural knee oblique joint line in total knee arthroplasty, has been shown to produce lower-limb kinematics similar to healthy controls during gait. However, its ability to maintain this advantage during more demanding activities remains unclear. This study evaluated lower-limb kinematics and muscle activation patterns during squatting in individuals who underwent iKA, adjusted mechanical alignment (aMA), and healthy controls. Kinematics were analyzed using a 3D Vicon system, while muscle activation patterns were recorded using electromyography. The iKA group (80.36° [27.43°]) exhibited knee range of motion comparable to healthy controls (95.25° [23.33°]), while the aMA group (67.39° [28.52°]) showed a significant difference (P = .004). Additionally, the aMA group showed reduced hip flexion compared with controls during squatting (P < .001). Although both iKA and aMA groups displayed differences in hip extension and ankle dorsiflexion compared with controls, no differences in muscle activation patterns were observed. These findings suggest that the iKA and aMA groups can squat without altering muscle activity patterns. However, iKA demonstrates biomechanical outcomes that resemble those of healthy controls in certain aspects. Persistent strength deficits in both surgical groups highlight the need for targeted rehabilitation to restore strength.
Differences in Ground Reaction Force During Foot Strength Testing in Sitting and Standing Positions.
Stevens KM, Olson ML, DiLiberto FE
J Appl Biomech · 2026 Feb · PMID 41352336 · Publisher ↗
Foot strength is important for gait, balance, and function, but it is challenging to measure. Evidence explaining why strength differences exist between sitting and standing test positions is needed to improve clinical v...
Foot strength is important for gait, balance, and function, but it is challenging to measure. Evidence explaining why strength differences exist between sitting and standing test positions is needed to improve clinical value. Observing changes in ground reaction force (Δ GRF) during strength testing may help explain these differences. Our purpose was to determine if Δ GRF differed between test positions, and if Δ GRF was associated with strength. Twenty healthy adults (x¯ = 24.7 y) were randomly assigned to a first test position, sitting or standing. With one foot on a force plate, subjects pressed down and pulled with their toes on a towel connected to a scale, for each test position. Paired t tests and Pearson correlation coefficients were used in analyses of strength and 3D Δ GRF outcomes. Mean peak foot strength and Δ GRFx (anterior-posterior direction) were greater in standing (P < .001). Correlations were strong between sitting and standing peak strength (r = .703) and between peak strength and Δ GRFx (r = .738) and Δ GRFz (superior-inferior) (r = .595) in standing. Greater strength production in standing, which was directly correlated to Δ GRF, was congruent with task demands and may reflect the importance of rearfoot stability during foot strength testing. From a clinical perspective, the standing test position is favored over sitting.
Examination of Gait Asymmetry During Walking With Additional Arm Weights.
Yang HS, Atkins LT, James CR
J Appl Biomech · 2026 Feb · PMID 41289990 · Publisher ↗
Gait symmetry is often assumed in healthy individuals, yet functional asymmetries arise from biomechanical and neurophysiological factors. Although light upper body loading can improve walking performance, its effect on...
Gait symmetry is often assumed in healthy individuals, yet functional asymmetries arise from biomechanical and neurophysiological factors. Although light upper body loading can improve walking performance, its effect on lower limb joint asymmetry remains unclear. This study examined how different loading conditions affect sagittal plane gait asymmetry at the hip, knee, and ankle. Twenty-two participants walked under 4 conditions: no weight, unilateral arm weight, bilateral arm weights, and waist weights each using 0.45-kg loads. Three-dimensional joint angles were normalized to 101 points across the gait cycle. Asymmetry was assessed using statistical parametric mapping and pointwise effect size. Two metrics were used: (1) temporal extent, defined as the percentage of the gait cycle with significant left-right differences (P < .05) and the percentage of the gait cycle with effect size >0.8 and (2) group-level prevalence, defined as the percentage of participants showing significant asymmetry at each time point. Significant asymmetries were observed across all joints and conditions, with hip and knee levels consistently exceeding those at the ankle. Effect size values often exceeded statistical thresholds, highlighting meaningful differences. Loading produced minimal systematic effects, though individual responses varied. Importantly, light arm weights did not increase asymmetry, supporting their use for gait enhancement.
Automated Classification of the Consequences of a Slip During Walking Using a Machine Learning Approach.
Amiaka CO, Yuan VF, Beaudette SM … +1 more , Tokuno CD
J Appl Biomech · 2026 Feb · PMID 41289987 · Publisher ↗
This study applied decision-tree (DT) machine learning models to determine whether this approach is more accurate when classifying slip outcome during walking, and to refine the cutoff thresholds of each slip type. Kinem...
This study applied decision-tree (DT) machine learning models to determine whether this approach is more accurate when classifying slip outcome during walking, and to refine the cutoff thresholds of each slip type. Kinematic data of the heel were collected from 50 adults (23.1 [3.6] y) during 516 walking trials. The first DT model (DT1) was trained with heel slip distance and heel slip velocity as predictor variables; the second model (DT2) added heel slip acceleration as the third predictor variable. Walking trials were first classified as a no-slip, slip-recovery, or slip-fall outcome based on visual observation, and these classifications were used as response labels to train the DT models. Results indicated that both DT models yielded different thresholds in classifying slip outcomes and were similar to thresholds suggested in previous studies. However, both DT models resulted in 4.1% to 7.6% greater overall prediction accuracy compared with previously suggested thresholds, with DT2 generally performing better than DT1. Although the improved performance was offset by a ∼7% lower sensitivity when classifying no-slip outcomes and greater model complexity, future studies examining slip responses during gait should incorporate the thresholds derived from the DT2 model to most accurately classify the type of slip outcome.
Erratum. Effects of Different Inertial Measurement Unit Sensor-to-Segment Calibrations on Clinical 3-Dimensional Wrist Joint Angles Estimation.
Journal of Applied Biomechanics
J Appl Biomech · 2026 Apr · PMID 41274281 · Publisher ↗
Abstract loading — click title to view on PubMed.
Relationship Between Shoulder External Rotation and Glenohumeral Joint Alignment Changes in Baseball Players.
Takahashi M, Mutsuzaki H, Iwamoto K … +7 more , Monma M, Nejishima M, Ono T, Inami H, Takemura M, Kawamura T, Tomita K
J Appl Biomech · 2026 Feb · PMID 41253138 · Publisher ↗
Clarification of glenohumeral joint alignment changes during the late cocking phase may reveal the mechanisms of throwing injuries. This study aimed to determine the effect of shoulder external rotation on humeral head c...
Clarification of glenohumeral joint alignment changes during the late cocking phase may reveal the mechanisms of throwing injuries. This study aimed to determine the effect of shoulder external rotation on humeral head center deviation relative to the scapular glenoid. Twenty-eight baseball players participated. The anteroposterior deviation of the humeral head center relative to the glenoid (humeral head translation) and the distance between the humeral head and posterior glenoid rim perpendicular to the glenoid articular surface (posterior glenohumeral distance) were measured. Magnetic resonance imaging of the throwing shoulder was performed at 90° abduction with 90°, 100°, and 110° external rotation; for the nonthrowing shoulder, measurements were conducted at 90° and 100°. In humeral head translation, the posterior translation of the humeral head relative to the glenoid was significantly greater at 110° compared to 90° external rotation position (P = .003). Humeral head translation was associated with posterior glenohumeral distance at the 90° (β-coefficient = 0.649) and 100° (β-coefficient = 0.556) external rotation positions. Increased shoulder external rotation resulted in posterior translation of the humeral head and proximity between the humeral head and the posterior glenoid rim. The factors identified as contributing to posterior deviation of the humeral head may trigger throwing shoulder injuries during the late cocking phase.
Regional Distribution of Myoelectric Median Frequency in the Erector Spinae Muscles Under the Influence of Delayed-Onset Muscle Soreness.
Pano-Rodriguez A, Ducas J, Vadez G … +1 more , Abboud J
J Appl Biomech · 2026 Feb · PMID 41183510 · Publisher ↗
Delayed-onset muscle soreness (DOMS) is a noninvasive pain model offering a unique opportunity to study trunk neuromuscular adaptations. While prior research has examined regional muscle activation in the lumbar region,...
Delayed-onset muscle soreness (DOMS) is a noninvasive pain model offering a unique opportunity to study trunk neuromuscular adaptations. While prior research has examined regional muscle activation in the lumbar region, the spatial distribution of median frequencies (MF) under DOMS has not been explored. This study investigated the effect of DOMS-induced pain on the spatial distribution of MF in the lumbar erector spinae muscles and its association with trunk force variability during submaximal contractions. Twenty healthy adults completed 2 laboratory sessions: 1 pain-free and 1 under low back DOMS. High-density surface electromyography was recorded bilaterally on the erector spinae during submaximal isometric trunk extensions. MF distribution was analyzed using centroid coordinates with and without DOMS. Force variability was also assessed. DOMS significantly increased perceived muscle pain and soreness in the lumbar region. It also caused a cranial and medial shift of the MF centroid, significant on 1 side of the trunk. However, force variability remained stable between conditions. These results suggest that DOMS induces regional adaptations in lumbar muscle MF. The spatial distribution of MF may serve as a novel and sensitive marker of neuromuscular adaptation to pain. The trunk system was able to maintain force steadiness despite pain and soreness.
Opposite Medial and Lateral Tibiofemoral Joint Compartment Responses Between Dominant and Nondominant Limbs When Walking With Load Carriage.
Jones BW, Willson JD, DeVita P … +1 more , Wedge RD
J Appl Biomech · 2026 Feb · PMID 41183505 · Publisher ↗
It is unknown whether interlimb differences in gait mechanics affect the magnitude or distribution of tibiofemoral joint contact forces or whether load carriage increases potential effects of limb dominance. Thus, this s...
It is unknown whether interlimb differences in gait mechanics affect the magnitude or distribution of tibiofemoral joint contact forces or whether load carriage increases potential effects of limb dominance. Thus, this study aimed to compare the effects of load carriage on total, medial, and lateral tibiofemoral joint contact force between the dominant and nondominant limbs. Twenty-four adults (12 women, 21 right-leg dominant) walked at 1.4 m·s-1 during 3 load carriage conditions (0%, 15%, and 30% body weight). Medial and lateral tibiofemoral joint contact forces were calculated during 5 stance phases for each limb in each condition. A 3 × 2 repeated-measures analysis of variance was used to compare the dominant and nondominant limbs across the 3 loading conditions. Peak tibiofemoral joint forces increased directly with load carriage (P < .001). The nondominant limb peak medial tibiofemoral joint contact force was greater than that of the dominant limb (P = .026), whereas dominant limb peak lateral tibiofemoral joint contact force was greater than that of the nondominant (P < .001) limb. Although the results were close to the minimal detectable difference, we concluded that the distribution of tibiofemoral joint contact force during load carriage may be influenced by limb dominance. These findings underscore the relevance of limb dominance as a consideration in research design and data interpretation.
Clinically Relevant Gait Biomechanics Improvements After Total Knee Arthroplasty.
Laudanski AF, Outerleys JB, Kirkwood R … +5 more , Hubley-Kozey CL, Young-Shand KL, Richardson CG, Dunbar MJ, Astephen Wilson JL
J Appl Biomech · 2025 Dec · PMID 41161300 · Publisher ↗
Improved joint function is a primary goal of total knee arthroplasty (TKA), yet persistent postoperative deficits in joint biomechanics are common, and the link between these and other clinical outcomes is poorly underst...
Improved joint function is a primary goal of total knee arthroplasty (TKA), yet persistent postoperative deficits in joint biomechanics are common, and the link between these and other clinical outcomes is poorly understood. Evidence on clinically meaningful gait outcomes after arthroplasty is limited, hindering their uptake in clinical trials and technological innovations in arthroplasty. This paper examined the associations between gait outcomes and satisfaction after TKA and defined minimal detectable and clinically meaningful thresholds for gait outcome changes. Thirty-one patients underwent instrumented gait analysis immediately before and 1 year after TKA and were categorized as high (>90) and lower (≤90) satisfaction with their joint replacement after surgery. Sixteen (51.6%) patients self-reported high satisfaction, and 15 (48.4%) reported lower satisfaction. There were no pre-TKA gait differences between the groups, but higher satisfaction postarthroplasty was associated with more a biphasic pattern improvement of the knee flexion/extension moment during stance from presurgery to postsurgery (r = .59, P = .001). Most patients, however, did not achieve minimal detectable or meaningful clinically important improvements in knee biomechanics from pre-TKA to post-TKA. The established thresholds for meaningful improvement in biomechanical variables may be used in future studies to relate measures of patient satisfaction to objective gait outcomes.
The Influence of Lateral Constraints on Walking: Effects of Walking Speed and Biological Sex.
Lordall J, Arnold CM, Donkers SJ … +3 more , Farthing JP, Lanovaz JL, Oates AR
J Appl Biomech · 2026 Feb · PMID 41151569 · Publisher ↗
This study examined the influence of lateral constraints and sex on walking in different settings. Thirty-eight adults (17 males: 25 [3] y, 21 females: 24 [4] y) walked overground for 20 m in open (no constraints), open...
This study examined the influence of lateral constraints and sex on walking in different settings. Thirty-eight adults (17 males: 25 [3] y, 21 females: 24 [4] y) walked overground for 20 m in open (no constraints), open pathway (defined by lines on the floor), and hallway (pathway defined by walls) settings at 3 speeds (slow, preferred, and fast). Inertial sensors recorded kinematics (Xsens Awinda, Movella) to calculate stride velocity, stride length (SL), cadence, and double support phase percentage. Stride velocity, SL, and cadence were also normalized to account for body size. Linear mixed models were used for statistical analysis (α = .05). No setting or setting by speed effects were found. Males had greater SL compared with females at preferred and fast speeds. Males had greater normalized SL compared with females at fast speeds. Females had greater cadence compared with males across conditions. Males had greater double support phase percentage compared with females at slow speeds. Wider hallways may allow for walking assessments generalizable to open settings. Considering sex differences in cadence at any speed, SL at preferred and fast speeds, normalized SL at fast speeds, and double support phase percentage at slow speeds may be valuable for interpreting walking assessments.
Correlations Between the Trochanteric Soft Tissue Stiffness and the Pelvis Stiffness During Sideways Falls.
Lim K, Kim SS, Yi CH … +4 more , Kwon O, Jeon HS, You SH, Choi WJ
J Appl Biomech · 2026 Feb · PMID 41151567 · Publisher ↗
The pelvis and trochanteric soft tissue stiffness influence hip impact force during falls. We examined potential relationships between the stiffness values acquired from different methodologies. Twenty-six individuals si...
The pelvis and trochanteric soft tissue stiffness influence hip impact force during falls. We examined potential relationships between the stiffness values acquired from different methodologies. Twenty-six individuals simulated sideways falls. During trials, force-deformation data of the trochanteric soft tissue were recorded, then fitted to polynomial and exponential functions. Stiffness was determined as a slope of the tangent line at maximum deformation (Ks_1st, Ks_2nd, and Ks_exp) and at 0.4 N (Ks_2nd_0.4 N, Ks_exp_0.4 N). Similarly, force-deformation data of the pelvis were fitted exponentially to determine the pelvis stiffness at peak impact force (Kb). We also used a clinical device to measure the trochanteric soft tissue stiffness (Ks_myoton). Correlation and regression analyses were performed. The Kb was correlated with Ks_1st and Ks_2nd (P < .05) and decreased 1.7 and 0.7 kN/m for every 1 kN/m increase in Ks_1st and Ks_2nd, respectively (R2 = .23 and R2 = .21), but no variables were correlated with the Ks_myoton (P > .05). When normalized, however, both Kb and Ks_myoton were correlated with Ks_1st and Ks_2nd (P < .05). These findings provide insights into hip impact dynamics, suggesting that trochanteric soft tissue stiffness measured with a clinical device may serve as a predictor of pelvis stiffness during falls.
Multijoint Coordination Contributes to the Minimization of Frontal Plane Center-of-Mass Displacement in Maximal Velocity Sprinting.
Vellucci CL, Beaudette SM
J Appl Biomech · 2025 Dec · PMID 41139408 · Publisher ↗
Previous studies on sprinting biomechanics have identified a variety of biomechanical characteristics that describe the outcome of improved sprint technique but in doing so have neglected to identify the postural control...
Previous studies on sprinting biomechanics have identified a variety of biomechanical characteristics that describe the outcome of improved sprint technique but in doing so have neglected to identify the postural control strategies that lead to improved sprint performance. The purpose of this study was to evaluate the relationship between frontal plane displacement of the center of mass (CoM) and sprint velocity, and to understand if multijoint coordination of the limbs and trunk were associated with minimizing the displacement. The results from this study suggest that stance phase frontal plane CoM cumulative path length is significantly associated with sprint velocity. Further, a multivariate linear regression model revealed that coordinative couplings of the bilateral limbs and trunk were associated with the minimization of the frontal plane CoM displacement. Specifically, the coordination of the knees (flexion-extension) and axial rotation of the thorax-pelvis were the most important interjoint couplings in minimizing frontal plane CoM displacement. Frontal plane CoM displacement provides coaches, athletes, and performance professionals with an interpretable metric to identify sprint technique quality in field using wearable sensors. Future work needs to further advance our understanding of postural control during sprinting so that effective coaching and rehabilitation interventions can be designed.
The Impact of Participant Instructions on Lumbopelvic Rhythm During Forward Spine Flexion and Return.
Sany SA, Wilkie AJ, Frey M … +2 more , Yi Y, De Carvalho D
J Appl Biomech · 2025 Dec · PMID 41067431 · Publisher ↗
Spine motion and outcome measures derived therein may be confounded by the motion instructions provided to participants during data collection. This observational analytical laboratory-controlled study explored the impac...
Spine motion and outcome measures derived therein may be confounded by the motion instructions provided to participants during data collection. This observational analytical laboratory-controlled study explored the impact of instructions for forward flexion trials on the lumbopelvic ratio (LPR) and spine kinematics. Twenty-five participants (mean age: 25.68 [9.31] y) performed forward bending trials with general instructions and then specific instructions to avoid hip motion and follow pacing. Participants were equipped with triaxial accelerometers at the lumbar spine (first lumbar vertebra) and pelvis (second sacral vertebra) to measure lumbar and pelvic excursions and LPR across the movement phases. The Wilcoxon signed-rank test was used to compare outcome variables between conditions. Lumbar excursion did not differ significantly between conditions, whereas pelvic excursion was significantly reduced in the specific instructions condition (P < .05). LPR showed considerable variability in the specific instructions condition, but there was no significant difference from the general instruction condition. Thus, instructing participants to limit hip motion appears to reduce pelvic excursion during forward bending without statistically affecting lumbar motion or the LPR. Providing and reporting clear and precise movement instructions to participants is important as they can change kinematics. Further, it appears that verbal instructions alone are unlikely to achieve complete spine movement isolation in all participants.
Validity of Poststroke Gait Spatiotemporal and Joint Excursion Metrics Between Inertial Measurement Units and a Marker-Based System.
Knight HL, Schonhaut EB, Jacobs CJ … +1 more , Dean JC
J Appl Biomech · 2025 Dec · PMID 41052758 · Full text
People with chronic stroke often walk with altered spatiotemporal parameters and joint excursions, metrics that can serve as intervention targets. Inertial measurement units (IMUs) allow such metrics to be quantified out...
People with chronic stroke often walk with altered spatiotemporal parameters and joint excursions, metrics that can serve as intervention targets. Inertial measurement units (IMUs) allow such metrics to be quantified outside of a traditional motion capture laboratory. The purpose of this study was to quantify the validity of common poststroke biomechanical gait metrics between an IMU-based and a marker-based system during treadmill walking, a context that facilitates gait training interventions. For 61 people with chronic stroke, we assessed the validity of stride duration, stride length, and sagittal plane joint excursions of the bilateral hip, knee, and ankle in 2 ways: (1) Across participants, revealing whether both systems similarly characterize participants' average gait parameters; and (2) Within participants, revealing whether both systems similarly quantify stride-by-stride variance. Across participants, all joint metrics had either excellent (Lin correlation coefficient; LCC > .75) or good (LCC .60-.74) validity, suggesting that IMU-derived metrics that are often the target of treatment can be appropriately compared to existing population norms. In contrast, median validity within participants was excellent for stride duration, but only poor (LCC < .40) to fair (LCC .40-.59) for stride length and most joint excursions. Therefore, IMU-derived gait metrics quantified on a stride-by-stride basis should be interpreted cautiously.
The Effects of Cheerleading Surfaces on Ankle Landing Characteristics During Vertical and Flip Landings.
Nguyen AV, Slavens BA, Cobb SC … +1 more , O'Connor KM
J Appl Biomech · 2025 Dec · PMID 41052756 · Publisher ↗
Lateral ankle sprains are common in cheerleading, especially during tumbling. Landing surfaces influence injury risk by affecting joint mechanics, but few studies compare vertical and flip landings. This study examined t...
Lateral ankle sprains are common in cheerleading, especially during tumbling. Landing surfaces influence injury risk by affecting joint mechanics, but few studies compare vertical and flip landings. This study examined the effects of a hard (HARD) and matted (MAT) surfaces on vertical drop (VERT) and flip (FLIP) landing tasks. Twelve collegiate cheerleaders performed both tasks with 3-dimensional kinematics and kinetics collected. Repeated-measures analyses of variance (task × surface, P < .05) analyzed sagittal and frontal plane variables. The FLIP task exhibited 84% greater peak ground reaction forces and 148% greater loading rates, as well as greater peak ankle angles and reduced ankle plantar flexion at initial contact compared to the VERT task. Increased foot velocities at initial contact during FLIP, driven by angular velocity, likely explained these heightened characteristics. HARD surface landings resulted in greater peak loading rates, peak angles, and inversion at initial contact. The peak plantar flexor moment was greater when landing on a HARD surface after a FLIP. Flip landings may elevate injury risks compared to vertical landings while supporting that harder landing surfaces increase injury risks. The significant differences between the tasks due to angular velocity differences also caution against generalizing vertical landings to landings within acrobatic sports.
Maximize or Normalize? Examining Single-Leg Drop-Land-Cut Distances in Young Athletes: A Pilot Study.
Butcher AJ, Clissold T, Ward S … +2 more , Richards J, Hébert-Losier K
J Appl Biomech · 2025 Dec · PMID 41027564 · Publisher ↗
This study investigated differences in leap distance for a single-leg drop-land-cut (CUT) task based on using either a maximal or normalized (150% leg length) method or the influence of condition order and leg dominance...
This study investigated differences in leap distance for a single-leg drop-land-cut (CUT) task based on using either a maximal or normalized (150% leg length) method or the influence of condition order and leg dominance on distance achieved. Twenty-six young court and field sport athletes (61.5% female) completed the single-leg drop-land-cut task on the dominant and nondominant leg under maximal and normalized conditions in a randomized order. Multivariate repeated measures analysis of variance tests with post hoc pairwise comparisons were used to determine the effect of condition (maximal and normalized), leg dominance (dominant and nondominant), and interaction effect on leaping distance. Potential order effects were explored as a between-subjects factor within the analysis of variance. Our findings showed significantly larger leap distances under the maximal condition (P < .001, ηp2 ≥ .417), with the maximal mean being 154.5 (24.7) cm (175.1% [18.6%] leg length) and the normalized mean being 140.7 (19.7) cm (159.0% [5.8%] of leg length). Furthermore, greater distances were achieved during the maximal task when performed following the normalized task (P < .001, 24.5% further). Practically, the normalized task may be better suited for heterogeneous samples; yet, the maximal task may be more suitable for homogeneous samples or pre-post study designs.
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