Journal Of Applied Biomechanics[JOURNAL]
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200 papers
Force-Time Characteristics of Repeated Bouts of Depth Jumps and the Effects of Compression Garments.
Brown F, Hill M, Renshaw D … +1 more , Tallis J
J Appl Biomech · 2024 Jun · PMID 38580303 · Publisher ↗
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 r...
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.
Prolonged Standing-Induced Low Back Pain Is Linked to Extended Lumbar Spine Postures: A Study Linking Lumped Lumbar Spine Passive Stiffness to Standing Posture.
Fewster KM, Gallagher KM, Callaghan JP
J Appl Biomech · 2024 Jun · PMID 38467122 · Publisher ↗
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...
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.
Shoulder External Over Internal Rotation Ratio Is Related to Biomechanics in Collegiate Baseball Pitching.
Stokes HL, Eaton K, Zheng N
J Appl Biomech · 2024 Jun · PMID 38467121 · Publisher ↗
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 shoul...
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.
Plantar Flexor Muscle Activity and Fascicle Behavior in Gastrocnemius Medialis During Running in Highly Cushioned Shoes With Carbon-Fiber Plates.
Hata K, Hamamura Y, Noro H … +4 more , Yamazaki Y, Nagato S, Kanosue K, Yanagiya T
J Appl Biomech · 2024 Jun · PMID 38458184 · Publisher ↗
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 embedd...
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.
Unrestrained Versus Vertically Restrained Loaded Countermovement Jumps: Are There Any Differences in the Components of Force Application?
Gutiérrez-Dávila M, Marcos-Frutos D, Gutiérrez-Cruz C … +1 more , García-Ramos A
J Appl Biomech · 2024 Jun · PMID 38237582 · Publisher ↗
The objective of this study was to compare a number of variables derived from the vertical and horizontal force components between loaded countermovement jumps performed in a Smith machine (SM modality; vertically restra...
The objective of this study was to compare a number of variables derived from the vertical and horizontal force components between loaded countermovement jumps performed in a Smith machine (SM modality; vertically restrained jumps) and with free weights (FW modality; unrestrained jumps). Twenty-three recreationally trained individuals, 6 women and 17 men, performed on a 3D force platform 5 maximal countermovement jump trials against 3 external loads (30%, 50%, and 70% of the SM 1-repetition maximum) using the SM and FW jumping modalities on separate sessions. The SM modality promoted greater values for virtually all the variables derived from the vertical force component (maximal force, maximal and minimum velocity, and impulse) and also shorter durations of the braking and propulsive phases. Regardless of the countermovement jump phase (braking or propulsive), the impulse directed toward the backward direction was always considerably greater for the SM compared with the FW modality. These results evidence that for recreationally trained individuals, the SM modality could be more effective to increase the general force capacity of the leg muscles due to increased external stability, while the FW modality is preferable when the orientation of force application is a crucial consideration, as it reduces the horizontal force component.
Comparison of Concurrent and Asynchronous Running Kinematics and Kinetics From Marker-Based and Markerless Motion Capture Under Varying Clothing Conditions.
Kanko RM, Outerleys JB, Laende EK … +2 more , Selbie WS, Deluzio KJ
J Appl Biomech · 2024 Apr · PMID 38237574 · Publisher ↗
As markerless motion capture is increasingly used to measure 3-dimensional human pose, it is important to understand how markerless results can be interpreted alongside historical marker-based data and how they are impac...
As markerless motion capture is increasingly used to measure 3-dimensional human pose, it is important to understand how markerless results can be interpreted alongside historical marker-based data and how they are impacted by clothing. We compared concurrent running kinematics and kinetics between marker-based and markerless motion capture, and between 2 markerless clothing conditions. Thirty adults ran on an instrumented treadmill wearing motion capture clothing while concurrent marker-based and markerless data were recorded, and ran a second time wearing athletic clothing (shorts and t-shirt) while markerless data were recorded. Differences calculated between the concurrent signals from both systems, and also between each participant's mean signals from both asynchronous clothing conditions were summarized across all participants using root mean square differences. Most kinematic and kinetic signals were visually consistent between systems and markerless clothing conditions. Between systems, joint center positions differed by 3 cm or less, sagittal plane joint angles differed by 5° or less, and frontal and transverse plane angles differed by 5° to 10°. Joint moments differed by 0.3 N·m/kg or less between systems. Differences were sensitive to segment coordinate system definitions, highlighting the effects of these definitions when comparing against historical data or other motion capture modalities.
Dose-Response Effect of an Inertia Flywheel Postactivation Performance Enhancement Protocol on Countermovement Jump Performance.
Hall KB, Immink MA, Martin DT … +2 more , Bennett H, Crowther RG
J Appl Biomech · 2024 Apr · PMID 38176403 · Publisher ↗
The purpose of this study was to investigate the dose-response effect of a high-load, 6-repetition, maximum effort inertial flywheel (IFw) squat postactivation performance enhancement (PAPE) protocol on countermovement j...
The purpose of this study was to investigate the dose-response effect of a high-load, 6-repetition, maximum effort inertial flywheel (IFw) squat postactivation performance enhancement (PAPE) protocol on countermovement jump (CMJ) performance metrics. Thirteen subjects completed 5 squat testing sessions: 1 session to determine back-squat 6-repetition maximum, 1 session to determine 6-repetition maximum IFw load, and 3 sessions to investigate the dose-response effect of an IFw PAPE protocol set at the load determined in the second session. In the IFw PAPE sessions, subjects completed either 1, 2, or 3 sets of IFw squats, then performed 5 CMJs over 12 minutes (1, 3, 6, 9, and 12 min post-IFw). All CMJ tests were conducted on a force platform where CMJ performance outcomes and impulse variables were calculated. There was no main time or volume effect for jump height, contact time, reactive strength index, peak force, or any of the impulse variables. A main time effect was identified for flight time (P = .006, effect size = 0.24) and peak power (P = .001, effect size = 0.28). The lack of change in jump height may indicate that too much fatigue was generated following this near-maximal IFw squat protocol, thereby reducing the PAPE effect.
Lower-Extremity Energetic Distribution During Rate-Controlled Ballet Jumps (Sautés) in Healthy Dancers.
Yamaguchi AC, Trejo LH, Shih HS … +2 more , Ortiz-Weissberg D, Kulig K
J Appl Biomech · 2024 Jun · PMID 38176401 · Publisher ↗
Dancers frequently perform jumps in the context of a prolonged, continuous dance piece. The purpose of this study is to explore the lower-extremity energetics in healthy dancers performing repetitive dance jumps (sautés)...
Dancers frequently perform jumps in the context of a prolonged, continuous dance piece. The purpose of this study is to explore the lower-extremity energetics in healthy dancers performing repetitive dance jumps (sautés) before and after typical dance-specific choreography. Lower-extremity kinetic data were collected from 14 healthy female dancers during a series of sautés performed before and after 3 minutes of dance. Percent contributions of the lower-extremity joints to the whole-limb mechanical energy expenditure during ground contact were calculated. The jumps performed at the beginning were compared with the jumps at the end of the dance choreography. Dancers maintained the jump rate and consistent whole-limb mechanical energy expenditure between the jump series. As expected, for both jump series, the sautés had greater relative energetic contribution from the ankle and knee as compared with lesser contribution from the hip and toe. However, we observed lesser contribution from the knee and greater contribution from the hip after a 3-minute dance. After performing typical dance choreography, the dancers demonstrated a distal to proximal redistribution of individual joints' contribution to whole-limb mechanical energy expenditure.
Alternative Models for Pelvic Marker Occlusion in Cycling.
Galindo-Martínez A, Vallés-González JM, López-Valenciano A … +1 more , Elvira JLL
J Appl Biomech · 2024 Jun · PMID 38176398 · Publisher ↗
Bike fitting aims to optimize riders' positions to improve their performance and reduce the risk of injury. To calculate joint angles, the location of the joint centers of the lower limbs needs to be identified. However,...
Bike fitting aims to optimize riders' positions to improve their performance and reduce the risk of injury. To calculate joint angles, the location of the joint centers of the lower limbs needs to be identified. However, one of the greatest difficulties is the location of the hip joint center due to the frequent occlusion of the anterior superior iliac spine markers. Therefore, the objective of this study was to validate a biomechanical model adapted to cycling (modified pelvic model, MPM), based on the traditional pelvic model (TPM) with an additional lateral technical marker placed on the iliac crests. MPM was also compared with a widely used model in cycling, trochanter model (TM). Thirty-one recreational cyclists pedaled on a roller bike while the movement was captured with a 7-camera VICON system. The position of the hip joint center and knee angle were calculated and compared with the TPM continuously (along 10 pedaling cycles) and discreetly at 90° and 180° crank positions. No significant differences were found in the position of the hip joint center or in the knee flexion/extension angle between the TPM and the MPM. However, there are differences between TPM and TM (variations between 4.1° and 6.9° in favor of the TM at 90° and 180°; P < .001). Bland-Altman graphs comparing the models show an average difference or bias close to 0° (limits of agreement [0.2 to -8.5]) between TPM and MPM in both lower limbs and a mean difference of between -4° and -7° (limits of agreement [-0.6 to -13.2]) when comparing TPM and TM. Given the results, the new cycling pelvic model has proven to be valid compared with the TPM when performing bike fitting studies, with the advantage that the occluded markers are avoided. Despite its simplicity, the TM presents measurement errors that may be relevant when making diagnoses, which makes its usefulness questionable.
Impaired Neuromotor Control During Gait in Concussed Adolescents-A Frequency Analysis.
Jain D, Graci V, Beam ME … +4 more , Master CL, Prosser LA, McDonald CC, Arbogast KB
J Appl Biomech · 2024 Apr · PMID 38154023 · Full text
Disruptions in gait function are common after concussion in adolescents; however, the neuromotor control deficits driving these gait disruptions are not well known. Fifteen concussed (age mean [SD]): 17.4 [0.6], 13 femal...
Disruptions in gait function are common after concussion in adolescents; however, the neuromotor control deficits driving these gait disruptions are not well known. Fifteen concussed (age mean [SD]): 17.4 [0.6], 13 females, days since injury: 26.3 [9.9]) and 17 uninjured (age: 18.0 [0.7], 10 females) adolescents completed 3 trials each of single-task gait and dual-task gait (DT). During DT, participants simultaneously walked while completing a serial subtraction task. Gait metrics and variability in instantaneous mean frequency in lower extremity muscles were captured by inertial sensors and surface electromyography, respectively. A 2-way analysis of covariance was used to compare gait metrics across groups and conditions. Functional principal components analysis was used to identify regions of variability in instantaneous mean frequency curves. Functional principal component scores were compared across groups using a Welch statistic. Both groups displayed worse performance on gait metrics during DT condition compared to single-task, with no differences between groups (P < .001). Concussed adolescents displayed significantly greater instantaneous mean frequency, indicated by functional principal component 1, in the tibialis anterior, biceps femoris, and semitendinosus (P < .05) during single-task and DT compared with uninjured adolescents. Our observations suggest that concussed adolescents display inefficient motor unit recruitment lasting longer than 2 weeks following injury, regardless of the addition of a secondary task.
The Biomechanics Research and Innovation Challenge: Development, Implementation, Uptake, and Reflections on the Inaugural Program.
Coltman CE, Barzan M, Besomi M … +28 more , Brackley V, Bousie JA, Choisne J, Diamond LE, Dick TJM, D'Souza N, Fien S, Fong Yan A, Gho SA, Giraldo-Pedroza A, Hutchinson LA, Hutchison LV, Kean CO, Kirk MM, Lewis A, Maharaj JN, Maher N, Mann KJ, Martin S, Mickle KJ, Nasseri A, Oon IH, Purdie R, Quinlan SL, Radcliffe CR, Snodgrass SJ, Verma S, Hall M
J Appl Biomech · 2024 Apr · PMID 38016463 · Publisher ↗
Biomechanics as a discipline is ideally placed to increase awareness and participation of girls and women in science, technology, engineering, and mathematics. A nationwide Biomechanics and Research Innovation Challenge...
Biomechanics as a discipline is ideally placed to increase awareness and participation of girls and women in science, technology, engineering, and mathematics. A nationwide Biomechanics and Research Innovation Challenge (BRInC) centered on mentoring and role modeling was developed to engage high school girls (mentees) and early-mid-career women (mentors) in the field of biomechanics through the completion of a 100-day research and/or innovation project. This manuscript describes the development, implementation, and uptake of the inaugural BRInC program and synthesizes the research and innovation projects undertaken, providing a framework for adoption of this program within the global biomechanics community. Eighty-seven high school girls in years 9 and 10 (age range: 14-16 y) were mentored in teams (n = 17) by women in biomechanics (n = 24). Using a design thinking approach, teams generated solutions to biomechanics-based problem(s)/research question(s). Eight key reflections on program strengths, as well as areas for improvement and planned changes for future iterations of the BRInC program, are outlined. These key reflections highlight the innovation, impact, and scalability of the program; the importance of a program framework and effective communication tools; and implementation of strategies to sustain the program as well as the importance of diversity and building a sense of community.
Sex-Related Differences in Shoulder Complex Joint Dynamics Variability During Pediatric Manual Wheelchair Propulsion.
Leonardis JM, Schnorenberg AJ, Vogel LC … +2 more , Harris GF, Slavens BA
J Appl Biomech · 2024 Apr · PMID 37984356 · Full text
More than 80% of adult manual wheelchair users with spinal cord injuries will experience shoulder pain. Females and those with decreased shoulder dynamics variability are more likely to experience pain in adulthood. Sex-...
More than 80% of adult manual wheelchair users with spinal cord injuries will experience shoulder pain. Females and those with decreased shoulder dynamics variability are more likely to experience pain in adulthood. Sex-related differences in shoulder dynamics variability during pediatric manual wheelchair propulsion may influence the lifetime risk of pain. We evaluated the influence of sex on 3-dimensional shoulder complex joint dynamics variability in 25 (12 females and 13 males) pediatric manual wheelchair users with spinal cord injury. Within-subject variability was quantified using the coefficient of variation. Permutation tests evaluated sex-related differences in variability using an adjusted critical alpha of P = .001. No sex-related differences in sternoclavicular or acromioclavicular joint kinematics or glenohumeral joint dynamics variability were observed (all P ≥ .042). Variability in motion, forces, and moments are considered important components of healthy joint function, as reduced variability may increase the likelihood of repetitive strain injury and pain. While further work is needed to generalize our results to other manual wheelchair user populations across the life span, our findings suggest that sex does not influence joint dynamics variability in pediatric manual wheelchair users with spinal cord injury.
The Combined Influence of Infant Carrying Method and Motherhood on Gait Mechanics.
Havens KL, Goldrod S, Mannen EM
J Appl Biomech · 2024 Apr · PMID 37984353 · Full text
Postpartum mothers are susceptible to lumbopelvic pain which may be exacerbated by loading, like carrying their infant in arms and with baby carriers. Nulliparous women carrying infant mannequins may biomechanically mimi...
Postpartum mothers are susceptible to lumbopelvic pain which may be exacerbated by loading, like carrying their infant in arms and with baby carriers. Nulliparous women carrying infant mannequins may biomechanically mimic mother-infant dyad, but this has not been studied. The purpose of our study was to investigate biomechanical differences of 10 mothers carrying their infants and 10 nulliparous women carrying infant mannequins under 3 gait conditions: carrying nothing, carrying in arms, and carrying in a baby carrier (babywearing). Spatiotemporal gait parameters, peak ground reaction forces and impulses, and lower extremity and trunk kinematics were collected using motion capture and force plates and compared using a mixed 2 × 3 (parity × condition) analysis of variance (α ≤ .05). The largest differences occurred between carrying conditions: carrying in arms or babywearing increased vertical and anteroposterior ground reaction forces, trunk extension, ankle dorsiflexion, and hip and knee flexion. Kinematic differences were identified between arms and babywearing conditions. Together this suggests alterations in joint loading for both groups. Our study also contributes a novel understanding of postpartum health by demonstrating alterations in step time, anterior forces, and ankle and knee mechanics, suggesting that during gait, mothers carrying their own infants choose different propulsive strategies than nulliparous women carrying mannequins.
The Effects of Optical Flow Perturbations on Standing Balance in People With Multiple Sclerosis.
Elie OS, Franz JR, Selgrade BP
J Appl Biomech · 2024 Apr · PMID 37963452 · Publisher ↗
Multiple sclerosis is a neurodegenerative disease that causes balance deficits, even in early stages. Evidence suggests that people with multiple sclerosis (PwMS) rely more on vision to maintain balance, and challenging...
Multiple sclerosis is a neurodegenerative disease that causes balance deficits, even in early stages. Evidence suggests that people with multiple sclerosis (PwMS) rely more on vision to maintain balance, and challenging balance with optical flow perturbations may be a practical screening for balance deficits. Whether these perturbations affect standing balance in PwMS is unknown. Therefore, the purpose of this study was to examine how optical flow perturbations affect standing balance in PwMS. We hypothesized that perturbations would cause higher variability in PwMS compared with matched controls during standing and that standing balance would be more susceptible to anterior-posterior (A-P) perturbations than medial-lateral (M-L) perturbations. Thirteen PwMS and 13 controls stood under 3 conditions: unperturbed, M-L perturbation, and A-P perturbations. A-P perturbations caused significantly higher A-P trunk sway variability in PwMS than controls, although both groups had similar center-of-pressure variability. Both perturbations increased variability in A-P trunk sway and center of pressure. Trunk variability data supported the hypothesis that PwMS were more susceptible to optical flow perturbations than controls. However, the hypothesis that A-P perturbations would affect balance more than M-L perturbations was partially supported. These results suggest potential for optical flow perturbations to identify balance deficits in PwMS.
Comparison Between Movement Pattern Training and Strengthening on Kinematics and Kinetics in Patients With Chronic Hip-Related Groin Pain.
Palaniappan R, Harris MD, Steger-May K … +4 more , Bove AM, Fitzgerald GK, Clohisy JC, Harris-Hayes M
J Appl Biomech · 2024 Apr · PMID 37939703 · Full text
The purpose of this study was to compare the preliminary effects of movement pattern training (MoveTrain) versus strengthening/flexibility (standard) treatment on hip and pelvic biomechanics in patients with chronic hip-...
The purpose of this study was to compare the preliminary effects of movement pattern training (MoveTrain) versus strengthening/flexibility (standard) treatment on hip and pelvic biomechanics in patients with chronic hip-related groin pain. This is a secondary analysis of data collected during a pilot randomized clinical trial. Thirty patients with hip pain, between the ages of 15 and 40 years, were randomized to MoveTrain or standard. Both groups completed 10 treatment sessions over 12 weeks along with a daily home exercise program. Three-dimensional motion analysis was used to collect kinematic and kinetic data of the pelvis and hip during a single-leg squat task at pretreatment and immediately posttreatment. Compared with the standard group, the MoveTrain group demonstrated smaller hip adduction angles (P = .006) and smaller hip external adduction moments (P = .008) at posttreatment. The desired changes to hip joint biomechanics, as found in this study, may require specificity in training that could allow health care professionals to better customize the rehabilitation of patients with hip pain. These findings can also be applied to the design and implementation of future clinical trials to strengthen our understanding of the long-term implications of different rehabilitation techniques for patients with hip pain.
The Contribution of Lower-Body Kinematics to Pitching and Hitting Performance in Baseball: Utilizing the OpenBiomechanics Project.
Perrett CS
J Appl Biomech · 2024 Apr · PMID 37939700 · Publisher ↗
As markerless motion capture systems become more affordable than ever, it is becoming far easier to collect and analyze kinematic data on baseballers. To ensure this data can be used impactfully, coaches and practitioner...
As markerless motion capture systems become more affordable than ever, it is becoming far easier to collect and analyze kinematic data on baseballers. To ensure this data can be used impactfully, coaches and practitioners should possess a good understanding of specific technique characteristics that are associated with enhanced performance in pitchers and hitters. This study used the open-source data provided by Driveline Baseball's OpenBiomechanics Project to evaluate the contribution of lower-body kinematics to pitch velocity and bat speed. In addition to correlational analyses to examine the association between discrete kinematic variables and performance, statistical nonparametric mapping was used to compare slow and fast velocity groups across the entirety of pitching and hitting motions from peak knee height to ball release/contact. It was found that rotation of the trail leg and extension of the lead knee were both associated with performance in pitchers and hitters. Consequently, coaches and practitioners should ensure that individuals possess an adequate level of strength and flexibility to facilitate optimal movement of the trail hip and lead knee during pitching and hitting movements. If deficiencies exist, then training programs should be designed to address these issues and eventually bring about an improvement in performance.
Experimentally Induced Pain Results in Reduced Activity of the Rotator Cuff Muscles in Healthy Subjects.
Cooper JL, Karduna AR
J Appl Biomech · 2024 Feb · PMID 37935173 · Publisher ↗
Shoulder pain is a complex, prevalent problem that is multifactorial in nature. While there are many potential causes, one common suspect is the rotator cuff musculature. The purpose of the present study was to induce pa...
Shoulder pain is a complex, prevalent problem that is multifactorial in nature. While there are many potential causes, one common suspect is the rotator cuff musculature. The purpose of the present study was to induce pain in the supraspinatus muscle of healthy subjects and observe the resulting changes in muscle activity. Eight muscles on 23 subjects were assessed using electromyography: anterior, middle, and posterior deltoid; pectoralis major; upper trapezius; latissimus dorsi; serratus anterior; supraspinatus; and infraspinatus. It was hypothesized that the rotator cuff muscles would display reduced activity during pain, and that reductions in activity would remain after the pain had dissipated. Both of the rotator cuff muscles measured did indeed display reduced activity in a majority of the dynamic, isometric, and maximal contractions. Many of those reductions remained after the pain had subsided.
Do Sex and Age Influence Scapular and Thoracohumeral Kinematics During a Functional Task Protocol?
Waslen A, Friesen KB, Lang AE
J Appl Biomech · 2024 Feb · PMID 37917968 · Publisher ↗
There is mixed evidence on the role that biological sex plays in shoulder biomechanics despite known differences in musculoskeletal disorder prevalence between males and females. Additionally, advancing age may contribut...
There is mixed evidence on the role that biological sex plays in shoulder biomechanics despite known differences in musculoskeletal disorder prevalence between males and females. Additionally, advancing age may contribute to shoulder kinematic changes. The purpose of this study was to determine if sex and age influenced scapular and thoracohumeral kinematics during a range of functional tasks. Sixty healthy participants aged 19-63 years (30 males; 30 females) completed a functional task protocol while their upper limb motion was recorded. Scapular and humeral angles were calculated and compared with multiple linear regressions to assess the interaction effects of sex and age. Shoulder kinematics were not different between sex and age groups for many of the functional tasks. However, females had lower humeral external rotation in the overhead lift task (15°, P < .001), and less scapular anterior tilt angles in the forward transfer task (6°, P < .001) than males. Age was positively associated with humeral elevation (R2 = .330, P < .001) and scapular rotation (R2 = .299, P < .001) in the Wash Axilla task. There exist some kinematic differences between sex and with advancing age for select functional tasks, which should be considered for musculoskeletal disorder development.
People With Low Back Pain Exhibit Higher Trunk Muscle Activity and Impaired Postural Control During Static and Dynamic Functional Tasks: A Cross-Sectional Study.
Salamat S, Talebian S, Maroufi N … +3 more , Kalbassi G, Salamat D, O'Sullivan K
J Appl Biomech · 2024 Feb · PMID 37917963 · Publisher ↗
The study compared superficial trunk muscle activity and postural control among an active extension subgroup of people with nonspecific chronic low back pain (AE-NSCLBP) with painfree controls during functional tasks. Th...
The study compared superficial trunk muscle activity and postural control among an active extension subgroup of people with nonspecific chronic low back pain (AE-NSCLBP) with painfree controls during functional tasks. Thirty-two people (17 people with low back pain [LBP] and 15 painfree controls) participated in this study. Muscle activity of 5 trunk muscles and postural control were investigated during both standing tasks (eyes open/closed; single/double-leg balance) and dynamic functional tasks (spinal forward flexion and return, and a sit to stand transfer). Results showed that during single-leg standing, people with AE-NSCLBP exhibit higher muscle activity than painfree controls for 3 trunk muscles, especially with their eyes closed. There were no significant differences in muscle activity between eye conditions during double-leg standing and sit to stand transfer, forward flexion, and return from flexion. The AE-NSCLBP subgroup also demonstrated significantly impaired postural control (lower time to boundary) in 4 of 8 conditions, especially during single-leg standing and with their eyes closed. These findings show people with LBP typically demonstrated greater trunk muscle activity and poorer postural control while maintaining standing posture. This pattern was most evident when the postural challenge was higher, such as single-leg standing or with eyes closed. While this study design cannot infer causality, these findings have implications for LBP rehabilitation, particularly regarding approaches which seek to alter muscle activation among people with LBP.
Increasing Breast Support is Associated With a Distal-to-Proximal Redistribution of Joint Negative Work During a Double-Limb Landing Task.
Fong HB, Nelson AK, McGhee D … +2 more , Ford KR, Powell DW
J Appl Biomech · 2024 Feb · PMID 37917960 · Publisher ↗
Female athletes exhibit greater rates of anterior cruciate ligament injury compared with male athletes. Biomechanical factors are suggested to contribute to sex differences in injury rates. No previous investigation has...
Female athletes exhibit greater rates of anterior cruciate ligament injury compared with male athletes. Biomechanical factors are suggested to contribute to sex differences in injury rates. No previous investigation has evaluated the role of breast support on landing biomechanics. This study investigates the effect of breast support on joint negative work and joint contributions to total negative work during landing. Thirty-five female athletes performed 5 landing trials in 3 breast support conditions. Lower-extremity joint negative work and relative joint contributions to total negative work were calculated. Univariate analyses of variance were used to determine the effect of breast support on negative joint work values. Increasing levels of breast support were associated with lower ankle negative work (P < .001) and ankle relative contributions (P < .001) and increases in hip negative work (P = .008) and hip relative contributions (P < .001). No changes were observed in total negative work (P = .759), knee negative work (P = .059), or knee contributions to negative work (P = .094). These data demonstrate that the level of breast support affects lower-extremity biomechanics. The distal-to-proximal shift in negative joint work and relative joint contributions may be indicative of a more protective landing strategy for anterior cruciate ligament injuries.
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