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Muscle Torque–Velocity Relationships and Fatigue With Reduced Knee Joint Range of Motion in Young and Older Adults

Zoe H. Smith, R. Anthony Martin, Erica Casto, Carol Bigelow, Michael A. Busa, and Jane A. Kent

The purpose of this study was to evaluate the influence of knee joint range of motion (RoM) on the torque–velocity relationship and fatigue in the knee extensor muscles of 7 young (median = 26 y) and 7 older (68 y) adults. Each leg was assigned a RoM (35° or 75°) over which to perform a torque–velocity protocol (maximal isokinetic contractions, 60–300°·s−1) and a fatigue protocol (120 maximal contractions at 120°·s−1, 0.5 Hz). Six older participants were unable to reach 300°·s−1 over 35°. Therefore, the velocity eliciting 75% of peak torque at 60°·s−1 (V 75, °·s−1) was calculated for each RoM from a fit of individual torque–velocity curves (60–240°·s−1), and ΔV 75 (35°–75°) was determined. Fatigue (final torque/initial torque) was used to calculate Δfatigue (35°–75°). ΔV 75 was not different from 0 in young (−28.3°·s−1 [−158.6 to 55.7], median [range], P = .091) or older (−18.5°·s−1 [−95.0 to 23.9], P = .128), with no difference by age (P = .710). In contrast, fatigue was greater for 75° in young (Δfatigue = 25.9% [17.5–30.3], P = .018) and older (17.2% [11.9–52.9], P = .018), with no effect of age (P = .710). These data indicate that, regardless of age, RoM did not alter the torque–velocity relationship between 60 and 240°·s−1, and fatigue was greater with a larger RoM.

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Comparing Knee Kinetics and Kinematics in Healthy Individuals and Those With Knee Osteoarthritis, With and Without Flat Feet

Maryam Sohrabi, Giti Torkaman, and Fariba Bahrami

Individuals with knee osteoarthritis (KOA) and flat feet are more likely to experience increased pain and cartilage damage. This study aimed to investigate the knee kinetics, kinematics, pain, and physical function in individuals with moderate symptomatic KOA, in comparison to asymptomatic control participants. Thirty volunteers with moderate KOA (with flat feet n = 15, with normal feet n = 15) and 30 asymptomatic people (with flat feet n = 15, with normal feet n = 15) were evaluated. The knee adduction angular impulse, knee flexion moment, knee flexion angular impulse, and knee flexion angle were measured during level walking. The pain was assessed in patients with KOA. The study found that individuals with KOA had a significant increase in the knee adduction angular impulse compared with the asymptomatic people (P < .05). The KOA with flat feet group had significantly lower knee flexion moment, knee flexion angular impulse, and knee flexion angle values than the KOA with normal feet group (P < .05). Furthermore, the KOA with flat feet group had a higher pain score than the KOA with normal feet group. Individuals with osteoarthritis and flat feet had lower knee flexion moments which may indicate reduced knee force exerted through compensatory mechanisms. Despite this reduction, they reported significantly higher levels of pain compared with those without flat feet, a finding that warrants further investigation in future studies.

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Fourier Analysis of the Vertical Ground Reaction Force During Walking: Applications for Quantifying Differences in Gait Strategies

Taylor P. Trentadue and Daniel Schmitt

Time series biomechanical data inform our understanding of normal gait mechanics and pathomechanics. This study examines the utility of different quantitative methods to distinguish vertical ground reaction forces (VGRFs) from experimentally distinct gait strategies. The goals of this study are to compare measures of VGRF data—using the shape factor method and a Fourier series-based analysis—to (1) describe how these methods reflect and distinguish gait patterns and (2) determine which Fourier series coefficients discriminate normal walking, with a relatively stiff-legged gait, from compliant walking, using deep knee flexion and limited vertical oscillation. This study includes a reanalysis of previously presented VGRF data. We applied the shape factor method and fit 3- to 8-term Fourier series to zero-padded VGRF data. We compared VGRF renderings using Euclidean L2 distances and correlations stratified by gait strategy. Euclidean L2 distances improved with additional harmonics, with limited improvement after the seventh term. Euclidean L2 distances were greater in shape factor versus Fourier series renderings. In the 8 harmonic model, amplitudes of 9 Fourier coefficients—which contribute to VGRF features including peak and local minimum amplitudes and limb loading rates—were different between normal and compliant walking. The results suggest that Fourier series-based methods distinguish between gait strategies.

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The Midfoot Joint Complex (Foot Arch) Contributes to the Upper Body Position in Bipedal Walking and Coordinates With the Lower Limb Joints

Leonardo D. Barsante, Paula M.M. Arantes, Daniela V. Vaz, Fabricio A. Magalhães, Diego S. Carvalho, Aline C. Cruz, Renan A. Resende, Juliana M. Ocarino, Sérgio T. Fonseca, and Thales R. Souza

This study estimated the contribution of the midfoot joint complex (MJC) kinematics to the pelvis anterior–posterior positions during the stance phase of walking and investigated whether the MJC is functionally coordinated with the lower limb joints to maintain similar pelvic positions across steps. Hip, knee, ankle, and MJC sagittal angles were measured in 11 nondisabled participants during walking. The joints’ contributions to pelvic positions were computed through equations derived from a link-segment model. Functional coordination across steps was identified when the MJC contribution to pelvic position varied and the summed contributions of other joints varied in the opposite direction (strong negative covariations [r ≤ −.7] in stance phase instants). We observed that the MJC plantarflexion (arch raising) during the midstance and late stance leads the pelvis backward, avoiding excessive forward displacement. The MJC was the second joint that contributed most to the pelvis positions (around 18% of all joints’ contributions), after the ankle joint. The MJC and ankle were the joints that were most frequently coordinated with the other joints (≅70% of the stance phase duration). The findings suggest that the MJC is part of the kinematic chain that determines pelvis positions during walking and is functionally coordinated with the lower limb joints.

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Force–Time Characteristics of Repeated Bouts of Depth Jumps and the Effects of Compression Garments

Freddy Brown, Matt Hill, Derek Renshaw, and Jason Tallis

No studies have reported ground reaction force (GRF) profiles of the repeated depth jump (DJ) protocols commonly used to study exercise-induced muscle damage. Furthermore, while compression garments (CG) may accelerate recovery from exercise-induced muscle damage, any effects on the repeated bout effect are unknown. Therefore, we investigated the GRF profiles of 2 repeated bouts of damage-inducing DJs and the effects of wearing CG for recovery. Nonresistance-trained males randomly received CG (n = 9) or placebo (n = 8) for 72 hours recovery, following 20 × 20 m sprints and 10 × 10 DJs from 0.6 m. Exercise was repeated after 14 days. Using a 3-way (set × bout × group) design, changes in GRF were assessed with analysis of variance and statistical parametric mapping. Jump height, reactive strength, peak, and mean propulsive forces declined between sets (P < .001). Vertical stiffness, contact time, force at zero velocity, and propulsive duration increased (P < .05). According to statistical parametric mapping, braking (17%–25% of the movement) and propulsive forces (58%–81%) declined (P < .05). During the repeated bout, peak propulsive force and duration increased (P < .05), while mean propulsive force (P < .05) and GRF from 59% to 73% declined (P < .001). A repeated bout of DJs differed in propulsive GRF, without changes to the eccentric phase, or effects from CG.

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Volume 40 (2024): Issue 2 (Apr 2024)

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Dr Charles J. (Chuck) Dillman: A Remembrance

Robert Shapiro, Robert Gregor, and John Challis

In August 2023, the biomechanics community suffered a significant loss with the death of Dr Charles J. Dillman. His work in the area of sport biomechanics was groundbreaking. In this tribute, 10 former students and 9 former colleagues remember “Chuck” and his impact on their lives, careers, and the field of biomechanics.

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Prolonged Standing-Induced Low Back Pain Is Linked to Extended Lumbar Spine Postures: A Study Linking Lumped Lumbar Spine Passive Stiffness to Standing Posture

Kayla M. Fewster, Kaitlin M. Gallagher, and Jack P. Callaghan

Postural assessments of the lumbar spine lack valuable information about its properties. The purpose of this study was to assess neutral zone (NZ) characteristics via in vivo lumbar spine passive stiffness and relate NZ characteristics to standing lumbar lordosis. A comparison was made between those that develop low back pain during prolonged standing (pain developers) and those that do not (nonpain developers). Twenty-two participants with known pain status stood on level ground, and median lumbar lordosis angle was calculated. Participants were then placed in a near-frictionless jig to characterize their passive stiffness curve and location of their NZ. Overall, both pain developers and nonpain developers stood with a lumbar lordosis angle that was more extended than their NZ boundary. Pain developers stood slightly more extended (in comparison to nonpain developers) and had a lower moment corresponding to the location of their extension NZ boundary. Overall, in comparison to nonpain developers, pain developers displayed a lower moment corresponding to the location of their extension NZ boundary which could correspond to greater laxity in the lumbar spine. This may indicate why pain developers have a tendency to stand further beyond their NZ with greater muscle co-contraction.

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Shoulder External Over Internal Rotation Ratio Is Related to Biomechanics in Collegiate Baseball Pitching

Hannah L. Stokes, Koco Eaton, and Naiquan Zheng

Altering baseball pitching mechanics affects both performance and the risk of injury. The purpose of this study is to investigate the relationships of shoulder external over internal rotation ratio (SEIR) and other shoulder rotational properties during physical exam and biomechanics of pitching for 177 collegiate baseball pitchers. The shoulder range of motion was quantitatively measured using a custom-made wireless device. Pitching motion data were collected at 240 Hz, and a custom program was created to calculate the throwing arm motion and loading during baseball pitching. Linear regression and analysis of variance tests were performed to investigate the relationships between the shoulder physical exam outcomes and throwing arm biomechanics. SEIR had significant correlations with shoulder horizontal adduction angle at foot contact, maximum shoulder external rotation angle, maximum shoulder linear velocity, and elbow angle at ball release. SEIR groups had significant differences in shoulder proximal force, adduction torque, internal rotation torque, and horizontal adduction torque, and in elbow medial force and varus torque. Glenohumeral internal rotation deficit and total rotational motion deficit had no relationships with throwing arm motions or joint loadings. Shoulder health should be monitored to improve understanding of pitching mechanics in collegiate baseball pitchers.

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Plantar Flexor Muscle Activity and Fascicle Behavior in Gastrocnemius Medialis During Running in Highly Cushioned Shoes With Carbon-Fiber Plates

Keiichiro Hata, Yuta Hamamura, Hiroaki Noro, Yohei Yamazaki, Shunsuke Nagato, Kazuyuki Kanosue, and Toshio Yanagiya

The purposes of this study were to clarify the electromyography (EMG) of plantar flexors and to analyze the fascicle and tendon behaviors of the gastrocnemius medialis (GM) during running in the carbon-fiber plate embedded in thicker midsole racing shoes, such as the Nike ZoomX Vaporfly (VF) and traditional racing shoes (TRAD). We compared the fascicle and series elastic element behavior of the GM and EMG of the lower limb muscles during running (14 km/h, 45 s) in athletes wearing VF or TRAD. GM EMGs in the push-off phase were approximately 50% lower in athletes wearing VF than in TRAD. Although the series elastic element behavior and/or mean fascicle-shortening velocity during the entire stance phase were not significantly different between VF and TRAD, a significant difference was found in both the mean EMG and integral EMG of the GM during the push-off phase. EMG of the gastrocnemius lateralis (GL) during the first half of the push-off phase was significantly different between VF and TRAD. Present results suggest that VF facilitates running propulsion, resulting in a decrease in GM and GL EMGs at a given running velocity during the push-off phase, leading to a reduction in metabolic cost.