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Coordination variability (CV) is commonly analyzed to understand dynamical qualities of human locomotion. The purpose of this study was to develop guidelines for the number of trials required to inform the calculation of a stable mean lower limb CV during overground locomotion. Three-dimensional lower limb kinematics were captured for 10 recreational runners performing 20 trials each of preferred and fixed speed walking and running. Stance phase CV was calculated for 9 segment and joint couplings using a modified vector coding technique. The number of trials required to achieve a CV mean within 10% of 20 strides average was determined for each coupling and individual. The statistical outputs of mode (walking vs running) and speed (preferred vs fixed) were compared when informed by differing numbers of trials. A minimum of 11 trials were required for stable mean stance phase CV. With fewer than 11 trials, CV was underestimated and led to an oversight of significant differences between mode and speed. Future overground locomotion CV research in healthy populations using a vector coding approach should use 11 trials as a standard minimum. Researchers should be aware of the notable consequences of an insufficient number of trials for overall study findings.

PURPOSE This study aimed to investigate the changes in lower limb kinematics, kinetics, and muscle activation during a high-intensity run to fatigue (HIRF). METHODS Eighteen male and female competitive middle-distance runners performed a HIRF on an instrumented treadmill at a constant but unsustainable middle-distance speed (~3 min) based on a preceding maximum oxygen uptake (V˙O2max) test. Three-dimensional kinematics and kinetics were collected and compared between the start, 33%, 67%, and the end of the HIRF. In addition, the activation of eight lower limb muscles of each leg was measured with surface EMG (sEMG). RESULTS Time to exhaustion was 181 ± 42 s. By the end of the HIRF (i.e., vs the start), ground contact time increased (+4.0%), whereas flight time (-3.2%), peak vertical ground reaction force (-6.1%), and vertical impulse (-4.1%) decreased (all P < 0.05), and joint angles at initial contact became more (dorsi)flexed (ankle, +1.9°; knee, +2.1°; hip, +3.6°; all P < 0.05). During stance, by the end of the HIRF: peak ankle plantarflexion moment decreased by 0.4 N·m·kg-1 (-9.0%), whereas peak knee extension moment increased by 0.24 N·m·kg-1 (+10.3%); similarly, positive ankle plantarflexion work decreased by 0.19 J·kg-1 (-13.9%), whereas positive knee extension work increased by 0.09 J·kg-1 (+33.3%; both P < 0.05) with no change in positive hip extension work. Hip extensor surface EMG amplitude increased during the late swing phase (+20.9-37.3%; P < 0.05). CONCLUSION Running at a constant middle-distance pace led primarily to the fatigue of the plantarflexors with a compensatory increase in positive work done at the knee. Improving the fatigue resistance of the plantarflexors might be beneficial for middle-distance running performance.

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

This study examined the effect of foot orthoses used on ground reaction forces, ankle, and knee kinematics when running at preferred and nonpreferred speeds. Sixteen runners ran on instrumented treadmills at various speeds (90%, 100%, and 110% of preferred speed) when wearing arch-support and flat-control orthoses. Two-way repeated analysis of variance (ANOVA) was performed on the mean and coefficient of variation of all variables. Results indicated that arch-support orthoses experienced larger maximum loading rates than flat-control orthoses (P = .017, 95% CI, 2.22 to 19.53). Slower speed was related to smaller loading rates (preferred: P = .002, 95% CI, −17.02 to −4.20; faster: P = .003, 95% CI, −29.78 to −6.17), shorter stride length (preferred: P P P P = .046, 95% CI, 0.035–1.117) than faster speed, while displaying no differences in flat-control condition. These findings suggest that the use of arch-support orthoses would influence impact loading, but not spatial-temporal and joint kinematics in recreational runners.

Study aim: Three-dimensional (3D) motion analysis is one of the available methods used to evaluate body kinematics. The aim of this study was to assess the intrarater reliability of measurement of pelvic and lower limb kinematics during two single leg landing tasks using 3D motion analysis. Material and methods: 19 healthy volunteers (8 women, 11 men, age 23.1 ± 2.8 years, weight 70.7 ± 9.2 kg, height 174.8 ± 6.7 cm) performed five repeated single leg hurdle hops (SLHH) (30 cm height) and five single leg drop landings (SLDL) from a box (40 cm height) in one measurement session with a 15-minute break and after marker replacement with 3D assessment. The intraclass correlation coefficient (ICC), standard error of measurement (SEM), and the smallest detectable differences (SDD) were used to examine the reliability of kinematic parameters during the landing phase. Results: The average intrarater ICC for SLHH was 0.92 (SEM = 1.69°, SDD 4.68°) and for SLDL was 0.96 (SEM = 0.81°, SDD = 2.26°). After marker replacement ICC decreased to an average value of 0.81 (SEM = 2.05°, SDD 5.68°) for SLHH and 0.82 (SEM = 2.36°, SDD 6.53°) for SLDL. Conclusions: Using the 3D method to evaluate pelvis and lower limb kinematics during single leg landing in one measurement session is a high reliability method for most parameters. Marker replacement is one of the factors that reduce the reliability of measures. When applying the SEM and SDD values, which the present paper contains, it is worth mentioning that the obtained results are caused by measurement error or they are due to individual issues.

Objective Purpose of the study was to compare lower-limb kinematics and interlimb asymmetry during stair ascent in individuals post-medial or lateral unicompartmental knee arthroplasty (UKA). Methods 60 patients (20 medial; 10 lateral) post-UKA and 30 matched healthy controls performed stair ascent. Spatio-temporal, lower-limb kinematics and interlimb asymmetries during stair ascent were compared. Results Medial-UKA group displayed 5° less knee extension of the UKA limb than controls (p = 0.005) and 2° less than the contralateral limb during stance phase. No interlimb asymmetries were found for lateral-UKA. Conclusion Patients post-UKA demonstrate satisfactory lower-limb kinematics and minimal interlimb asymmetry during stair ascent compared to healthy individuals.

Patellofemoral pain is common amongst recreational runners and associated with altered running kinematics. However, it is currently unclear how sex may influence kinematic differences previously reported in runners with patellofemoral pain. This case-control study aimed to evaluate lower limb kinematics in males and females with and without patellofemoral pain during running. Lower limb 3D kinematics were assessed in 20 runners with patellofemoral pain (11 females, 9 males) and 20 asymptomatic runners (11 females, 9 males) during a 3 km treadmill run. Variables of interest included peak hip adduction, internal rotation and flexion angles; and peak knee flexion angle, given their previously reported association with patellofemoral pain. Age, height, mass, weekly run distance and step rate were not significantly different between groups. Mixed-sex runners with patellofemoral pain were found to run with a significantly greater peak hip adduction angle (mean difference = 4.9°, d = 0.91, 95% CI 1.4-8.2, p = 0.01) when compared to matched controls, but analyses for all other kinematic variables were non-significant. Females with patellofemoral pain ran with a significantly greater peak hip adduction angle compared to female controls (mean difference = 6.6°, p = 0.02, F = 3.41, 95% CI 0.4-12.8). Analyses for all other kinematic variables between groups (males and females with/without PFP) were non-significant. Differences in peak hip adduction between those with and without patellofemoral pain during running appear to be driven by females. This potentially highlights different kinematic treatment targets between males and females. Future research is encouraged to report lower limb kinematic variables in runners with patellofemoral pain separately for males and females.

To date there is a paucity of information about how different types of conventional running shoes influence lower limb kinematics. The aim of the study was to determine the influence of motion control, neutral, and cushioned running shoes upon lower limb kinematics. Twenty-eight active males completed one test session running in standardized motion control, neutral, and cushioned running shoes on a treadmill at a self-selected pace (2.9 [0.6] m·s

The purpose of this study was to examine the acute effects of different stretching techniques on performance and lower limb kinematics, kinetics and muscle activities during vertical jump in female aerobics athletes. 10 female college aerobics athletes participated in this study. Three-dimensional kinematic and kinetic data, as well as electromyography of rectus femoris, biceps femoris and gastrocnemius medialis were collected using Vicon motion analysis system, Kistler force plate and Wireless surface electromyographic system respectively during the test. No significant differences in jump height had been determined among these 3 warm-up methods. Hip peak flexion and internal rotation angles decreased significantly after BSM and peak adduction angle decreased significantly after SSM and BSM during landing. Knee peak flexion and internal rotation angles increased significantly after SSM and BSM during take-off. Also, BSM showed significantly greater peak flexion compared with SSM. Ankle peak plantarflexion angle increased significantly after BSM. In addition, BSM showed significantly greater improvement in the variation range than SSM except for the ankle int-external rotation. Existence of no significant differences in the peak value of vertical ground reaction force during take-off and landing phase had been determined among these 3 warm-up methods, and muscle activities of rectus femoris, biceps femoris and gastrocnemius medialis were likewise not significantly different. The results of this study suggest that it would be suitable for female aerobics athletes to perform ballistic stretching in warm-up in order to improve flexibility without decreasing the following vertical jumping event and may also reduce the risk of ankle sprain injury.

Among the functional limitations associated with hip osteoarthritis (OA), the alteration of gait capabilities represents one of the most invalidating as it may seriously compromise the quality of life of the affected individual. The use of quantitative techniques for human movement analysis has been found valuable in providing accurate and objective measures of kinematics and kinetics of gait in individuals with hip OA, but few studies have reported in-depth analyses of lower limb joint kinematics during gait and, in particular, there is a scarcity of data on interlimb symmetry. Such aspects were investigated in the present study which tested 11 individuals with hip OA (mean age 68.3 years) and 11 healthy controls age- and sex-matched, using 3D computerized gait analysis to perform point-by-point comparisons of the joint angle trends of hip, knee, and ankle. Angle-angle diagrams (cyclograms) were also built to compute several parameters (i.e., cyclogram area and orientation and Trend Symmetry) from which to assess the degree of interlimb symmetry. The results show that individuals with hip OA exhibit peculiar gait patterns characterized by severe modifications of the physiologic trend at hip level even in the unaffected limb (especially during the stance phase), as well as minor (although significant) alterations at knee and ankle level. The symmetry analysis also revealed that the effect of the disease in terms of interlimb coordination is present at knee joint as well as hip, while the ankle joint appears relatively preserved from specific negative effects from this point of view. The availability of data on such kinematic adaptations may be useful in supporting the design of specific rehabilitative strategies during both preoperative and postoperative periods.

Knee joint muscle activation imbalances, especially weakness in the vastus medialis oblique, are related to patellofemoral pain within the female population. The available literature presents the leg press as an exercise which potentially targets vastus medialis oblique activation, thus reducing imbalances in the quadriceps muscles. The main aim of the present study was to compare thigh muscle activation and kinematic parameters under different conditions during the inclined leg press exercise in a young female population. A cross-sectional study was conducted on 10 young, trained females. Muscle activation of the vastus medialis oblique, vastus lateralis, rectus femoris and gluteus medialis was analyzed under five different inclined leg press conditions, modifying the feet rotation (0&ndash, 45&deg, external rotation) and the stance width (100&ndash, 150% hip width) on the footplate. All the conditions were performed at two different movement velocities: controlled velocity (2&Prime, eccentric&ndash, 2&Prime, concentric) and maximal intended velocity. Mean propulsive velocity, maximum velocity and maximum power were also assessed. The results show that both controlled velocity conditions and maximal intended velocity conditions elicited a similar muscle activation pattern with greater activation during the concentric phase (p &lt, 0.001, &eta, p2 = 0.96). The maximal intended velocity conditions showed greater overall muscle activation (p &lt, p2 = 0.91). The vastus medialis oblique presented the greatest muscle activation, followed by the rectus femoris, vastus lateralis and, the gluteus medialis. Furthermore, the inclined leg press condition with 0&ordm, feet rotation, 100% hip width distance and the maximal intended velocity generated the greatest kinematic parameter outputs. In conclusion, the inclined leg press exercise might be an optimal exercise to target vastus medialis activation regardless of the feet rotation and stance width conditions.

This study investigated differences of lower limb kinematics and muscle activity during table tennis topspin loop against backspin movements between elite players (EPs) and amateur players (APs). Ten EPs and ten APs performed crosscourt backhand loop movements against the backspin ball with maximal power. Vicon motion analysis and a MEGA ME6000 system was used to capture kinematics and surface EMG data. The motion was divided into two phases, including the backswing and swing. The joints’ flexion and extension angle tendency between EPs and APs differed significantly. The coefficient of multiple correlation (CMC) values for EPs were all beyond 0.9, indicating high similarity of joint angles change. APs presented moderate similarity with CMC values from 0.5 to 0.75. Compared to APs, EPs presented larger ankle eversion, knee and hip flexion at the beginning moment of the backswing. In the sEMG test, EPs presented smaller standardized AEMG (average electromyography) of the lower limb muscles in the rectus femoris and tibia anterior on both sides. Additionally, the maximum activation of each muscle for EPs was smaller and MPF (mean power frequency) of the lower limb was greater during the whole movement. The present study revealed that EPs could complete this technical motion more economically than APs, meanwhile, EPs were more efficient in muscle usage and showed better balance ability.

The Re-Link Trainer (RLT) is a modified walking frame with a linkage system designed to apply a non-individualized kinematic constraint to normalize gait trajectory of the left limb. The premise behind the RLT is that a user’s lower limb is constrained into a physiologically normal gait pattern, ideally generating symmetry across gait cycle parameters and kinematics. This pilot study investigated adaptations in the natural gait pattern of healthy adults when using the RLT compared to normal overground walking. Bilateral lower limb kinematic and electromyography data were collected while participants walked overground at a self-selected speed, followed by walking in the RLT. A series of 2-way analyses of variance examined between-limb and between-condition differences. Peak hip extension and knee flexion were reduced bilaterally when walking in the RLT. Left peak hip extension occurred earlier in the gait cycle when using the RLT, but later for the right limb. Peak hip flexion was significantly increased and occurred earlier for the constrained limb, while peak plantarflexion was significantly reduced. Peak knee flexion and plantarflexion in the right limb occurred later when using the RLT. Significant bilateral reductions in peak electromyography amplitude were evident when walking in the RLT, along with a significant shift in when peak muscle activity was occurring. These findings suggest that the RLT does impose a significant constraint, but generates asymmetries in lower limb kinematics and muscle activity patterns. The large interindividual variation suggests users may utilize differing motor strategies to adapt their gait pattern to the imposed constraint.

Objectives To explore feasibility of recruitment and retention of runners with patellofemoral pain (PFP), before delivering a step rate intervention. Design Feasibility study. Setting Human performance laboratory. Participants A mixed-sex sample of runners with PFP (n = 11). Main outcome measures Average/worst pain and the Kujala Scale were recorded pre/post intervention, alongside lower limb kinematics and surface electromyography (sEMG), sampled during a 3 KM treadmill run. Results Recruitment and retention of a mixed-sex cohort was successful, losing one participant to public healthcare and with kinematic and sEMG data lost from single participants only. Clinically meaningful reductions in average (MD = 2.1, d = 1.7) and worst pain (MD = 3.9, d = 2.0) were observed. Reductions in both peak knee flexion (MD = 3.7°, d = 0.78) and peak hip internal rotation (MD = 5.1°, d = 0.96) were observed, which may provide some mechanistic explanation for the identified effects. An increase in both mean amplitude (d = 0.53) and integral (d = 0.58) were observed for the Vastus Medialis Obliqus (VMO) muscle only, of questionable clinical relevance. Conclusions Recruitment and retention of a mixed sex PFP cohort to a step rate intervention involving detailed biomechanical measures is feasible. There are indications of both likely efficacy and associated mechanisms. Future studies comparing the efficacy of different running retraining approaches are warranted.

The aim of the current investigation was to examine the effects of tennis shoes and running footwear on the loads experienced by the ACL during a maximal change of direction task. Thirteen male participants performed maximal change of direction movements in tennis shoes and running footwear. Lower limb kinematics were collected using an 8 camera motion capture system and ground reaction forces were quantified using an embedded force platform. Anterior cruciate ligament (ACL) loading was examined via a musculoskeletal modelling approach and the frictional properties of the footwear were examined using ground reaction force information. Differences in ACL loading parameters between footwear were examined using one-way repeated measures ANOVA and multiple regression analyses were used to determine frictional predictors of ACL loading. Peak ACL force was significantly larger in the tennis shoes (2308.35 N) in relation to running footwear (1859.21 N) conditions. In addition, it was shown that the peak rotational moment was a significant predictor of peak ACL force in the tennis shoes (Adjusted R2 = 0.68) and running footwear (Adjusted R2 = 0.61) conditions. The findings from the current investigation indicate that the specific tennis shoes examined in the current investigation may place athletes at increased risk from ACL pathology during maximal change of direction movements. However, further exploration using a more ecologically valid research design is required before this notion can be truly substantiated.

Load and footwear condition are two crucial elements varying the kinematic responses during walking, which probably lead to chronic injury. Fifteen healthy male individuals with no obvious gait abnormalities participated in this study. Apart from a no-load condition, four external load conditions with two load levels were investigated. Work boots were compared with running shoes to determine footwear effects. Significant impacts were found for lower limb range of motion at certain joints when carrying loads. A greater hip and ankle flexion-extension while wearing the work boots indicated that participants needed to lift the leg higher to complete toe clearance off the walking surface. Work boots also increased the vertical excursion of the center of body mass, which may impact body balance and induce falling. No significant influencing pattern of carrying modes was found, which was probably due to the light load and relatively stable mode of shoulder carrying.

The aim of this work was to examine the effects of barefoot, cross-fit, minimalist and conventional footwear on patellofemoral loading during running. Twelve cross-fit athletes ran at 4.0 m/s in each of the four footwear conditions. Lower limb kinematics were collected using an 8 camera motion analysis system and patellofemoral loading was estimated using a mathematical modelling approach. Differences between footwear were examined using one-way repeated measures ANOVA. The results showed the peak patellofemoral force and stress were significantly reduced when running barefoot (force = 3.42 BW & stress = 10.71 MPa) and in minimalist footwear (force = 3.73 BW & stress = 11.64 MPa) compared to conventional (force = 4.12 BW & stress = 12.69 MPa) and cross-fit (force = 3.97 BW & stress = 12.30 MPa) footwear. In addition, the findings also showed that patellofemoral impulse was significantly reduced when running barefoot (0.35 BW·s) and in minimalist footwear (0.36 BW·s) compared to conventional (0.42 BW·s) and cross-fit (0.38 BW·s) footwear. Given the proposed association between patellofemoral loading and patellofemoral disorders, the outcomes from the current investigation suggest that cross-fit athletes who select barefoot and minimalist footwear for their running activities may be at reduced risk from patellofemoral joint pathology in comparison to conventional and cross-fit footwear conditions.

The purpose of this study was to investigate the effect of different outsole hardness of turf cleats shoes on the lower limb kinematics and kinetics of soccer players playing on artificial turf. The participants were required to complete tasks of straight running and 45° left sidestep cutting movements, respectively, at the speed of 4.5 ± 0.2 m/s on artificial turf. They were asked to randomly select turf cleats shoes with a soft outsole (SO), medium hardness outsole (MO) and hard outsole (HO). During the stance phase of straight running, peak pressure and force-time integral in medial forefoot (MFF) of players wearing cleats shoes with MO were significantly higher than those wearing cleats shoes with SO. During the stance phase of a 45° cutting maneuver, players wearing cleats shoes with SO showed significantly higher peak knee flexion and abduction angles than the HO group. Players wearing cleats shoes with SO also showed higher ankle dorsiflexion and inversion angles compared with those wearing cleats shoes with HO. The vertical average loading rate (VALR) as well as peak pressure and force-time integral in the heel (H) and lateral forefoot (LFF) regions of players wearing cleats shoes with HO were significantly higher than those wearing shoes with SO. On the contrary, peak pressure and force-time integral of players wearing shoes with SO were significantly higher than those wearing shoes with HO in MFF. A higher vertical loading rate and plantar pressure of some areas may increase the potential risk of metatarsal stress fractures and plantar fasciitis. Therefore, this finding about turf cleats shoes could give some theoretic support for the design of turf cleats shoes and material optimization in the future.

Human legs operate like springs with adjustable stiffness during locomotion, improving movement economy and versatility. The potential for the foot to contribute to this spring-like mechanism has been established. However, due to previous modelling approaches assuming a rigid-foot segment, it is unknown if ankle and foot quasi-stiffness can be actively regulated, quasi-stiffness being a measure of joint deformation under an applied load. In this study, we sought to determine if midfoot quasi-stiffness was increased in a similar manner as the ankle with increasing load demands, and if these changes were mediated by increased activation of the intrinsic foot muscles. We also quantified differences in measures of ankle joint quasi-stiffness attributable to the modelling assumption of a rigid-foot segment versus a multi-segment foot. Twenty-two healthy individuals performed a single-leg hopping task at three frequencies (2.0 Hz, 2.3 Hz, and 2.6 Hz) while measuring lower limb kinematics, kinetics and muscle activation (EMG). Kinetics and kinematics were calculated at the midfoot and using two different ankle models: rigid-foot model (shank-foot) and an anatomical ankle (shank-calcaneus). Midfoot quasi-stiffness increased with hopping-frequency (p < 0.05), while contact phase intrinsic foot muscle activation decreased (p < 0.05). The assumption of a rigid-foot model overestimated ankle ROM by ∼10° and underestimated ankle quasi-stiffness by 45-60%. This study demonstrates that midfoot quasi-stiffness increases with hopping-frequency; however, the mechanism for these changes remains unclear. Furthermore, this study demonstrates the need to assess the ankle and foot independently, using appropriate models, to avoid significant inaccuracies in basic ankle kinematic and kinetic outputs, such as range of motion and joint quasi-stiffness.

This study investigated the effects of shoe drop on lower limb kinematics and kinetics in female runners. Fifteen healthy female runners ran on a 15-m runway at their preferred speed with three different shoe-drop conditions: 0 (

Minimalist footwear has been the subject of much attention in footwear research. More recently, maximalist footwear, which feature an oversized midsole have been developed. The aim of the current investigation was to compare the kinetics and kinematics of running in minimalist, maximalist and conventional footwear. Twelve male runners ran over an embedded force platform at 4.0 m s−1 in the three footwear conditions. Lower limb kinematics were collected using an eight-camera motion capture system, and tibial accelerations were obtained using an accelerometer. Differences in kinetics and kinematics between footwear were examined using one-way repeated measures ANOVA. The results showed that both instantaneous loading rate and peak tibial acceleration were significantly larger in the minimalist (305.58 BW/s and 9.54 g) compared to the maximalist (141.67 BW/s and 7.99 g) and conventional (127.30 BW/s and 6.73 g) footwear. In addition, peak tibial internal rotation was significantly larger in the minimalist (9...

The strengths of interpersonal dyads formed by the attacker and defender in one-on-one situations are crucial for performance in team ball sports such as soccer. The purpose of this study was to analyze the kinematics of one-on-one defensive movements in soccer competitions, and determine the relationships between lower limb kinematics and the center of mass translation during cutting actions. Six defensive scenes in which a player was responding to an offender’s dribble attack were selected for analysis. To reconstruct the three-dimensional kinematics of the players, we used a photogrammetric model-based image-matching technique. The hip and knee kinematics were calculated from the matched skeleton model. In addition, the center of mass height was expressed as a ratio of each participant’s body height. The relationships between the center of mass height and the kinematics were determined by the Pearson’s product-moment correlation coefficient. The normalized center of mass height at initial contact was correlated with the vertical center of mass displacement (r = 0.832, p = 0.040) and hip flexion angle at initial contact (r = −0.823, p = 0.044). This suggests that the lower center of mass at initial contact is an important factor to reduce the downwards vertical center of mass translation during defensive cutting actions, and that this is executed primarily through hip flexion. It is therefore recommended that players land with an adequately flexed hip at initial contact during one-on-one cutting actions to minimize the vertical center of mass excursion.

Purpose. The aim of the current investigation was to determine whether female recreational runners exhibit distinct patellar tendon loading patterns in relation to their male counterparts. Methods. Twelve male (age 26.55 ± 4.11 years, height 1.78 ± 0.11 m, mass 77.11 ± 5.06 kg) and twelve female (age 26.67 ± 5.34 years, height 1.67 ± 0.12 m, mass 63.28 ± 9.75 kg) runners ran over a force platform at 4.0 m · s-1. Lower limb kinematics were collected using an eight-camera optoelectric motion capture system which operated at 250 Hz. Patellar tendon loads were examined using a predictive algorithm. Sex differences in limb, knee and ankle joint stiffness were examined statistically using independent samples t tests. Results. The results indicate that patellar tendon force (male = 6.49 ± 2.28, female = 7.03 ± 1.35) and patelllar tendon loading rate (male = 92.41 ± 32.51, female = 111.05 ± 48.58) were significantly higher in female runners. Conclusions. Excessive tendon loading in female runners indicates that female runners may be at increased risk of patellar tendon pathologies.

article i nfo Background: Peak internal knee abduction moment is a common surrogate variable associated with medial compartment knee loading. Stair descent has been shown to yield a greater peak knee abduction moment compared to level-walking. Changes in step width (SW) may lead to changes in frontal plane lower extrem- ity limb alignment in the frontal plane and alter peak knee abduction moment. The purpose of this study was to investigate the effects of increased SW on frontal plane knee biomechanics during stair descent in healthy older adults. Methods: Twenty healthy adults were recruited for the study. A motion analysis system was used to obtain three-dimensional lower limb kinematics during testing. An instrumented 3-step staircase with two additional customized wooden steps was used to collect ground reaction forces (GRF) data during stair de- scent trials. Participants performed five stair descent trials at their self-selected speed using preferred, wide (26% leg length), and wider (39% leg length) SW. Results: The preferred normalized SW in older adults during stair descent was 20% of leg length. Wide and wider SW during stair descent reduced both first and second peak knee adduction angles and abduction moments compared to preferred SW in healthy adults. Conclusions: Increased SW reduced peak knee adduction angles and abduction moments. The reductions in knee abduction moments may have implications in reducing medial compartment knee loads during stair descent.

Purpose: As drop vertical jumps (DVJ) are widely used as a screening task, the assessment of the reliability of lower-limb biomechanical parameters during DVJ is important. The aim of this study was to assess the reliability of the kinematic and kinetic peak values as well as of the waveforms for lower-limb parameters obtained with the Liverpool John Moores University biomechanical model (LJMU model) during performance of DVJ. Methods: The reliability was analyzed by calculating the intertrial (o¸trial), intersession (o¸sess), and intertherapist (o¸ther) errors of hip and knee joint parameters in a repeated-measures design including two therapists and a total of six sessions. Results: The results showed o¸trial that ranged from 1.1- to 3.5- for all peak kinematic parameters and from 3.6 to 12.9 NIm for all peak kinetic parameters. The o¸sess of the peak values ranged from 1.9- to 5.7- for all angles and from 5.4 to 19.8 NIm for the hip and knee joint moments in all planes. The o¸ther of the peak values ranged from 2.7- to 6.4- for all angles and from 5.8 to 22.4 NIm for all moments. Most of the kinematic and kinetic peak parameters had o¸ther-trial e 2.0- and 4.3 NIm, respectively, suggesting a small extrinsic variability. Furthermore, the entire waveforms also showed a rather high o¸trial relative to other types of variability. Conclusions: The present findings indicated that DVJ kinetics and kinematics show small extrinsic variability. The reported errors are useful for clinical interpretation processes of DVJ performance as screening task for injury risk and rehabilitation outcome taking into consideration the different types of measurement error over time.

There is currently no consensus regarding the effect that barefoot (BFT) running has on running economy (RE). Stride length and shoe mass are confounding variables, with a BFT stride length being shorter than a shod (SH) stride length. Comparison of SH, minimalist shod (MS) and BFT allows controlled variation of cushioning and somatosensory feedback to determine the effect that either and/or both have on RE and running mechanics. Methods: Fifteen female habitually shod, recreational runners visited the laboratory twice. Familiarisation with BFT and SH treadmill running occurred during visit one, in addition to determining SH stride length and BFT stride length. During visit two participants ran BFT, SH and MS with BFT stride length and MS with SH stride length at 10 km·h−1 for six minutes with 10-minute rest periods between each condition. Lower limb kinematics, electromyography, impact acceleration and O2 were recorded during the final two minutes of each run. Results: BFT RE was significantly better tha...

Purpose: Unstable footwear lacks peer-review published research to support concepts and claims. The present study was therefore undertaken to quantify and compare the effect of commercially available unstable sandals on single-leg balance in a healthy female population. Methods: Fifteen participants stood on their right-leg in one control sandal (Earth) and four sandals that are marketed as unstable footwear (FitFlop, Masai Barefoot Technology, Reebok Easy-Tone and Skechers Tone-Ups). Centre of pressure trajectory, lower limb kinematics and lower limb muscle activation were recorded as participants undertook three 30 second trials in each sandal. Results: The unstable sandals altered parameters related to stability in participants. Namely Masai Barefoot Technology increased centre of pressure range in the anterior-posterior direction and concurrently increased sagittal ankle motion. Reebok Easy-Tone had a similar effect in the coronal plane at the ankle. Muscle activation increased in the unstable sandals...