Reliability of Xsens IMU-Based Lower Extremity Joint Angles during In-Field Running.

The Xsens Link motion capture suit has become a popular tool in investigating 3D running kinematics based on wearable inertial measurement units outside of the laboratory. In this study, we investigated the reliability of Xsens-based lower extremity joint angles during unconstrained running on stable (asphalt) and unstable (woodchip) surfaces within and between five different testing days in a group of 17 recreational runners (8 female, 9 male). Specifically, we determined the within-day and between-day intraclass correlation coefficients (ICCs) and minimal detectable changes (MDCs) with respect to discrete ankle, knee, and hip joint angles.

Bilateral Deficits in Dynamic Postural Stability in Females Persist Years after Unilateral ACL Injury and Are Modulated by the Match between Injury Side and Leg Dominance.

Previous research has documented brain plasticity after an anterior cruciate ligament (ACL) tear and suggests that these neural adaptations contribute to poorer motor control. Since both brain hemispheres show adaptations, we hypothesized that reduced dynamic stability occurs not only in the injured, but also the contralateral, uninjured leg. Further, given brain hemispheric specialization's impact on motor coordination, we hypothesized the need to consider the injury side.

Ergonomic saddle design features influence lumbar spine motion and can reduce low back pain in mountain biking.

Low back pain is common in mountain biking due to the sustained flexion of the lumbar spine, particularly during fatiguing hill climbs. In this study, we investigated whether an ergonomic mountain bike saddle including a raised rear, a longitudinal dip, and a subtle lateral instability (the 'Active'-technology) can reduce acute low back pain at the end of a hill climb (>1 h) in a group of mountain bikers with a history of cycling-related low back pain ( = 28). In addition, we conducted a laboratory experiment to investigate the isolated effects of the 'Active'-technology on the cyclists' pelvis and spine motion as well as on the activity of surrounding muscles.

Whole-body movement analysis using principal component analysis: What is the internal consistency between outcomes originating from the same movement simultaneously recorded with different measurement devices?

A growing number of studies apply Principal Component Analysis (PCA) on whole-body kinematic data to facilitate an analysis of posture changes in human movement. An unanswered question is, how much the PCA outcomes depend on the chosen measurement device. This study aimed to assess the internal consistency of PCA outcomes from treadmill walking motion capture data simultaneously collected through laboratory-grade optical motion capture and field-suitable inertial-based motion tracking.

Intervention for Better Knee Alignment during Jump Landing: Is There an Effect of Internally vs. Externally Focused Instructions?

Externally focused attention is known to induce superior results in the movement outcome, whereas focusing attention on the moving body (internal focus) causes conscious control and constrains action. The study investigated effects on knee trajectory and whole-body movement complexity when addressing knee alignment using externally (EF) vs. internally (IF) focused instructions.

Implications of Optimal Feedback Control Theory for Sport Coaching and Motor Learning: A Systematic Review.

Best practice in skill acquisition has been informed by motor control theories. The main aim of this study is to screen existing literature on a relatively novel theory, Optimal Feedback Control Theory (OFCT), and to assess how OFCT concepts can be applied in sports and motor learning research. Based on 51 included studies with on average a high methodological quality, we found that different types of training seem to appeal to different control processes within OFCT.

Fatigue-related reductions in movement smoothness during a lateral shuffle and side-cutting movement.

Although movement smoothness is considered a hallmark of well-coordinated motor tasks, it is unknown whether markers of movement smoothness can be used to assess the quality of neuromuscular control in athletes. As a first step into this direction, the purpose of this study was to test whether movement smoothness is reduced following a fatiguing lateral shuffle protocol due to fatigue-related adaptations in neuromuscular control. Sixteen healthy adults (7 females) completed a submaximal 3-minute lateral shuffle trial and a maximal fatiguing shuffle trial until task failure.

Principal postural acceleration and myoelectric activity: Interrelationship and relevance for characterizing neuromuscular function in postural control.

One approach to investigating sensorimotor control is to assess the accelerations that produce changes in the kinematic state of the system. When assessing complex whole-body movements, structuring the multi-segmental accelerations is important. A useful structuring can be achieved through a principal component analysis (PCA) performed on segment positions followed by double-differentiation to obtain "principal accelerations" (PAs).

Systematic reduction of leg muscle activity throughout a standard assessment of running footwear.

Purpose: This study aimed to investigate whether there is a systematic change of leg muscle activity, as quantified by surface electromyography (EMG), throughout a standard running footwear assessment protocol at a predetermined running speed.

Methods: Thirty-one physically active adults (15 females and 16 males) completed 5 testing rounds consisting of overground running trials at a speed of 3.5 m/s.

Shoe feature recommendations for different running levels: A Delphi study.

Providing runners with footwear that match their functional needs has the potential to improve footwear comfort, enhance running performance and reduce the risk of overuse injuries. It is currently not known how footwear experts make decisions about different shoe features and their properties for runners of different levels. We performed a Delphi study in order to understand: 1) definitions of different runner levels, 2) which footwear features are considered important and 3) how these features should be prescribed for runners of different levels.

Reply to Comments: Hurdle Clearance Detection and Spatiotemporal Analysis in 400 Meters Hurdles Races Using Shoe-Mounted Magnetic and Inertial Sensor.

The current document answers the comment addressed by Schmidt, M [...

Adolescent Awkwardness: Alterations in Temporal Control Characteristics of Posture with Maturation and the Relation to Movement Exploration.

A phenomenon called adolescent awkwardness is believed to alter motor control, but underlying mechanisms remain largely unclear. Since adolescents undergo neurological and anthropometrical changes during this developmental phase, we hypothesized that adolescents control their movements less tightly and use a different coordinative structure compared to adults. Moreover, we tested if emerging differences were driven by body height alterations between age groups.

Hurdle Clearance Detection and Spatiotemporal Analysis in 400 Meters Hurdles Races Using Shoe-Mounted Magnetic and Inertial Sensors.

This research aimed to determine whether: (1) shoe-worn magnetic and inertial sensors can be used to detect hurdle clearance and identify the leading leg in 400-m hurdles, and (2) to provide an analysis of the hurdlers' spatiotemporal parameters in the intervals defined by the hurdles' position. The data set is composed of MIMU recordings of 15 athletes in a competitive environment. The results show that the method based on the duration of the flight phase was able to detect hurdle clearance and identify the leading leg with 100% accuracy.

Classification of gait muscle activation patterns according to knee injury history using a support vector machine approach.

Abnormal muscle activation patterns during gait following knee injury that persist past the acute injury and rehabilitation phase (>three years) are not well characterized but may be related to post-traumatic knee osteoarthritis. The aim was to characterize the abnormal muscle activity from electromyograms of five leg muscles that were recorded during treadmill walking for young adults with and without a previous knee injury 3-12 years prior. The wavelet transformed and amplitude normalized electromyograms yielded intensity patterns that reflect the muscle activity of these muscles resolved in time and frequency.

Quadriceps-hamstrings intermuscular coherence during single-leg squatting 3-12 years following a youth sport-related knee injury.

The purpose of this study was to determine the degree of co-contraction as per electromyographic gamma-band intermuscular coherence of the quadricep (Q) and hamstring (H) muscles during single-leg squatting (SLS), and to assess the influence of sex and self-reported knee complaints on the association between knee injury history and medial and lateral Q-H intermuscular coherence. Participants included 34 individuals who suffered a youth sport-related intra-articular knee injury 3-12 years previously, and 37 individuals with no knee injury history. Surface electromyographic signals were recorded from medial and lateral thigh muscles bilaterally to determine the gamma-band (30-60 Hz) intermuscular coherence between medial and lateral Q-H muscle pairs during SLS.

Beta, gamma band, and high-frequency coherence of EMGs of vasti muscles caused by clustering of motor units.

The vasti muscles stabilize the knee joint during the running movement. This requires some motor units to synchronize. Test the hypothesis that EMGs from the vasti muscles (VM and VL) are coherent in four frequency bands, one below 30 Hz, the 40 Hz (30-45 Hz), the middle band up to 120 Hz, and the high-frequency band (135-280 Hz).

Intermuscular Coherence Between Surface EMG Signals Is Higher for Monopolar Compared to Bipolar Electrode Configurations.

The vasti muscles have to work in concert to control knee joint motion during movements like walking, running, or squatting. Coherence analysis between surface electromyography (EMG) signals is a common technique to study muscle synchronization during such movements and gain insight into strategies of the central nervous system to optimize neuromuscular performance. However, different assessment methods related to EMG data acquisition, e.

A wavelet based time frequency analysis of electromyograms to group steps of runners into clusters that contain similar muscle activation patterns.

Purpose: To wavelet transform the electromyograms of the vastii muscles and generate wavelet intensity patterns (WIP) of runners. Test the hypotheses: 1) The WIP of the vastus medialis (VM) and vastus lateralis (VL) of one step are more similar than the WIPs of these two muscles, offset by one step. 2) The WIPs within one muscle differ by having maximal intensities in specific frequency bands and these intensities are not always occurring at the same time after heel strike.

Reliability of the knee muscle co-contraction index during gait in young adults with and without knee injury history.

Despite the frequent use of the electromyography-based muscle co-contraction index (CCI) to examine muscular control of the knee joint in young adults with and without knee injury history, the reliability of the CCI in this population is unknown. The purpose of this study was to quantify within-day and between-day reliability of the knee muscle CCI during gait in young adults with and without knee injury history. Twenty young adults (10 males, 10 females) with and without history of intra-articular knee injury performed repeated gait analyses on two different days.

The Preferred Movement Path Paradigm: Influence of Running Shoes on Joint Movement.

Purpose: (A) To quantify differences in lower extremity joint kinematics for groups of runners subjected to different running footwear conditions, and (B) to quantify differences in lower extremity joint kinematics on an individual basis for runners subjected to different running footwear conditions.

Methods: Three-dimensional ankle and knee joint kinematics were collected for 35 heel-toe runners when wearing three different running shoes and when running barefoot. Absolute mean differences in ankle and knee joint kinematics were computed between running shoe conditions.

Task-Dependent Intermuscular Motor Unit Synchronization between Medial and Lateral Vastii Muscles during Dynamic and Isometric Squats.

Purpose: Motor unit activity is coordinated between many synergistic muscle pairs but the functional role of this coordination for the motor output is unclear. The purpose of this study was to investigate the short-term modality of coordinated motor unit activity-the synchronized discharge of individual motor units across muscles within time intervals of 5ms-for the Vastus Medialis (VM) and Lateralis (VL). Furthermore, we studied the task-dependency of intermuscular motor unit synchronization between VM and VL during static and dynamic squatting tasks to provide insight into its functional role.

Increased Athletic Performance in Lighter Basketball Shoes: Shoe or Psychology Effect?

Purpose: To determine the effect of shoe mass on performance in basketball-specific movements and how this affects changes if an athlete is aware or not of the shoe's mass relative to other shoes.

Methods: In an experimental design, 22 male participants were assigned to 2 groups. In the "aware" group, differences in the mass of the shoes were disclosed, while participants in the other group were blinded to the mass of shoes.