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Static assessment and grouping of riders by competition level are prevalent in equestrian coaching practice and research. This study explored sagittal pelvic tilt in 35 competitive dressage riders to analyse the relationship between static and dynamic postures and assess the interaction of competition level. Riders were assessed using optical motion capture on a riding simulator at halt and in walk, trot, and left and right canter. Mean, minimum and maximum pelvic tilt, and range of motion (ROM) were measured as the pitch rotation of a rigid body formed by markers placed on the rider's left/right anterior and posterior superior iliac spines and sacrum, averaged over six time-normalised strides. Three key results emerged: (1) there are correlations between the rider's mean pelvic tilt in simulated walk, trot and canter, but not at halt; (2) mean pelvic tilt values are not significantly influenced by competition level (p = 0.233); and (3) the minimum and maximum pelvic tilt values illustrate individual strategies between gaits. Therefore, results from static assessment and grouping of riders by competition level should be interpreted with caution. Riders should be assessed as individuals, during dynamic riding-specific tasks, to understand their postural strategies. [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]

Background: With hydrotherapy rising in the United Kingdom, before understanding the effect of hydrotherapy in animals with pathologies, kinematics data for healthy animals is required. Objectives: To assess how different water levels on an underwater treadmill (UWTM) can affect joint kinematics. Methods: Zinc oxide markers were placed on bony landmarks on the limbs of 10 healthy dogs, randomly split into five groups. An UWTM was used with water levels to the digits, tarsus, stifle and hip. The maximum flexion, extension and ROM were determined and a repeated measures ANOVA or Friedman's was used to determine significant differences. Results: We have detected various changes in kinematics following exercise at different water levels, in comparison with a dry treadmill, including consistent increases in flexion of the elbow, stifle and tarsal joints, which were observed for all water levels. The carpal joint had increases in flexion all water levels apart from digit level. An increase in shoulder flexion was seen only with water on or above stifle level, while hip kinematics had the fewest changes with only ROM increasing at high water level (hip level). Extension of the limbs joints was not markedly affected, with only a few data being significant. The carpal joint had an overall decrease in extension with water at all levels, and the stifle joint had a decreased extension when water was at stifle height. Conclusions: Water level can significantly affect joint kinematics, and knowledge of how each water level affects the joints is relevant to design tailored hydrotherapy protocols. [ABSTRACT FROM AUTHOR]

Background: Femoroacetabular impingement (FAI) has been extensively investigated and is strongly associated with athletic participation. Purpose: To assess (1) the prevalence of cam-type FAI across various sports; (2) whether kinematic variation among sports influences hip morphology; and (3) whether performance level, duration, and frequency of participation or other factors influence hip morphology in a sporting population. Study Design: Systematic review; Level of evidence, 4. Methods: A systematic search of Embase, PubMed, and the Cochrane Library was undertaken following the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Prospective and retrospective case series, case reports, and review articles published after 1999 were screened, and those that met the inclusion criteria decided a priori were included for analysis. Results: The literature search identified 58 relevant articles involving 5683 participants. A total of 49 articles described a higher prevalence of FAI across various "hip-heavy" sports, including soccer, basketball, baseball, ice hockey, skiing, golf, and ballet. In studies including nonathlete controls, a greater prevalence of FAI was reported in 66.7% of studies (n = 8/12). The highest alpha angle was identified at the 1-o'clock position (n = 9/9) in football, skiing, golf, ice hockey, and basketball. The maximum alpha angle was located in a more lateral position in goalkeepers versus positional players in ice hockey (1 vs 1:45 o'clock). A positive correlation was also identified between the alpha angle and both age and activity level (n = 5/8 and n = 2/3, respectively) and between prevalence of FAI and both age and activity level (n = 2/2 and n = 4/5). Conclusion: Hip-heavy sports show an increased prevalence of FAI, with specific sporting activities influencing hip morphology. There is some evidence to suggest that a longer duration and higher level of training also result in an increased prevalence of FAI. Registration: CRD4202018001 (PROSPERO). [ABSTRACT FROM AUTHOR]

Context: A valgus position of the knee on functional loading tasks has been reported to be associated with patellofemoral-joint pain. Training programs to reduce knee valgus have been shown to be effective but take time. It would appear logical to use a brace or strap to help control this knee motion to reduce symptoms. Objective: To assess the impact of the SERF strap on knee valgus and patellofemoral-joint pain. Design: Repeated measures. Setting: University human performance laboratory. Participants: 12 women with patellofemoral pain (mean age 24 ± 3.2 y). Intervention: Application of SERF strap. Main Outcome Measures: Knee-valgus angle on single-leg squat and step landing and visual analog scale pain score. Results: The application of the SERF brace significantly reduced the pain (P < .04) and knee valgus (P < .034) during both tasks. Conclusion: The SERF brace brings about a significant reduction in pain during functional tasks. Although the brace brought about a significant reduction in knee valgus, this failed to exceed the smallest-detectable-difference value, so the difference is likely to be related to measurement error. The mechanism as to why this the reduction in pain occurs therefore remains unclear, as this study in line with many others failed to demonstrate meaningful changes in kinematics that could provide an obvious explanation. [ABSTRACT FROM AUTHOR]

Background: Osteoarthritis of the knee is a common condition that is expected to rise in the next two decades leading to an associated increase in total knee replacement (TKR) surgery. Although there is little debate regarding the safety and efficacy of modern TKR, up to 20% of patients report poor functional outcomes following surgery. This study will investigate the functional outcome of two TKRs; the JOURNEY II Bi-Cruciate Stabilised knee arthroplasty, a newer knee prosthesis designed to provide guided motion and improve knee kinematics by more closely approximating a normal knee, and the GENESIS II, a proven existing design.Aim: To compare the change in Patient-reported Outcome Measures (PROMs) scores of the JOURNEY II BCS and the GENESIS II from pre-operation to 6 months post operation.Methods: CAPAbility is a pragmatic, blinded, two-arm parallel, randomised controlled trial recruiting patients with primary osteoarthritis due to have unilateral TKR surgery across two UK hospitals. Eligible participants (n = 80) will be randomly allocated to receive either the JOURNEY II or the GENESIS II BCS knee prosthesis. Baseline measures will be taken prior to surgery. Patients will be followed at 1 week, 6 to 8 weeks and 6 months post-operatively. The primary outcome is the Oxford Knee Score (OKS) at 6 months post-operatively. Secondary outcomes include: other PROMs, biomechanical, radiological (computerised tomography, (CT)), clinical efficacy and safety outcomes. An embedded qualitative study will also investigate patients' perspectives via interview pre and post surgery on variables known to affect the outcome of TKR surgery. A sub-sample (n = 30) will have additional in-depth interviews to explore the themes identified. The surgeons' perspectives on the operation will be investigated by a group interview after all participants have undergone surgery.Discussion: This trial will evaluate two generations of TKR using PROMS, kinematic and radiological analyses and qualitative outcomes from the patient perspective.Trial Registration: International Standard Randomised Controlled Trials Number Registration, ID: ISRCTN32315753. Registered on 12 December 2017. [ABSTRACT FROM AUTHOR]

We investigated the relationship between lower limb osteoarthritis (OA) and muscle strength and power (assessed by jumping mechanography) in UK community-dwelling older adults. We recruited 249 older adults (144 males, 105 females). OA was assessed clinically at the knee according to ACR criteria and radiographically, at the knee and hip, using Kellgren and Lawrence grading. Two-footed jumping tests were performed using a Leonardo Mechanography Ground Reaction Force Platform to assess maximum muscle force, power and Esslinger Fitness Index. Linear regression was used to assess the relationship between OA and jumping outcomes. Results are presented as β (95% confidence interval). The mean age of participants was 75.2 years (SD 2.6). Males had a significantly higher maximum relative power during lift off (mean 25.7 W/kg vs. 19.9 W/kg) and maximum total force during lift off (mean 21.0 N/kg vs. 19.1 N/kg) than females. In adjusted models, we found significant associations in males between clinical knee OA and maximum relative power [- 6.00 (CI - 9.10, - 2.94)] and Esslinger Fitness Index [- 19.3 (- 29.0, - 9.7)]. In females, radiographic knee OA was associated with total maximum power [- 2.0 (- 3.9, - 0.1)] and Esslinger Fitness Index [- 8.2 (- 15.9, - 0.4)]. No significant associations were observed for maximum total force. We observed significant negative associations between maximum relative power and Esslinger Fitness Index and clinical knee OA in males and radiographic knee OA in females. We have used novel methodology to demonstrate relationships between muscle function and OA in older adults. [ABSTRACT FROM AUTHOR]

Background: Anterolateral complex injuries are becoming more recognized. While these are known to affect tibiofemoral mechanics, it is not known how they affect patellofemoral joint behavior. Purpose: To determine the effect of (1) sectioning the anterolateral complex and (2) performing a MacIntosh tenodesis under various conditions on patellofemoral contact mechanics and kinematics. Study Design: Controlled laboratory study. Methods: Eight fresh-frozen cadaveric knees were tested in a customized rig, with the femur fixed and tibia free to move, with optical tracking to record patellar kinematics and with thin pressure sensors to record patellofemoral contact pressures at 0°, 30°, 60°, and 90° of knee flexion. The quadriceps and iliotibial tract were loaded with 205 N throughout testing. Intact and anterolateral complex–sectioned states were tested, followed by 4 randomized tenodeses applying 20- and 80-N graft tension, each with the tibia in its neutral intact alignment or left free to rotate. Statistical analyses were undertaken with repeated measures analysis of variance, Bonferroni post hoc analysis, and paired samples t tests. Results: Patellar kinematics and contact pressures were not significantly altered after sectioning of the anterolateral complex (all: P > .05). Similarly, they were not significantly different from the intact knee in tenodeses performed when fixed tibial rotation was combined with 20- or 80-N graft tension (all: P > .05). However, grafts tensioned with 20 N and 80 N while the tibia was free hanging resulted in significant increases in lateral patellar tilt (P < .05), and significantly elevated lateral peak patellofemoral pressures (P < .05) were observed for 80 N. Conclusion: This work did not find that an anterolateral injury altered patellofemoral mechanics or kinematics, but adding a lateral tenodesis can elevate lateral contact pressures and induce lateral patellar tilting if the tibia is pulled into external rotation by the tenodesis. Although these in vitro changes were small and might not be relevant in a fully loaded knee, controlling the position of the tibia at graft fixation is effective in avoiding overconstraint at time zero in a lateral tenodesis. Clinical Relevance: Small changes in lateral patellar tilt and patellofemoral contact pressures were found at time zero with a MacIntosh tenodesis. These changes were eliminated when the tibia was held in neutral rotation at the time of graft fixation. The risk of overconstraint after a lateral tenodesis therefore seems low and in accordance with recent published reports. [ABSTRACT FROM AUTHOR]

Foot drop is a common gait impairment in people with MS (pwMS) but in some foot drop may only occur after a period of prolonged walking and may be a sign of motor fatigability. The purpose of the study was to explore whether, for pwMS, an adapted six-minute walk test (6minWT) would result in an increase in foot drop as measured using electrogoniometry. Sagittal ankle kinematics were recorded for fifteen participants (10 females and 5 males, aged 37-64) with MS (EDSS 4-6) throughout the 6minWT. Ankle kinematics and temporal stride parameters were compared between the first and last 10 gait cycles of the 6minWT. Peak dorsiflexion in swing was significantly reduced at the end of the 6minWT compared to the start, with six of the fifteen participants having a decrease of two degrees or more. Statistically significant changes in temporal stride parameters suggested a decrease in walking speed. Our results suggest that with the protocol used in this study it is feasible to identify patients who experience increased foot drop as a result of a prolonged exercise task. [ABSTRACT FROM AUTHOR]

Recreational tennis players tend to have higher incidence of tennis elbow, and this has been hypothesised to be related to one-handed backhand technique and off-centre ball impacts on the racket face. This study aimed to investigate for a range of participants the effect of off-longitudinal axis and off-lateral axis ball–racket impact locations on racket and forearm joint angle changes immediately following impact in one-handed tennis backhand groundstrokes. Three-dimensional racket and wrist angular kinematic data were recorded for 14 university tennis players each performing 30 “flat” one-handed backhand groundstrokes. Off-longitudinal axis ball–racket impact locations explained over 70% of the variation in racket rotation about the longitudinal axis and wrist flexion/extension angles during the 30 ms immediately following impact. Off-lateral axis ball–racket impact locations had a less clear cut influence on racket and forearm rotations. Specifically off-longitudinal impacts below the longitudinal axis forced the wrist into flexion for all participants with there being between 11° and 32° of forced wrist flexion for an off-longitudinal axis impact that was 1 ball diameter away from the midline. This study has confirmed that off-longitudinal impacts below the longitudinal axis contribute to forced wrist flexion and eccentric stretch of the wrist extensors and there can be large differences in the amount of forced wrist flexion from individual to individual and between strokes with different impact locations. [ABSTRACT FROM AUTHOR]

The aim of this study was to analyse lower limb work patterns in world-class race walkers. Seventeen male and female athletes race walked at competitive pace. Ground reaction forces (1000 Hz) and highspeed videos (100 Hz) were recorded and normalised joint moments, work and power, stride length, stride frequency and speed estimated. The hip flexors and extensors were the main generators of energy (24.5 J (±6.9) and 40.3 J (±8.3), respectively), with the ankle plantarflexors (16.3 J (±4.3)) contributing to the energy generated during late stance. The knee generated little energy but performed considerable negative work during swing (-49.1 J (±8.7)); the energy absorbed by the knee extensors was associated with smaller changes in velocity during stance (r = .783, P < .001), as was the energy generated by the hip flexors (r = -.689, P = .002). The knee flexors did most negative work (-38.6 J (±5.8)) and the frequent injuries to the hamstrings are probably due to this considerable negative work. Coaches should note the important contributions of the hip and ankle muscles to energy generation and the need to develop knee flexor strength in reducing the risk of injury. [ABSTRACT FROM AUTHOR]

Background Ankle inversion injuries are one of the most common and burdensome injuries in athletic populations. Research that prospectively identifies characteristics associated with this injury is lacking. This prospective study compared baseline anthropometric and biomechanical gait characteristics of military recruits who sustained an ankle inversion injury during training, with those who remained injury-free. Methods Bilateral plantar pressure and three-dimensional lower limb kinematics were recorded in 1065 male, injury-free military recruits, during barefoot running. Injuries that occurred during the 32-week recruit training programme were subsequently recorded. Data were compared between recruits who sustained an ankle inversion injury during training (n = 27) and a sample (n = 120) of those who completed training injury-free. A logistic regression analysis was used to identify risk factors for this injury. Findings A narrower bimalleolar width and an earlier peak pressure under the fifth metatarsal were predictors of ankle inversion injury. Those who sustained an ankle inversion injury also had a lower body mass, body mass index, and a smaller calf girth than those who completed training injury-free. Interpretation Anthropometric and dynamic gait characteristics have been identified that may predispose recruits to an ankle inversion injury during Royal Marine recruit training, allowing identification of recruits at higher risk at the start of training. [ABSTRACT FROM AUTHOR]

Asymmetry in gymnastics underpins successful performance and may also have implications as an injury mechanism; therefore, understanding of this concept could be useful for coaches and clinicians. The aim of this study was to examine kinematic and external kinetic asymmetry of the arm segments during the contact phase of a fundamental skill, the forward handspring on floor. Using a repeated single subject design six female National elite gymnasts (age: 19 ± 1.5 years, mass: 58.64 ± 3.72 kg, height: 1.62 ± 0.41 m), each performed 15 forward handsprings, synchronised 3D kinematic and kinetic data were collected. Asymmetry between the lead and non-lead side arms was quantified during each trial. Significant kinetic asymmetry was observed for all gymnasts (p < 0.005) with the direction of the asymmetry being related to the lead leg. All gymnasts displayed kinetic asymmetry for ground reaction force. Kinematic asymmetry was present for more gymnasts at the shoulder than the distal joints. These findings provide useful information for coaching gymnastics skills, which may subjectively appear to be symmetrical. The observed asymmetry has both performance and injury implications. [ABSTRACT FROM AUTHOR]

BACKGROUND: Static radiographic techniques are unable to capture the wealth of kinematic information available from lumbar spine sagittal plane motion. OBJECTIVE: Demonstration of a viable non-invasive technique for acquiring and quantifying intervertebral motion of the lumbar spine in the sagittal plane. METHODS: Videofluoroscopic footage of sagittal plane lumbar spine flexion-extension in seven symptomatic volunteers (mean age = 48 yrs) and one asymptomatic volunteer (age = 54 yrs) was recorded. Vertebral bodies were digitised using customised software employing a novel vertebral digitisation scheme that was minimally affected by out-of-plane motion. RESULTS: Measurement errors in intervertebral rotation (± 1°) and intervertebral displacement (± 0.5 mm) compare favourably with the work of others. Some subjects presenting with an identical condition (disc prolapse) exhibited a similar column vertebral flexion-extension relative to S1 (L3: max. 5.9°, min. 5.6°), while in others (degenerative disc disease) there was paradoxically a significant variation in this measurement (L3: max. 28.1°, min. 0.7°). CONCLUSIONS: By means of a novel vertebral digitisation scheme and customised digitisation/analysis software, sagittal plane intervertebral motion data of the lumbar spine data has been successfully extracted from videofluoroscopic image sequences. Whilst the intervertebral motion signatures of subjects in this study differed significantly, the available sample size precluded the inference of any clinical trends. [ABSTRACT FROM AUTHOR]

We examined whether adults with autism had difficulty imitating atypical biological kinematics. To reduce the impact that higher-order processes have on imitation we used a non-human agent model to control social attention, and removed end-state target goals in half of the trials to minimise goal-directed attention. Findings showed that only neurotypical adults imitated atypical biological kinematics. Adults with autism did, however, become significantly more accurate at imitating movement time. This confirmed they engaged in the task, and that sensorimotor adaptation was self-regulated. The attentional bias to movement time suggests the attenuation in imitating kinematics might be a compensatory strategy due to deficits in lower-level visuomotor processes associated with self-other mapping, or selective attention modulated the processes that represent biological kinematics. [ABSTRACT FROM AUTHOR]

Horizontal jumps are discrete, fast, over-ground movements requiring coordination of the centre of mass (CoM) and base of support and are routinely assessed in sports settings. There is currently no biomechanics-based system to aid in their quick and objective large-scale assessment. We describe a practical system combining a single low-cost depth-sensing camera and point-cloud processing (PCP) to capture whole-body CoM and foot kinematics. Fourteen participants performed 10 single-leg horizontal jumps for distance. Foot displacement, CoM displacement, CoM peak velocity and CoM peak acceleration in the anterior-posterior direction of movement were compared with a reference 15-segment criterion model, captured concurrently using a nine-camera motion capture system (Vicon Motion Systems, UK). Between-system Pearson's correlations were very-large to near-perfect (n = 140; foot displacement = 0.99, CoM displacement = 0.98, CoM peak velocity = 0.97, CoM peak acceleration = 0.79), with mean biases being trivial–small (-0.07 cm [0.12%], 3.8 cm [3.5%], 0.03 m·s−1 [1.6%], 0.42 m·s−2 [7%], respectively) and typical errors being trivial–small for displacement (foot: 0.92 cm [0.8%]; CoM: 3.8 cm [3.4%]) and CoM peak velocity (0.07 m·s−1 [4.3%]), and large for CoM peak acceleration (0.72 m·s−2 [15%]). Limits of agreement were −1.9 to 2.0 cm for foot displacement, −11.3 to 3.6 cm for CoM displacement, −0.17 to 0.12 m·s−1 for CoM peak velocity and −2.28 to 1.43 m·s−2 for CoM peak acceleration. The practical system captured CoM and foot kinematics during horizontal jumps with acceptable precision. Further work to improve estimates of CoM accelerations and different populations are warranted. [ABSTRACT FROM AUTHOR]

This study aimed to characterise the biomechanics of the widely practiced eccentric heel-drop exercises used in the management of Achilles tendinosis. Specifically, the aim was to quantify changes in lower limb kinematics, muscle lengths and Achilles tendon force, when performing the exercise with a flexed knee instead of an extended knee. A musculoskeletal modelling approach was used to quantify any differences between these versions of the eccentric heel drop exercises used to treat Achilles tendinosis. 19 healthy volunteers provided a group from which optical motion, forceplate and plantar pressure data were recorded while performing both the extended and flexed knee eccentric heel-drop exercises over a wooden step when barefoot or wearing running shoes. This data was used as inputs into a scaled musculoskeletal model of the lower limb. Range of ankle motion was unaffected by knee flexion. However, knee flexion was found to significantly affect lower limb kinematics, intersegmental loads and triceps muscle lengths. Peak Achilles load was not influenced despite significantly reduced peak ankle plantarflexion moments (p < 0.001). The combination of reduced triceps lengths and greater ankle dorsiflexion, coupled with reduced ankle plantarflexion moments were used to provide a basis for previously unexplained observations regarding the effect of knee flexion on the relative loading of the triceps muscles during the eccentric heel drop exercises. This finding questions the role of the flexed knee heel drop exercise when specifically treating Achilles tendinosis. [ABSTRACT FROM AUTHOR]

Breast asymmetry is common in females, despite a similar driving force; dynamic activity may result in asymmetrical breast motion. This preliminary study investigated how breast categorisation (left/right or dominant/non-dominant) may affect breast support recommendations and its relationship with breast pain. Ten females ran on a treadmill at 10 kph in three breast supports (no bra, everyday bra, sports bra). Five reflective markers on the thorax and nipples were tracked using infrared cameras (200 Hz) during five running gait cycles in each breast support. Multiplanar displacements of both breasts were calculated relative to the thorax. Although the maximum individual participant difference was 2.4 cm (mediolaterally) between the left and right breast, no left/right differences were found in any direction or support condition. Notably, correlations between breast pain and anterioposterior breast displacement were stronger with the left breast (r = 0.614) and moderate with the right breast (r = 0.456). Following participant categorisation according to the greatest magnitude of superioinferior breast displacement (dominant breast), results showed significant differences in displacement for all directions across different breast supports. When using breast kinematic data to examine relationships with breast pain or to recommend breast support requirements, data on both breasts should be collected. [ABSTRACT FROM AUTHOR]

This paper analyzes the scan line survey data of the geological discontinuities collected from three quarry sites of West Malvern in Malvern Hills, UK, which remaine done of the major resource of geological materials for building stones and aggregates in the area. The kinematic analysisof the discontinuity data of the quarry sites was performed by using the DIPS software, which showed the likelihood of wedge, plane and toppling failures of the slopes. However, no failure is likely even for the steepest slope faces if planned to cut in the dip direction range of 30° to 70° and 130° to 230°. [ABSTRACT FROM AUTHOR]

This study investigated changes in performance and technique that occur during maximal effort bend sprinting compared with straight-line sprinting under typical outdoor track conditions. Utilising a repeated measures design, three-dimensional video analysis was conducted on seven male sprinters in both conditions (bend radius: 37.72 m). Mean race velocity decreased from 9.86  to 9.39 m/s for the left step (p = 0.008) and from 9.80  to 9.33 m/s for the right step (p = 0.004) on the bend compared with the straight, a 4.7% decrease for both steps. This was mainly due to a 0.11 Hz (p = 0.022) decrease in step frequency for the left step and a 0.10 m (p = 0.005) reduction in race step length for the right step. The left hip was 4.0° (p = 0.049) more adducted at touchdown on the bend than the straight. Furthermore, the bend elicited significant differences between left and right steps in a number of variables including ground contact time, touchdown distance and hip flexion/extension and abduction/adduction angles. The results indicate that the roles of the left and right steps may be functionally different during bend sprinting. This specificity should be considered when designing training programmes. [ABSTRACT FROM PUBLISHER]

The article presents a study on topic of “Length Change Patterns in the Lateral Extra-articular Structures of the Knee and Related Reconstructions" done by Cristoph Kittl and colleagues at Imperial College London, UK. The article mentions specimen preparation, data analysis, statistical analysis and results with clinical relevance. The findings show that the selection of graft attachment points and graft course affects length change pattern during knee flexion.

The article presents a study on the adverse effects of progressive medialization and lateralization on patellofemoral joint (PFJ) kinematics, contact mechanics and stability. Topics covered include patellfemoral tracking, contact pressures, and tibial tuberosity-trochlear groove (TT-TG). Also mentioned is the use of an optical tracking system.

The article reports on research which was conducted to compare acute counter movement jump (CMJ) responses after functional isometric (FI) and dynamic half (DH) squats. Researchers evaluated 10 male subjects who performed either FI or DH squats. They found that because of a lack of CMJ responses the use of DH squats rather than FI squats should be considered for training and precompetition situations.

The article reports on research which was conducted to investigate the kinematics and kinematics of two types of military athletic footwear; the PT-03 cross-trainer and PT 1000 running shoe. They found that the PT-3 was linked to kinetic and kinematic factors associated with injuries and concluded that the PT 1000 should be used for running exercises.

Context: A number of acute and overuse knee pathologies share a mechanism involving a poor dynamic alignment of the limb creating increased stress in the tissues. Inappropriate execution of a correct strategy during landing has been suggested to involve insufficient activity of the hip abductor and external rotator muscles. Limited data describing the relationships between hip-abductor muscle fatigue and hip/knee joint mechanics exists. Objective: To investigate the effect of fatigue of the hip abductor muscles on knee valgus angle. Design: Repeated measures. Participants: 30 asymptomatic subjects: 15 female (age 20.4 ± 1.4, range 18-26 years; height 1.66 m, range 1.60-1.76 m; weight 63.9 kg, range 58-68 kg) and 15 male subjects (age 22 ± 3.2, range 18-28 years; height 1.84 m, range 1.65-1.90 m; weight 82.1 kg, range 69-93 kg). Main Outcome Measures: Knee valgus (frontal plane projection) angle was assessed during a step landing task before and following a fatiguing protocol of the hip abductor muscles involving repeated 10 s maximal isometric contractions of the hip abductor muscles, until strength was recorded as 50 % of preintervention score. Results: Males showed no significant change in knee valgus angle at initial ground contact (p = .9 ES 0.1) or in maximum knee valgus (p = .64 ES 0.5) following the fatiguing. Females showed a significant increase in maximum knee valgus angle following the fatiguing (p = .0018 ES 1.0), though the knee valgus angle at initial contact was not changed (p = . 12 ES 0.67). They also demonstrated a significant increase in the change in knee valgus angle between initial contact and maximum following the fatiguing (p = .0004 ES 0.88). Conclusion: Females appear more susceptible to the effects of hip muscle fatigue, leading to a detrimental change in landing kinematics which may then predispose them to knee injury. [ABSTRACT FROM AUTHOR]

The article reports on research which was conducted to measure changes in gait parameters over the course of a 10 kilometer treadmill run. Researchers evaluated 15 competitive male runners. They found that while foot contact time decreased and flight time increased over the course of the run no other gait variables changed.

This study investigated the effect of projection angle on the distance attained in a rugby place kick. A male rugby player performed 49 maximum-effort kicks using projection angles of between 20 and 50°. The kicks were recorded by a video camera at 50 Hz and a 2-D biomechanical analysis was conducted to obtain measures of the projection velocity and projection angle of the ball. The player's optimum projection angle was calculated by substituting a mathematical expression for the relationship between projection velocity and projection angle into the equations for the aerodynamic flight of a rugby ball. We found that the player's calculated optimum projection angle (30.6°, 95% confidence limits ±1.9°) was in close agreement with his preferred projection angle (mean value 30.8°, 95% confidence limits ±2.1°). The player's calculated optimum projection angle was also similar to projection angles previously reported for skilled rugby players. The optimum projection angle in a rugby place kick is considerably less than 45° because the projection velocity that a player can produce decreases substantially as projection angle is increased. Aerodynamic forces and the requirement to clear the crossbar have little effect on the optimum projection angle. [ABSTRACT FROM AUTHOR]

The article examines whether nonanatomic positioning of the tunnel or graft overtensioning during medial patellofemoral ligament (MPFL) reconstruction will adversely affect patellar tracking and patellofemoral joint contact mechanics. The study found that anatomically positioned reconstruction with 2-N tension fixed at 30 degrees or 60 degrees of knee flexion restored joint contact pressures and tracking. The importance of a correct femoral tunnel position and graft tensioning is also noted.

Correct bicycle fit is important, and kinematic instability must be addressed to reduce the risk of knee injury. A change in Q Factor (horizontal distance between crank arms) has been shown to decrease metabolic cost. The combined effect upon gross mechanical efficiency (GME) and knee variability is unclear, however; there is no known simple method to predict self-selected Q Factor (SSQ). The SSQ was hypothesized to provide the greatest GME and least variability at the knee. Ten trained cyclists completed bouts of submaximal cycling at a range of Q Factors. The effectiveness of hanging and stepping tasks as predictors of SSQ was also tested. Measured SSQ (142 mm) provided the best combination of GME and knee stability compared with other Q Factors, and could be accurately predicted using a simple hanging task. The SSQ has the potential to lower the risk of knee injury and provide increased efficiency whilst cycling. [ABSTRACT FROM AUTHOR]

Objective. To describe the effect of customized foot orthoses (FOs) on the kinematic, kinetic and EMG features in patients with RA, tibialis posterior (TP) tenosynovitis and associated pes plano valgus.Methods. Patients with RA and US-confirmed tenosynovitis of TP underwent gait analysis, including three-dimensional (3D) kinematics, kinetics, intramuscular EMG of TP and surface EMG of tibialis anterior, peroneus longus, soleus and medial gastrocnemius. Findings were compared between barefoot and shod with customized FO conditions.Results. Ten patients with RA with a median (range) disease duration of 3 (1–18) years were recruited. Moderate levels of foot pain and foot-related impairment and disability were present with moderately active disease states. Altered timing of the soleus (P = 0.05) and medial gastrocnemius (P = 0.02) and increased magnitude of tibialis anterior (P = 0.03) were noted when barefoot was compared with shod with FO. Trends were noted for reduced TP activity in the contact period (P = 0.09), but this did not achieve statistical significance. Differences in foot motion characteristics were recorded for peak rearfoot eversion (P = 0.01), peak rearfoot plantarflexion (P < 0.001) and peak forefoot abduction (P = 0.02) in the shod with FOs compared with barefoot conditions. No differences in kinetic variables were recorded.Conclusion. This study has demonstrated, for the first time, alterations in muscle activation profiles and foot motion characteristics in patients with RA, pes plano valgus and US-confirmed TP tenosynovitis in response to customized FOs. Complex adaptations were evident in this cohort and further work is required to determine whether these functional alterations lead to improvements in patient symptoms. [ABSTRACT FROM PUBLISHER]

Our aim was to develop and evaluate a new antipronation foot orthosis that addressed problems perceived by clinicians and users with existing foot orthoses. Clinicians and users were engaged to develop a user specification for the orthosis, and orthotic geometry and materials were developed using clinical reasoning. The orthotic material properties were tested and the ability of the orthosis to reduce foot pronation evaluated on 27 individuals. Clinicians expressed concern that current prefabricated orthoses often did not offer sufficient support to the foot because of a combination of the shape and materials used, and users concurred but also highlighted issues of durability and hygiene. The geometry of the new orthosis was, therefore, adjusted to enable individual foot size orthoses to be produced. A material was selected that was harder and more durable than materials used in many prefabricated orthoses. When the new orthosis was being worn, maximum rearfoot eversion was reduced in both walking (mean reduction -3.8 degrees, p < 0.001) and running (mean reduction -2.5 degrees, p < 0.001). Through a structured process, orthotic design decisions were made that addressed the specific concerns of clinicians and users and the new orthosis was proven to reduce rearfoot pronation. [ABSTRACT FROM AUTHOR]

Background: Distance running continues to experience increased participation in the Western world, although it is associated with high injury rates. Barefoot running has been increasingly proposed as a means to prevent overuse injury due to various biomechanical differences, including reduced joint loading rates and altered kinematics and muscle activity patterns compared to shod running. Objective: The aim of this review was to systematically evaluate biomechanical differences between running barefoot and shod, including the quality of available evidence, in order to provide guidance on the phenomenon of barefoot running to the running and sports medicine communities. Data sources: A comprehensive search of MEDLINE, Web of Knowledge and EMBASE from inception to January 2013 was performed. Study selection: Trials evaluating injury-free recreational or competitive adults who participate in long-distance running (≥5 km), where a comparison of barefoot and shod running lower-limb kinetics, kinematics and/or electromyography were included. Studies examining sprinting and studies of single-subject design were excluded. Study appraisal and synthesis methods: Following initial searching, two reviewers identified a shortlist of relevant studies based on title and abstract, with the full text of these studies being tested against the inclusion criteria. References of included studies were examined and citation tracking was performed in Web of Knowledge. Two independent reviewers evaluated the methodological quality of each included study using a modified version of the Downs and Black quality index. Results of the quality assessment were used to identify high- and low-quality studies, data pooling was completed where possible and levels of evidence were determined based on the van Tulder criteria. Results: Eighteen studies were identified, all of low methodological quality. Effect size (ES) calculation was possible for 12 studies. Pooled results indicate moderate evidence that barefoot running is associated with reduced peak ground reaction force (GRF), increased foot and ankle plantarflexion and increased knee flexion at ground contact compared with running in a neutral shoe. Limited evidence indicates barefoot running is associated with reduced impact GRF, reduced peak knee flexion and varus joint moments, and a higher stride frequency compared to a neutral shoe. Very limited to limited evidence also indicates power absorption at the knee is decreased while being increased at the ankle whilst barefoot running. Additionally, the effects of barefoot running on loading rate appear dependent on strike pattern adopted, with a forefoot strike pattern found to reduce loading rate, whilst a rearfoot strike pattern increases loading rate when running barefoot compared to shod. Limitations: Key methodological weaknesses that must be addressed in future research were identified. Of particular note were absence of investigator blinding, infrequent intervention randomisation, small sample sizes and lack of evaluation following habituation. Two studies could not be retrieved because of publication in a non-English-language journal. Of particular note is that the validity of the body of work is compromised by the lack of evaluation after habituation, or re-training, of previously shod rearfoot-striking runners to barefoot forefoot-striking running styles. Conclusions: There has been a great deal of publicity for barefoot running, and many claims made about its effects and risks. Despite a large amount of biomechanical data available for meta-analysis, clear guidance for clinical practice is limited because of the low methodological quality of the associated studies. Preliminary biomechanical differences identified suggest barefoot running may be associated with positive biomechanical changes in regards to injury prevention, although this may be dependent on strike pattern adopted. Further research employing more robust methodology, which addresses weaknesses highlighted in this review, is needed to confirm current preliminary evidence. Additionally, prospective research would have higher validity were the biomechanical effects of habituating to barefoot running fully examined alongside an evaluation of prevention of repetitive use injury. [ABSTRACT FROM AUTHOR]

The interaction between footwear and surfaces influences the forces experienced by tennis players. The purpose of this study was to investigate traction demand and kinematic adaptation during tennis-specific movements with changes in traction characteristics of surfaces. We hypothesised that players would increase the utilised coefficient of friction (horizontal to vertical ground reaction force ratio) when the shoe surface combination had a high coefficient of friction and flex their knee after contact to facilitate braking. Eight participants performed two separate movements, side jump out of stance and running forehand. Ground reaction force was measured and three-dimensional kinematic data were recorded. Clay surface and cushioned acrylic hard court (low vs. high shoe–surface friction) were used. The peak utilised coefficient of friction was greater on clay than the hard court. The knee was less flexed at impact on clay ( − 5.6 ± 10.2°) and at peak flexion ( − 13.1 ± 12.0°) during the running forehand. Our results indicate that tennis players adapt the level of utilised friction according to the characteristics of the surface, and this adaptation favours sliding on the low friction surface. Less knee flexion facilitates sliding on clay, whereas greater knee flexion contributes to braking on the hard court. [ABSTRACT FROM AUTHOR]

The treadmill is an attractive device for the investigation of human locomotion, yet the extent to which lower limb kinematics differ from overground running remains a controversial topic. This study aimed to provide an extensive three-dimensional kinematic comparison of the lower extremities during overground and treadmill running. Twelve participants ran at 4.0 m/s ( ± 5%) in both treadmill and overground conditions. Angular kinematic parameters of the lower extremities during the stance phase were collected at 250 Hz using an eight-camera motion analysis system. Hip, knee, and ankle joint kinematics were quantified in the sagittal, coronal, and transverse planes, and contrasted using pairedt-tests. Of the analysed parameters hip flexion at footstrike and ankle excursion to peak angle were found to be significantly reduced during treadmill running by 12° (p = 0.001) and 6.6° (p = 0.010), respectively. Treadmill running was found to be associated with significantly greater peak ankle eversion (by 6.3°,p = 0.006). It was concluded that the mechanics of treadmill running cannot be generalized to overground running. [ABSTRACT FROM PUBLISHER]

The aim of this study was to investigate the technique adaptations made when performing sprint-based tasks without (free condition) and with (constrained condition) the constraints of carrying a field hockey stick. Three free and three constrained maximal sprint accelerations were performed by 18 experienced university male field hockey players (age = 20 ± 1 years, body mass = 73.3 ± 7.1 kg, and stature = 1.78 ± 0.05 m). An automatic motion analysis system tracked sagittal plane active marker locations (200 Hz).Msprint velocity during the 18–22 m (free: 8.03 ± 0.43 m/s; constrained: 7.93 ± 0.36 m/s) interval was significantly (p = 0.03) different between free and constrained conditions. While theMstride length and stride frequency was similar between free and constrained conditions in the 2–13 m capture volume, the free condition elicited a 0.10 m/s faster (p = 0.03) stride velocity. Further significant differences were found between free and constrained kinematic profiles (p ≤ 0.05) for the hip angular velocity at touchdown during the 2–12 m interval of the sprints and in the overall sprint technique coordination between free and constrained conditions. Performance and technique adaptations indicated that sprint-training protocols for field sports should integrate specific equipment constraints to ensure explicit replication of the mechanical demands of the skills underpinning superior performance. [ABSTRACT FROM PUBLISHER]

This study investigated the effect of the coefficient of friction of a running surface on an athlete's sprint time in a sled-towing exercise. The coefficients of friction of four common sports surfaces (a synthetic athletics track, a natural grass rugby pitch, a 3G football pitch, and an artificial grass hockey pitch) were determined from the force required to tow a weighted sled across the surface. Timing gates were then used to measure the 30-m sprint time for six rugby players when towing a sled of varied weight across the surfaces. There were substantial differences between the coefficients of friction for the four surfaces (μ = 0.21–0.58), and in the sled-towing exercise the athlete's 30-m sprint time increased linearly with increasing sled weight. The hockey pitch (which had the lowest coefficient of friction) produced a substantially lower rate of increase in 30-m sprint time, but there were no significant differences between the other surfaces. The results indicate that although an athlete's sprint time in a sled-towing exercise is affected by the coefficient of friction of the surface, the relationship relationship between the athlete's rate of increase in 30-m sprint time and the coefficient of friction is more complex than expected. [ABSTRACT FROM PUBLISHER]

The article discusses research which was conducted to identify any differences between variations of the power clean, across a range of loads, in inexperienced female collegiate athletes. Researchers evaluated 16 health female athletes who performed one repetition maximum of the power clean and three repetitions of three variations of the power clean. They found that there were no kinetic differences during variations of the power clean in the athletes.

The article discusses research investigating the internal joint moments of the lower limb during vertical jumping and the weightlifting jerk. According to the authors, the purpose of the study is to improve awareness of the control strategies and correspondence between these activities and facilitate an understanding of the transfer of training effects. Topics include the study's experimental design, the collection and analysis of kinematic data, and a discussion of the results.

The aims of this study were to evaluate the accuracy of centre of pressure (COP) data obtained during transition of load across the boundary between two force plates, and secondly to examine the effect of such COP data on joint kinetics during sprint running performances. COP data were collected from two piezoelectric force plates as a trolley wheel was rolled across the boundary between the plates. Position data for the trolley were collected using an opto-electronic motion analysis system for comparison with COP data. Mean COP errors during transition across the plate boundary were 0.003 ± 0.002 m relative to a control point. Kinematic and kinetic data were also collected from eight athletes during sprint running trials to demonstrate the sensitivity of the inverse dynamics analysis to COP error for the ground contact phase of the dynamic movement trials. Kinetic sensitivity to the COP error was assessed during the entire stance phase for the ankle, knee, and hip joints and was less than 5% and 3% for joint moment and power data, respectively. Based on the small COP error during transition across plate boundaries, it is recommended that foot contacts overlapping two force plates may be included in inverse dynamics analyses. [ABSTRACT FROM AUTHOR]

Cardan/Euler and helical angles are the popular methods of quantifying angular kinematics. Cardan angles are sequence dependent and crosstalk can influence the kinematic calculations. The International Society of Biomechanics (ISB) recommends a sagittal, coronal, and then transverse (XYZ) sequence of rotations, although it has been proposed that when calculating rotations outside of the sagittal plane, this may not be the most appropriate method. This study investigated the influence of the helical and six available Cardan sequences on three-dimensional (3D) ankle joint kinematics. Kinematic data were obtained using an eight-camera motion analysis system as participants ran at 4.0 m/s ± 5%. Repeated measures ANOVAs were used to compare kinematic parameters, and intra-class correlations were employed to identify evidence of crosstalk across planes. The results indicate that in the transverse and coronal planes, peak angle and range of motion values using the YXZ and ZXY sequences were significantly greater than the other sequences. Furthermore, utilization of YXZ and ZXY sequences was associated with the strongest correlations from the sagittal plane, and the XYZ sequence was found to be associated with the lowest correlations. It appears that for the representation of 3D ankle joint kinematics, the XYZ sequence is associated with minimal planar crosstalk and as such its use is encouraged. [ABSTRACT FROM AUTHOR]

To investigate how people with Autism are affected by the presence of goals during imitation, we conducted a study to measure movement kinematics and eye movements during the imitation of goal-directed and goal-less hand movements. Our results showed that a control group imitated changes in movement kinematics and increased the level that they tracked the hand with their eyes, in the goal-less compared to goal-direction condition. In contrast, the ASD group exhibited more goal-directed eye movements, and failed to modulate the observed movement kinematics successfully in either condition. These results increase the evidence for impaired goal-less imitation in ASD, and suggest that there is a reliance on goal-directed strategies for imitation in ASD, even in the absence of visual goals. [ABSTRACT FROM AUTHOR]

The article discusses research which was conducted to determine the differences between seated and supine peak torques and strength ratios and examine the interaction of position with joint velocity. Researchers evaluated isokinetic knee extensor and flexor concentric and eccentric peak torque and seated and supine torques (10° hip flexion) at 1.04 and 3.14 rads~' in 11 Rugby players. They found that hip angle affects isokinetic peak torques and knee joint strength ratios.

The article discusses research which was conducted to perform a biomechanical comparison of the traditional squat, the powerlifting squat and the box squat. Researchers evaluated 12 male powerlifters who performed the exercises with 30, 50, and 70% of their measured one repetition maximum. They found that there was a range of significant kinematic and kinetic differences between the exercises and that these differences had an impact on the spine, ankle and hip.

The article reports on research which was conducted to compare measures of power output applied to the center of mass of the barbell and body system during lower body resistance exercise. Researchers evaluated ten resistance trained men who performed back squats with barbells. After their evaluations the researchers concluded that barbell kinematics similar to the ones that they used should not be used to estimate power output during lower-body resistance exercise.

The article reports on research which was conducted to investigate the impact loading had on kinematic and kinetic variables in 16 subjects who performed the midthigh clean pull. Researchers found that increased loading results in significant decreases in peak power and peak velocity during the midthigh clean pull. They concluded that if weightlifters want to maximize force production during the clean pull then they should train at a higher load.

This study aimed to establish the nature of lower extremity intra-limb coordination variability in cycling and to investigate the coordinative adaptations that occur in response to changes in cadence and work rate. Six trained and six untrained males performed nine pedalling bouts on a cycle ergometer at various cadences and work rates (60, 90, and 120 revolutions per minute (rpm) at 120, 210, and 300 W). Three-dimensional kinematic data were collected and flexion/extension angles of the ankle, knee, and hip joints were subsequently calculated. These data were used to determine two intra-limb joint couplings [hip flexion/extension–knee flexion/extension (HK) and knee flexion/extension–ankle plantar-flexion/dorsi-flexion (KA)], which were analysed using continuous relative phase analysis. Trained participants displayed significantly (p < 0.05) lower coordination variability (6.6 ± 4.0°) than untrained participants (9.2 ± 4.7°). For the trained subjects, the KA coupling displayed significantly more in-phase motion in the 120 rpm (19.2 ± 12.3°) than the 60 (30 ± 7.1°) or 90 rpm (33.1 ± 7.4°) trials and the HK coupling displayed significantly more in-phase motion in the 90 (33.3 ± 3.4°) and 120 rpm (27.9 ± 13.6°) than in the 60 rpm trial (36.4 ± 3.5°). The results of this study suggest that variability may be detrimental to performance and that a higher cadence is beneficial. However, further study of on-road cycling is necessary before any recommendations can be made. [ABSTRACT FROM AUTHOR]

Tkachev on uneven bars is a release and re-grasp skill performed using variations of preparatory longswing techniques; the reasons why different techniques are chosen remains unclear. This study examined kinematic and key release parameters specific to three distinct techniques with the aim of understanding the relative benefits of each. During two international artistic gymnastics competitions six arch, straddle and pike longswings preceding the straddle Tkachev were recorded using twin video cameras. Calibration and movement images were digitised and reconstructed using 3D DLT. Shoulder and hip angular kinematics, angular momentum and key release parameters were compared between techniques. In the arch longswing, the first and second hip functional phases began significantly earlier than the straddle or pike. No significant differences were established for release parameters although large effect sizes for horizontal release velocity and angular momenta about the mass centre and bar were reported between the arch and other two variants. Therefore, the arch variant may provide the opportunity to develop more complex combinations following the Tkachev. Providing insight into mechanical advantages of specific longswing techniques, and highlighting those that elicit desirable characteristics offers the potential to provide coaches with objective data on technique selection and ultimately skill development. [ABSTRACT FROM AUTHOR]

Background: The posterolateral corner (PLC) resists tibial varus angulation, external rotation, and, to a lesser extent, posterior translation. It is important that reconstructions of posterolateral knee injuries restore joint laxity and patient function, but residual laxities are often observed.Hypothesis: The knee laxity after a new 4-strand PLC reconstruction would be closer to normal than after a 2-strand “modified Larson” reconstruction.Study Design: Controlled laboratory study.Methods: Fourteen intact cadaveric knees were mounted in a 6 degrees of freedom rig and subjected to the following external loading conditions: a 90-N posterior tibial force, a 5-N·m external rotation torque, and 5-N·m varus moment. Knee kinematics were recorded with an active optical tracking system for the intact, PLC-deficient, modified Larson PLC reconstruction and 4-strand PLC reconstruction.Results: With external tibial torque, the rotational laxity in 4-strand reconstruction was significantly less than in the PLC-deficient (P < .0001) and modified Larson reconstruction (P = .0112) and did not differ significantly from intact laxity at any angle of flexion. In response to posterior load, posterior translation did not change in any of the tested conditions, while the coupled external rotation laxity in 4-strand PLC reconstruction was significantly less than in the PLC-deficient (P < .0001) and modified Larson reconstruction (P < .0486) and was not significantly different from the intact movements for both reconstructions. The varus angulation-versus-flexion curves were significantly different between the PLC-deficient and both PLC reconstructions (P < .0001). The varus laxity was not significantly different between the modified Larson reconstruction, the 4-strand reconstruction, and the intact knee.Conclusion: This study showed that the rotational knee laxity in response to both external rotation and posterior translation load were significantly better after the 4-strand PLC reconstruction than after the modified Larson reconstruction, although significant differences were not found between the 2 procedures for varus laxity.Clinical Relevance: The 4-strand PLC reconstruction may produce a better biomechanical outcome, especially during external rotation and posterior translation tibial load. The authors suggest that this relates to load sharing among 4 graft strands crossing the joint. [ABSTRACT FROM AUTHOR]

The aim of this study was to analyse the important kinematic variables in elite men's and women's 20 km race walking. Thirty men and 30 women were analysed from video data recorded during the World Race Walking Cup. Video data were also recorded at four points during the European Cup Race Walking and 12 men and 12 women analysed from these data. Two camcorders operating at 50 Hz recorded at each race for 3D analysis. The two main performance determinants of speed were step length and cadence. Men were faster than women because of their greater step lengths but there was no difference in cadence. A reduction in step length was the initial cause of slowing down with later decreases in speed caused by reductions in cadence. Shorter contact times were important in optimising both step length and cadence, and faster athletes tended to have longer flight times than slower athletes. It was less clear which other kinematic variables were critical for successful walking, particularly with regard to joint angles. Different associations were found for some key variables in men and women, suggesting that their techniques may differ due to differences in height and mass. [ABSTRACT FROM AUTHOR]