Three-dimensional angular kinematics of the lumbar spine and pelvis during running

The objective of this study were to: (i) describe the typical three-dimensional (3D) angular kinematics of the lumbar spine and pelvis during running and; (ii) assess whether the movements of the lumbar spine and pelvis during running are coordinated. A cohort of 20 non-injured male runners who usually ran >20 km/week were voluntarily recruited. All trials were conducted on a treadmill at a running speed of 4.0 m/second. Reflective markers were placed over anatomical landmarks of the thoraco-lumbar spine and pelvis. Data were captured using a VICON motion analysis system. The lumbar spine and pelvis both displayed complex 3D angular kinematic patterns during running. High correlations were found for the comparisons of flexion-extension of the lumbar spine with anterior-posterior tilt of the pelvis (r=-0.84) and lateral bend of the lumbar spine with obliquity of the pelvis (r=-0.75). However, a poor correlation was found for the comparison of axial rotation of the lumbar spine with axial rotation of the pelvis (r=0.37). A phase difference of 21% of the running cycle was evident between axial rotation of the lumbar spine and pelvis. The identified coordinated kinematic patterns of the lumbar spine and pelvis during running serve as a basis for future investigations exploring the relationship between atypical kinematic patterns and injury.     

Position of the non-stance leg during the single leg squat affects females and males differently

BackgroundKinematic differences between females and males for the single leg squat (SLS) have been identified. However, kinetic differences between sexes and how variations of the non-stance leg position during the SLS may affect kinematics and kinetics differently in females and males have not been examined.ObjectivesExamine sex-specific kinematic and kinetic differences during the SLS task with 3 different non-stance leg positions.DesignControlled laboratory study, cross-sectional design.MethodsThirty-two healthy adults (16 females, 16 males) performed the 3 SLS tasks while data were collected using a motion capture system and force plates. At 60 degrees of knee flexion (60KF) and peak knee flexion (PKF), kinematics and joint moments were compared between sexes and SLS tasks using a linear regression analysis.ResultsFemales exhibited less ipsilateral trunk flexion (P < 0.001) and greater anterior pelvic tilt (P ≤ 0.021) and hip adduction (P < 0.001) than males across tasks at 60KF and PKF. Across tasks, females had a smaller knee flexion moment than males at PKF (P = 0.001). Females had a greater hip abduction moment during SLS-Front than SLS-Middle (P = 0.044) and SLS-Back (P = 0.003) at PKF, but males had similar hip abduction moments across tasks (P ≥ 0.299). At 60KF, males had a greater knee adduction moment during SLS-Front compared to the other tasks (P ≤ 0.019) while females had similar hip abduction moments across tasks (P ≥ 0.459).ConclusionAltering the non-stance leg position during the SLS affects the kinematics and kinetics of both females and males. The position of the non-stance leg can be modified for assessment and treatment purposes and should be reported in research.     

The effect of shoe and floor characteristics on walking kinematics

It is common sense that walking on sand poses challenges to postural control. However, there are no studies quantifying the kinematics of sand walking compared to other types of postural perturbations such as unstable shoes. The aim of the study was to investigate differences in walking kinematics during walking on solid ground, in unstable shoes and on unstable surfaces. Nineteen healthy young adults (23.5 ± 1.5 years) performed three different walking tasks: 1) walking at preferred speed while wearing regular shoes; 2) Walking at preferred speed wearing Masai Barefoot Technology shoes and 3) barefoot walking at preferred speed on a large sand grave. Full-body kinematics were recorded during all conditions using an inertial motion capture system. Basic gait parameters (walking speed, stride length and duration), relative vertical center-of-mass position (rvCOM), and ankle, knee and hip joint angles in the sagittal plane were compared across the tasks through statistical parametric mapping over the course of full walking cycles. Participants presented similar walking speed, as well as stride length and duration across different conditions (p > 0.05). However, walking on sand reduced the rvCOM (p < 0.05), while also requiring greater ankle plantarflexion during stance phase (p < 0.05), as well as greater knee and hip flexion during leg swing and initial contact when compared to the other conditions (p < 0.05). It was concluded that walking on sand substantially changes walking kinematics, and may cause greater postural instability than unstable shoes. Therefore, walking on sand can be an alternative to improve postural control in patients undergoing walking rehabilitation.     

Single leg landing movement differences between male and female badminton players after overhead stroke in the backhand-side court

Females showed higher anterior cruciate ligament (ACL) injuries rate on the opposite side of dominant hand compared with males during single leg landing in the backhand-side court after overhead stroke. The purpose of this study was to conduct biomechanics testing including kinematics and kinetics to provide some insights on the ACL injuries risks during single leg landing in the backhand-side court after overhead stroke between females and males. Twenty collegiate badminton players (10 females, 10 males) voluntarily participated in this study. Sagittal plane kinematic and kinetic data of the lower limb, and their ground reaction forces during the single leg landing in the backhand-side court after overhead stroke were collected. Results shown that, at the peak posterior ground reaction force (GRF) moment, the ankle dorsiflexion, knee and hip flexion angles of the female were lower than that of male. Meantime, the knee extension moment of the female was lower than that of males but the hip extension moment of the female was larger compared to males at the peak posterior GRF moment. The peak vertical and posterior GRF of female badminton players were larger than that of males. Decreased hip, knee, and ankle flexion angles at the peak posterior GRF moment and greater peak vertical and posterior GRF may expose female badminton players to the higher risk ACL injuries compared to males during single leg landing after overhead stroke in the backcourt-side. Preventative training programs designed to prevent the ACL injuries rate of female badminton players should take these factors into consideration.     

Effects of calcaneal eversion on three-dimensional kinematics of the hip, pelvis and thorax in unilateral weight bearing

Understanding the kinematic chain from foot to thorax will provide a better basis for assessment of malalignment of the body. The purpose of this study was to investigate the effects of induced calcaneal eversion on the kinematics of the hip, pelvis and thorax in three dimensions under unilateral weight-bearing. Twenty-eight healthy males were requested to stand on one leg under three conditions: normal (standing directly on the floor), and on wedges producing 5° and 10° calcaneal eversion. Recorded kinematic parameters included the angles of the hip joint, pelvis, and thorax in three dimensions. Eversion induced by wedges produced significant increases in hip flexion, hip medial rotation, pelvic anterior tilt, and thoracic lateral tilt and axial rotation to the standing side. In the frontal plane, pelvic lateral tilt to the standing side was decreased in 5° eversion condition compared with normal condition; conversely, it was increased in 10° eversion condition compared with 5° eversion condition. Arch height was negatively correlated with change in thoracic axial rotation to standing side from the normal to 10° eversion (r = −.528, p < .01). We concluded that induced calcaneal eversion affects the three-dimensional kinematics of the thorax through the hip joint and the pelvis.     

Interval endurance capacity of talented youth soccer players

The purpose of this study, in which 113 talented youth soccer players (M = 16.0 yr., SD = 1.5), selected by their age and level of performance participated, was to investigate interval endurance capacity needed to play at the highest level of competition in the age-category 12 through 18. Multivariate analyses of covariance with factors of level of performance and age category showed that players ages 16 through 18 years outscored the players ages 12 through 15 years on the interval endurance capacity (p < .05). In both age categories, elite players outscored less skilled players (p < .05). In the age category 12-15 years, the elite players participated more in soccer training than less skilled players (p < .05), whereas less skilled players participated more in additional training than the elite players (p < .05). No differences were found for total training (p > .05). In conclusion, development of the interval endurance capacity seems crucial for a talented youth soccer player to be successful.     

Motor learning methods that induce high practice variability reduce kinematic and kinetic risk factors of non-contact ACL injury

The prevention of non-contact anterior cruciate ligament (ACL) injuries often involves movement training, but the effectiveness of different motor learning methods has not been fully investigated. The purpose of this study was therefore to examine the effects of linear pedagogy (LP), nonlinear pedagogy (NLP) and differential learning (DL) motor learning methods on changing kinetic and kinematic factors during expected sidestep cutting related to non-contact ACL injuries. These methods primarily differ in the amount and type of movement variability they induce during practice. Sixty-six beginner male soccer players (27.5 ± 2.7 years, 180.6 ± 4.9 cm, 78.2 ± 4.6 kg) were randomly allocated to a group that trained for 12 weeks with either a LP, NLP or DL type of motor learning methods. All participants completed a biomechanical evaluation of side-step cutting before and after the training period. Analysis of covariance was used to compare post-testing outcomes among the groups while accounting for group differences in baseline performance. Changes in all kinematic and kinetic variables in NLP and DL groups were significantly higher compared to the LP group. Most comparisons were also different between NLP and DL group with the exception of vertical ground reaction force, the knee extension/flexion, knee valgus, and ankle dorsiflexion moments. Our findings indicate that beginner male soccer players may benefit from training programs incorporating NLP or DL versus LP to lower biomechanical factors associated with non-contact ACL injury, most likely because of the associated increased execution variability during training. We discuss that practitioners should consider using the NLP or DL methods, and particular the NLP, during which variability is induced to guide search, when implementing training programs to prevent ACL injuries in soccer.     

Muscle Strength Training Alters Muscle Activation of the Lower Extremity during Side-Step Cutting in Females

Abstract

The objective of this study was to examine the effects of muscle strength training on knee kinematics/kinetics and muscle activation patterns during anticipated side-step cutting. Three-dimensional knee kinematics/kinetics data and muscle activation of selected lower extremity muscles were measured while performing cutting before and after completing 10-week circuit strength training mixed typical resistance training and power training (intervention) or no training (control) from 25 female subjects. The muscle strength of quadriceps and hamstrings were measured before and after training using isokinetic dynamometer. No statistically significant differences were observed in quadriceps and hamstrings muscle strength, all kinematic/kinetic variables, and muscle activation for the control group. Both quadriceps (p?=?0.005) and hamstrings (p?=?0.030) muscle strength were increased after training. An increased biceps femoris (p?=?0.003) and H:Q ratio of activation (p?=?0.016), as well as decreased gastrocnemius muscle activation (p?=?0.012) during pre-activation phase in intervention group were found. No significant differences were found in knee kinematics and kinetics both at the time frame of the initial contact and the peak tibial anterior shear force after training. In conclusion, muscle strength training altered some muscle activations of lower extremity muscles, which might affect the risk of ACL injury, but it did not change the kinematic/kinetic parameters.     

Effects of back loading on the biomechanics of sit-to-stand motion in healthy children

The goal of the present study was to determine the thus far unstudied effects of back loading on the kinematics and kinetics of sit-to-stand (STS) motion in healthy children. Fifteen children (8 boys, 7 girls, mean age 9.6 years, SD 1.2 years) were tested with no back load and with a back load of 10% and 20% of body weight, respectively. A motion analysis system was used with six infrared cameras and two force plates. Total STS duration did not change; however, differential effects were shown for the durations of its phases. Back loading increased ankle dorsiflexion yielding a greater maximal dorsiflexion angle. Effects on the knee angle were limited except for a significant decrease in final knee flexion. Initial and maximal hip flexion increased but final hip angle did not change. Initial backward pelvic tilt decreased and a shift to forward pelvic tilt occurred at an earlier stage of STS motion. Back loading affected trunk motion: maximal and final forward shoulder tilt increased. Maximal ankle and knee moments and powers increased; however, hip joint kinetics was not affected significantly. Therefore, while maintaining the general pattern of STS motion, participants showed selectively significant adjustments to back loading during its different phases. The main kinematic adjustments were increased trunk flexion and greater ankle dorsiflexion, while the major kinetic adjustment was increased knee extension moment. Increased back loading yielded more pronounced effects, primarily in the ankle. In sum, back loading substantially affected the biomechanics of STS motion even for the lower load level studied. This finding may be of clinical relevance for musculoskeletal disorders, but this needs to be examined.     

Adaptation of Neuromuscular Synergies During Intentional Constraints of Space-Time Relationships in Human Gait

Tight frequency-to-amplitude relationships are observed in spontaneous human steady gait. They can be modified, if required; that flexibility forms a fundamental basis of the intentional adaptive capabilities of locomotion. In the present experiments, the processes underlying that flexibility were investigated at both the level of joint kinematics and the level of neuromuscular synergies. Subjects (N = 4) walked at the same speed either with a preferred or a nonpreferred frequency-to-amplitude relationship (i.e., constrained, short steps at a high frequency [COS condition] or constrained, long steps at a low frequency [COL condition]); their swing and stance phases were separately analyzed. In the COS condition, increases in EMG activity were specifically required during the swing phase. In the COL condition, several muscles required increases in EMG activity during the stance phase, but decreases of the hamstring muscles were needed during the swing phase. Whereas, in preferred walking, modification of the frequency affects the EMG patterns globally (the gain increasing with the frequency in both the stance and swing phases), the present results show that changing the frequency in a constrained manner either affects the swing phase specifically or affects both phases, but in the opposite direction. That finding indicates mat a separate control is needed in both the swing and the stance phases.     

Effects of experience on the coordination of internally and externally timed soccer kicks

The authors investigated differences in the soccer kick between 8 experienced and 10 less experienced participants in 2 different task conditions (kicking a stationary ball or a moving ball at a target). The experienced participants were more accurate than their less experienced counterparts, whereas there were no differences in maximum foot velocity between groups or between conditions. When compared with their performance in the stationary condition, participants kicked the moving ball with a smaller range of movement at the knee of the kicking leg, maintaining a proximodistal coordination pattern. Because of their significantly shorter knee-flexion phase, the participants in the experienced group displayed a significantly shorter time between initiation of the forward swing of the kick and ball contact than that of those in the less experienced group. The rapid knee flexion may have been a strategy of exploiting passive dynamics to increase accuracy rather than velocity. Members of both groups showed a proximodistal initiation sequence in the kicking leg, which suggests that players can acquire that coordination pattern with relatively little structured practice and that further practice leads to improvement possibly through the increased exploitation of passive dynamics.     

It Pays to Pay Attention: A Mindfulness-Based Program for Injury Prevention With Soccer Players

The aim of this study was to examine the extent to which a mindfulness-based program could reduce the number of sport injuries in a sample of soccer players. A total of 41 junior elite soccer players were randomly assigned to the treatment or the attentional control group. The treatment group took part in a 7-session program based on the mindfulness, acceptance, and commitment approach. The attentional control group was offered 7 sessions of sport psychology presentations with a particular focus on soccer. There were no statistically significant differences in injury rates between the two groups, U(39) = 149.50, z = ?1.77, p =.077, but there was a medium effect size (adjusted Cohen's d = ? 0.59), approx. 80% confidence interval for d [?0.37, ?0.74]. Moreover, 67% of the players in the mindfulness group remained injury free in comparison to 40% in the control group. This result implies that an intervention program focusing on strategies for improving attention could decrease injury risk. Recommendations include applying mindfulness exercises in athletes’ daily training to help lower injury risk.     

Lower limb tri-joint synchrony during running gait: A longitudinal age-based study

Biomechanical research exploring the age-based mechanics of running gait can provide valuable insight into the reported decline in master endurance running performance. However, few studies have shown consistent biomechanical differences in the gait of trained distance runners compared to their younger counterparts. It might be that differences occur in the interaction between joints. The aim was to explore the differences in tri-joint synchrony of the lower limb, quantified through cluster phase analysis, of runners at 50 years of age compared to seven years later. Cluster phase analysis was used to examine changes in synchrony between 3 joints of the lower limb during the stance phase of running. Ten male, endurance-trained athletes M50 (age = 53.54 ± 2.56 years, mass = 71.05 ± 7.92 kg) participated in the study and returned after seven years M57 (age = 60.49 ± 2.56 years, mass = 69.08 ± 8.23 kg). Lower limb kinematics (Vicon, 120 Hz) and ground reaction forces (Kistler, 1080 Hz) were collected as participants performed multiple trials at a horizontal running velocity = 3.83 ± 0.40 m·s⁻¹ over the force plate. Significant increase (31%) in rate of force development in the absorption phase, and significantly reduced sagittal plane knee joint range of motion (30.50 v 23.68°) were found following the seven years of ageing. No further discrete single joint measures were significantly different between M50 and M57. Joint synchrony between the hip, knee and ankle was significantly higher at M57 compared to M50 during the absorption phase of stance. The force attenuation strategy is compromised after seven years of ageing, which is associated with more synchronous movements in the lower limb joints. Increased joint synchrony as a function of age could be a mechanism associated with this key injury provoking phase of running gait.     

Generation of forward angular impulse with different initial conditions

Generation of angular impulse during foot contact is regulated by controlling the relative orientation between the total body center of mass (CoM) and the reaction force (RF) applied to the feet. Between-task differences in initial CoM horizontal momentum were hypothesized to alter how forward angular impulse was generated during two forward translating tasks. Five skilled athletes performed standing (SFS) and running (RFS) forward somersaulting dives. Sagittal plane kinematics and RFs were obtained during the take-off phase of both tasks. The initial CoM momentum differences resulted in significant differences in control of the CoM relative to the RF, RF generation mechanisms, and knee and hip net joint moments (NJMs). During the RFS, angular impulse was generated by positioning the feet anterior to the CoM at initial contact so that the RF passed posterior to the CoM throughout the take-off phase. During the SFS, angular impulse was generated by positioning the CoM anterior to the feet prior to the push interval so that the RF passed posterior to the CoM. Task-specific differences in segment kinematics and RF direction contributed to the redistribution of knee and hip NJMs. These results suggest that initial conditions influence strategies the nervous system uses to satisfy task objectives.     

The commitment of young soccer players

The main purpose of this study was to test the Sport Commitment Model in young soccer players. Participants' ( N = 437) age ranged from 14 to 16 years. Based on the sport commitment model proposed by Scanlan and colleagues, 6 scales and 28-items constitute the Sport Commitment Questionnaire (SCQ). Results of this study provide some support for the reliability and validity of the SCQ, using a sample of young soccer players. Reliability analysis provided acceptable internal consistency for four scales: Sport Commitment, Sport Enjoyment, Involvement Alternatives and Social Constraints. Sport Enjoyment (Beta= .56, p <.001) and Involvement Alternatives (Beta= -.40, p <.001) were the strongest sport commitment predictors. Further studies with a broader age range, different genders, and other sports or competitive levels are required to continue analyzing the sport commitment model.     

A prospective comparison of lower extremity kinematics and kinetics between injured and non-injured collegiate cross country runners

Collegiate cross country runners are at risk for running related injuries (RRI) due to high training volume and the potential for aberrant lower extremity biomechanics. However, there is a need for prospective research to determine biomechanical risk factors for RRI. The purpose of this study was to prospectively compare ankle, knee, and hip kinematics and kinetics and ground reaction force characteristics between injured and non-injured cross country runners over a 14-week season. Biomechanical running analyses were conducted on 31 collegiate-cross country runners using a 3-dimensional motion capture system and force plate prior to the start of the season. Twelve runners were injured and 19 remained healthy during the course of the season. Peak external knee adduction moment (KAM), a surrogate for frontal plane knee loading, and peak ankle eversion velocity were greater in runners who sustained an injury compared to those who did not, and no differences were noted in ground reaction force characteristics, or hip kinematics and kinetics. Reducing the KAM and ankle eversion velocity may be an important aspect of preventing RRI.     

Effects of gait pattern and arm swing on intergirdle coordination

Mature locomotion in humans is characterized by an anti-phase coordination (moving in opposite directions) between the pelvic and the scapular girdles. This pattern involves a specific relationship between the arm and leg motion is deemed to be most flexible and dynamically efficient. Still, when the arms are involved in another task, like a field player running with a ball in the hands, locomotion is still possible. In order to probe the flexibility of the locomotor synergy, the present study aimed to determine the persistence and the strength of the coordination patterns between the pelvic and scapular girdles when no arm swing was allowed during walking and running. Relative phase, the time difference between the girdle rotations, measured the ongoing inter-girdle coordination of eight healthy participants asked to walk and run with or without arm swing. Results showed that an absence of arm swing led to a change from an anti-phase to in-phase pattern (girdles moving in the same direction) and that an increase in velocity strengthened the adopted pattern. Moreover, the frequency distribution of relative phase for all gait patterns with arm swing proved to be bimodal, indicating that the prevailing anti-phase pattern was always mixed with a noticeable proportion of in-phase coordination. The presence of the in-phase pattern in the easy, natural locomotion with arm swing manifests its persistence and its stability, perhaps pertaining to its prevalence in earlier times in ontogeny or evolution.     

Ankle dorsiflexion range of motion is associated with kinematic but not kinetic variables related to bilateral drop-landing performance at various drop heights

Limited evidence is available concerning ankle dorsiflexion range of motion (DF ROM) and its relationship with landing performance from varying drop heights. The aim of this investigation was to determine the relationship between ankle DF ROM and both kinetic and kinematic variables measured during bilateral drop-landings from 50%, 100% and 150% of countermovement jump height. Thirty-nine participants were measured for their ankle DF ROM using the weight-bearing lunge test, after which five bilateral drop-landings were performed from 50%, 100% and 150% of maximal countermovement jump height. Normalized peak vertical ground reaction force (vGRF), time to peak vGRF and loading rate was calculated for analysis, alongside sagittal-plane initial contact angles, peak angles and joint displacement for the hip, knee and ankle. Frontal-plane projection angles were also calculated. Ankle DF ROM was not related to normalized peak vGRF, time to peak vGRF or loading rate (P > 0.05), regardless of the drop height. However, at drop heights of 100% and 150% of countermovement jump height, there were numerous significant (P < 0.05) moderate to large correlations between ankle DF ROM and initial contact angles (r = −0.34 to −0.40) and peak angles (r = −0.42 to −0.52) for the knee and ankle joint. Knee joint displacement (r = 0.39–0.47) and frontal-plane projection angle (r = 0.37–0.40) had a positive relationship with ankle DF ROM, which was consistent across all drop heights. Ankle DF ROM influences coordination strategies that allow for the management of vGRF during bilateral drop-landings, with alterations in alignment for the knee and ankle joints at both initial contact and peak angles.     

Perceptual-cognitive expertise, practice history profiles and recall performance in soccer

We examined whether high- or low-performing soccer players, classified based on established measures of perceptual-cognitive expertise, differed in regard to their practice history profiles and ability to recall elements of match performance. In Study 1, we measured perceptual-cognitive expertise in elite (n= 48) and non-elite (n= 12) youth soccer players using empirical tests of perceptual-cognitive skill. We then used a quartile split to stratify elite players into either high-performing (n= 12) or low-performing (n= 12) groups based on their test scores. A group of non-elite soccer players (n= 12) acted as controls. In Study 2, we used an established questionnaire to examine retrospectively the participation history profiles of the three groups. The high-performing group had accumulated more hours in soccer-specific play activity over the last 6 years of engagement in the sport compared to their low-performing counterparts and the non-elite controls. No differences were reported for hours accumulated in soccer-specific practice or competition between the high- and low-performing groups. In Study 3, a novel test was developed to examine episodic memory recall in soccer. Although this test successfully differentiated elite from non-elite players, no differences were evident between high- and low-performing groups, implying that episodic memory recall may not be a crucial component of perceptual-cognitive expertise in soccer.     

Visual behaviors of soccer players while kicking with the inside of the foot

This study analyzed the visual behaviors of soccer players while they kicked with the inside of the foot, which involved near and far aiming skills. Participants (N = 8) were required to step forward and kick a ball to hit a target. The top three scorers were defined as the High-score group, and the three low scorers were defined as the Low-score group. Analysis indicated that the High-score group was characterized by longer quiet eye durations, which were defined as the final fixation durations on the target prior to the initiation of a kicking movement, than the Low-score group in the preparation phase. The High-score group also set their visual pivot on the frontal space between the target and the ball in the kicking phase. These two visual behaviors of the High-score group are important for soccer players to kick a ball successfully with the inside of the foot.