Differences in Lower-Extremity Joint Coordination During Two Landing Phases of a Drop Jump Task.

Musculoskeletal injuries often occur during the execution of dynamic sporting tasks that involve rotation. The prescription of appropriate prevention strategies of musculoskeletal injury relies on assessments to identify risk, but current assessment tools focus on uniplanar movements. The purpose of this paper is to demonstrate the utility of the unilateral 180° jump as a potential assessment tool for injury risk in the lower body by (1) providing descriptive kinematics of the knee, thigh, and pelvis (2) conducting inter-segmental coordination analysis, and (3) comparing the knee kinematics between the dominant and non-dominant limb (NDL) during the loading (LOP) and landing phase (LAP). Elite rugby players completed one session, performing five 180° unilateral jumps on each limb while collecting kinematic data. Independent t-tests were used to compare peak angles of DL and NDL. Continuous Relative Phase (CRP) plots were constructed for thorax and pelvis in the transverse plane. At the loading phase, the non-dominant limb had greater peak knee abduction (ABD) (p = 0.01). At the landing phase, the dominant limb had greater peak knee adduction (ADD) (p = 0.05). At the landing phase, the non-dominant limb had greater peak knee ABD (p = 0.01). CRP plots indicate participants can utilize a thorax-led, pelvis-led, or synchronized rotational method. Bilateral asymmetries were observed, indicated by significant differences in the bilateral landing phase peak ADD/ABD, which is of particular interest considering all participants were healthy. Therefore, additional research is needed to determine thresholds for injury risk during rotational tasks.

To investigate the association between lower extremity alignment during unilateral and bilateral drop jump tests and the risk of acute noncontact knee or ankle injuries in young team sport athletes. Prospective cohort study. A 2-dimensional video analysis was used to measure the frontal plane knee projection angle in the single-leg vertical drop jump (VDJ) and the bilateral VDJ in young team sport athletes. Out of the 364 athletes (187 male, 177 female), 189 played basketball and 175 played floorball. Six male athletes sustained knee injuries and 23 sustained ankle injuries. Frontal plane knee projection angle in the single-leg VDJ or the bilateral VDJ was not associated with ankle injuries among male athletes. No statistical analysis was performed for the knee injuries. Among female athletes, 28 sustained knee and 41 sustained ankle injuries. Frontal plane knee projection angle during the single-leg VDJ or the bilateral VDJ was not a risk factor for knee or ankle injuries. Lower extremity alignment during unilateral and bilateral drop jump tests was not associated with future noncontact knee or ankle injuries among young team sport athletes. The findings should be interpreted cautiously due to the small number of injuries. J Orthop Sports Phys Ther 2020;50(5):267-274. doi:10.2519/jospt.2020.9247.

Stress urinary incontinence (SUI) symptoms can be provoked during impact loads such as vertical jumps. To investigate and compare pelvic floor muscle (PFM) activity in women with SUI and continent women (CON) during drop jumps (DJ) and counter movement jumps (CMJ) could clarify the activity of the PFMs during impact loads. A tripolar vaginal probe was used to record surface electromyographic (EMG) activity of the PFMs during DJ and CMJ. Time intervals of 30ms were used to parameterize data from 30ms before (pre-activity) to 150ms after (reflex activity) ground contact on a force plate during the landing and take-off phase. EMG signals were normalized to the mean of the peak values of two maximal voluntary contractions (MVC) and expressed in percentage (% MVC). For all time intervals during the landing and take-off phase, no statistically significant differences could be found between women with SUI and CON. EMG values exceeded 100% MVC for all time intervals during all landing and take-off phases. Maximal PFM activation was measured during the first landing of DJ and was 404.1% MVC for SUI and 370.2% MVC for CON. Vertical jumps seem to stimulate pre-activity before and reflex activity after ground contact during the landing phase and activate PFMs up to 400% MVC. Jumping stimuli inducing involuntary PFM contraction could show a beneficial factor to be integrated in a PFM rehabilitation program.

Recreational and sporting injury to the adolescent knee and ankle: Prevalence and causes

Background: Musculoskeletal injuries have a substantial impact on athletes, affecting sports performance and increasing the risk of future musculoskeletal disorders (e.g., osteoarthritis). Injury prevention programs are essential to reduce the risk of sport-related injuries and meta-analyses can provide a large amount of information in a single article. Objective: To summarize the pooled effects of injury prevention programs focused on any form of physical exercise in the incidence and risk of musculoskeletal injuries and reinjuries by sports and musculoskeletal body regions. Methods: The CINAHL (via EBSCOhost), Embase (via Elsevier), Epistemonikos, PubMed, Scopus, SPORTDiscus (via EBSCOhost), and the Cochrane Library e-databases were searched from inception to 7 October 2024. Systematic reviews with meta-analyses of randomized clinical trials were considered. The methodological quality of systematic reviews was assessed with AMSTAR 2. The degree of overlap between meta-analyses of interest was calculated. Results: Fourteen systematic reviews were included. Thirteen of these reviews were focused on soccer. Overall, meta-analyses including a specific injury prevention program (FIFA 11+ and FIFA 11+ kids) found that these programs may reduce the risk of musculoskeletal injuries among soccer players. Concretely, FIFA 11+ may reduce the risk of ankle, knee, hip/groin, and hamstring injuries, whereas FIFA 11+ kids may decrease the risk of ankle and knee injuries. Conclusions: FIFA 11+ and FIFA 11+ kids may reduce the risk of sports musculoskeletal injuries, mainly in the lower limbs. However, many clinical and methodological issues (e.g., the lack of meta-analyses in many types of sports) were discussed and highlighted the difficulty of making robust clinical recommendations with the current data.

Parkinson’s disease (PD) is a progressive neurodegenerative disease associated with motor impairments. Deep brain stimulation (DBS) is associated with vast improvements in the motor symptoms of PD. Recent evidence has identified improvements in movement complexity during treadmill walking in response to DBS [1]. However, the effects of DBS on gait coordination have not been well elucidated. PURPOSE: to evaluate the effects of DBS on ankle and knee joint coordination and coordination variability during a treadmill walking task. METHODS: Five individuals with PD performed a four-minute treadmill walking task while 3D kinematics were collected over two 30-s periods. Participants completed testing in the DBS-ON followed by DBS-OFF conditions to avoid the confounding factor of fatigue. Kinematics were recorded simultaneously using an 9-camera motion capture system (120 Hz, Qualisys Inc., Goteburg, Sweden). Visual 3D was used to calculate segmental angles and velocities. Custom software (MATLAB, MathWorks) calculated continuous relative phase angles. Mean absolute relative phase (MARP) and deviation phase (DP) were used to quantify joint coordination (MARP) and coordination variability (DP). A paired samples t-test was used to determine the effects of DBS on MARP and DP. RESULTS: At the ankle, DBS was associated with greater MARP values (p=0.016; DBS-ON: 3.2±1.5; DBS-OFF: 2.1±0.9) and DP values (p=0.047; DBS-ON: 2.2±1.0; DBS-OFF: 1.4±0.4). At the knee, DBS was associated with greater MARP (p=0.021; DBS-ON: 6.8±2.8; DBS-OFF: 5.1±2.8) and DP values (p=0.045; DBS-ON: 2.9±1.5; DBS-OFF: 2.0±0.6). CONCLUSIONS: DBS allows individuals with PD to perform walking tasks with greater freedom of coordination and coordination variability. Increased availability of coordinative patterns may represent a greater number of successful strategies available to the system to optimize mechanical and metabolic efficiency during walking. [1] Powell, Blackmore, Puppa, Lester, Murray, Reed-Jones, Xia 2018.

Given the number of muscles and joints of the arm, more ways are available to produce an identical hand movement when pointing to a target than are strictly necessary. How the nervous system manages these abundant degrees of freedom was the focus of this study of pointing to targets of low and high indices of difficulty (ID). Two essential features of movement synergies were examined. The first reflects the preferred relations among the outputs of each movement element and was studied through principal component analysis. The second feature of synergy reflects the flexibility of those relationships evidenced by the use of multiple, goal-equivalent solutions to joint coordination. This second feature, which is the main focus of this report, was studied using the uncontrolled manifold approach. Motor abundance was defined operationally as the component of variance of joint combinations that left unchanged the value of important performance variables (goal-equivalent variability, GEV). This variance component was contrasted with the component of variance leading to a change in the value of these variables (non-goal-equivalent variability, NGEV). The difference between GEV and NGEV was evaluated with respect to the performance variables movement extent, movement direction, and path of the arm's center of mass. More than 90% of the variance of joint motions across the pointing trial were accounted for by one principal component, indicating a consistent temporal coupling among most joint motions in a single functional synergy. The flexible nature of this synergy was revealed by the variability analysis. All subjects had significantly higher GEV than NGEV for most of the movement path. Thus, variable patterns of joint coordination did not represent noise but the use of equivalent coordinative solutions related to stabilizing important performance variables. Higher GEV than NGEV was present regardless of the task's ID. One exception was at the time of peak velocity, leading to poorer control of movement extent than movement direction. Increasing the task's ID led to an overall reduction of joint configuraion variance, particularly GEV. These results support earlier work indicating that the use of goal-equivalent solutions to joint coordination is a common feature of the control of this and many other motor tasks. Functionally important performance variables appear to be controlled through flexible but task-specific coordination among the motor elements.

Curve analyses reveal altered knee, hip, and trunk kinematics during drop–jumps long after anterior cruciate ligament rupture

PurposeTo investigate the relationship between the biomechanical characteristics of lower extremity and anterior cruciate ligament (ACL) loading during single-leg landing in patients with chronic ankle instability (CAI) who have different ankle sprain frequencies within a year.Study DesignCross-sectional study; Level of evidence, 3.MethodsThe incidence of ankle sprains among 74 male participants was meticulously documented over a one-year period. The participants had an average age of 21.78 years, a height of 176.37 cm, and a weight of 72.61 kg. Subsequently, a one-year monitoring period was implemented to assess the incidence of ankle sprains among the participants. The participants were classified into five groups according to their documented frequency of ankle sprains. The categories were as follows: The 2, 3, 4, 5, and 6 or more ankle sprain groups. Kinematic, kinetic, and electromyographic data were collected while participants performed a single-leg landing task. Lower extremity muscle force and ACL loading were modeled using OpenSim software.ResultsCAI patients with more than four ankle sprains had higher peak ACL loading during single-leg landing than those with only two or three ankle sprains (P < 0.05). Additionally, CAI patients with more than four ankle sprains exhibited a limited range of ankle dorsiflexion and biceps femoris muscle force, which was significantly correlated with ACL loading (P < 0.05). CAI patients with more than 5 ankle sprains had greater ankle inversion angle, inversion angular velocity, vertical ground reaction force (GRF), rectus femoris muscle strength, and lower gastrocnemius, soleus muscle force during single-leg landing, and these biomechanical indices were significantly correlated with ACL strain (P < 0.05).ConclusionBased on these findings, it appears that experiencing four ankle sprains within a year might be a threshold for the development of knee compensation in CAI patients. This compensation could result in a significant increase in ACL loading. The study also found that CAI patients with more than four ankle sprains commonly exhibited altered motor characteristics such as limited ankle dorsiflexion angle, increased ankle inversion angle, excessive vertical GRF, and insufficient gastrocnemius and soleus muscle force during the landing phase. These characteristics might be responsible for the observed increase in ACL loading. In the future, clinical practice and scientific research may benefit from targeted interventions to prevent ACL injuries in CAI patients with different sprain histories, in accordance with the findings of this study.

ObjectiveTo investigate if a combination of an online and onsite implementation strategy was superior to an online-only strategy in enhancing the use of an injury prevention exercise programme (IPEP) and...

Moir, GL, Munford, SN, Snyder, BW, and Davis, SE. Mechanical differences between adolescents and adults during two landing phases of a drop jump task. J Strength Cond Res XX(X): 000-000, 2020-The mechanical differences between the first and second landing phases of a drop jump (DJ) task performed by adolescent and adult male players were investigated. Eleven adolescent basketball players (age: 16.5 ± 0.7 years) and 11 resistance-trained adults (age: 22.3 ± 1.9 years) performed DJs from a height of 0.40 m. Force plates and a 3-dimensional motion analysis system were used to determine mechanical variables, including landing velocity, normalized vertical stiffness, normalized peak impact force, and work as well as mechanical characteristics of the hip, knee, and ankle joints during the absorption phase of each landing. The adolescents produced greater peak impact forces (mean difference [xDiff] = 42 N·kg; effect size [ES] = 1.15) and vertical stiffness (xDiff = 126 N·kg·m; ES = 1.28) during shorter absorption phases (xDiff = 0.09 seconds; ES = 2.67) compared with the adults, despite their lower landing velocities (xDiff = 0.21 m·s; ES = 1.37). Furthermore, the adolescents generated greater peak extensor joint moments at the lower-body joints compared with the adults (xDiff = 2.3 N·m·kg; ES = 1.17), but they did not effectively modulate the energy absorbed by the joint moments in response to the changing demands of the landing tasks. The assessment of the biomechanical characteristics of the 2 landing phases associated with a DJ task revealed that adolescent male basketball players adopt neuromuscular strategies that may increase the risk of incurring musculoskeletal injuries compared with resistance-trained adults.

ObjectivesThis study examines the incidence of ankle injuries and identifies ankle injury risk among contemporary preprofessional dancers.MethodsA total of 91 first-year contemporary preprofessional dancers were prospectively followed during one academic...

ABSTRACTThis study investigates how interlimb joint coordination influences foot speed during soccer instep kicking, using continuous relative phase (CRP) as a quantitative method. The sample includes 15 elite and 15 amateur players to examine potential differences in coordination patterns and their impact on performance. Specifically, we focused on the coordination between hip, knee, and ankle joints in the forefoot‐back kicking motion. Results indicated that elite players exhibited significantly higher hip‐knee CRP in the coronal plane during 62%–81% of movement duration (p = 0.015) and higher knee‐ankle CRP in the vertical plane during 78%–100% (p = 0.013). Moreover, elite players had significantly greater hip‐knee mean absolute relative phase (MARP) and deviation phase (DP) in the coronal plane (p < 0.001), as well as increased knee‐ankle DP (p = 0.04). In the horizontal plane, hip‐knee MARP was also greater in the elite players compared to amateurs (p < 0.001). Further analysis revealed a significant negative correlation between hip‐knee CRP and foot velocity in the sagittal plane (R = −0.66, p < 0.001), whereas a significant positive correlation was observed between knee‐ankle CRP and foot velocity in the horizontal plane (R = 0.56, p = 0.002). These findings suggest that elite players have superior joint coordination, which contributes to a faster foot velocity at the moment of ball impact. Understanding these coordination patterns provides valuable insights into optimizing kicking techniques. The findings of this study suggest that joint coordination may play an important role in enhancing kicking foot speed, which could inform future training approaches aimed at improving soccer performance.

This study was aimed to compare the variability of inter-joint coordination in the lower-extremities during gait between active individuals with transtibial amputation (TTAs) and healthy individuals (HIs). Fifteen active male TTAs (age: 40.6 ± 16.24 years, height: 1.74 ± 0.09 m, and mass: 71.2 ± 8.87 kg) and HIs (age: 37.25 ± 13.11 years, height: 1.75 ± 0.06 m, and mass: 74 ± 8.75 kg) without gait disabilities voluntarily participated in the study. Participants walked along a level walkway covered with Vicon motion capture system, and their lower-extremity kinematics data were recorded during gait. The spatiotemporal gait parameters, lower-extremity joint range of motion (ROM), and their coordination and variability were calculated and averaged to report a single value for each parameter based on biomechanical symmetry assumption in the lower limbs of HIs. Additionally, these parameters were separately calculated and reported for the intact limb (IL) and the prosthesis limb (PL) in TTAs individuals. Finally, a comparison was made between the averaged values in HIs and those in the IL and PL of TTAs subjects. The results showed that the IL had a significantly lower stride length than that of the PL and averaged value in HIs, and the IL had a significantly lower knee ROM and greater stance-phase duration than that of HIs. Moreover, TTAs showed different coordination patterns in pelvis-to-hip, hip-to-knee, and hip-to-ankle couplings in some parts of the gait cycle. It concludes that the active TTAs with PLs walked with more flexion of the knee and hip, which may indicate a progressive walking strategy and the differences in coordination patterns suggest active TTA individuals used different neuromuscular control strategies to adapt to their amputation. Researchers can extend this work by investigating variations in these parameters across diverse patient populations, including different amputation etiologies and prosthetic designs. Moreover, Clinicians can use the findings to tailor rehabilitation programs for TTAs, emphasizing joint flexibility and coordination.

This study sought to assess the relationship between different jumping asymmetries and associated performance variables in high-level male senior and professional football players. Nineteen football players with at least 12 years of training experience (23.2 ± 3.1 years of age; 75.2 ± 4.8 kg of body mass and 181 ± 0.06 cm of height) participated in this study performing countermovement jump (CMJ), squat jump (SJ), single-leg CMJ and drop jump (DJ), associated performance variable eccentric utilization ratio (EUR), stretch-shortening cycle (SSC), bilateral deficit (BLD), and limb symmetry index (LSI) were determined. High correlations were observed between different methodologies of jump tests and associated performance indicators (SSC, BLD, EUR), except LSI. Moreover, CMJ and SJ results were different (p < 0.05), but no differences were found between interlimb in CMJ (p = 0.19) and DJ (p = 0.14). Between the same limbs and different jumps differences were detected in CMJ and DJ (p < 0.01), and it has also been found that the laterality effect size on strength was small in CMJ (ES = 0.30) and DJ (ES = 0.35). LSI between CMJ and DJ was not different despite higher mean values in CMJ, and although mean BLD was positive (>100%), the results highlight the need for individual evaluation since eight players scored negatively. An in-depth and accurate analysis of performance in preseason screening jump tests should be considered, aiming to detect injury risk, specifically evaluating different jumping test methodologies, and determining jumping associated performance variables for each test, namely EUR, SSC, BLD, and LSI. Specific muscle-strengthening exercises could be implemented based on this study results and outcomes, aiming to reduce injury risks and lower extremity asymmetries and to enhance individual football performance in high-level male senior and professional football players. Sports institutions should pay special attention regarding potential health problems in athletes exposed to daily high training loads.