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This scoping review aimed to identify and summarise evidence on the comfort and functional performance of police officer personal protective equipment (PPE). The Arksey and O'Malley (2005) five-stage framework for scoping reviews was followed. PubMed, CINAHL, Scopus, and Web of Science were searched, and 35 articles were included in the review. The findings show that increased police PPE mass increases heart rate, metabolic energy expenditure, and perceived exertion in response to exercise. Unisex armour designs cause increased discomfort for females with larger bra sizes. PPE reduces joint-specific range of motion, with the design and location impairing movement more than mass. Jumping and sprinting performance is decreased with heavy PPE but unaffected by lighter protection, while agility is compromised with most forms of protection. Future research is needed on the fit and function of PPE for specialist police units, such as mounted police, along with further investigations on how fit can affect functional performance. PRACTITIONER SUMMARY: This paper identifies and reviews existing evidence on the comfort and functional performance of police officer personal protective equipment (PPE). This is significant because it summarises and categorises key concepts that underpin research in this area, whilst highlighting gaps in the current knowledge and areas for future research. [ABSTRACT FROM AUTHOR]

Purpose: To determine prevalence of musculoskeletal complaints (MSCs) in adults with major congenital upper limb differences (CoULD) compared to able-bodied controls, and to examine associations of MSCs and disability with various biopsychosocial factors. Materials and methods: Questionnaire-based cross-sectional study assessing MSCs, disability (using the Disabilities of the Arm, Shoulder and Hand questionnaire (DASH)), general and mental health status, physical work demands, and upper extremity range of motion. Results: Seventy-one individuals with CoULD (participation rate: 41%) and 71 controls matched on age, gender, and education were included (49% female, mean age 28.9 years). Year prevalence of MSCs was significantly higher in the CoULD group (35%) than in the control group (18%). The CoULD group was less often employed and had lower scores on all measures of upper limb range of motion and hand grip. MSCs were associated with higher DASH scores and higher reported work demands. Disability was associated with female gender, more joints with limited range of motion, unemployment, and lower general and mental health. Factors associated with disability did not differ between groups. Conclusions: MSCs are a frequent problem in young adults with major CoULD. To prevent or reduce MSC and disability, clinicians and researchers should be aware of the associated factors. Implications for rehabilitation: The year prevalence of musculoskeletal complaints (MSCs) in those with major congenital upper limb differences (CoULD) was approximately double to that of the control group, implying a potential relationship between CoULD and MSCs. Rehabilitation professionals should develop personalized strategies to manage work demands in those with CoULD, considering the association between MSCs and higher reported work demands. Recognizing the impact of a negatively perceived body image on mental health, clinicians should integrate psychological counseling into rehabilitation treatments to support mental well-being and improve overall quality of life in those with CoULD. Rehabilitation professionals should educate individuals with CoULD about the potential associations between upper limb work demands, MSCs, and disability. [ABSTRACT FROM AUTHOR]

The functional importance of trunk muscle strength for running movement is widely recognised, but the kinematic effects of undertaking specific training are unclear. This study investigated the change in joint angle and its variability during running following trunk muscle training. Eighteen young female and novice runners participated. Using Plug-in-gait model with infrared markers attached to the body surface, the lower limb and lumber angles during running were measured, and the variability was examined by calculating the coefficient variation and Lyapunov exponent. Measurements of trunk endurance were also performed. Over four weeks of training, the subjects performed trunk muscle endurance trainings three times a week. Following this intervention, trunk endurance was found to have significantly increased. The Lyapunov exponent of lumbar flexion-extension angle also significantly increased. Moreover, a decreased range of the ankle angle and increased range of the hip angle were observed following the training. These results demonstrate that the trunk training promoted adjustments to lumbar movement and altered the movement patterns of the participants' lower limbs during running. [ABSTRACT FROM AUTHOR]

Purpose: The aim was to quantify jump performance in children with cerebral palsy (CP) and determine if the expected deficit is related to their lower body joint kinetics and kinematics. Methods: Twenty-four ambulatory (n = 17 level I and 7 level II in the Gross Motor Function Classification System) children with spastic CP (n = 13 unilateral and 11 bilateral) and 24 age-, sex-, and race matched typically developing controls were studied. Jump height and peak power and range of motion at the hip, knee, and ankle of the more affected limb in children with CP and the nondominant limb in controls were assessed during a countermovement jump using three-dimensional motion capture and a force platform. Results: Compared with controls, children with CP had lower jump height (33%, Cohen's d (d) = 1.217), peak power at the knee (39%, d = 1.013) and ankle (46%, d = 1.687), and range of motion at the hip (32%, d = 1.180), knee (39%, d = 2.067), and ankle (46%, d = 3.195; all P < 0.001). Jump height was positively related to hip, knee, and ankle power and range of motion in children with CP (rs range = 0.474-0.613, P < 0.05), and hip and ankle power and knee and ankle range of motion in controls (rs range = 0.458-0.630, P < 0.05). The group difference in jump height was no longer detected when ankle joint power, ankle range of motion, or knee range of motion was statistically controlled (P > 0.15). Conclusions: Jump performance is compromised in children with CP and is associated with low power generation and range of motion in the lower limb, especially at the ankle. [ABSTRACT FROM AUTHOR]

Altering running cadence is commonly done to reduce the risk of running-related injury/reinjury. This study examined how altering running cadence affects joint kinetic patterns and stride-to-stride kinetic variability in uninjured female runners. Twenty-four uninjured female recreational runners ran on an instrumented treadmill with their typical running cadence and with a running cadence that was 7.5% higher and 7.5% lower than typical. Ground reaction force and kinematic data were recorded during each condition, and principal component analysis was used to capture the primary sources of variability from the sagittal plane hip, knee, and ankle moment time series. Runners exhibited a reduction in the magnitude of their knee extension moments when they increased their cadence and an increase in their knee extension moments when they lowered their cadence compared with when they ran with their typical cadence. They also exhibited greater stride-to-stride variability in the magnitude of their hip flexion moments and knee extension moments when they deviated from their typical running cadence (ie, running with either a higher or lower cadence). These differences suggest that runners could alter their cadence throughout a run in an attempt to limit overly repetitive localized tissue stresses. [ABSTRACT FROM AUTHOR]

The purpose of this study was to determine shoulder joint reaction forces and muscle moments during 2 speeds (1.3 and 2.2 m/s) of wheelchair propulsion and to investigate the relationship between joints reaction forces, muscle moments, and shoulder pain. The measurements were obtained from 20 manual wheelchair users. A JR3 6-channel load sensor (±1% error) and a Qualisys system were used to record 3-dimensional pushrim kinetics and kinematics. A 3-dimensional inverse dynamic model was generated to compute joint kinetics. The results demonstrated significant differences in shoulder joint forces and moments (P <.01) between the 2 speeds of wheelchair propulsion. The greatest peak shoulder joint forces during the drive phase were anterior directed (Fy, 184.69 N), and the greatest joint moment was the shoulder flexion direction (flexion moment, 35.79 N·m) at 2.2 m/s. All the shoulder joint reaction forces and flexion moment were significantly (P <.05) related to shoulder pain index. The forces combined in superior and anterior direction found at the shoulder joint may contribute to the compression of subacromial structure and predispose manual wheelchair users to potential rotator cuff impingement syndrome. [ABSTRACT FROM AUTHOR]

Context: Elite golfers have a high incidence of low back pain. Recent reviews have emphasized the need for investigation into how to prevent low back pain in golfers, prompting the current study. Design: Prospective longitudinal cohort study. Methods: Forty-one injury-free golfers were included in this study. At baseline, lower quadrant joint angles and club and ball performance were measured while each golfer performed 10 drives. The golfers were then monitored for 6 months and were allocated into 2 groups depending on whether or not they developed low back pain. The initial, baseline kinematic variables of the low back pain group and the uninjured group were then compared. Results: Over the 6-month monitoring period, 17 (41%) of the golfers developed low back pain. At baseline assessment, the low back pain group had 4° less lead ankle dorsiflexion at setup (P = .01; effect size = 0.82), 6° less lead knee flexion at the top of the backswing (P = .05; effect size = 0.64), 6° less lead ankle dorsiflexion at the top of the backswing (P = .01; effect size = 0.82), 6° more trail hip adduction at the top of the backswing (P = .02; effect size = 0.79), 9° more trail knee flexion at impact (P = .05; effect size = -0.64), and 6° more trail hip adduction at the end of follow through (P < .00; effect size = 1.00). Conclusion: Golfers who developed low back pain during the 6-month monitoring period displayed distinct differences in biomechanics at baseline when all golfers were injury free. These biomechanical differences may be considered a precursor to injury. Three-dimensional motion analysis may indicate whether elite golfers are at risk of developing low back pain. Research is needed to assess whether targeted exercise and sports drills aimed at addressing the biomechanical risk factors identified may prevent low back pain in elite golfers. [ABSTRACT FROM AUTHOR]

To examine intraobserver and interobserver reliability of the clinical measurement of pediatric joint motion of upper and lower extremities, based on participant condition and measurement technique. PubMed, CINAHL, and Web of Science were searched using combinations of children or adolescents, range of motion, and reliability. Reference lists and citations of reviewed studies were searched for additional publications. Thirty-one studies of pediatric samples of developing typically, orthopedic injuries, athletes, cerebral palsy, and other diagnoses were reviewed. For techniques, measurements were made most frequently with a goniometer followed by visual estimation, inclinometer, smartphone apps, and specialized devices. The reliability of hip abduction measurements of participants with cerebral palsy was evaluated most often and varied widely for both intraobserver and interobserver. In general, goniometric results indicated greater reliability for upper than lower extremities and for intraobserver than interobserver. As the other techniques were each utilized in only a few studies, involving different participant conditions, joint motions and statistics, the analysis of their reliability was limited. Intraobserver and interobserver reliability have not been established for pediatric joint motion measurements. Further research should include various joint motion measurements for different pediatric conditions using appropriate statistics. Results would provide important information for making clinical decisions. [ABSTRACT FROM AUTHOR]

Background: This study aimed to: (1) identify assessment methods that can detect greater ankle dorsiflexion range of motion (DROM) limitation in the injured limb; (2) determine whether differences in weightbearing measurements exist even in the absence of DROM limitations in the injured limb according to non-weightbearing measurements; and (3) examine associations between DROM in the weightbearing and non-weightbearing positions and compare those between a patient group with foot and ankle injuries and a healthy group. Methods: Eighty-two patients with foot and ankle injuries (e.g., fractures, ligament and tendon injuries) and 49 healthy individuals participated in this study. Non-weightbearing DROM was measured under two different conditions: prone position with knee extended and prone position with knee flexed. Weightbearing DROM was measured as the tibia inclination angle (weightbearing angle) and distance between the big toe and wall (weightbearing distance) at maximum dorsiflexion. The effects of side (injured, uninjured) and measurement method on DROM in the patient groups were assessed using two-way repeated-measures ANOVA and t-tests. Pearson correlations between measurements were assessed. In addition, we analyzed whether patients without non-weightbearing DROM limitation (≤ 3 degrees) showed limitations in weightbearing DROM using t-tests with Bonferroni correction. Results: DROM in patient groups differed significantly between legs with all measurement methods (all: P < 0.001), with the largest effect size for weightbearing angle (d = 0.95). Patients without non-weightbearing DROM limitation (n = 37) displayed significantly smaller weightbearing angle and weightbearing distance on the injured side than on the uninjured side (P < 0.001 each), with large effect sizes (d = 0.97–1.06). Correlation coefficients between DROM in non-weightbearing and weightbearing positions were very weak (R = 0.17, P = 0.123) to moderate (R = 0.26–0.49, P < 0.05) for the patient group, and moderate to strong for the healthy group (R = 0.51–0.69, P < 0.05). Conclusions: DROM limitations due to foot and ankle injuries may be overlooked if measurements are only taken in the non-weightbearing position and should also be measured in the weightbearing position. Furthermore, DROM measurements in non-weightbearing and weightbearing positions may assess different characteristics, particularly in patient group. Level of evidence: Level IV, cross-sectional study. [ABSTRACT FROM AUTHOR]

Isometric strength training has been reported to benefit various sport-related dynamic performances. However, it is still unknown whether performing isometric strength training at single or multiple joint angles would elicit greater benefit. Purpose: To compare the effects of isometric bench press performed at single (SIBP) and multiple (MIBP) joint angles on dynamic strength and overhead throwing performance. Methods: Sixteen male softball and baseball athletes performed overhead throwing, 1-repetition-maximum (1RM) bench press, and ballistic push-up during pretest and posttest. They were then randomly assigned to either SIBP or MIBP to undergo 12 strength training sessions. During the training, isometric bench press was performed at only 90° elbow angle for SIBP but at 60°, 90°, and 120° elbow angles for MIBP. Results: A significant main time effect was observed for bench press 1RM (P =.003) and relative 1RM (P <.001). Similarly, a significant main time effect was observed for ballistic push-up peak power only (P =.037). There was no significant change in overhead throwing velocity in either group. There was also no significant difference in change in all measures between groups. However, a moderate effect in favor of MIBP was observed for change in ballistic push-up peak power (P =.180, g = 0.67). Conclusions: Based on the current findings, the inclusion of both SIBP and MIBP were equally beneficial to maximal strength development. However, performing MIBP had a greater effect on power development. [ABSTRACT FROM AUTHOR]

Fall-related injuries are associated with muscle weakness and common during slope walking in older adults. However, no study has evaluated the relationship between muscle weakness, measured by maximal lower limb extension power, and older adults' ability to navigate slope walking for a better understanding of fall prevention. Therefore, the purpose of this study was to investigate the association between maximal lower limb extension power and joint mechanics during slope walking. Fifteen healthy older adults were tested. Lower limb extension power was measured using the Leg Extension Power Rig. Kinematic and kinetic analysis was performed during level (0°), incline (10°), and decline (10°) slope walking. Greater maximal lower limb extension power was significantly (p <.050; Cohen's f2 > 0.35) associated with multiple kinetic and kinematic joint mechanic variables across stance phase of the gait cycle during level, incline, and decline walking. These findings will allow clinicians to better educate patients and develop interventions focused on fall prevention and improving functional mobility in older adults. [ABSTRACT FROM AUTHOR]

The objectives of this study were to (1) investigate the effect of the timing of the upper body joint motions in baseball batting on the bat-head speed and (2) develop and evaluate a simulation model inputting the individual hand forces on the bat. Twenty-three male collegiate baseball players performed tee batting set at waist height. A 10-segment angle-driven simulation model consisting of a bat and upper body was driven using the coordinate data of the standard motion. Performance optimization was conducted by changing the timing of the joint angle time histories of the upper body to increase the maximum bat-head speed. The optimization simultaneously estimated the individual hand forces by polynomial approximation dependent on the total bat forces to assess joint torques of the upper body. The bat-head speed increased to 39.2 m/s from 35.6 m/s, and the optimized timings were characterized by the earlier timing of the barrel-side elbow supination, wrist radial flexion, torso right lateral flexion, and the later timing of the barrel-side shoulder abduction. It is concluded that the skillful coordination of the individual joint movements for the upper body can produce a higher bat-head speed through effective sequencing of proximal to distal movements. [ABSTRACT FROM AUTHOR]

Reliability of joint motion and muscle length measurement in children with cerebral palsy was examined. Twenty-one studies of intraobserver and/or interobserver reliability were reviewed: joint motion of upper extremities in four and lower extremities in 13; muscle length of upper extremities in one and lower extremities in 15. Intraclass correlation coefficients for goniometric interobserver reliability varied widely for joint motion (range 0.38–0.92) and muscle length (range 0.20–0.95). Inclusion of an error measurement to provide clinicians with a value indicating true change was limited. Further research is required to determine intraobserver and interobserver reliability for these important pediatric clinical measurements. [ABSTRACT FROM AUTHOR]

Purpose: Individuals with anterior cruciate ligament reconstruction (ACLR) generally exhibit limb underloading behaviors during walking, but most research focuses on per-step comparisons. Cumulative loading metrics offer unique insight into joint loading as magnitude, duration, and total steps are considered, but few studies have evaluated if cumulative loads are altered post-ACLR. Here, we evaluated if underloading behaviors are apparent in ACLR limbs when using cumulative load metrics and how load metrics change in response to walking speed modifications. Methods: Treadmill walking biomechanics were evaluated in 21 participants with ACLR at three speeds (self-selected (SS); 120% SS and 80% SS). Cumulative loads per step and per kilometer were calculated using knee flexion and adduction moment (KFM and KAM) and vertical ground reaction force (GRF) impulses. Traditional magnitude metrics for KFM, KAM, and GRF were also calculated. Results: The ACLR limb displayed smaller KFM and GRF in early and late stances, but larger KFM and GRF during midstance compared with the contralateral limb (P <0.01). Only GRF cumulative loads (per step and per kilometer) were reduced in the ACLR limb (P <0.01). In response to speed modifications, load magnitudes generally increased with speed. Conversely, cumulative load metrics (per step and per kilometer) decreased at faster speeds and increased at slow speeds (P < 0.01). Conclusions: Patients with ACLR underload their knee in the sagittal plane per step, but cumulatively over the course of many steps/distance, this underloading phenomenon was not apparent. Furthermore, cumulative load increased at slower speeds, opposite to what is identified with traditional single-step metrics. Assessing cumulative load metrics may offer additional insight into how load outcomes may be impacted in injured populations or in response to gait modifications. [ABSTRACT FROM AUTHOR]

This study determined changes in lower limb joint stiffness when running with body-borne load, and whether they differ with stride or sex. Twenty males and 16 females had joint stiffness quantified when running (4.0 m/s) with body-borne load (20, 25, 30, and 35 kg) and 3 stride lengths (preferred or 15% longer and shorter). Lower limb joint stiffness, flexion range of motion (RoM), and peak flexion moment were submitted to a mixed-model analysis of variance. Knee and ankle stiffness increased 19% and 6% with load (P <.001, P =.049), but decreased 8% and 6% as stride lengthened (P =.004, P <.001). Decreased knee RoM (P <.001, 0.9°–2.7°) and increased knee (P =.007, up to 0.12 N.m/kg.m) and ankle (P =.013, up to 0.03 N.m/kg.m) flexion moment may stiffen joints with load. Greater knee (P <.001, 4.7°–5.4°) and ankle (P <.001, 2.6°–7.2°) flexion RoM may increase joint compliance with longer strides. Females exhibited 15% stiffer knee (P =.025) from larger reductions in knee RoM (4.3°–5.4°) with load than males (P <.004). Stiffer lower limb joints may elevate injury risk while running with load, especially for females. [ABSTRACT FROM AUTHOR]

During initial acceleration, the first steps of a maximal‐effort (sprint) run often determine success or failure in the capture and evasion of an opponent, and is therefore a vital factor of success in many modern sports. However, accelerative events are commonly performed after having already run considerable distances, and the associated fatigue should impair muscle force production and thus reduce acceleration. Despite this, the effects of running‐induced fatigue on our ability to accelerate as well as the running technique used to achieve it have received little attention. We recorded 3‐D kinematics and ground reaction forces during the first three steps of the acceleration phase from a standing start before and after performing a high‐speed, multi‐directional, fatiguing run‐walk protocol in well‐trained running athletes who were habituated to accelerative sprinting. We found that the athletes were able to maintain their acceleration despite changing running technique, which was associated with use of a more upright posture, longer ground contact time, increased vertical ground reaction impulse, decreased hip flexion and extension velocities, and a shift in peak joint moments, power, and positive work from the hip to the knee joint; no changes were detected in ankle joint function. Thus, a compensatory increase in knee joint function alleviated the reduction in hip flexor‐extensor capacity. These acute adaptations may indicate that the hip extensors (gluteal and hamstring muscle groups) were more susceptible to fatigue than the ankle and knee musculature, and may thus be a primary target for interventions promoting fatigue resistance. [ABSTRACT FROM AUTHOR]

Prosthetics are an extension of the human body and must provide functionality similar to that of a non-disabled individual to be effective. Sports prosthetics such as the Flex-Foot Cheetah from Össur have demonstrated the value of creating devices that both provide mechanical support and introduce passive energy return to mimic forces otherwise produced at joints. These energy return mechanisms have not yet been demonstrated for upper limb prosthetics but could improve their effectiveness and provide a greater range of motion and control. Using multi-material 3D printing technology, we extend energy return components to upper limb prosthetics by developing novel force-sensing springs and applying them to a basketball prosthetic. The 3D-printed springs compensate for the forces otherwise generated by wrist and finger flexion while measuring the mechanical deflection. We discuss design guidelines, methods for integrated 3D printed energy return within prosthetics, and broader applications in assistive technologies. [ABSTRACT FROM AUTHOR]

Background The purpose of this study is to examine the association between physical activity and contracture in older patients confined to bed in long-term care (LTC) facilities. Methods Patients wore ActiGraph GT3X+ for 8 hours on their wrists, and vector magnitude (VM) counts were obtained as the amount of activity. The passive range of motion (ROM) of joints was measured. The severity of ROM restriction classified, as the tertile value of the reference ROM of each joint, was scored 1-3 points. Spearman's rank correlation coefficients (Rs) were used to measure the association between the VM counts per day and ROM restrictions. Results The sample comprised 128 patients with a mean (SD) age of 84.8 (8.8) years. The mean (SD) of VM was 84574.6 (115195.2) per day. ROM restriction was observed in most joints and movement directions. ROMs in all joints and movement directions, except wrist flexion and hip abduction, were significantly correlated with VM. Furthermore, the VM and ROM severity scores showed a significant negative correlation (Rs = -0.582, p < .0001). Conclusions A significant correlation between the physical activity and ROM restrictions indicates that a decrease in the amount of physical activity could be one of the causes of contracture. [ABSTRACT FROM AUTHOR]

Purpose: This study examined lower extremity kinematics in healthy weight (HW) and overweight (OW) children during water- and land-based stationary exercises (stationary running, frontal kick, and butt kick) at light submaximal intensity. Methods: Participants included OW (N = 10; body fat percentage: 34.97 [8.60]) and HW (N = 15; body fat percentage: 18.33 [4.87]) children, aged 10 to 13 years. Spatiotemporal data, lower extremity joint kinematics, and rating of perceived exertion (RPE) were collected during water- and land-based stationary exercises. Repeated measures analysis of variance compared kinematic variables and RPE between groups and environments. A polygon area function compared coordination patterns between environments. Results: RPE responses were significantly greater in OW than HW children on land (13.6 [0.7] vs 11.6 [0.7]; P <.001), whereas the RPE responses were similar between groups in water (11.2 [0.7] vs 11.1 [0.8]; P >.05). OW children were significantly more upright than HW children during land-based exercise, whereas there were no differences observed between groups during aquatic-based exercise. The duration of stance and swing phases, angular velocity, and cadence were significantly lower in water than on land. Conclusion: Compared with HW children, OW children performed stationary exercises in a more upright posture on land, with higher RPE. However, these differences diminished in water. Aquatic-based exercise may be effective in minimizing the effects of excess mass on OW children's ability to complete physical activity. [ABSTRACT FROM AUTHOR]

Although decline surfaces or a more upright trunk posture during running increase the patellofemoral joint (PFJ) contact force and stress, less is known about these kinetic parameters under simultaneous changes to the running posture and surface height. This study aimed to investigate the interaction between Step (10-cm drop-step and level step) and Posture (trunk angle from the vertical: self-selected, ~15°; backward, ~0°; forward, ~25°) on PFJ kinetics (primary outcomes) and knee kinematics and kinetics as well as hip and ankle kinetics (secondary outcomes) in 12 runners at 3.5 ms-1. Two-way repeated measures analyses of variance (a = 0.05) revealed no step-related changes in peak PFJ kinetics across running postures; however, a decreased peak knee flexion angle and increased joint stiffness in the drop-step only during backward trunk-leaning. The Step main effect revealed significantly increased peak hip and ankle extension moments in the drop-step, signifying pronounced mechanical demands on these joints. The Posture main effect revealed significantly higher and lower PFJ kinetics during backward and forward trunk-leaning, respectively, when compared with the self-selected condition. Forward trunk-leaning yielded significantly lower peak knee extension moments and higher hip extension moments, whereas the opposite effects occurred with backward trunk-leaning. Overall, changes to the running posture, but not to the running surface height, influenced the PFJ kinetics. In line with the previously reported efficacy of forward trunk-leaning in mitigating PFJ stress while even or decline running, this technique, through a distal-to-proximal joint load redistribution, also seems effective during running on surfaces with height perturbations. [ABSTRACT FROM AUTHOR]

Purpose: Running with increased duty factors (DF) has been shown to effectively reduce external forces during running. In this study, we investigated whether running with increased DF (INCR) also reduces internal musculoskeletal loading measures, defined as peak muscle forces, muscle force impulses, and peak joint contact forces compared with a runners' preferred running pattern (PREF). Method: Ten subjects were instructed to run with increased DF at 2.1 m·s−1. Ground reaction forces and three-dimensional kinematics were simultaneously measured. A musculoskeletal model was used to estimate muscle forces based on a dynamic optimization approach, which in turn were used to calculate muscle force impulses and (resultant and three-dimensional) joint contact forces of the ankle, knee, and hip joint during stance. Results: Runners successfully increased their DF from 40.6% to 49.2% on average. This reduced peak muscle forces of muscles that contribute to support during running, i.e., the ankle plantar flexors (−19%), knee extensors (−18%), and hip extensors (−15%). As a consequence, peak joint contact forces of the ankle, knee, and hip joint reduced in the INCR condition. However, several hip flexors generated higher peak muscle forces near the end of stance. Conclusions: Running with increased DF lowers internal loading measures related to support during stance. Although some swing-related muscles generated higher forces near the end of stance, running with increased DF can be considered as a preventive strategy to reduce the occurrence of running-related injuries, especially in running populations that are prone to overuse injuries. [ABSTRACT FROM AUTHOR]

BACKGROUND: Hand injuries affect a person's functioning, thus impeding their abilities to return to work. There is a limited understanding in return to work of the overall predictors when including hand characteristics and functional abilities. Therefore, it is essential to identify the most relevant predictors in return to work among individuals with a hand injury. OBJECTIVES: (1) To compare hand function characteristics and functional abilities of injured workers who have or have not returned to work. (2) To estimate hand function characteristics and functional abilities as predictors to return to work. METHODS: One hundred and fifteen adult workers with hand injuries aged 18– 59 years old from five general hospitals in Malaysia participated in a cross-sectional study. Predictors were estimated using logistic regression. RESULTS: There was a significant association between occupational sector (p = 0.012), injury duration (p = 0.024), occupational performance (p = 0.009) and satisfaction with performance (p < 0.001), grip strength of injured hand (p = 0.045– 0.002) and the Disability of Arm, Shoulder and Hand (DASH) disability/symptom (p = 0.001) with the person's return to work status. Significant predictors of return to work were identified using the Canadian Occupational Performance Measure (COPM) satisfaction's score, DASH disability/symptoms' score and duration of the injury. CONCLUSION: As two main predictors of return to work were COPM satisfaction and DASH disability/symptoms, occupational therapists working in rehabilitation should focus on achieving functional performance and satisfaction within the optimal time. [ABSTRACT FROM AUTHOR]

Paramedics represent a unique occupational group where the nature of their work, providing prehospital emergency care, makes workplace modifications to manage and control injury risks difficult. Therefore, the provision of workplace education and training to support safe lifting remains a viable and important approach. There is, however, a lack of evidence describing movement strategies that may be optimal for paramedic work. The purpose of this study was to determine if a strategy leveraging a greater contribution of work from the lower body relative to the torso was associated with lower biomechanical exposures on the spine. Twenty-five active duty paramedics performed 3 simulated lifting activities common to paramedic work. Ground reaction forces and whole body kinematics were recorded to calculate: peak spine moment and angle about the L4/L5 flexion-extension axis as indicators of biomechanical exposure; and, joint work, integrated from net joint power as a measure of technique inclusive of movement dynamics. Paramedics generating more work from the lower body, relative to the trunk, were more likely to experience lower peak L4/L5 spine moments and angles. These data can inform the development of workplace training and education on safe lifting that focuses on paramedics generating more work from the lower body. [ABSTRACT FROM AUTHOR]

Purpose: Due to the paucity of information regarding the lower limb biomechanics in running at slow speed, as well as the concentration of most previous studies on a single movement plane, this study aimed to investigate lower limb joint kinetics with increasing running speed. Methods: Twenty-eight runners were asked to stay on the treadmill at a bent velocity which was incrementally increased to 2.5 m/s, 3.5 m/s, and 4.5 m/s speeds. The three-dimensional joint moment and sagittal mechanical muscle power of the lower limb were calculated during the stance phase of running. Repeated measures analysis of variance (ANOVA) with Bonferroni post hoc test was used to examine the variables during running at various speeds. Results: The results showed that at the hip joint in the frontal plane, an adduction moment developed in the middle of the stance phase, and the highest peak adduction moment was obvious at the highest speed condition (4.5 m/s). Also, the time elapsed to peak in the highest speed condition was less than the others. In the transverse plane, although the 3.5 m/s-speed condition experienced the maximum external rotation peak moment, the 4.5 m/s-condition speed reached the internal status earlier than the two other speeds. In the sagittal plane, the highest speed condition showed the highest extension and flexion moments. Conclusion: Increasing running speed in runners leads to more kinetic output and mechanical power gradient. [ABSTRACT FROM AUTHOR]

BACKGROUND: There is insufficient knowledge about the rate of force development (RFD) characteristics over both single and multiple joint movements and the electromechanical delay (EMD) values obtained in athletes and untrained individuals. OBJECTIVE: To compare single and multiple joint functions and the neural drive of trained athletes and untrained individuals. METHODS: Eight trained athletes and 10 untrained individuals voluntarily participated to the study. The neuromuscular performance was assessed during explosive and maximum voluntary isometric contractions during leg press and knee extension related to single and multiple joint. Explosive force and surface electromyography of eight superficial lower limb muscles were measured in five 50-ms time windows from their onset, and normalized to peak force and electromyography activity at maximum voluntary force, respectively. The EMD was determined from explosive voluntary contractions (EVC's). RESULTS: The results showed that there were significant differences in absolute forces during knee extension maximum voluntary force and EVC's (p < 0.01) while trained athletes achieved greater relative forces than untrained individuals of EVC at all five time points (p < 0.05). CONCLUSIONS: The differences in explosive performance between trained athletes and untrained individuals in both movements may be explained by different levels of muscle activation within groups, attributed to variation in biarticular muscle function over both activities. [ABSTRACT FROM AUTHOR]

The ankle, knee, and hip joints work together in the sagittal plane to absorb landing forces. Reduced sagittal plane motion at the ankle may alter landing strategies at the knee and hip, potentially increasing injury risk; however, no studies have examined the kinematic relationships between the joints during jump landings. Healthy adults (N = 30; 15 male, 15 female) performed jump landings onto a force plate while three-dimensional kinematic data were collected. Joint displacement values were calculated during the loading phase as the difference between peak and initial contact angles. No relationship existed between ankle dorsiflexion displacement during landing and three-dimensional knee and hip displacements. However, less ankle dorsiflexion displacement was associated with landing at initial ground contact with larger hip flexion, hip internal rotation, knee flexion, knee varus, and smaller plantar flexion angles. Findings of the current study suggest that restrictions in ankle motion during landing may contribute to contacting the ground in a more flexed position but continuing through little additional motion to absorb the landing. Transverse plane hip and frontal plane knee positioning may also occur, which are known to increase the risk of lower extremity injury. [ABSTRACT FROM AUTHOR]

Purpose: To investigate differences in lower extremity joint angles between a forward (FSD) and lateral (LSD) step-down task at different heights (4 and 6 inches). Methods: Eighteen healthy adults performed four variations of the step-down task while hip, knee, and ankle kinematics were measured. A two-way repeated measures analysis of variance was performed. Results: There was a significant interaction and main effect for step direction and height for knee external rotation and ankle dorsiflexion angle (P <.05). Participants exhibited greater hip adduction, knee flexion, knee adduction, and ankle dorsiflexion during performance of the FSD than the LSD at the 4- and 6-inch height. For each step direction, participants demonstrated greater hip flexion, hip adduction, knee flexion, knee adduction, and ankle dorsiflexion during performance of the task at the 6-inch height. Conclusions: The FSD requires greater movement of the lower extremity than the LSD and increasing step height increases the biomechanical demands of the lower extremity. [Athletic Training & Sports Health Care. 2021;13(4):e212–e220.] [ABSTRACT FROM AUTHOR]

Despite recent research on joint motion measurement to monitor human body movement, current measurement techniques and tools have significant limitations, including requiring large space for measurement and causing discomfort in test subjects wearing motion sensors. Our study aims, first, to develop carbon nanotube (CNT)-based textile joint motion sensors. Second, ours study aims to identify the most suitable CNT-based sensor structure and attachment method for use on a wearable platform during general exercise speeds. Lastly, we used these sensors on the human body, using sleeves and legs to find the most stable location, and we used the CNT-based sensor condition to monitor joint motions. We utilized our CNT-based sensor, which has proper elasticity as well as conductivity, and applied it to the elbow and knee joints. Based on the strain gauge principle, we monitored the variance of electric resistance that occurred when the CNT-based sensor was stretched due to limb motion. Our study tested 48 types of sensors. These sensors were applied to the CNT using different base knit textiles as well as different attachment methods, layers, sensor lengths, and sensor widths. The four most successful sensor types, which showed superior efficacy over the others in joint motion measurement, were selected for further study. These four sensors were then used to measure the elbow and knee joint motions of human subjects by placing them on different locations on sleeves and legs. The CNT knit textile sensors best suited to measuring joint motions are those with a double-layered CNT knit and 5 cm long × 0.5 cm or 1 cm wide sensors attached to a polyester¬-based knit using a welding method. The best position for the sensor to more stably monitor joint motions was the "below hinge position" from the elbow or knee hinge joint. Our study suggests an alternative strategy for joint-motion measurement that could contribute to the development of more comfortable and human-friendly methods of human limb motion measurement. [ABSTRACT FROM AUTHOR]

Background: Age-related changes of human gait characteristics associated with muscle weakness have been reported in previous studies. Human gait is considered as a cyclic motion adapted to individual body-characteristics and the surrounding-environment based on motion criteria. Based on this hypothesis, elderly gait characteristics may be caused by an adaptation to muscle weakness.Research Question: What role does gait adaptation to muscle weakness play in the development of elderly gait, and what criteria are used in elderly gait adaptation?Methods: We examined the effects of gait adaptation to muscle weakness on steady gait characteristics using computational forward dynamics simulation with a two-dimensional neuro-musculo-skeletal model. For gait adaptation, we tested two motion criteria: (i) energy cost minimization, which is a widely used criterion for healthy adults; and (ii) energy rate minimization, based on existing measurements of elderly gait characteristics.Results: Progression of muscle weakness enhanced the reduction of joint angle motion and minimum toe clearance, and finally resulted in falling. Gait adaptation to muscle weakness successfully formed stable walking patterns regardless of motion criteria, even at muscle weakness of 30 %, which represents a moderate degree of elderly muscle weakness. When criterion (i) was used, the time courses of joint motion were similar to those of healthy adults and a relatively high level of muscle activation was found in the whole gait cycle to compensate for muscle weakness. When criterion (ii) was used, the muscle activity level was lower than that of criterion (i) to minimize the energy rate, and the constructed gait successfully captured the characteristics of elderly gait reported in previous studies.Significance: These findings suggest that gait adaptation to muscle weakness plays an essential role in the development of stable gait characteristics, whereas elderly people might use a different motion criterion compared with healthy adults in gait adaptation. [ABSTRACT FROM AUTHOR]

Case report. Zone III extensor tendon injuries are typically treated with early mobilization or by a period of immobilization followed by gradual motion. In both scenarios, the use of multiple orthoses is required. This case report examines the effective use of a single, modified relative motion orthosis throughout the protected rehabilitation phase after a zone III extensor tendon repair. A patient with extensor tendon zone III laceration to his index finger (10th revision of the International Statistical Classification of Diseases and Related Health Problems s66.328) was treated using a single, relative motion with dorsal hood orthosis. The exercise protocol followed a modified immediate short arc motion program. Following laceration and complete rupture of the central slip, the patient regained full range of motion, strength, and function. It is becoming more common to use a relative motion flexion (RMF) orthosis to correct or improve extensor lag due to boutonniere deformity or stiffness after finger fractures. There is very little literature to support the use of the RMF orthosis after zone III extensor tendon repair. To produce a single orthosis that is useful through the entire protected phase of rehabilitation, the RMF orthosis is easily modified by addding a dorsal hood to create the relative motion dorsal hood orthosis (RMDH). Our case report shows the successful treatment of a zone III extensor tendon repair using a single relative motion with dorsal hood orthosis and early active motion throughout the entire protected phase of rehabilitation. • Effective use of a single, modified relative motion orthosis for zone 3 extensor tendon repair. • Rationale based on research performed with early active and relative motion protocols. • Multiple images are presented that describe the design of the orthosis. [ABSTRACT FROM AUTHOR]

The current study aimed to investigate the effect of ankle restriction on the coordination of vertical jumping and discuss the influence of energy transfer through m. gastrocnemius on the multijoint movement. Eight participants performed two types of vertical jumps: a normal squat jump, and a squat jump with restricted ankle joint movement. Mechanical outputs were calculated using an inverse dynamics analysis. Custom-made shoes were used to restrict plantar flexion, resulting in significantly (P < .001) reduced maximum power and work at the ankle joint to below 2% and 3%, while maintaining natural range of motion at the hip and knee. Based on the comparison between the two types of jumps, we determined that the ankle restriction increased (P < .001) the power (827 ± 346 W vs. 1276 ± 326 W) and work (92 ± 34 J vs. 144 ± 36 J) at the knee joint. A large part of the enhanced output at the knee is assumed to be due to ankle restriction, which results in the nullification of energy transport via m. gastrocnemius; that is, reduced contribution of the energy transfer with ankle restriction appeared as augmentation at the knee joint. [ABSTRACT FROM AUTHOR]

Compared to level running (LR), different strategies might be implemented by runners to cope with specific challenges of graded running at different speeds. The changes in joint kinetics and kinematics associated with graded running have been investigated, but their interactions with speed are unknown. Nineteen participants ran on an instrumented treadmill at five grades (0°, ±5° and ± 10°) and three speeds (2.50, 3.33 and 4.17 m/s), while 3D motion and forces were recorded. Three speed × five‐grade repeated‐measures ANOVA was used to analyze kinetic and kinematic variables. A speed × grade interaction was observed for hip range of motion (ROM). Downhill running (DR) at fastest speed did not reduce ROM at the hip, compared to LR. Compared to LR, it was observed that the hip joint was responsible for a greater contribution of energy generation while running at the fastest speed at +10°. Speed × grade interactions were also observed for the energy absorption, peak moment, and peak power at the knee. Contrary to LR, running faster during UR did not require higher peak power at the knee. Finally, DR at the fastest speed did not increase peak negative power at the knee compared to LR. This study demonstrates that ankle, knee, and hip joint kinetics depend on speed and grade of running, while the effect of grade on joint kinematics was not substantially modulated by speed. [ABSTRACT FROM AUTHOR]

Supplemental digital content is available in the text. Introduction: Athletes returning to sport after anterior cruciate ligament reconstruction (ACLR) demonstrate prolonged changes in landing kinematics, kinetics, and muscle activation, predisposing them for reinjury, knee osteoarthritis, and/or knee instability. So far, researchers have been focusing on how kinematics and kinetics change in every joint separately. However, as the human body operates within a kinetic chain, we will assess whether single-joint changes are associated with whole-body changes. Methods: Twenty-one athletes who had an ACLR and 21 uninjured controls performed five unilateral landing tasks, whereas lower limb kinematics, kinetics, and muscle activations of vastus medialis, vastus lateralis, biceps femoris, semitendinosus, semimembranosus, gastrocnemius, and gluteus medius were recorded. Single-joint landing kinematics, kinetics, and muscle activations of the ACL-injured leg were compared with the uninjured leg and compared with the control group. Whole-body changes were assessed by decomposing movements into fundamental components using marker-based principal component analysis (PCA). Results: We found several single-joint changes in landing kinematics, kinetics, and muscle activations in the athletes with ACLR that were seen across all tasks and therefore of major interest as they are likely to occur during sports as well. Hamstrings activation increased and external knee flexion moments decreased in the ACL-injured leg compared with their uninjured leg. Furthermore, hip adduction moments and knee abduction angles decreased compared with the control group. The PCA could detect changes in whole-body movement, which were task-specific. Conclusions: Athletes with ACLR still show protective task-independent single-joint kinematic, kinetic, and muscle activation changes during single-leg landings at the time of return to sport. These single-joint changes were not consistently accompanied by changes in whole-body movements (revealed by marker-based PCA). Whole-body expressions of the single-joint compensations are likely to be affected by the demands of the task. [ABSTRACT FROM AUTHOR]

Background/aims: Cerebral palsy is a lifelong condition resulting in weakness in the muscles, difficulty moving and excessive tension in the muscles of the arms and legs. This study aimed to investigate the effects of adding Kinesio taping and neuromuscular electrical stimulation to neurodevelopmental treatment on joint range of motion, muscle tone and functional ability in children with cerebral palsy. Methods: A total of 30 children were included in the study. They were allocated to one of two groups: Kinesio taping (n=15) or neuromuscular electrical stimulation (n=15). The children in both groups received 20 sessions of twice-weekly neurodevelopmental treatment. Range of motion, Modified Ashworth Scale, Duruoz Hand Index, Manual Ability Classification System, Gross Motor Function Classification System, Minnesota Hand Skill Test and Jebsen Hand Function Test were assessed before and after the treatment programme. Results: Statistically significant improvements (P<0.05) were found in all measures except Gross Motor Function Classification System in both groups. Significant between-group differences in left shoulder flexion, left shoulder abduction and unilateral Minnesota Hand Skill Test were found in favour of neuromuscular electrical stimulation; whereas significant improvement in left elbow flexion was found in favour of Kinesio taping. Conclusions: The addition of Kinesio taping and neuromuscular electrical stimulation to neurodevelopmental treatment improved the joint range of motion and functional ability of children with cerebral palsy. [ABSTRACT FROM AUTHOR]

To evaluate the effects of silicone ankle sleeves (SASs) and lace-up ankle braces (LABs) on neuromuscular control, net joint torques, and cutting agility in healthy, active individuals. Markerless motion-capture technology tracked subjects fitted with SASs, LABs, or no brace while they performed the movements: Y-excursion, left cutting, right cutting, single-leg drop vertical jump (SLDVJ), 45-degree bound, and single-leg squat (SLS). University Laboratory. Ten healthy, active individuals (5 males and 5 females, mean ± SD 23.60 ± 1.43 years of age). Degrees of joint range of motion (ROM), Newton-meters of joint torque, time to perform a cutting maneuver. SASs and LABs resulted in significantly different knee and ankle ROM and hip internal rotation in the SLDVJ, SLS, Y-excursion, cutting maneuver, and 45-degree bound when compared to control (p <.05). Both ankle and knee torque were significantly reduced in the 45-degree bound and cutting movements with both types of PABs (p <.05). There were minimal differences between the SASs and LABs for all conditions. There were no statistically significant differences in cutting times for any of the 3 conditions. Both SAS and LAB positively impacted neuromuscular control, reduced net joint torque, and neither impaired cutting agility when compared to control. • Silicone ankle sleeves (SAS) and lace-up ankle braces (LAB) reduced net joint torque. • SAS and LAB improved neuromuscular control during dynamic movement. • SAS and LAB did not impact cutting agility. [ABSTRACT FROM AUTHOR]

Background: Deteriorated bone-graft interaction at the tunnel entrance following ACL reconstruction (ACLR) is considered one of the primary causes of long-term tunnel enlargement and graft wear. Methods have been introduced to improve the long-term outcome, such as novel graft materials or alternative fixation methods, but have been met with varying degrees of success. This study aims to design a protection liner to improve the bone-graft interaction at the tunnel entrances. Methods: A finite element model of a human cadaveric knee was used to simulate traditional ACLR and ACLR using the protection liner. Stress distribution around the tunnel entrances and on the ACL graft were calculated under a combined loading of 103 N anterior tibial load, 7.5 Nm internal tibial moment, and 6.9 Nm valgus tibial moment at a joint flexion angle of 20°. Results were compared between the traditional ACLR and ACLR using a double liner (femoral and tibial) setup, as well as between the ACLR using a double liner setup and a single liner (femoral side) setup. Different materials (PEEK, Ti-6Al-4V, CoCrMo) for the liner were also evaluated. Results: The traditional ACLR resulted in concentrated stress on the graft where it contacted the tunnel entrance. Correspondingly, there were stress concentrations at the distal posterior zone of the femoral tunnel entrance and medial posterior zone of the tibial tunnel entrance, while the other zones suffered from a stress reduction. Use of the protection liner reduced the stress concentration around the tunnel entrances by up to 89% and increased the stress at the unloaded zones by up to 106%. Also, stress concentration on the graft was slightly decreased (15.4 vs 15.1 MPa) after using the liner. The single liner setup increased the stress concentration around the tibial tunnel entrance. Stiffer materials improved the stress distribution around tunnel entrances but had little effect on the stress on the graft. Conclusions: The novel protection liner can improve the stress distribution on the graft and at the tunnel entrances, which may be beneficial for improving the clinical outcome of ACLR. [ABSTRACT FROM AUTHOR]

Badminton atypical actions and hitting movements often occur during the game; therefore, many special footwork methods have been developed to facilitate the rapid movements required to hit the shuttlecock, including quick turning and jumping and quick directional change movements. Studies have shown that the majority of badminton sport injuries occur in the lower extremity joints of athletes. The purpose of this study was to investigate the influences of hitting motion and unanticipated hitting direction on landing mechanics after backhand lateral jump smashing and landing to analyze joint stiffness and torque changes in three lower extremity joints. Recruited sixteen badminton athletes.The capture frequency of the Vicon Motion System (300Hz), Kistler force platform (1500Hz) and Vicon Nexus Version 1.8.5 software were used simultaneously to capture the kinematic and kinetic parameter of backhand side lateral jump smash footwork. The swing actions were divided into two situations, shadow (footwork and racket swinging practice without targets) and hitting (footwork and stroke shuttlecock) actions, whereas the directions were divided into directional and non-directional. Two-way repeated measures ANOVA with the LSD correction was used to compare the differences among the four conditions. The significance level was set to a = 0.05. Results shown that, at the peak of torque, the ankle plantar flexion of the non-directional shadow (p < 0.05) were greater than that of directional shadow (p < 0.05); meantime, ankle torque change of non-directional shadow (p < 0.05) and directional hitting (p < 0.05) was lower than that of non-directional hitting, but the non-directional hitting was larger compared to non-directional shadow (p < 0.05) at the maximum vertical GRF. The hip extension at peak of torque of directional hitting were larger than that of non-directional shadow (p < 0.05). The shadow actions hip flexion angle was larger than that of directional hitting at initial contact, but the non-directional hitting hip abduction was has the significant difference among all the conditioning. The hip flexion angle of non-directional shadow was larger than that of directional hitting (p < 0.05), the hip abduction angle of the nondirectional hitting was greater than that of non-directional shadow (p < 0.05) at the peak VGRF. Elite badminton players execute different training movements; the joint stiffness was in the same state. In the hitting actions has greater ankle and hip joint torque than shadow actions. The badminton player was change joint range of motion to adjust lower limbs stiffness. [ABSTRACT FROM AUTHOR]

Objectives: This study aims to investigate the correlations between clinical features and mouth opening in patients with systemic sclerosis (SSc). Patients and methods: Eighty patients with SSc (13 males, 67 females; mean age 53.4±11.7 years; range, 31 to 76 years) followed in our clinic were enrolled in the study. Skin involvement was assessed using the modified Rodnan skin score (mRSS), joint/tendon involvement with finger-tip to palm (FTP) distance and interstitial lung disease (ILD) was evaluated with clinical and radiologic methods. The interincisal distance (ID) measurement was used to assess the maximal mouth opening capacity. We examined associations between the ID and clinical features of SSc. Results: The ID was lower in females compared with males, and in diffuse type compared with the limited type (p<0.001 and p<0.001, respectively). A significant negative correlation was found between the ID with mRSS and FTP distance (p<0.001 and p=0.001, respectively). The ID was lower in patients with ILD than in patients without ILD (p=0.006). A formula was constituted to predict the maximal mouth opening of the patient with regression analysis. According to the formula, being male was associated with an increase of 6.14 mm, the presence of ILD with a decrease of 3.19 mm, every 10 mm increment in mRSS with a decrease of 3.72 mm and FTP distance >0 mm with a decrease of 5.13 mm in mouth opening. Conclusion: Microstomia is associated with low quality of life in patients with SSc. In our study, sex, ILD, mRSS, and FTP distance were observed to be the most important factors that were related with mouth opening in patients with SSc. [ABSTRACT FROM AUTHOR]

This study aimed to describe stationary overhead throwing biomechanics in South African cricketers, considering playing level, and relative to baseball. Kinematics and ground reaction forces were collected during throwing trials. Inverse dynamics was used to calculate joint kinetics. Inter-subject variability was calculated using the coefficient of variance. A one-dimensional statistical parametric mapping ANOVA was conducted to assess differences between the kinematic waveforms in elite and amateur cricketers (p < 0.05). Fifteen cricketers (elite = 8; amateur = 7) participated in this study. The basic parameters of a cricketer's throwing action are described. Substantial inter-subject variability was noted for all variables, except lumbopelvic movement. Cricketers presented with 74.9 ± 27.3° glenohumeral external rotation and 94.8 ± 23.7° elbow flexion, at maximum external rotation (MER). Amateur cricketers displayed decreased elbow flexion range of motion between 2-14% of the throwing cycle (F = 9.365;p = 0.01); greater shoulder (121.0vs85.9 N; F = 0.36,p = 0.021) and elbow compression (105.6vs72.8 N;F = 0.007,p = 0.043), and superior shoulder force (203.1vs115.5 N;F = 2.43,p = 0.022) at MER, when compared with elite cricketers. Cricketers display similarities to baseball pitchers when throwing overhead from a stationary position. The "preparatory arc" utilised is different to the wind-up noted for baseball. The forces exerted on the shoulder and elbow, in amateur cricketers specifically, are substantially greater at MER and may indicate the potential risk for injury. [ABSTRACT FROM AUTHOR]

Fast bowling is categorised into four action types: side-on, front-on, semi-open and mixed; however, little biomechanical comparison exists between action types in junior fast bowlers. This study investigated whether there are significant differences between action-type mechanics in junior fast bowlers. Three-dimensional kinematic and kinetic analyses were completed on 60 junior male fast bowlers bowling a five-over spell. Mixed-design factorial analyses of variance were used to test for differences between action-type groups across the phases of the bowling action. One kinetic difference was observed between groups, with a higher vertical ground reaction force loading rate during the front-foot contact phase in mixed and front-on compared to semi-open bowlers; no other significant group differences in joint loading occurred. Significant kinematic differences were observed between the front-on, semi-open and mixed action types during the front-foot contact phase for the elbow and trunk. Significant kinematic differences were also present for the ankle, T12-L1, elbow, trunk and pelvis during the back-foot phase. Overall, most differences in action types for junior fast bowlers occurred during the back-foot contact phase, particularly trunk rotation and T12-L1 joint angles/ranges of motion, where after similar movement patterns were utilized across groups during the front-foot contact phase. [ABSTRACT FROM AUTHOR]

Angular isokinetic dynamometry (AID) is widely regarded as the gold standard for dynamic muscle performance testing. Based on the rotational movement of its actuator, AID targets single-joint (knee, shoulder, hip, etc.) configurations namely measurement of muscle potential while it moves the lever armlimb assembly ostensibly around a single fixed axis. On the other hand, the application of multiple-joint isokinetic dynamometry (MID) is relatively narrow, both in research and in practice. This situation is due, possibly, to the fact that these dynamometers are generally more limited in scope namely to testing/conditioning of combined hip, knee, ankle motion (leg press), combined shoulder, elbow motion, and lifting motion patterns, despite the fact that all 3 are associated with higher functionality. However, with the emerging importance of MID, this critical review takes a fresh look at its various aspects including the terminology and classification of multiple-joint isokinetic dynamometers; the problem of scaling namely the need to adjust the range of motion and linear velocities to subjective anthropometric measures; specific technical and methodological issues that underlie the valid application of these dynamometers; available reference values; and the reproducibility of MID-based test findings. Analysis of these topics indicates that MID may validly and effectively be applied for the assessment and conditioning of specific muscle action patterns. However, there is a clear need for standardization of tests and for conditioning protocols alongside research into the use of this method in various clinical cohorts [ABSTRACT FROM AUTHOR]

BACKGROUND: The inherent stride-to-stride fluctuations during walking are altered in the aging population and could provide insight into gait impairments and falls in patients with COPD. Stride-to-stride fluctuations are quantified two ways: variability of the fluctuations (eg, standard deviation), and movement patterns within the fluctuations. Our objective was to investigate stride-to-stride fluctuations by evaluating the variability and movement patterns of lower limb joints in subjects with COPD compared to subjects without COPD as control subjects. METHODS: In this cross-sectional study, 22 subjects with COPD (age 63 ± 9 y; FEV1 54 ± 19% predicted) and 22 control subjects (age 62 ± 9 y; FEV1 95 ± 18% predicted) walked for 3 min on a treadmill while their gait was recorded. The amount of variability (ie, standard deviation and coefficient of variation) and movement patterns (ie, predictability and consistency in organization) were quantified for the range of motion and joint angle of the hip, knee, and ankle, at 3 walking speeds (ie, self-selected, fast, and slow). General linear mixed models were used for analysis. RESULTS: Control subjects had more consistent organization of the hip and knee joint movement patterns compared to subjects with COPD (P = .02 and P = .02, respectively). Further, control subjects adapted to speed changes by demonstrating more consistent organization of movement patterns with faster speeds, whereas subjects with COPD did not. At the fast walking speed, subjects with COPD demonstrated less consistent organization of knee and hip joint movement patterns as compared to control subjects without COPD (P = .03 and P = .005, respectively). The amount of variability did not differ between groups. CONCLUSIONS: Although subjects with COPD did not demonstrate decreased amount of variability, their hip and knee joint movement patterns were less consistent in organization during walking. Reduced consistency in organization of movement patterns may be a contributing factor to falls and mobility problems experienced by patients with COPD. [ABSTRACT FROM AUTHOR]

Mizuno, T. Combined effects of static stretching and electrical stimulation on joint range of motion and muscle strength. J Strength Cond Res 33(10): 2694-2703, 2019-The purpose of this study was to examine the effects of the combination of static stretching (SS) and electrical stimulation (ES) for 8 weeks on joint range of motion (ROM), muscle strength, and muscle architecture. Thirty-one subjects were divided into 3 groups: the SS combined with ES (SS + ES) group, SS group, and control group. The SS + ES group performed calf stretching simultaneously with ES to the gastrocnemius medialis, whereas the SS group performed calf stretching only. The training regimen consisted of four 30-second sets of stretching, with 30-second rest intervals, 3 days per week for 8 weeks. The control group did not perform any intervention exercise. Before and after training, measurements were taken to determine the ankle ROM, plantar flexion 1 repetition maximum strength, muscle thickness, pennation angle, and circumference of the lower leg. The results showed that 8 weeks of training led to significant improvements in the ankle ROM and muscle thickness in both the SS + ES and SS groups. There were significant increases in plantar flexion 1 repetition maximum strength and pennation angle in all 3 groups. For all parameters, there was no difference between the SS + ES and SS groups. These results clarify that 8 weeks of SS improves joint ROM and muscle thickness and shows that there is no additional benefit gained by combining ES with SS in this particular training regime. [ABSTRACT FROM AUTHOR]

Sprint cycling performance depends upon the balance between muscle and drag forces. This study assessed the influence of upper body position on muscle forces and aerodynamics during seated sprint cycling. Thirteen competitive cyclists attended two sessions. The first session was used to determine handlebar positions to achieve pre-determined hip flexion angles (70–110° in 10° increments) using dynamic bicycle fitting. In the second session, full body kinematics and pedal forces were recorded throughout 2x6-s seated sprints at the pre-determined handlebar positions, and frontal plane images were used to determine the projected frontal area. Leg work, joint work, muscle forces and frontal area were compared at three upper body positions, being optimum (maximum leg work), optimal+10° and optimal-10° of hip flexion. Larger hip (p = 0.01–0.02) and reduced knee (p = 0.02–0.03) contribution to leg work were observed at the optimal+10° position without changes at the ankle joint (p = 0.39). No differences were observed in peak muscle forces across the three body positions (p = 0.06–0.48). Frontal area was reduced at optimum+10° of hip flexion when compared to optimum (p = 0.02) and optimum-10° (p < 0.01). These findings suggest that large changes in upper body position can influence aerodynamics and alter contributions from the knee and hip joints, without influencing peak muscle forces. [ABSTRACT FROM AUTHOR]

This study aimed to explore the biomechanical differences between single and double peak ground reaction force-time curves during the countermovement jump with respect to kinematics, kinetics, and coordination of the lower extremities. Twenty-five college students were stratified into a single peak curve group and a double peak curve group. Eight infrared cameras and two force platforms were synchronized to collect the data. Independent t-tests were performed with groups for each dependent kinematic, kinetic and time of the joint extensor concentric contraction variable. Repeated one-way analysis of variance measurements were performed for the time of the ankle, knee and hip extensor concentric contraction in each group. The double peak curve was associated with larger jump height, reactive strength index modified, rate of force development, impulse, hip, knee and ankle flexion, extension angular displacement, and hip and knee moments (p<0.05). The double peak curve group revealed a better hip, knee and ankle (proximal to distal) timing of extensor concentric contractions sequence of the lower extremities during the countermovement jump (p<0.05). The double peak curve group exhibited a more effective countermovement jump movement with respect to biomechanics compared to the single peak curve group. [ABSTRACT FROM AUTHOR]

Background: Hip microinstability is an increasingly recognized source of hip pain and disability. Although the clinical entity has been well described, the pathomechanics of this disease remain poorly understood. Purpose/Hypothesis: The purpose of this study was to determine the role of capsular laxity in atraumatic hip microinstability. Our hypothesis was that cyclic stretching of the anterior hip capsule would result in increased hip range of motion and femoral head displacement. Study Design: Controlled laboratory study. Methods: In this study, 7 hip specimens met inclusion criteria (age, 18-46 years). Specimens were stripped of all soft tissue, aligned, cut, and potted by use of a custom jig. A materials testing system was used to cyclically stretch the anterior hip capsule in extension and external rotation while rotating about the mechanical axis of the hip. A motion tracking system was used to record hip rotation and displacement of the femoral head relative to the acetabulum in the anterior-posterior, medial-lateral, and superior-inferior directions. Testing was conducted at baseline, after venting, and after capsular stretching. Results: With the hip in anatomic neutral alignment, cyclic stretching of the anterior hip capsule resulted in increased hip rotation (P < .001). Femoral head displacement significantly increased relative to the vented state in the medial-lateral (P < .001), anterior-posterior (P = .013), and superior-inferior (P = .036) planes after cyclic stretching of the anterior hip capsule. Conclusion: The anterior hip capsule plays an important role in controlling hip rotation and femoral head displacement. This study is the first to display significant increases in femoral head displacement through a controlled cyclic stretching protocol of the anterior hip capsule. Clinical Relevance: This study is directly applicable to the treatment of atraumatic hip microinstability. The results quantitatively define the relative importance of the hip capsule in controlling femoral head motion. This allows for a better understanding of the pathophysiological process of hip microinstability and serves as a platform to develop effective surgical techniques for treatment of this disease. [ABSTRACT FROM AUTHOR]

Joint mechanical impedance is commonly measured by applying dynamic perturbations about a joint at a fixed operating point/background torque, and quantifying torque change vs. angle change. Impedance characterization in functional tasks, therefore, requires multiple experimental trials over a range of operating points-a cumbersome, invasive, time-consuming and impractical task. As an alternative, studies have related EMG to impedance, after which EMG can estimate impedance without applying joint perturbations. But, the cumbersome calibration trials are still required. We describe a method of single contraction perturbations in which the background torque slowly ramps over the operating range, with EMG simultaneously acquired. Using one such "quasi-static" contraction for model training and another for testing, we show this method to be a reasonable surrogate for traditional second-order, linear impedance modeling. A simple, short-duration calibration results. We compared our single-trial ramp method to multiple constant background torque trials at 10, 20, 30, and 40% maximum effort (extension and flexion), finding only limited differences in traditional vs. EMG-based ramp impedance estimates (12-22%, most prominent at the two lower contraction levels). Such constant force and slowly-variable force contractions are relevant to many practical applications, including ergonomics assessment, prosthetic control and clinical biomechanics. [ABSTRACT FROM AUTHOR]

Both foam rolling and joint distraction training with elastic bands are very popular interventions designed to improve muscular function, motor performance, and joint range of motion, as well as to reduce feeling of fatigue and delayed onset of muscle soreness. The heterogeneity of methods used among studies however prevents from drawing firm conclusions about the optimal content of pre/post interventions. The present study aims at answering the following questions: i) Do foam rolling and joint distraction with elastic band training improve joint range of motion in national rugby players? ii) Do short and long rolling durations have similar effects on range of motion? In a first experiment, we compared ankle, knee, and hip flexibility scores in 30 national rugby players after a 7-week foam rolling training program involving either a short (20s) or long (40s) rolling duration. Data revealed that foam rolling substantially improved all range of motion scores, regardless the rolling duration (performance gains ranged from 9 to 18° in the foam rolling groups, i.e. 8 to 20% increase, but remained under 2° in the control group). In a second experiment, we investigated the effect of a 5-week joint distraction with elastic band training program on hamstring and adductor range of motion in 23 national rugby players. Data showed that elastic band training significantly improved sit-and-reach (29.16% increase, p = 0.01) as well as side split (2.31% increase, p < 0.001) stretching performances. Taken together, present findings confirm that both foam rolling and joint distraction exercises with elastic bands are likely to enhance joint range of motion and specific mobility patterns during sport performance, and further serve prophylaxis. Such effects therefore constitute a promising avenue for clinical, home therapy, and personal flexibility training. [ABSTRACT FROM AUTHOR]

Abstract Background Biomechanical data in cerebral palsy are inherently variable but no optimal model of translational joint constraint has been identified. The primary aim of this study was to determine which model of translational joint constraint resulted in the lowest within-participant variability of lower limb joint angles and moments. The secondary aim was to determine which model best distinguished known functional groups in Cerebral Palsy. Methods Three models (three degrees of freedom, six degrees of freedom and six degrees of freedom with specified joint translation constraint) were applied to data from running trials of 40 children with cerebral palsy. Findings Joint angle standard deviations were largest using the six degrees of freedom model and smallest using the constrained six degrees of freedom model (p < 0.050). For all joints in all planes of motion, joint moment standard deviations were largest using the six degrees of freedom model and smallest using the constrained six degrees of freedom model; standard deviations using the constrained model were smaller than the three degrees of freedom model by 10–30% of moment magnitude (0.01–0.03 Nm/kg; p < 0.001). The six degrees of freedom models distinguished functional subgroups with larger effect size than the three degrees of freedom model only for hip power generation in swing. Interpretation A model with specified joint constraint minimized within-participant variability during running and was useful for detecting differences in functional capacity in cerebral palsy. Highlights • A 6DoF biomechanical model with customised joint constraints is described. • Customised joint translation constraints decrease extrinsic variability. • This results in a larger effect size for hip power generation in swing. [ABSTRACT FROM AUTHOR]