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This study examines the effects of limb dominance and lead limb in task initiation on the kinetics and kinematics of step-off drop landings. Nineteen male participants performed drop landings led by the dominant and non-dominant limbs at 45-cm and 60-cm drop heights. Ground reaction force (GRF) and lower body kinematic data were collected. Between-limb time differences at the initial ground contact were calculated to indicate temporal asymmetry. Statistical Parametric Mapping (SPM) was applied for waveform analysis while two-way repeated measures ANOVA was used for discrete parameters. SPM results revealed greater GRF and lesser ankle dorsiflexion in the lead limb compared to the trail limb in 3 out of 4 landing conditions. The dominant limb displayed a greater forefoot loading rate (45 cm: p=.009, ηp2 = 0.438; 60 cm: p=.035, ηp2 = 0.225) and greater ankle joint quasi-stiffness (45 cm: p <.001, ηp2 = 0.360; 60 cm: p <.001, ηp2 = 0.597) than the non-dominant limb. Not all 380 trials were lead-limb first landings, with a smaller between-limb time difference (p=.009, d = 0.60) at 60 cm (4.1 ± 2.3 ms) than 45 cm (5.6 ± 2.7 ms). In conclusion, the step-off drop landing is not an ideal protocol for examining bilateral asymmetry in lower limb biomechanics due to potential biases introduced by limb dominance and the step-off limb. [ABSTRACT FROM AUTHOR]

Loading both lateral and medial compartments is crucial to understanding the effect of muscle fatigue during sidestep cutting. The present study investigated the changes in tibiofemoral contact forces in the medial and lateral compartments and the muscle force contributions during the sidestep-cutting manoeuvre after a handball-specific fatigue protocol. Twenty female handball athletes performed three trials of the sidestep-cutting manoeuvre before (baseline) and after the fatigue protocol. Motion capture and ground reaction forces were measured, and the data were processed in OpenSim. The variables were compared using statistical parametric mapping (SPM), with a significance level of p < 0.05. The results showed a decreased knee flexion angle during fatigue in the early stance phase. In addition, the post-fatigue analysis demonstrated significantly reduced forces in vasti muscles. Similarly, during fatigue, the SPM analysis showed decreased tibiofemoral contact forces in the vertical and anterior directions. Vertical force applied to both medial and lateral condyles demonstrated a significant reduction after the fatigue protocol. These results indicated that forces applied to the tibiofemoral joint were reduced following the fatigue protocol compared to the baseline values. However, no consistent evidence exists that fatigue increases the risk of knee injuries. [ABSTRACT FROM AUTHOR]

Recently, a variety of technical approaches in world-class pole-vaulters' behaviour have been observed. The aim of this study was to investigate the presence of subgroups using different technical approaches and to compare biomechanical performance differences. Biomechanical analysis of performances over 5.00 metres from 99 athletes were clustered with K-means methodology based on the relative position of the top hand at take-off and the direction of the top of the pole from take-off to the maximal pole bending. Analysis revealed four subgroups that were distinguished by higher and lower direction angle and relative position values. Despite differences in technique, the analysis did not reveal significant differences between these four groups in performance, take-off speed, or athlete anthropometrics. Nevertheless, these clusters showcased variations in pole–athlete interactions and pole bending, suggesting different strategies and physical requirements associated with each approach. Cluster 2 characterised the classical technique with a high direction angle and a take-off position close to the vertical plane. Cluster 4 displayed a technique with a low take-off angle, suggesting the influence of athletes like Lavillenie, in deviating from the conventional model. Understanding and categorising athletes based on their preferred technique can aid coaches in providing tailored instructions, leading to performance improvements. [ABSTRACT FROM AUTHOR]

This study aimed to investigate inter- and intra-athlete technique variability in pre-elite and elite Australian fast bowlers delivering new ball conventional swing bowling. Ball grip angle and pelvis, torso, shoulder, elbow, wrist, upper arm, forearm, and hand kinematics were investigated at the point of ball release for inswing and outswing deliveries. Descriptive evaluations of group and individual data and k-means cluster analyses were used to assess inter- and intra-bowler technique variability. Inter-athlete technique and ball grip variability were identified, demonstrating that skilled bowlers use individualised strategies to generate swing. Functional movement variability was demonstrated by intra-athlete variability in successful swing bowling trials. Bowlers demonstrated stable technique parameters in large proximal body segments of the pelvis and torso, providing a level of repeatability to their bowling action. Greater variation was observed in bowling arm kinematics, allowing athletes to manipulate the finger and ball position to achieve the desired seam orientation at the point of ball release. This study demonstrates that skilled bowlers use individualised techniques and grips to generate swing and employ technique variations in successive deliveries. Coaches should employ individualised training strategies and use constraints-led approaches in training environments to encourage bowlers to seek adaptive movement solutions to generate swing. [ABSTRACT FROM AUTHOR]

Unanticipated trunk perturbation is commonly observed when anterior cruciate ligament (ACL) injuries occur during direction-changing manoeuvres. This study aimed to quantify the effect of mid-flight medial-lateral external trunk perturbation directions/locations on ACL loading variables during sidestep cuttings. Thirty-two recreational athletes performed sidestep cuttings under combinations of three perturbation directions (no-perturbation, ipsilateral-perturbation, and contralateral-perturbation relative to the cutting leg) and two perturbation locations (upper-trunk versus lower-trunk). The pushing perturbation was created by customised devices releasing a slam ball to contact participants near maximum jump height prior to cutting. Perturbation generally resulted in greater peak vertical ground reaction force and slower cutting velocity. Upper-trunk contralateral perturbation showed the greatest lateral trunk bending away from the travel direction, greatest peak knee flexion and abduction angles, and greatest peak internal knee adduction moments compared to other conditions. Such increased ACL loading variables were likely due to the increased lateral trunk bending and whole-body horizontal velocity away from the cutting direction caused by the contralateral perturbation act at the upper trunk. The findings may help understand the mechanisms of indirect contact ACL injuries and develop effective cutting techniques for ACL injury prevention. [ABSTRACT FROM AUTHOR]

The purpose was to compare two non-laboratory based running retraining programs on lower limb and trunk kinematics in recreational runners. Seventy recreational runners (30 ± 7.3 years old, 40% female) were randomised to a barefoot running group (BAR), a group wearing a digital metronome with their basal cadence increased by 10% (CAD), and a control group (CON). BAR and CAD groups included intervals from 15 to 40 min over 10 weeks and 3 days/week. 3D sagittal kinematics of the ankle, knee, hip, pelvis, and trunk were measured before and after the retraining program, at comfortable and high speeds. A 3 × 2 mixed ANOVA revealed that BAR and CAD groups increased knee and hip flexion at footstrike, increased peak hip flexion during stance and flight phase, decreased peak hip extension during flight phase, and increased anterior pelvic tilt at both speeds after retraining. In addition, BAR increased ankle plantar flexion at footstrike and increased anterior trunk tilt. Both retraining programs demonstrated significant moderate to large effect size changes in parameters that could reduce the mechanical risks of injury associated with excessive knee stress, which is of interest to coaches, runners and those prescribing rehabilitation and injury prevention programs. [ABSTRACT FROM AUTHOR]

Patellofemoral pain syndrome (PFPS) is a common injury among runners, and it is thought that abnormal lower extremity biomechanics contribute to its development. However, the relationship between biomechanical changes after a marathon and PFPS injury remains limited. This study aims to investigate whether differences in knee and hip kinematics and lower extremity muscle activities exist in recreational runners before and after a marathon. Additionally, it aims to explore the relationship between these biomechanical changes and the development of PFPS injury. 12 recreational runners participated in the study. Kinematics and muscle activities of the lower extremity were recorded during walking (5 km/h) and running (10 km/h) tasks within 24 hours before and within 5 hours after a marathon. After the marathon, there was a significant decrease in peak knee flexion (walking: p = 0.006; running: p = 0.006) and an increase in peak hip internal rotation (walking: p = 0.026; running: p = 0.015) during the stance phase of both walking and running compared to before the marathon. The study demonstrates a decrease in knee flexion and an increase in hip internal rotation during the stance phase of gait tasks after completing a marathon, which may increase the risk of developing PFPS injury. [ABSTRACT FROM AUTHOR]

Volleyball-specific footwear with higher collar heights (a mid-cut shoe) are worn to restrict ankle motion. Reduced ankle dorsiflexion has been associated with increased frontal plane motion and injury risk at the knee. With the high frequency of unilateral landings in volleyball, the purpose of this study was to determine the effect of volleyball-specific shoes and limb dominance on knee landing mechanics in collegiate volleyball players. It was hypothesized that participants would exhibit smaller sagittal plane and greater frontal plane knee joint mechanics in mid-cut and dominant limb and that vertical and posterior directed ground reaction forces would be greater wearing mid-cut, yet similar between limbs. Seventeen female volleyball players performed unilateral landings on each limb in mid-cut and low-top volleyball shoes. For shoe main effects, smaller peak dorsiflexion angle and internal peak plantarflexion moment and greater peak medial ground reaction force were found in the mid-cut but with no impact on knee mechanics. For limb main effects, the internal peak knee abduction moment was greater in the dominant limb. Greater peak lateral ground reaction force was found in the interaction between the non-dominant limb and low-top. Further research is warranted to better understand shoe and limb impact in volleyball players. [ABSTRACT FROM AUTHOR]

Horizontal deceleration technique is an underpinning factor to musculoskeletal injury risk and performance in multidirectional sport. This study primarily assessed within- and between-session reliability of biomechanical and performance-based aspects of a horizontal deceleration technique and secondarily investigated the effects of limb dominance on reliability. Fifteen participants completed four horizontal decelerations on each leg during test and retest sessions. A three-dimensional motion analysis system was used to collect kinetic and kinematic data. Completion time, ground contact time, rate of horizontal deceleration, minimum centre of mass height, peak eccentric force, impulse ratio, touchdown distance, sagittal plane foot and knee angles at initial contact, maximum sagittal plane thorax angle, and maximum knee flexion moment were assessed. Coefficients of variation (COV) and intraclass correlation coefficients (ICC) were used to assess within- and between-session reliability, respectively. Seven variables showed "great" within-session reliability bilaterally (COV ≤9.13%). ICC scores were 'excellent' (≥0.91; n = 4), or 'good' (0.76-0.89; n = 7), bilaterally. Limb dominance affected five variables; three were more reliable for the dominant leg. This horizontal deceleration task was reliable for most variables, with little effect of limb dominance on reliability. This deceleration task may be reliably used to assess and track changes in deceleration technique in healthy adults. [ABSTRACT FROM AUTHOR]

LEOMO™ is a commercial inertial measurement unit system that provides cycling-specific motion performance indicators (MPIs) and offers a mobile solution for monitoring cyclists. We aimed to validate the LEOMO sensors during sprint cycling using gold-standard marker-based three-dimensional (3D) motion technology (Qualisys, AB). Our secondary aim was to explore the relationship between peak power during sprints and MPIs. Seventeen elite track cyclists performed 3 × 15s seated start maximum efforts on a cycle ergometer. Based on intraclass correlation coefficient (ICC3,1), the MPIs derived from 3D and LEOMO showed moderate agreement (0.50 < 0.75) for the right foot angular range (FAR); left foot angular range first quadrant (FARQ1); right leg angular range (LAR); and mean angle of the pelvis in the sagittal plane. Agreement was poor (ICC < 0.50) between MPIs derived from 3D and LEOMO for the left FAR, right FARQ1, left LAR, and mean range of motion of the pelvis in the frontal and transverse planes. Only one LEOMO-derived (pelvic rotation) and two 3D-derived (right FARQ1 and FAR) MPIs showed large positive significant correlations with peak power. Caution is advised regarding use of the LEOMO for short maximal cycling efforts and derived MPIs to inform peak sprint cycling power production. [ABSTRACT FROM AUTHOR]

Force attenuation during landing requires coordinated motion of the ankle, knee, hip, and trunk, and strategies may differ between sexes. Sagittal plane coordination of the ankle/knee, knee/hip, and knee/trunk, and lower extremity and trunk kinematics and kinetics was compared throughout landing between 28 males and 28 females. Coordination was assessed with a modified vector coding technique and binning analysis. Total support moments (TSM), each joint's percent contribution, and timing of the TSM were compared. Females landed with less isolated knee flexion in the ankle/knee, knee/hip, and knee/trunk couplings, but more simultaneous ankle/knee flexion, less simultaneous knee flexion/hip extension, and more simultaneous trunk/knee flexion. Females landed with larger plantarflexion angles from 0–16% and smaller trunk flexion angles from 0–78%. In females, absolute TSM were larger from 0–6% and smaller from 42–100%, and normalized TSM were larger from 0–8% and 26–42%. Females had greater ankle contribution to the TSM from 14–15% and 29–35%, smaller absolute peak TSM, and the peak TSM occurred earlier. Females compensated for less isolated knee flexion with greater simultaneous ankle/knee flexion early in landing and knee/trunk flexion later in landing. Coordination and TSM differences may influence force attenuation strategies and have implications for knee injury disparity between sexes. [ABSTRACT FROM AUTHOR]

Low back pain (LBP) is the most common injury in golfers of all abilities. The primary aim of this review was to improve understanding of human golf swing biomechanics associated with LBP. A systematic review using the PRISMA guidelines was performed. Nine studies satisfying inclusion criteria and dually reporting golf swing biomechanics and LBP were identified. Human golf swing biomechanics potentially associated with LBP include: reduced lumbar flexion velocity; reduced transition phase length; reduced lumbar torsional load; earlier onset of erector spinae contraction; increased lumbar lateral flexion velocity; reduced or greater erector spinae activity; and earlier onset of external oblique contraction. These potential associations were undermined by a very limited and conflicting quality of evidence, study designs which introduced a severe potential for bias and a lack of prospective study design. There is no conclusive evidence to support the commonly held belief that LBP is associated with "poor" golf swing technique. The potential associations identified should be further investigated by prospective studies of robust design, recruiting participants of both sexes and dexterities. Once firm associations have been identified, further research is required to establish how this knowledge can be best integrated into injury prevention and rehabilitation. LBP has the highest incidence of any injury in elite, sub-elite and recreational golfers, causing a significant burden of injury worldwide. There is very limited and conflicting evidence that some human biomechanical factors in the golf swing may be associated with LBP. Prospective studies investigating the full movement pattern are required in order to improve understanding of the potential relationship between the biomechanics of the golf swing and LBP. [ABSTRACT FROM AUTHOR]

Producing comparable/greater ground reaction forces (GRFs) at faster running speeds is beneficial for sprint performance, and assisted sprint training is used to induce faster running speed conditions. This study aimed to demonstrate the characteristics of assisted sprinting at the maximal speed phase and investigate acute differences to control sprinting. Fifteen sprinters completed control and assisted (5 kg) sprints over force platforms. Assisted sprinting increased running speed (9.3% mean difference), while propulsive mean force (−4.3%) and impulse (−12.4%) decreased, suggesting that running speed improvements were caused primarily by assisted pulling force rather than improvements in anteroposterior force production of athletes. In addition, vertical mean force increased (4.2%), probably due to braking mean force (34.2%) and impulse (32.5%) increases. Magnitude of control trial maximum speed was achieved earlier (during acceleration) in assisted trials, and net anteroposterior (includes both braking and propulsive components) mean force (67.2%) and impulse (67.9%) increased at this matched speed, suggesting that assisted sprints could be used to practice producing greater GRFs at comparable speeds. Running speed improvement by pulling force was associated with contact time decreases (r = -.565), suggesting that shortening contact time may be important for effective assisted sprinting. [ABSTRACT FROM AUTHOR]

Patellofemoral pain (PFP) is a common musculoskeletal pain disorder experienced by runners. While biomechanics of those with PFP have been extensively studied, methodological considerations may omit important adaptations exhibited by those experiencing and recovered from pain. Instead of a priori selection of discrete biomechanical variables, a data mining approach was leveraged to account for the high dimensionality of running gait data. Biomechanical data of runners symptomatic for, recovered from, and who had never experienced PFP were collected at the 1st (M1) and 21st (M21) minutes of a treadmill run. Principal component analysis and a logistic regression model were used to classify healthy and symptomatic runners, and a feature ranking process determined the important features. The M1 model achieved an accuracy of 82.76% with features related to knee flexion angle, hip abduction moment and gluteus maximus activation, while the M21 model required an additional nine features to achieve an accuracy of 79.31%. Data for recovered runners were projected onto the models, resulting in five and seven out of twelve symptomatic classifications at M1 and M21, respectively. Following the onset of pain, a greater number of features were required to classify runners with PFP, suggesting they may experience individual pain adaptation strategies. [ABSTRACT FROM AUTHOR]

The purpose of this study was to determine if curved non-motorized treadmills can reproduce overground running better than motorized treadmills by analysing the differences in joint kinematics (hip, knee, and ankle) using SPM. Nineteen recreational runners completed three randomized running tests on these surfaces. Kinematic data from the hip, knee, and ankle joints were collected. Two-tailed SPM t-tests were performed to analyse time-continuous gait cycles in three anatomical planes of each joint. Higher within-subject variability was observed in the frontal and transverse planes during curved non-motorized treadmill running. SPM analysis showed more significant differences (p < 0.05) between curved non-motorized treadmill and overground than between motorized treadmill and overground, mainly in knee (from 12% to 30% and 93% to 99% of the gait cycle) and ankle (from 19% to 23% of the gait cycle) in the sagittal plane. Therefore, running on curved non-motorized treadmills is more biomechanically different compared to overground than motorized treadmills, and might not be the best strategy to replicate overground running in terms of joint kinematics during highly controlled research studies. However, they could be an interesting tool in rehabilitation or training environments since the changes observed in joint kinematics were likely not functionally relevant. [ABSTRACT FROM AUTHOR]

This study examined the reliability of expert tennis coaches/biomechanists to qualitatively assess selected features of the serve with the aid of two-dimensional (2D) video replays. Two expert high-performance coaches rated the serves of 150 male and 150 female players across three different age groups from two different camera viewing angles. Serve performance was rated across 13 variables that represented commonly investigated and coached (serve) mechanics using a 1–7 Likert rating scale. A total of 7800 ratings were performed. The reliability of the experts' ratings was assessed using a Krippendorffs alpha. Strong agreement was shown across all age groups and genders when the experts rated the overall serve score (0.727–0.924), power or speed of the serve (0.720–0.907), rhythm (0.744–0.944), quality of the trunk action (0.775–1.000), leg drive (0.731–0.959) and the likelihood of back injury (0.703–0.934). They encountered greater difficulty in consistently rating shoulder internal rotation speed (0.688–0.717). In high-performance settings, the desire for highly precise measurement and large data sets powered by new technologies, is commonplace but this study revealed that tennis experts, through the use of 2D video, can reliably rate important mechanical features of the game's most important shot, the serve. [ABSTRACT FROM AUTHOR]

This study assessed the lead and trail arm peak and average extensor carpi ulnaris (ECU) muscle activity in association with tri-planar angular velocities of the lead and trail wrists during the golf swing. Fifteen sub-elite, male right-handed golfers (Mage = 34.7 years ±13.3, Mhandicap = 1.5 ± 2.2) were recruited to execute five shots each with their pitching wedge, 7-iron and driver clubs in an indoor golf simulator. Surface electromyography (EMG) sensors were placed over the ECU muscle belly and inertial measurement unit sensors were placed bi-laterally on the distal forearm and dorsum of the hand. There was a statistically greater recruitment of the trail ECU muscle during the downswing (p < 0.001) for all clubs. The lead ECU muscle was recruited more during the backswing (p < 0.001) and follow through (p < 0.024) phases. There were statistically different tri-planar movement patterns between the lead and trail wrist throughout all three phases of the golf swing. No significant relationships were found between downswing EMG data and clubhead kinematics at impact. In conclusion, differing wrist kinematics and associated muscle activity may contribute to the asymmetrical injury pattern seen clinically. [ABSTRACT FROM AUTHOR]

This study aims to identify stroke regulation profiles and tipping-points in stroke regulation timing during international open water races according to performance level. Twelve elite or world-class swimmers were analysed during 18 international races. Stroke rate and jerk cost were computed cycle-to-cycle using an Inertial Measurement Unit and regulations profiles fitted using polynomials. We performed two-ways mixed-ANOVA to compare stroke kinematics among race segments and performance groups (G1 -fastest- to G3 -slowest-). Swimmers displayed specific regulation profiles (i.e., J-shape with end-spurt, J-shape without end-spurt and reverse L-shape for stroke rate and U-shape, reverse J-shape and reverse L-shape for jerk cost, for respectively G1, G2 and G3) with significant effect of race segment on stroke kinematics for G1 and G2. We highlighted tipping-points in stroke regulations profiles (TP1 and TP2) at respectively 30% and 75% of the race with greater magnitude in G1 than G2. TP1 reflects the end of a stroke economy period (0–30%) and TP2 the end of a progressive increase in stroke kinematics (30–75%) towards end-spurt (75–100%). Open water races follow a high-grading dynamics requiring biomechanical regulations along the race. Targeting stroke rate reserve and management of stroke smoothness should be considered during training of open water swimmers. [ABSTRACT FROM AUTHOR]

During prolonged jogging, joint moment and work tend to decrease in the distal (ankle) joint but increase at proximal (hip/knee) joints as performance fatigue manifests, and such adaptations might be expected to occur in sprinting. Fatigue is also thought to increase inter-limb asymmetries, which is speculated to influence injury risk. However, the effects of fatigue on sprint running gait have been incompletely studied, so these hypotheses remain untested. Using statistical parametric mapping, we compared 3-D kinematics and ground reaction force production between the dominant (DL) and non-dominant (NDL) legs of 13 soccer players during both non-fatigued and fatigued sprint running. Contrary to the tested hypotheses, relative between-leg differences were greater in non-fatigued than fatigued sprinting. DL generated higher propulsive impulse due to increased ankle work, while NDL exhibited greater vertical impulse, potentially due to greater hip flexion prior to downward foot acceleration. Whilst few changes were detected in DL once fatigued, NDL shifted towards greater horizontal force production, largely resulting from an increase in plantar flexion (distal-joint) moments and power. After fatiguing running, inter-limb asymmetry was reduced and no distal-to-proximal shift in joint work was detected. These adaptations may attenuate decreases in running speed whilst minimising injury risk. [ABSTRACT FROM AUTHOR]

This study evaluated the effects of 6-week multimodal training on the sprinting performance and biomechanics of adolescent rugby players. Twenty-four players were assigned to control group (CG) or intervention group (IG). For 6 weeks, CG maintained their training routine, while IG completed a training programme consisting of unresisted sprints, as well as heavy-resisted sprints, running technique drills and lumbopelvic stability. Before and after, sprint performance, horizontal force-velocity profile (FV-h), sprinting kinematics and spatiotemporal data were obtained. After the training, IG reduced the 0–5 m (p = 0.044), 0–10 m (p = 0.046) and 25–30 m (p = 0.035) split times compared with CG. In FV-h, IG displayed a higher maximal theoretical horizontal force (p = 0.035) and ratio of force (p = 0.048) than CG. Regarding kinematic and spatiotemporal variables, only IG improved step length (p < 0.001), step rate (p = 0.005) and distance between knees (p = 0.048) compared with baseline, but there were no between-group differences. Six weeks of multimodal training improved sprinting acceleration and mechanical variables of force application during sprinting of adolescent rugby players. Although IG improved some biomechanical variables compared with baseline, these changes were similar to those observed in CG. [ABSTRACT FROM AUTHOR]

Chronological age classifies elite male gymnasts into developmental performance classifications: senior (18+ years), junior (14–18 years) and development (8–14 years). Here, we examine the influence of age and experience on the biomechanics of the high bar longswing across classifications. Joint angular kinematics and kinetics were obtained from 30 gymnasts performing three sets each of eight consecutive longswings. Differences between groups and relations between age, experience and key biomechanical variables were correlated. Kinetic variables and range of motion of the hip and knee were highest for development gymnasts. In all age groups, a dominant shoulder kinetic contribution was found, although circle location of the peak joint kinetics occurred earliest for junior gymnasts. Hip work contributed more prominently in development gymnasts. Age and experience were positively correlated to an increase in peak shoulder moments and powers and negatively correlated to peak hip and knee moments. The findings reveal that age and experience combine to influence the functional phase, joint kinematics and relative joint kinetic contribution, particularly with the senior group demonstrating a shoulder dominant technique. Changes in musculoskeletal loading across the age groups suggest that factors such as relative strength and practice may have influenced this joint mode transition of the longswing. [ABSTRACT FROM AUTHOR]

The main purpose of this study was to investigate the relationship among Achilles tendon (AT) dimensions, ankle joint stiffness, and footfall patterns in recreational rearfoot and non-rearfoot runners. Based on the foot strike index, a total of 107 runners were divided into rearfoot (47 females/40 males) and non-rearfoot runners (14 females/6 males). All participants had theirs AT dimensions (AT length, AT thickness, and AT moment arm) measured using a combination of ultrasound and motion capture systems. In addition, all performed running trials measured at self-selected speed in laboratory-neutral shoes. A partial correlation coefficient was used for correlations between the selected variables. The results revealed a significant relationship between ankle joint stiffness and level of footfall pattern in rearfoot (r = 0.232, p = 0.032) and non-rearfoot runners (r = -0.811, p < 0.001). The results also suggest a relationship between AT thickness and foot strike index (r = -0.486) in non-rearfoot runners. Runners whose footfall pattern is closer to the heel have greater ankle joint stiffness. Non-rearfoot runners whose footfall pattern is closer to the toe have a thinner AT. Non-rearfoot runners with thicker AT had greater ankle joint stiffness. [ABSTRACT FROM AUTHOR]

This study aimed to quantitatively investigate and report the biomechanical characteristics of concussive and sub-concussive impacts in youth sports. A systematic search was conducted in September 2022 to identify biomechanical impact studies in athletes ≤18 years of age. Twenty-six studies met the inclusion criteria for quantitative synthesis and analysis. DerSimonian Laird random effects model was used to pool data across the included studies. The pooled estimate of mean peak linear and rotational acceleration of concussive impacts in male youth athletes was 85.56 g (95% CI 69.34–101.79) and 4505.58 rad/s2 (95% CI 2870.28–6140.98), respectively. The pooled estimate of mean peak linear and rotational acceleration of sub-concussive impacts in youth athletes was 22.89 g (95% CI 20.69–25.08) and 1290.13 rad/s2 (95% CI 1050.71–1529.55), respectively. A male vs female analysis in sub-concussive impacts revealed higher linear and rotational acceleration in males and females, respectively. This is the first study to report on impact data in both sexes of youth athletes. Disparity in kinematic impact values suggests future research should aim for standardised measures to reduce heterogeneity in data. Despite this, the data reveals notable impact data that youth athletes are exposed to, suggesting modifications may be required to reduce long-term neurological risks. [ABSTRACT FROM AUTHOR]

The penalty kick is a crucial opportunity to score and determine the outcome of a soccer match or championship. Anticipating the direction of the ball is key for goalkeepers to enhance their defensive capabilities, considering the ball's swift travel time. However, it remains unclear which kinematic cues from the kicker can predict the ball's direction. This study aimed to identify the variables that predict the ball's direction during a soccer penalty kick. Twenty U19 soccer players executed penalty kicks towards four targets positioned in the goal, while kinematic analysis was conducted using a 3D motion analysis system. Logistic regression analysis revealed that trunk rotation in the transverse plane (towards the goal – left; or slightly to the right – right) served as the primary predictor of the ball's horizontal direction at 250 and 150 ms before the kicking foot made contact. Additionally, the height of the kicking foot in the sagittal plane solely predicted the vertical direction at the moment of contact. This information, encompassing trunk rotation and kicking foot height, can be employed in perceptual training to enhance decision-making and the implementation of feints during penalty kicks. [ABSTRACT FROM AUTHOR]

This study investigated the short-term responses of step characteristics in sprinters and team-sports players under different bend conditions. Eight participants from each group completed 80 m sprints in four conditions: banked and flat, in lanes two and four (L2B, L4B, L2F, L4F). Groups showed similar changes in step velocity (SV) across conditions and limbs. However, sprinters produced significantly shorter ground contact times (GCT) than team sports players in L2B and L4B for both left (0.123 s vs 0.145 s and 0.123 s vs 0.140 s) and right steps (0.115 s vs 0.136 s and 0.120 s vs 0.141 s) (p > 0.001–0.029; ES = 1.15–1.37). Across both groups, SV was generally lower in flat conditions compared to banked (Left: 7.21 m/s vs 6.82 m/s and Right: 7.31 m/s vs 7.09 m/s in lane two), occurring due to reduced step length (SL) rather than step frequency (SF), suggesting that banking improves SV via increased SL. Sprinters produced significantly shorter GCT in banked conditions that led to non-significant increases in SF and SV, highlighting the importance of bend sprinting specific conditioning and training environments representative of indoor competition for sprint athletes. [ABSTRACT FROM AUTHOR]

Running has a high incidence of overuse injuries. Achilles tendon (AT) injuries may occur due to high forces and repetitive loading during running. Foot strike pattern and cadence have been linked to the magnitude of AT loading. The effect of running speed on AT stress and strain, muscle forces, gait parameters and running kinematics is not well addressed in recreational runners with lower pace of running. Twenty-two female participants ran on an instrumented treadmill between 2.0 and 5.0 m/s. Kinetic and kinematic data were obtained. AT cross-sectional area data were collected using ultrasound imaging. Inverse dynamics with static optimization was used to calculate muscle forces and AT loading. AT stress, strain and cadence increased with greater running speed. Foot inclination angle indicated a rearfoot strike pattern among all participants, which increased as running speed increased but the latter plateaued after 4.0 m/s. The soleus contributed more force in running compared to the gastrocnemius throughout all speeds. Highest running speeds had the most stress on the AT, with changes to foot inclination angle and cadence. Understanding the relation of AT loading variables with running speed may aid in understanding how applied load may influence injury. [ABSTRACT FROM AUTHOR]

This study aimed to increase understanding of the biomechanics and dynamics of the upper limbs during the contact phase of the round-off (RO) performed using three techniques. Twenty female gymnasts performed six successful RO trials in each condition: parallel, T-shape and reverse. Kinetic and kinematic data were collected for each trial. All analyses focused on the contact phase for each hand. Continuous joint profiles examined the dynamics of these tasks as well as the kinetic sequencing. In each case, joint angles, angular velocity, moments and powers at the wrist and elbow joint were reported. Difference between the contact phases of the techniques was examined using a one-way ANOVA SPM. The T-shape technique demonstrated negative power at the wrist during contact; however, the elbow joint compensated with a significantly greater positive power generation during the propulsive phase, suggesting a more effective technique compared to the reduced powers of the reverse and parallel. The order of the peak joint powers during the contact phase, the reverse technique, demonstrated a proximal to distal sequence, in contrast to the distal to proximal for the other techniques. These findings highlight the task-specific coordinative structures during this closed chained action. [ABSTRACT FROM AUTHOR]

The aim of the present study was to examine whether relative strength influences lifting kinematics (e.g., lifting time, barbell velocity, vertical displacement) during the bench press (BP) exercise with healthy men. Loaded BP 6-repetition maximum normalized to body mass (i.e., relative strength) was examined in 110 resistance-trained men (age: 22.9 ± 2.5 years, height: 180.9 ± 6.9 cm, body mass: 80.3 ± 7.9 kg), by analysing lifting kinematics using a linear encoder. According to relative BP strength, subjects were classified as beginners, recreationally trained, intermediate, and advanced. Results showed that in the intermediate (p = 0.004, ES = 0.85) and advanced (p = 0.016, ES = 0.81) groups barbell velocity was lower in the sticking region of the BP action, compared with beginners, however there were no significant differences between groups for vertical displacement (p = 0.122–1.000) and lifting time (p = 0.052–1.000). These findings suggest that greater relative strength improves the capacity to perform the eccentric but not the concentric phase of BP. Enhanced barbell lowering indicates that the sticking region is caused by a high demand for eccentric force production during biomechanically disadvantageous conditions. [ABSTRACT FROM AUTHOR]

Biomechanical analyses of pitching possess limitations in accurately measuring dynamic scapular orientation and are thus unable to distinguish between glenohumeral and scapulothoracic contributions to global shoulder motion. In lieu of direct measurement, several methods to estimate scapular kinematics have been developed. This study evaluated the ability of the linear model and the double calibration acromion marker cluster (D-AMC) approaches to estimate scapular kinematics throughout a full-speed pitching motion. Each approach's estimates were compared against scapulothoracic range of motion limits established in a non-pitching biplane fluoroscopy study involving various functional arm movements that approximate physiological limits of scapular motion. Fourteen healthy collegiate pitchers participated. Motion capture measured upper extremity joint kinematics during full-speed fastball pitches. Linear model and D-AMC approaches estimated scapulothoracic kinematics during each pitch. Linear model estimates of scapulothoracic kinematics were largely within established physiological limits on each scapular axis of motion while D-AMC estimates exceeded fluoroscopy-established bounds for more subjects and by larger, less physiologically plausible amounts. These findings demonstrate that the linear model outperforms the D-AMC and suggest that it is a viable approach to estimate scapular kinematics during pitching. Finally, these results offer additional evidence to support the accepted pattern of scapular kinematics during pitching. [ABSTRACT FROM AUTHOR]

This study investigated the effect of a handball-specific fatigue protocol on hip and knee kinematics. Twenty female handball athletes performed three trials of the single-leg landing (SLL), sidestep cutting manoeuvre (SCM), and drop vertical jump (DVJ) before and after the fatigue protocol. Knee and hip angle waveforms were compared using statistical parametric mapping (p < 0.05). During the SLL, the fatigue increased hip adduction (4–7% cycle) and knee abduction (4–9% and 25–27%). For the SCM, hip flexion was reduced under fatigue during 14–29% and 44–68% of the cycle. Similarly, the knee flexion decreased between 7–36% and 53–73%. Besides, during the fatigue state, the athletes reduced the hip abduction between 0–11% of the cycle and increased the knee abduction between 20–23%. During the DVJ task, when fatigued, the hip flexion decreased between 19–44% of the cycle and the knee flexion between 1–16% and 18–77%. The fatigue protocol altered the lower limb kinematics, decreasing knee and hip flexions during the SCM and DVJ and increasing the knee valgus during both single-leg landing tasks. [ABSTRACT FROM AUTHOR]

Vibration has the potential to compromise performance in cycling. This study aimed to investigate the effects of vibration on full-body kinematics and muscle activation time series. Nineteen male amateur cyclists (mass 74.9 ± 5.9 kg, body height 1.82 ± 0.05 m, Vo2max 57 ± 9 ml/kg/min, age 27 ± 7 years) cycled (216 ± 16 W) with (Vib) and without (NoVib) vibration. Full-body kinematics and muscle activation time series were analysed. Vibration did not affect lower extremity joint kinematics significantly. The pelvic rotated with vibration towards the posterior direction (NoVib: 22.2 ± 4.8°, Vib: 23.1 ± 4.7°, p = 0.016, d = 0.20), upper body lean (NoVib: 157.8 ± 3.0°, Vib: 158.9 ± 3.4°, p = 0.001, d = 0.35) and elbow flexion (NoVib: 27.0 ± 8.2°, Vib: 29.4 ± 9.0°, p = 0.010, d = 0.28) increased significantly with vibration. The activation of lower extremity muscles (soleus, gastrocnemius lat., tibialis ant., vastus med., rectus fem., biceps fem.) increased significantly during varying phases of the crank cycle due to vibration. Vibration increased arm and shoulder muscle (triceps brachii, deltoideus pars scapularis) activation significantly over almost the entire crank cycle. The co-contraction of knee and ankle flexors and extensors (vastus med. – gastrocnemius lat., vastus med. – biceps fem., soleus – tibialis ant.) increased significantly with vibration. In conclusion vibrations influence main tasks such as propulsion and upper body stabilization on the bicycle to a different extent. The effect of vibration on the task of propulsion is limited due to unchanged lower body kinematics and only phase-specific increases of muscular activation during the crank cycle. Additional demands on upper body stabilization are indicated by adjusted upper body kinematics and increased muscle activation of the arm and shoulder muscles during major parts of the cranking cycle. [ABSTRACT FROM AUTHOR]

We conducted an exploratory analysis to compare running kinematics of 16 male recreational runners wearing Nike Vaporfly 4% (VP4), Saucony Endorphin racing flat (FLAT), and their habitual (OWN) footwear. We also explored potential relationships between kinematic and physiological changes. Runners (age: 33 ± 12 y, V ˙ O2peak: 55.2 ± 4.3 ml · kg−1·min−1) attended 3 sessions after completing an V ˙ O2peak test in which sagittal plane 3D kinematics at submaximal running speeds (60%, 70% and 80% ʋ V ˙ O2peak) were collected alongside economy measures. Kinematics were compared using notched boxplots, and between-shoe kinematic differences were plotted against between-shoe economy differences. Across intensities, VP4 involved longer flight times (6.7 to 10.0 ms) and lower stance hip range of motion (~3°), and greater vertical pelvis displacement than FLAT (~0.4 cm). Peak dorsiflexion angles (~2°), ankle range of motion (1.0° to 3.9°), and plantarflexion velocities (11.3 to 89.0 deg · sec−1) were greatest in FLAT and lowest in VP4. Foot-ground angles were smaller in FLAT (2.5° to 3.6°). Select kinematic variables were moderately related to economy, with higher step frequencies and shorter step lengths in VP4 and FLAT associated with improved economy versus OWN. Footwear changes from OWN altered running kinematics. The most pronounced differences were observed in ankle, spatiotemporal, and foot-ground angle variables. [ABSTRACT FROM AUTHOR]

The aim was to investigate the effects of a gym-based strength training intervention on biomechanics and intermuscular coordination patterns during short-term maximal cycling. Twelve track sprint cyclists performed 3 × 4 s seated sprints at 135 rpm, interspersed with 2 × 4 s seated sprints at 60 rpm on an isokinetic ergometer, repeating the session 11.6 ± 1.4 weeks later following a training programme that included two gym-based strength training sessions per week. Joint moments were calculated via inverse dynamics, using pedal forces and limb kinematics. EMG activity was measured for 9 lower limb muscles. Track cyclists 'leg strength" increased (7.6 ± 11.9 kg, P = 0.050 and ES = 0.26) following the strength training intervention. This was accompanied by a significant increase in crank power over a complete revolution for sprints at 135 rpm (26.5 ± 36.2 W, P = 0.028 and ES = 0.29). The increase in leg strength and average crank power was associated with a change in biceps femoris muscle activity, indicating that the riders successfully adapted their intermuscular coordination patterns to accommodate the changes in personal constraints to increase crank power. [ABSTRACT FROM AUTHOR]

A simple and accurate method of determining foot strike angle (FSA) during running can simplify data collections and validations of wearable sensors. The purpose of this study was to determine the validity of two simplified methods for estimating FSA and foot angle (throughout the ground contact) from three-dimensional kinematics. Markers were placed on the heel and head of the second metatarsal (HEEL-TOE) or on the lateral side of the head of the fifth metatarsal (HEEL-MET5). When compared to the reference foot segment, the HEEL-TOE method performed similarly with a minimal mean difference (0.28° [0.19°,0.36°], p < 0.001), a high Pearson's r (r = 0.994; p < 0.001), and low bias (−0.20°±1.05°). Alternatively, the HEEL-MET5 method underestimated FSA: mean difference = 4.28° [4.07°,4.91°] (p < 0.001), Pearson's r = 0.968 (p < 0.001), and bias = −4.58°±2.61°. Throughout the contact phase, significant SPM cluster regions were identified, indicating that the HEEL-MET5 method underestimated the angle of the foot for all foot strike patterns in the first 23–34% of the stance (p < 0.025). This study supports the idea that the HEEL-TOE method can be used as a simplified method for determining FSA from 3D kinematics. Researchers should proceed with caution when employing the HEEL-MET5 method, as it is likely underestimating FSA due to foot inversion in the early stance phase. [ABSTRACT FROM AUTHOR]

This study aimed to measure the contribution of each body segment to the production of total body kinetic energy (KE) during a 40-m sprint. Nine recreational sprinters performed two 40-m sprints wearing a MVN Biomech suit (Xsens). Data recorded were used to calculate total body KE, and the KE of each segment. The KE of each segment was then expressed as a percentage of the total body KE. We divided the sprint into three phases: 1 – start to maximal power (Pmax), 2 – Pmax to maximal velocity (Vmax), and 3 – Vmax to the end of the 40 m. Total body KE increased from the start to the end of the 40-m sprint (from 331.3 ± 68.4 J in phase 1 to 2378.8 ± 233.0 J in phase 3; p ≤ 0.001). The contribution of the head–trunk increased (from 39.5 ± 2.4% to 46.3 ± 1.1%; p ≤ 0.05). Contribution of the upper and lower limbs decreased over the three phases (respectively from 15.7 ± 2.5% to 10.6 ± 0.6% and from 44.8 ± 2.1% to 43.1 ± 1.5%; p ≤ 0.05). This study revealed the important contribution of the trunk to forward propulsion throughout the entire acceleration phase. [ABSTRACT FROM AUTHOR]

This study aimed to identify how body dimensions interact with anteroposterior block distances to influence lower limb joint angles in the "set" position, how these angles relate to block clearance kinetic and kinematic parameters, and how these biomechanical parameters influence sprint start performance in sprinters of both sexes and of different ability levels. Seventy-eight sprinters performed six maximal-effort 10 m sprints. Joint angles in the "set" position were quantified through 2D video analysis, and the forces generated during block exit were measured by dynamometric starting blocks. Lower limb length was associated with the front block-starting line distance ([FB/SL], partial correlation [rPC] = 0.48) and was a significant predictor of FB/SL (R2 = 0.39). The FB/SL was associated with front hip angle (rPC = 0.38), which was consequently associated with numerous kinetic variables during block clearance (rPC from −0.41 to −0.61). Coaches should be encouraged to explore the interactions between individual lower limb lengths and the FB/SL distance in both male and female sprinters to manipulate the front hip angle in the "set" position in an attempt to achieve more favourable block clearance kinetics. [ABSTRACT FROM AUTHOR]

The Nordic hamstring exercise (NHE) is employed as a component of preventative training programmes to minimise hamstring strain injury risk. Variation in the methods and terminology used to assess the NHE makes comparison between studies difficult. We aimed to compare the utility of kinetic and kinematic metrics by comparing several collected concurrently. 18 male recreational rugby union participants completed 3 bilateral NHE repetitions on a hamstring device equipped with in-line strain gauge load cells, integrated with a 3-dimensional motion tracking system. Mean break-point angle occurred after the angle at first acceleration (121.5 ± 10.4° vs. 119.2 ± 7.1°) whereas break-torque angle (BTA) occurred later in the NHE action (126.0 ± 9.8°) showing highest correlation to the angle at greatest acceleration (123.9 ± 7.9°, r = 0.85). Future research should consider movement quality as the angular velocity of the knee joint at BTA demonstrated large variation (range = 3.6–93.4 deg·s1), with high intrasubject variability of relative trunk-to-thigh angle at peak-torque (range = 0.4–44.7°). This study proposes standardisation of methods and terminology used to define the NHE. Measuring BTA is recommended to represent the point at which hamstring muscle failure occurs, specific to the proposed injury mechanism during high-speed running. [ABSTRACT FROM AUTHOR]

The aims of this study were to assess the effects of stroke rate (SR) on the ability of trained rowers to: a) comply with concurrent biomechanical biofeedback on knee-back-elbow joint sequencing; and b) transfer any changes to competition-intensity conditions (maximal rowing task). Following a five-minute maximal rowing task (Baseline), 30 trained rowers were randomised to four groups. Two groups rowed at high SRs (90% maximum SR with biofeedback (BFb90) or control), while others rowed at low SRs (60% maximum SR with biofeedback (BFb60) or control) for 3 sessions. All rowers then completed another maximal rowing task (Transfer). Rowers complied with the biofeedback at both SRs, which promoted coordinative changes to knee-elbow motions during the pull. During Transfer, control rowers did not improve whereas those receiving biofeedback covered significantly greater distances (increase from Baseline: BFb60 = 6 ± 5%; BFb90 = 5 ± 4%; p < 0.05). However, movement adaptations were temporally different between SRs and were better maintained into Transfer by those that rowed at higher rates. This indicated biofeedback specificity, as transference of modified movement patterns appeared better when acquisition and transfer conditions were similar. These findings have practical implications for assimilating biofeedback into training programmes. [ABSTRACT FROM AUTHOR]

The aim of this was study to examine the inter-task relationships and compare change of direction (COD) biomechanics between different angles (45°, 90°, and 180°). Twenty-seven men performed three COD tasks, whereby lower-limb and trunk kinematics and kinetics were assessed via 3D motion and ground reaction force (GRF) analysis. Key mechanical differences (p ≤ 0.025, η2 = 0.024–0.940) in velocity profiles, GRF, sagittal joint angles and moments, multiplanar knee joint moments, and technical parameters existed between CODs. The primary findings were that as COD angle increased, velocity profiles decreased (p < 0.001, d = 1.56–8.96), ground contact times increased (p < 0.001, d = 3.00–5.04), vertical GRF decreased (p < 0.001, d = 0.87–3.48), and sagittal peak knee joint moments decreased (p ≤ 0.040, d = 0.62–2.73). Notably, the greatest peak knee internal rotation (KIRMs) and abduction moments (KAMs) and angles were observed during the 90° COD (p < 0.001, d = 0.88–1.81), indicating that this may be the riskiest COD angle. Small to very large (r = 0.260–0.702) associations in KAMs and KIRMs were observed between tasks, indicating that evaluations at different angles are needed to develop an athlete's biomechanical injury risk profile. The results support the concept that COD biomechanics and potential surrogates of non-contact anterior cruciate ligament injury risk are "angle-dependent"; which have important implications for COD coaching, screening, and physical preparation. [ABSTRACT FROM AUTHOR]

Key areas of sports science research investigate the functional role of muscle activations within human movement. Even within relatively constrained movements like cycling, significant variability is observed in muscle activation strategies. Particular attention has been given to particular muscles, despite Soleus and Tibialis anterior muscles presenting a potentially functionally relevant split between monomodal and bimodal activation strategies. The current study (N = 54) investigated the prevalence and functional implications of these different strategies and identified, in addition to monomodal [Soleus: N = 24, Tibialis anterior: N = 7] and bimodal [Soleus: N = 12, Tibialis anterior: N = 31] strategies, a third group switching between strategies [Soleus: N = 16, Tibialis anterior: N = 13]. The combined Soleus group showed significantly higher Index of Force Effectiveness, lower negative work and lower radial forces than the bimodal group. Furthermore, bimodal Soleus strategies produced a period of significantly greater plantar flexion during the upstroke. No differences were found between the Tibialis anterior groups. These data show an identifiable group of cyclists utilising a combination of monomodal and bimodal strategies potentially benefiting mechanical effectiveness. Awareness of such functional implications can aid researchers and practitioners when interpreting cycling biomechanics data or intervention responses. Further research should investigate the factors that mediate transitions between activation strategies within the combined groups. [ABSTRACT FROM AUTHOR]

Uphill training is applied to induce specific overload on the musculoskeletal system to improve sprinting mechanics. This study aimed to identify unique kinematic features of uphill sprinting at different slopes and to suggest practical implications based on comparisons we early stance phase. At take-off, steeper slopes induced significantly more extended joint angles and higher ROMs during the late stance phase. Compared with moderate slopes, more anti-phase coordination patterns were detected at steeper slopes. Thus, uphill sprinting at steeper slopes shares essential kinematic features with the early acceleration phase of level sprinting. Moderate inclinations induce biomechanical adaptations similar to those in the late acceleration phase of level sprinting. Hence, the specific transfer of uphill sprinting to acceleration depends on the slope inclinations. [ABSTRACT FROM AUTHOR]

This study examined the relationships between physical capacity, bowling technique and ball speed in 20 fast-bowlers. Technique factors correlated with ball speed were; bowling action duration (r = -0.639, p = 0.002), run-up velocity (r = 0.616, p = 0.004), back foot contact (BFC) time (r = -0.608, p = 0.004), front foot contact (FFC)-ball release (BR) duration (r = -0.602, p = 0.005), delivery stride phase acceleration (r = -0.582, p = 0.007), delivery stride duration (r = -0.547, p = 0.012), time of peak horizontal braking force (r = -0.538, p=0.014), peak pelvis COM velocity (BFC-BR) (r = 0.469, p = 0.037) and peak vertical GRF time (r = -0.461, p = 0.041). Physical capacities were; 10-30 m split (r = -0.554, p = 0.011), 30 m sprint (r = -0.482, p = 0.031) and IMTP (r = 0.471, p = 0.036). Stepwise regression showed bowling action duration and 10-30 m split explained 54% (p = 0.001) of ball speed variation. Ball speed was associated with faster run-ups, shorter BFC times and abrupt FFC GRF application. Coaches should also consider sprint speed and lower-body strength as important modifiable factors for fast-bowlers. [ABSTRACT FROM AUTHOR]

Biofeedback (BFb) is a useful tool to accelerate the skill development process. Limited research has applied BFb to the whole lower-limb in a complex skill therefore the aim of this research was to assess the effectiveness of a biofeedback intervention targeting whole lower limb kinematics. Thirty-two healthy participants were randomized to a BFb (n = 16) and a Control group (n = 16). Participants visited a motion capture laboratory on three occasions during one week, and returned for retention testing at 4–6 weeks. Following introduction to a novel lunge-touch task, visual BFb on lower limb joint kinematic extension angular velocities (ω) and timing were provided following each lunge. BFb was effective in increasing Hipω (F = 3.746, p = 0.03) and Kneeω (F = 10.241, p = 0.01). Peak Ankleω remained unchanged (F = 1.537, p = 0.23, η2 = 0.05), however Peak Ankleθ (F = 10.915, p < 0.001, η2 = 0.27) and AnkleROM (F = 9.543, p < 0.001, η2 = 0.24) significantly increased. Despite kinematic changes, there were no significant changes in any external kinetics. No significant correlations were found between Hipω, Kneeω or Ankleω and horizontal impulse (ImpulseY: r = 0.20, p = 0.26; r = −0.11, p = 0.24; and r = 0.22, p = 0.28, respectively). Findings demonstrate that BFb can be used to alter multiple kinematic variables in a complex skill, but do not necessarily alter associated kinetic variables not directly targeted by BFb. [ABSTRACT FROM AUTHOR]

Comprehensive information regarding neuromuscular function, as assessed through force-velocity-power (FVP) profiling, is of importance for training optimization in athletes. However, neuromuscular function is highly task-specific, potentially governed by dissimilarity of the overall orientation of forceapplication. The hip thrust (HT) exercise is thought to be of relevance for sprinting considering its antero-posterior force orientation and considerable hip-extensor recruitment, however, the association between their respective FVP profiles remains unexplored. Therefore, to address the concept of force orientation specificity within FVP profiling, the maximal theoretical neuromuscular capabilities of 41 professional male footballers (22.1 ± 4.1 years, 181.8 ± 6.4 cm, 76.4 ± 5.5 kg) were assessed during sprint acceleration, squat jumping (SJ) and the HT exercise. No significant associations were observed for maximal theoretical force or velocity between the three FVP profiling modalities, however, maximal theoretical power (Pmax) was correlated between sprinting and SJ (r = 0.73, P < 0.001) and HT and SJ (r = 0.44, P = 0.01), but not between sprinting and HT (r = 0.18, P = 0.36). In conclusion, although Pmax may be considered a somewhat universal lower-extremity capability, neuromuscular function is associated with substantial task-specificity not solely governed by the overall direction of force orientation. [ABSTRACT FROM AUTHOR]

We aimed to determine whether there were any differences in how surfers used their lead and trail limbs when landing two variations of a simulated aerial manoeuvre, and whether technique affected the forces generated at landing. Fifteen competitive surfers (age 20.3 ± 5.6 years, height 178.2 ± 9.16 cm, mass 71.0 ± 10.5 kg) performed a Frontside Air (FA) and Frontside Air Reverse (FAR), while we collected the impact forces, ankle and knee muscle activity, and kinematic data. A principal component analysis (PCA) was used to reduce 41 dependent variables into 10 components. A two-way MANOVA revealed that although there were no limb x aerial variation interactions, surfers generated significantly higher relative loading rates at landing for the trail limb compared to the lead limb (+28.8 BW/s; F(1,303) = 20.660, p < 0.0001, η2 = 0.064). This was likely due to the surfers "slapping" the trail limb down when landing, rather than controlling placement of the limb. Similarly, higher relative loading rates were generated when landing the FA compared to the FAR (+23.6 BW/s; F(1,303) = 31.655, p < 0.0001, η2 = 0.095), due to less time over which the forces could be dissipated. No relationships between aerial variation or limb were found for any of the kinematic or muscle activity data. Practitioners should consider the higher relative loading rates generated by a surfer's trail limb and when surfers perform a FA when designing dry-land training to improve the aerial performance of surfing athletes. [ABSTRACT FROM AUTHOR]

In swimming relay races, various start techniques are performed by swimmers, but it remains unclear which technique leads to a better start performance. Therefore, the purpose of the present study was to compare the kinematic characteristics of different relay start techniques with the new starting block Omega OSB11. Eleven international youth swimmers were filmed during 1) no step with parallel feet, 2) no step with separated feet and 3) one-step starts and their centre of mass kinematics calculated with 2D-DLT algorithms. Results indicate that differences between techniques were detected in the spatiotemporal parameters of the block and aerial start phases (e.g., initial and take-off positions, entry height, preparation and changeover times) and in selected parameters of the underwater phase (e.g., emersion time and distance, underwater time and distance). However, no statistical effects were found in 5 m, 10 m and 15 m start times, nor in horizontal take-off velocity, despite an observed trend for the one-step start to be superior to the non-step techniques. These results suggest that differences between relay techniques could rely more on the swimmer's body posture (angular kinematics) on the block, flight and underwater phases than on the centre of mass linear kinematics. [ABSTRACT FROM AUTHOR]

Pacing profiles of 19 elite and sub-elite 200-m kayak athletes were examined through stroke-by-stroke analysis, using GPS/accelerometer methodology. Stroke rates and lengths were also quantified across multiple race segments. Whilst athletes reached peak velocity at between 40 and 60 m, it was not possible to determine specifically whether an all-out or positive strategy was employed. Race times were strongly and negatively correlated with the acceleration over the first ~25% of race distance (r = −0.95 ± 0.04) as well as average velocity over the first 30 m of the race (r>-0.9), i.e. faster starts were associated with faster finishing times. Furthermore, the maintenance of velocity, stroke rate and stroke length after reaching their maxima were strongly associated with race times. Stroke rates were higher (Cohen's d = 5.19) in the elite than sub-elite athletes (group categorisation based on race times), but there were no substantial differences in stroke rates between athletes within the elite cohort. Nonetheless, longer stroke lengths were associated with faster race times within the elite cohort (r = −0.48 to −0.85). The current study suggests that faster rates of acceleration and the ability to exhibit greater stroke lengths at relatively high stroke rates are determinants of 200-m kayak race performance. [ABSTRACT FROM AUTHOR]

The purpose of this study was to use regularised regression models to identify the most important biomechanical predictors of throwing distance in elite male (M) and female (F) javelin throwers at the 2017 IAAF world championships. Biomechanical data from 13 male and 12 female javelin throwers who competed at the 2017 IAAF world championships were obtained from an official scientific IAAF report. Regularised regression models were used to investigate the associations between throwing distance and release parameters, whole-body kinematic and joint-level kinematic data. The regularised regression models identified two biomechanical predictors of throwing distances in both M and F javelin throwers: release velocity and knee flexion angle of the support leg at the moment of javelin release. In addition, the length of the delivery stride was an important predictor of throwing distance in M throwers, whereas the javelin's attitude angle and the distance between the whole-body centre of mass and the centre of mass of the back foot at the beginning of the delivery phase were important predictors of throwing distance in F throwers. [ABSTRACT FROM AUTHOR]

Dancers spend large amounts of time practicing and performing, where fatigue may occur, resulting in adverse movement patterns. The purpose of this study was to compare sauté landings before and after acute physical fatigue in experienced female dancers. Twenty-one dancers completed 10 sauté jumps before and after a dance-specific fatigue protocol. A 12-camera motion capture system and a force plate were utilized to collect three-dimensional kinematic and kinetic data. After fatigue, dancers demonstrated an increase in mediolateral centre of mass displacement, pelvis excursion, peak knee abduction, peak ankle eversion and external rotation, as well as decreased peak metatarsophalangeal (MTP) joint extension, indicating less desirable movement patterns. Peak vertical ground reaction force was decreased after fatigue due to a softer landing strategy, demonstrated by increased peak hip flexion, knee flexion, and ankle dorsiflexion. There was some indication of shifting demands demonstrated by an increased peak knee extensor moment and decreased peak MTP flexor moment after fatigue. With jump landing kinematics and kinetics affected after only an average of 5 minutes of dancing, dancers may benefit from developing greater endurance and more eccentric strength to allow them to slow down properly while landing and to sustain the aesthetic demands throughout performance. [ABSTRACT FROM AUTHOR]

The open stance forehand has been hypothesized to be more traumatic for knee injuries in tennis than the neutral stance forehand. This study aims to compare kinematics and kinetics at the knee during three common forehand stroke stances (attacking neutral stance ANS, attacking open stance AOS, defensive open stance DOS) to determine if the open stance forehand induces higher knee loadings and to discuss its potential relationship with given injuries. Eight advanced tennis players performed eight repetitions of forehand strokes with each stance (ANS: forward run and stroke with feet parallel with the hitting direction, AOS: forward run and stroke with feet perpendicular to the hitting direction, DOS: lateral run and stroke with feet perpendicular to the hitting direction) at maximal effort. All the trials were recorded with an optoelectronic motion capture system. The flexion-extension, abduction-adduction, external-internal rotation angles, intersegmental forces and torques of the right knee were calculated. Ground reaction forces were measured with a forceplate. The DOS increases vertical GRF, maximum knee flexion and abduction angles, range of knee flexion-extension, peak of compressive, distractive and medial knee forces, peak of knee abduction and external rotation torques. Consequently, the DOS appears potentially more at risk for given knee injuries. [ABSTRACT FROM AUTHOR]