Lower Extremity Movement Patterns Research Articles

Does Deep Squat Quality Affect the Propulsion of Baseball Throwing?

This study investigates the influence of the quality of the "deep squat" movement, adapted from the Functional Movement Screen (FMS) system, on the lower extremity movement pattern during baseball throwing, and its potential impact on throwing performance and propulsion efficiency. Twenty-two baseball players were recruited and categorized into two groups: 13 in the high-score squat group (HSS) and 9 in the low-score squat group (LSS), based on their deep squat screening results. This research explored disparities in ball velocity, propulsion efficiency, propulsion ground reaction force (GRF) characteristics, and throwing kinematics between these two groups. The findings revealed no significant difference in ball velocity between the groups. However, the LSS group demonstrated a lower propulsion GRF efficiency (p < 0.030, ES = 0.46), along with a higher vertical peak GRF (p < 0.002, ES = 0.66). In the pivot leg, the HSS group exhibited significantly lower impulse forces in the Impulse Fresultant (p < 0.035, ES = 0.45), throwing direction (p < 0.049, ES = 0.42), and vertical direction (p < 0.048, ES = 0.42). Additionally, the contribution to the ball velocity of the pivot leg was significantly greater in the HSS group, along with significantly better efficiency in Impulse Fresultant (p < 0.035, ES = 0.45), throwing direction (p < 0.053, ES = 0.41), and vertical direction (p < 0.032, ES = 0.46). In the leading leg, the HSS group demonstrated significantly lower impulse forces in the Impulse Fresultant (p < 0.001, ES = 0.69), throwing direction (p < 0.007, ES = 0.58), and vertical direction (p < 0.001, ES = 0.70). Moreover, the contribution to the ball velocity of the leading leg was significantly greater in the HSS group, accompanied by significantly better efficiency in Impulse Fresultant (p < 0.003, ES = 0.63), throwing direction (p < 0.005, ES = 0.60), and vertical direction (p < 0.021, ES = 0.49). In conclusion, this study suggests that squat screening is a valuable tool for assessing propulsion efficiency. Coaches and trainers should be mindful of players with low squat quality but high throwing performance, as they may face increased impact and injury risks in the future.

Unexpected inversion perturbation during a single-leg landing in patients with chronic ankle instability

ABSTRACT It remains unclear how unexpected perturbations during single-leg landings affect lower extremity kinematics and muscle activations in patients with chronic ankle instability (CAI). The purpose of this study was to identify the differences in lower extremity movement patterns among CAI subjects, copers, and healthy controls. Sixty-six people including 22 CAI subjects, 22 copers, and 22 healthy controls volunteered to participate in the study. Lower extremity joint kinematics and EMG activations from 200-ms pre to 200-ms post the initial contact during unexpected tilted landings were measured. Functional data analysis was used to evaluate between-group differences for outcome measures. Relative to copers and healthy controls, CAI subjects showed more inversion from 40-ms to 200-ms after initial contact. Relative to healthy controls, CAI subjects and copers showed more dorsiflexion. Relative to healthy controls, CAI subjects and copers showed more muscle activation in tibialis anterior and peroneus longus, respectively. In conclusion, CAI subjects demonstrated greater inversion angles and muscle activation before initial contact compared to LAS copers and healthy controls. This suggests that CAI subjects and copers prepare for their landing with protective movements, but the prepared movements shown by CAI subjects may be insufficient to reduce risk of recurrent injury.

Altered Running Biomechanics in Youth Soccer Players with a Lateral Ankle Sprain History

PURPOSE This study aimed to identify movement pattern differences in the running of youth soccer players with and without lateral ankle sprain (LAS) histories. METHODS A total of 12 participants were recruited and assigned to the LAS group or the control group. All participants were assessed for anthropometric data, and they filled in the subjective ankle function questionnaires. Then, reflective markers were attached to their bodies, and they were instructed to run at the preferred speed on the 9-m runway thrice. 3D joint angles for ankle, knee, and hip joints were exported, and their mean values and 95% confidence intervals were calculated. Ensemble curve analysis was conducted to compare running kinematics between the groups. RESULTS The LAS group exhibited fewer dorsiflexion angles and more inversion angles compared to the control group. Excluding the dorsiflexion deficits and more inverted ankles, there were no significant differences between the groups. CONCLUSIONS Although the ankle kinematic patterns found in this paper are not considered LAS risk factors, it will be able to identify precise LAS risk factors with prospective design (e.g., lower extremity movement patterns) as well as intrinsic risk factors.

Trunk and Lower Extremity Movement Patterns, Stress Fracture Risk Factors, and Biomarkers of Bone Turnover in Military Trainees.

Military service members commonly sustain lower extremity stress fractures (SFx). How SFx risk factors influence bone metabolism is unknown. Understanding how SFx risk factors influence bone metabolism may help to optimize risk-mitigation strategies. To determine how SFx risk factors influence bone metabolism. Cross-sectional study. Military service academy. Forty-five men (agepre = 18.56 ± 1.39 years, heightpre = 176.95 ± 7.29 cm, masspre = 77.20 ± 9.40 kg; body mass indexpre = 24.68 ± 2.87) who completed Cadet Basic Training (CBT). Individuals with neurologic or metabolic disorders were excluded. We assessed SFx risk factors (independent variables) with (1) the Landing Error Scoring System (LESS), (2) self-reported injury and physical activity questionnaires, and (3) physical fitness tests. We assessed bone biomarkers (dependent variables; procollagen type I amino-terminal propeptide [PINP] and cross-linked collagen telopeptide [CTx-1]) via serum. A markerless motion-capture system was used to analyze trunk and lower extremity biomechanics via the LESS. Serum samples were collected post-CBT; enzyme-linked immunosorbent assays determined PINP and CTx-1 concentrations, and PINP : CTx-1 ratios were calculated. Linear regression models demonstrated associations between SFx risk factors and PINP and CTx-1 concentrations and PINP : CTx-1 ratio. Biomarker concentration mean differences with 95% confidence intervals were calculated. Significance was set a priori using α ≤ .10 for simple and α ≤ .05 for multiple regression analyses. The multiple regression models incorporating LESS and SFx risk factor data predicted the PINP concentration (R2 = 0.47, P = .02) and PINP : CTx-1 ratio (R2 = 0.66, P = .01). The PINP concentration was increased by foot internal rotation, trunk flexion, CBT injury, sit-up score, and pre- to post-CBT mass changes. The CTx-1 concentration was increased by heel-to-toe landing and post-CBT mass. The PINP : CTx-1 ratio was increased by foot internal rotation, lower extremity sagittal-plane displacement (inversely), CBT injury, sit-up score, and pre- to post-CBT mass changes. Stress fracture risk factors accounted for 66% of the PINP : CTx-1 ratio variability, a potential surrogate for bone health. Our findings provide insight into how SFx risk factors influence bone health. This information can help guide SFx risk-mitigation strategies.

Progressive Changes in Walking Kinematics and Kinetics After Anterior Cruciate Ligament Injury and Reconstruction: A Review and Meta-Analysis.

Anterior cruciate ligament (ACL) injury and ACL reconstruction (ACLR) result in persistent alterations in lower extremity movement patterns. The progression of lower extremity biomechanics from the time of injury has not been described. To compare the 3-dimensional (3D) lower extremity kinematics and kinetics of walking among individuals with ACL deficiency (ACLD), individuals with ACLR, and healthy control participants from 3 to 64 months after ACLR. We searched PubMed and Web of Science from 1970 through 2013. We selected only articles that provided peak kinematic and kinetic values during walking in individuals with ACLD or ACLR and comparison with a healthy control group or the contralateral uninjured limb. A total of 27 of 511 identified studies were included. Weighted means, pooled standard deviations, and 95% confidence intervals were calculated for the healthy control, ACLD, and ACLR groups at each reported time since surgery. The magnitude of between-groups (ACLR versus ACLD, control, or contralateral limb) differences at each time point was evaluated using Cohen d effect sizes and associated 95% confidence intervals. Peak knee-flexion angle (Cohen d = -0.41) and external knee-extensor moment (Cohen d = -0.68) were smaller in the ACLD than in the healthy control group. Peak knee-flexion angle (Cohen d range = -0.78 to -1.23) and external knee-extensor moment (Cohen d range = -1.39 to -2.16) were smaller in the ACLR group from 10 to 40 months after ACLR. Reductions in external knee-adduction moment (Cohen d range = -0.50 to -1.23) were present from 9 to 42 months after ACLR. Reductions in peak knee-flexion angle, external knee-flexion moment, and external knee-adduction moment were present in the ACLD and ACLR groups. This movement profile during the loading phase of gait has been linked to knee-cartilage degeneration and may contribute to the development of osteoarthritis after ACLR.

The effect of performance demands on lower extremity biomechanics during landing and cutting tasks

BackgroundAnterior cruciate ligament (ACL) injuries commonly occur during the early phase of landing and cutting tasks that involve sudden decelerations. The purpose of this study was to investigate the effects of jump height and jump speed on lower extremity biomechanics during a stop-jump task and the effect of cutting speed on lower extremity biomechanics during a side-cutting task. MethodsThirty-six recreational athletes performed a stop-jump task under 3 conditions: jumping fast, jumping for maximum height, and jumping for 60% of maximum height. Participants also performed a side-cutting task under 2 conditions: cutting at maximum speed and cutting at 60% of maximum speed. Three-dimensional kinematic and kinetic data were collected. ResultsThe jumping fast condition resulted in increased peak posterior ground reaction force (PPGRF), knee extension moment at PPGRF, and knee joint stiffness and decreased knee flexion angle compared with the jumping for maximum height condition. The jumping for 60% of maximum height condition resulted in decreased knee flexion angle compared with the jumping for maximum height condition. Participants demonstrated greater PPGRF, knee extension moment at PPGRF, knee valgus angle and varus moment at PPGRF, knee joint stiffness, and knee flexion angle during the cutting at maximum speed condition compared with the cutting at 60% maximum speed condition. ConclusionPerforming jump landing at an increased jump speed resulted in lower extremity movement patterns that have been previously associated with an increase in ACL loading. Cutting speed also affected lower extremity biomechanics. Jump speed and cutting speed need to be considered when designing ACL injury risk screening and injury prevention programs.

The Comparative Analysis of Lower Extremity Movement Pattern in Vertical Jumps between Taekwondo Demonstration Members and Healthy Young Men

The Comparative Analysis of Lower Extremity Movement Pattern in Vertical Jumps between Taekwondo Demonstration Members and Healthy Young Men

Predictive Neuromuscular Fatigue of the Lower Extremity Utilizing Computer Modeling.

This paper studies the modeling of lower extremity muscle forces and their correlation to neuromuscular fatigue. Two analytical fatigue models were combined with a musculoskeletal model to estimate the effects of hamstrings fatigue on lower extremity muscle forces during a side step cut. One of the fatigue models (Tang) used subject-specific knee flexor muscle fatigue and recovery data while the second model (Xia) used previously established fatigue and recovery parameters. Both fatigue models were able to predict hamstrings fatigue within 20% of the experimental data, with the semimembranosus and semitendinosus muscles demonstrating the largest (11%) and smallest (1%) differences, respectively. In addition, various hamstrings fatigue levels (10-90%) on lower extremity muscle force production were assessed using one of the analytical fatigue models. As hamstrings fatigue levels increased, the quadriceps muscle forces decreased by 21% (p < 0.01), while gastrocnemius muscle forces increased by 36% (p < 0.01). The results of this study validate the use of two analytical fatigue models in determining the effects of neuromuscular fatigue during a side step cut, and therefore, this model can be used to assess fatigue effects on risk of lower extremity injury during athletic maneuvers. Understanding the effects of fatigue on muscle force production may provide insight on muscle group compensations that may lead to altered lower extremity motion patterns as seen in noncontact anterior cruciate ligament (ACL) injuries.

Ankle dorsiflexion among healthy men with different qualities of lower extremity movement.

Lower extremity movement patterns have been implicated as a risk factor for various knee disorders. Ankle-dorsiflexion (DF) range of motion (ROM) has previously been associated with a faulty movement pattern among healthy female participants. To determine the association between ankle DF ROM and the quality of lower extremity movement during the lateral step-down test among healthy male participants. Cross-sectional study. Training facility of the Israel Defense Forces. Fifty-five healthy male Israeli military recruits (age = 19.7 ± 1.1 years, height = 175.4 ± 6.4 cm, mass = 72.0 ± 7.6 kg). Dorsiflexion ROM was measured in weight-bearing and non-weight-bearing conditions using a fluid-filled inclinometer and a universal goniometer, respectively. Lower extremity movement pattern was assessed visually using the lateral step-down test and classified categorically as good or moderate. All measurements were performed bilaterally. Weight-bearing and non-weight-bearing DF ROM were more limited among participants with moderate quality of movement than in those with good quality of movement on the dominant side (P = .01 and P = .02 for weight-bearing and non-weight-bearing DF, respectively). Non-weight-bearing DF demonstrated a trend toward a decreased range among participants with moderate compared with participants with good quality of movement on the nondominant side (P = .03 [adjusted P = .025]). Weight-bearing DF was not different between participants with good and moderate movement patterns on the nondominant side (P = .10). Weight-bearing and non-weight-bearing ankle DF ROM correlated significantly with the quality of movement on both sides (P < .01 and P < .05 on the dominant and nondominant side, respectively). Ankle DF ROM was associated with quality of movement among healthy male participants. The association seemed weaker in males than in females.

Influence of Ankle Injury on Muscle Activation and Postural Control During Ballet Grand Plié

Ballet deep squat with legs rotated externally (grand plié) is a fundamental movement for dancers. However, performing this task is a challenge to ankle control, particularly for those with ankle injury. Thus, the purpose of this study was to investigate how ankle sprains affect the ability of postural and muscular control during grand plié in ballet dancers. Thirteen injured dancers and 20 uninjured dancers performed a 15 second grand plié consisting of lowering, squatting, and rising phases. The lower extremity motion patterns and muscle activities, pelvic orientation, and center of pressure (COP) excursion were measured. In addition, a principal component analysis was applied to analyze waveforms of muscle activity in bilateral medial gastrocnemius, peroneus longus, and tibialis anterior. Our findings showed that the injured dancers had smaller pelvic motions and COP excursions, greater maximum angles of knee flexion and ankle dorsiflexion as well as different temporal activation patterns of the medial gastrocnemius and tibialis anterior. These findings suggested that the injured dancers coped with postural challenges by changing lower extremity motions and temporal muscle activation patterns.

Current Concepts for Injury Prevention in Athletes After Anterior Cruciate Ligament Reconstruction

Ligament reconstruction is the current standard of care for active patients with an anterior cruciate ligament (ACL) rupture. Although the majority of ACL reconstruction (ACLR) surgeries successfully restore the mechanical stability of the injured knee, postsurgical outcomes remain widely varied. Less than half of athletes who undergo ACLR return to sport within the first year after surgery, and it is estimated that approximately 1 in 4 to 1 in 5 young, active athletes who undergo ACLR will go on to a second knee injury. The outcomes after a second knee injury and surgery are significantly less favorable than outcomes after primary injuries. As advances in graft reconstruction and fixation techniques have improved to consistently restore passive joint stability to the preinjury level, successful return to sport after ACLR appears to be predicated on numerous postsurgical factors. Importantly, a secondary ACL injury is most strongly related to modifiable postsurgical risk factors. Biomechanical abnormalities and movement asymmetries, which are more prevalent in this cohort than previously hypothesized, can persist despite high levels of functional performance, and also represent biomechanical and neuromuscular control deficits and imbalances that are strongly associated with secondary injury incidence. Decreased neuromuscular control and high-risk movement biomechanics, which appear to be heavily influenced by abnormal trunk and lower extremity movement patterns, not only predict first knee injury risk but also reinjury risk. These seminal findings indicate that abnormal movement biomechanics and neuromuscular control profiles are likely both residual to, and exacerbated by, the initial injury. Evidence-based medicine (EBM) strategies should be used to develop effective, efficacious interventions targeted to these impairments to optimize the safe return to high-risk activity. In this Current Concepts article, the authors present the latest evidence related to risk factors associated with ligament failure or a secondary (contralateral) injury in athletes who return to sport after ACLR. From these data, they propose an EBM paradigm shift in postoperative rehabilitation and return-to-sport training after ACLR that is focused on the resolution of neuromuscular deficits that commonly persist after surgical reconstruction and standard rehabilitation of athletes.

Prevention of ACL Injury, Part II: Effects of ACL Injury Prevention Programs on Neuromuscular Risk Factors and Injury Rate

Prevention strategies have been developed based on existing knowledge in an attempt to alter neuromuscular control and lower extremity biomechanics in order to reduce anterior cruciate ligament (ACL) injury rates. These strategies have included different training programs ranging from injury education to multicomponent training. Many training programs have been demonstrated as resulting in altered lower extremity movement patterns. The effects of current training programs on ACL injury rate, however, are inconsistent. This review was focused on the effects of current ACL injury training programs on neuromuscular risk factors and ACL injury rate. Recommendations were made based on the available evidence for clinicians and coaches to implement ACL injury prevention programs.

Biomechanical risk factors of non-contact ACL injuries: A stochastic biomechanical modeling study

Significant efforts have been made to identify modifiable risk factors of non-contact anterior cruciate ligament (ACL) injuries in male and female athletes. However, current literature on the risk factors for ACL injury are purely descriptive. An understanding of biomechanical relationship between risk and risk factors of the non-contact ACL injury is necessary to develop effective prevention programs. To compare lower extremity kinematics and kinetics between trials with and without non-contact ACL injuries and to determine if any difference exists between male and female trials with non-contact ACL injuries regarding the lower extremity motion patterns. In this computer simulation study, a stochastic biomechanical model was used to estimate the ACL loading at the time of peak posterior ground reaction force (GRF) during landing of the stop-jump task. Monte Carlo simulations were performed to simulate the ACL injuries with repeated random samples of independent variables. The distributions of independent variables were determined from in vivo laboratory data of 40 male and 40 female recreational athletes. In the simulated injured trials, both male and female athletes had significantly smaller knee flexion angles, greater normalized peak posterior and vertical GRF, greater knee valgus moment, greater patella tendon force, greater quadriceps force, greater knee extension moment, and greater proximal tibia anterior shear force in comparison to the simulated uninjured trials. No significant difference was found between genders in any of the selected biomechanical variables in the trials with simulated non-contact ACL injuries. Small knee flexion angle, large posterior GRF, and large knee valgus moment are risk factors of non-contact ACL injury determined by a stochastic biomechanical model with a cause-and-effect relationship.

Two Different Fatigue Protocols and Lower Extremity Motion Patterns During a Stop-Jump Task

Altered neuromuscular control strategies during fatigue probably contribute to the increased incidence of noncontact anterior cruciate ligament injuries in female athletes. To determine biomechanical differences between 2 fatigue protocols (slow linear oxidative fatigue protocol [SLO-FP] and functional agility short-term fatigue protocol [FAST-FP]) when performing a running-stop-jump task. Controlled laboratory study. Laboratory. A convenience sample of 15 female soccer players (age = 19.2 ± 0.8 years, height = 1.67 ± 0.05 m, mass = 61.7 ± 8.1 kg) without injury participated. Five successful trials of a running-stop-jump task were obtained prefatigue and postfatigue during the 2 protocols. For the SLO-FP, a peak oxygen consumption (Vo(2)peak) test was conducted before the fatigue protocol. Five minutes after the conclusion of the Vo(2)peak test, participants started the fatigue protocol by performing a 30-minute interval run. The FAST-FP consisted of 4 sets of a functional circuit. Repeated 2 (fatigue protocol) × 2 (time) analyses of variance were conducted to assess differences between the 2 protocols and time (prefatigue, postfatigue). Kinematic and kinetic measures of the hip and knee were obtained at different times while participants performed both protocols during prefatigue and postfatigue. Internal adduction moment at initial contact (IC) was greater during FAST-FP (0.064 ± 0.09 Nm/kgm) than SLO-FP (0.024 ± 0.06 Nm/kgm) (F(1,14) = 5.610, P = .03). At IC, participants had less hip flexion postfatigue (44.7° ± 8.1°) than prefatigue (50.1° ± 9.5°) (F(1,14) = 16.229, P = .001). At peak vertical ground reaction force, participants had less hip flexion postfatigue (44.7° ± 8.4°) than prefatigue (50.4° ± 10.3°) (F(1,14) = 17.026, P = .001). At peak vertical ground reaction force, participants had less knee flexion postfatigue (-35.9° ± 6.5°) than prefatigue (-38.8° ± 5.03°) (F(1,14) = 11.537, P = .001). Our results demonstrated a more erect landing posture due to a decrease in hip and knee flexion angles in the postfatigue condition. The changes were similar between protocols; however, the FAST-FP was a clinically applicable 5-minute protocol, whereas the SLO-FP lasted approximately 45 minutes.

Knee instability after acute ACL rupture affects movement patterns during the mid‐stance phase of gait

The purpose of this study was to identify gait asymmetries during the mid-stance phase of gait among subjects with knee instability ("non-copers") after acute anterior cruciate ligament (ACL) rupture. Twenty-one non-copers with acute, isolated ACL injury ambulated at their intentional walking speed as kinetic, kinematic, and electromyographic (EMG) data were collected bilaterally. Lower extremity movement patterns and muscle activity were analyzed during the mid-stance and weight acceptance phases of stance. When compared to the uninjured limb, subjects exhibited lower sagittal plane knee excursions and peak knee angles, and higher muscle co-contraction on the injured limb. There was a lower knee flexion moment at peak knee extension, a trend for the knee contribution to the total support moment to be lower, and a higher ankle contribution to the total support moment on the injured limb. There were differences in the magnitude of muscle activity which included higher hamstring activity and lower soleus activity on the injured limb. Changes in quadriceps, soleus, and hamstring muscle activity on the injured limb were identified during weight acceptance that had not previously been reported, while hip compensation for a lower knee contribution to the total support moment has been described. Non-copers consistently stabilize their knee with a stiffening strategy involving less knee motion and higher muscle contraction. The variable combination of muscle adaptations that produce joint stiffness, and the ability of both the ankle and the hip to compensate for lower knee control indicate the non-coper neuromuscular system may be more malleable than previously believed.

EFFECTS OF SPEED AND INCLINE ON LOWER EXTREMITY KINEMATICS DURING TREADMILL JOGGING IN HEALTHY SUBJECTS

Recently, there are more people jogging with a treadmill at the gym or the home setting. The main available selected modes for treadmill jogging are speed and slope of incline. Increased speeds and incline slopes will not only increase the cardiopulmonary loading but may also alter the lower extremity (LE) movement patterns. There are few systematic investigations of the effect of the speed and incline on LE kinematics. Most studies have used 2D methods which focused on movements in sagittal plane only and this has limitations in the acquired data since lower extremity movements also include frontal and transverse planes. The current study aimed to investigate LE movement during jogging at different speeds and incline slopes using a high speed three-dimensional (3D) motion analysis system.Eighteen young healthy males were recruited. The video-based motion capture system with six CCD cameras, HIRES Expert Vision System (Motion Analysis Corporation, CA, USA), was used to collect kinematic data at a sampling frequency of 120Hz. Nineteen passive reflective markers were attached to bilateral lower extremities of the subject. The joint angle is calculated by Euler angle using the rotation sequence: 2-1-3 (y-x′-z″). Four speeds were selected: 2 m/s, 2.5 m/s, 3 m/s, 3.5 m/s with the slope at 0, and four slopes were selected: 0%, 5%,10%,15% at a speed of 3 m/s. Repeated-measures ANOVA was used to test hypotheses regarding changes in jogging condition on LE kinematic variables. The significance level was set at 0.05.As the jogging slope increased, the hip, knee and ankle demonstrated a significantly greater maximum flexion in swing phase (p&lt;0.001), but the maximum extension angles in stance phase were relatively unchanged. Increased LE flexion during swing phase is important to ensure foot clearance with increased slope. For increased speed, the hip and ankle joints had significantly greater maximum joint extension angles during stance phase and the hip and knee joint had significantly larger maximum flexion angles in swing phase (p&lt;0.001). Increased motion during swing phase account for a larger step length and increased motion during stance phase may facilitate the generation of power during forward propulsion as the jogging speed increased. As the slope and speed increased, LE movement patterns were changed in the transverse plane: the significantly increased (p&lt;0.01) internal hip rotation at terminal stance, the increased toe-in of foot (p&lt;0.001) during terminal stance phase and decreased (p&lt;0.05) toe-out during swing phase. Increased hip motion in transverse plane could lengthen the stride distance and increase foot toe-in for providing a stable lever for push off to increase propulsion force as speed or slope is increased. By way of systematic 3D kinematic investigation of the LE in jogging, the results further elucidate the effect of changing speed and incline on LE joints movements. This information could provide guidelines for rehabilitation clinicians or coaches to select an appropriate training mode for jogging.

Age and Gender Effects on Lower Extremity Kinematics of Youth Soccer Players in a Stop-Jump Task

Background Gender differences in lower extremity motion patterns were previously identified as a possible risk factor for non-contact anterior cruciate ligament injuries in sports. Hypothesis Gender differences in lower extremity kinematics in the stop-jump task are functions of age for youth soccer players between 11 and 16 years of age. Study Design Descriptive laboratory study. Methods Three-dimensional videographic data were collected for 30 male and 30 female adolescent soccer players between 11 and 16 years of age performing a stop-jump task. The age effects on hip and knee joint angular motions were compared between genders using multiple regression analyses with dummy variables. Results Gender and age have significant interaction effects on standing height (P = .00), body mass (P = .00), knee flexion angle at initial foot contact with the ground (P = .00), maximum knee flexion angle (P = .00), knee valgus-varus angle (P = .00), knee valgus-varus motion (P = .00), and hip flexion angle at initial foot contact with the ground (P = .00). Conclusion Youth female recreational soccer players have decreased knee and hip flexion angles at initial ground contact and decreased knee and hip flexion motions during the landing of the stop-jump task compared to those of their male counterparts. These gender differences in knee and hip flexion motion patterns of youth recreational soccer players occur after 12 years of age and increase with age before 16 years. Clinical Relevance The results of this study provide significant information for research on the prevention of noncontact anterior cruciate ligament injuries.

Age and Gender Effects on Lower Extremity Kinetics of Youth Soccer Players Performing a Stop-Jump Task

1064 Several investigators have speculated that anterior cruciate ligament (ACL) injuries frequently occur during the stop-jump phase of movement tasks, yet minimal data exists in comparing lower extremity motion patterns between different age groups and gender performing stop-jump tasks. PURPOSE: To compare knee kinetics of male and female youth soccer players to determine if there are motion pattern differences between gender and age groups (11–16 yrs.) when performing a stop-jump task. METHODS: Knee kinetics of 30 female (age = 13.80 ± 1.76 yrs, height = 1.58 ± .09 m, weight = 49.89 ± 10.19 kg) and 26 male (age = 13.54 ± 1.79 yrs, height = 1.63 ± .11 m, weight = 52.90 ± 13.25 kg) youth soccer players were collected. Subjects took a three-step approach and performed a stop-jump maneuver to “head” an imaginary soccer ball. The dependent variables (normalized to bodyweight and height) were proximal anterior tibial shear force maximum and at initial foot contact; knee flexion (+)/extension (−) and varus (+)/valgus (−) moments at maximum proximal anterior tibial shear force and at initial foot contact during a stop-jump task. RESULTS: Preliminary analyses were performed using a stepwise multiple regression analysis on each dependent variable for age and gender effects to evaluate the motion pattern trends. A significant gender effect was found for proximal anterior tibial shear force at initial foot contact and knee flexion/extension moment at initial foot contact. Females demonstrated greater proximal anterior tibial shear force at initial foot contact and greater knee extensor moment at initial foot contact as compared to males. A significant age effect was found for knee varus/valgus moment at maximum proximal anterior tibial shear force and at initial foot contact. Younger aged youth soccer players demonstrated a smaller knee valgus moment at maximum proximal anterior tibial shear force, while older aged players demonstrated a greater knee valgus moment. Younger aged players demonstrated greater knee valgus moment at initial foot contact, while older aged players demonstrated a knee varus moment. No statistical difference was found for maximum proximal anterior tibial shear force, but the data indicate a trend that females had increased shear force as compared to their male counterparts. CONCLUSIONS: These findings suggest that age and gender differences occur in youth soccer players' lower extremity motion patterns when performing a stop-jump task. The findings of this study provide a basis for further research comparing age and gender jump-landing differences, which may be valuable for the development of noncontact ACL injury prevention programs.

Age and Gender Effects on Landing Kinematics of Youth Soccer Players during a Stop-jump task

1063 PURPOSE: Anterior cruciate ligament (ACL) injury is one of the most commonly seen knee injuries in sports. Motor control has been identified as a potential risk factor for non-contact ACL injuries. Previous studies reported gender differences in lower extremity kinematics and kinetics in selected athletic tasks. The purpose of this study was to investigate age effect on gender differences in lower extremity kinematics of youth soccer players during a stop-jump task. METHODS: Sixty youth recreational soccer players between 11 and 16 years of age were recruited and divided into 6 age groups with 5 males and 5 females in each group. Each subject performed five trials of the stop-jump task with maximum vertical jump effort. Three-dimensional hip and knee angles were collected. Regression analyses with dummy variables were performed to determine the trends of age and gender effects on body mass, standing height, relative body mass (body mass/standing height), and hip and knee joint angles during the landing of the stop-jump task. RESULTS: Age and gender have significant interaction effects on the knee and hip flexion angles and motions of youth recreational soccer players during the landing of the stop-jump task. Female and male players demonstrate similar knee flexion angles at initial ground contact and maximum knee flexion angles before 12 years of age. Female players had less knee flexion at the initial ground contact and maximum knee flexion after 13 years of age. These gender differences increased with age. Similar trends of age and gender interaction effects were also found for hip flexion at the initial contact and maximum knee flexion. The trends of age and gender interaction effects on knee and hip flexion angles were similar to those on body mass, standing height, and relative body mass (body mass/standing height). Female players also showed significantly increased knee valgus angles and increased hip external rotation angles during landing. CONCLUSIONS: Some of the gender differences in lower extremity motion patterns may occur after certain ages, and may be related to the physiological development such as strength. The findings of this study provide a basis for further studies on the age and gender differences in lower extremity motion patterns and on the prevention of non-contact ACL injuries.