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Purpose: Advanced footwear technology is prevalent in distance running, with research focusing on these "super shoes" in competitive athletes, with less understanding of their value for slower runners. The aim of this study was to compare physiological and biomechanical variables between a model of super shoes (Saucony Endorphin Speed 2) and regular running shoes (Saucony Cohesion 13) in recreational athletes. Methods: We measured peak oxygen uptake (VO2peak) in 10 runners before testing each subject 4 times in a randomly ordered crossover design (ie, Endorphin shoe or Cohesion shoe, running at 65% or 80% of velocity at VO2peak [vVO2peak]). We recorded video data using a high-speed camera (300 Hz) to calculate vertical and leg stiffnesses. Results: 65% vVO2peak was equivalent to a speed of 9.4 km·h−1 (0.4), whereas 80% vVO2peak was equivalent to 11.5 km·h−1 (0.5). Two-way mixed-design analysis of variance showed that oxygen consumption in the Endorphin shoe was 3.9% lower than in the Cohesion shoe at 65% vVO2peak, with an interaction between shoes and speed (P =.020) meaning an increased difference of 5.0% at 80% vVO2peak. There were small increases in vertical and leg stiffnesses in the Endorphin shoes (P <.001); the Endorphin shoe condition also showed trivial to moderate differences in step length, step rate, contact time, and flight time (P <.001). Conclusions: There was a physiological benefit to running in the super shoes even at the slower speed. There were also spatiotemporal and global stiffness improvements indicating that recreational runners benefit from wearing super shoes. [ABSTRACT FROM AUTHOR]

Our aim was to validate a sacral-mounted inertial measurement unit (IMU) for reconstructing running kinematics and comparing movement patterns within and between runners. IMU data were processed using Kalman and complementary filters separately. RMSE and Bland–Altman analysis assessed the validity of each filtering method against a motion capture system. Running data from 24 recreational runners were analyzed using Fourier transform coefficients, PCA, and k-means clustering. High agreement was found for Kalman-filtered data in the frontal, sagittal, and transverse planes, with a Bland–Altman bias of ~2 mm on average, compared to a bias of ~10.5 mm for complementary-filtered data. Pelvic angles calculated from Kalman-filtered data had superior agreement, with systematic biases of ~0.3 versus 3.4 degrees for complementary-filtered data. Our findings suggest that inertial sensors are viable alternatives to motion capture for reconstructing pelvic running kinematics and movement patterns. In the second part of our study, negligible intra-individual differences were observed with changes in speed, while inter-individual differences were large. Two clusters of runners were identified, each showing distinct movement patterns and ranges of motion. These observations highlight the potential usefulness of inertial sensors for performance analysis and rehabilitation as they may permit the use of individual-specific and cluster-specific practice programs. [ABSTRACT FROM AUTHOR]

Wearing an intraoral dental splint may enhance ventilatory function and exercise performance. Nineteen runners performed on a 400-m outdoor track: (a) an incremental protocol to assess the velocity at maximal oxygen uptake (vVO2max) and (b) 2 square wave bouts wearing 2 intraoral splints (with and without mandibular forward repositioning). The time until exhaustion at vVO2max (TLimv VO2max), ventilatory variables, oxygen uptake (VvO2) kinetics, energetic profiling, perceived exertion and kinematics, were all measured. Ventilatory data were assessed breath-by-breath and perceived exertion evaluated using the Borg 6-20-point scale at the end of TLimv VvO2max bouts. Images were recorded by video cameras (120 Hz) and kinematic measures retrieved using Kinovea. A paired t test was computed for comparison of splints (p # 0.05). With (vs. without) mandibular forward repositioning, runners increased their TLimv VO2max by; 6% (p 5 0.03), coupled with higher ventilation (151 6 22 vs. 147 6 23 L·min-1, p 5 0.04), end-tidal oxygen tension (114.3 6 3.7 vs. 112.9 6 3.9 mm Hg, p 5 0.003), and lower inspiratory time (0.526 6 0.083 vs. 0.540 6 0.090 seconds, p 5 0.02), despite similar vVO2 kinetics (e.g., 49.0 6 8.7 vs. 47.7 6 8.6 ml·kg·min-1 of fast component amplitude) being observed. The energy expenditure was; 8% higher (p 5 0.03) with the mandible forward, coupled with lower perceived exertion scores (p 5 0.04). Mandibular forward repositioning was effective in acutely improving running performance at vVO2max with ergogenic effects on ventilatory and perceived variables. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the post-activation performance enhancement effects of drop jumps (DJs) on lower limb stiffness [leg stiffness (Kleg); vertical stiffness (Kvert)] and the related mechanical [maximal ground reaction force (Fmax), vertical displacement of the centre of mass (Δy), and lower limb length (ΔL)] and kinematic parameters [step length (SL), step frequency (SF), flight time (FT), and contact time (CT)] during high-speed treadmill running. For this purpose, 18 male physical education students performed 10 s running bouts on a treadmill at a speed of 6.67 m·s−1 in an experimental condition (EC) or in a control condition (CC). During the EC, following a 5 min treadmill running warm-up at 2.22 m·s−1, the participants were tested pre and 3 min post five DJs, while during the CC, the participants did not perform DJs. The study results revealed that EC significantly increased Fmax, Δy, SL, and FT, while SF decreased after performing drop jumps (mean differences: 0.026 ± 0.007 kN, p = 0.003; 0.001 ± 0.001 m, p = 0.025; 0.034 ± 0.013 m, p = 0.019; 0.05 ± 0.001 s, p = 0.005 and −0.057 ± 0.023 Hz, p = 0.026, respectively). Kleg and Kvert showed no significant differences (p > 0.05) following the preconditioning exercise. The findings suggest that a plyometric stimulus of low volume and a short recovery period prior to high-speed treadmill running may be beneficial to acutely improve running mechanical and kinematic parameters without affecting lower limb stiffness. [ABSTRACT FROM AUTHOR]

Background: The purpose of this randomized cross-over controlled trial was to evaluate the biomechanical effects of ankle taping using rigid tape (RT) or kinesiotape (KT) compared to no taping during treadmill running in well-trained amateur runners. Methods: A total of 22 participants (15 men and 7 women) completed three running sessions on a treadmill, each lasting 30 min, under different conditions: no taping (CG), RT, and KT. Sagittal and frontal plane kinematics were analyzed using the Kinovea software to assess the ankle dorsiflexion, knee flexion, hip extension, tibial angle, foot strike pattern, heel eversion, and pelvic drop across three intervals (0–10, 10–20, and 20–30 min). Results: The results demonstrated no significant differences in sagittal plane variables (ankle dorsiflexion, knee flexion, hip extension, and cadence) or frontal plane variables (heel eversion and pelvic drop) between the CG, RT and KT groups at any time point. Although heel eversion significantly increased over time due to fatigue, the taping conditions did not affect running kinematics. Conclusions: These findings suggest that neither RT nor KT alters running biomechanics in well-trained runners over prolonged treadmill running. The study highlights that taping, commonly used to prevent ankle injuries, does not significantly modify lower limb kinematics in the absence of injury. Further research is needed to evaluate the effects of taping in novice or injured runners and under more demanding conditions, such as overground running. [ABSTRACT FROM AUTHOR]

Abstract Background The relationship between hip strength deficiency in various planes and musculoskeletal injuries within the movement system has been well-established in numerous studies. The present study sought to explore the relationships between hip strength and specific aspects of lower extremity running kinematics. Methodology To achieve this objective, the three-dimensional running kinematics of 21 male elite middle-distance runners (mean age: 19.7 ± 1.2 years; mean experience 6.5 ± 1.0 years) were assessed using nine high-speed cameras on a treadmill at a speed of 16 km·h⁻¹. Concurrently, isokinetic hip strength was measured at a speed of 60 deg·s⁻¹ in both the dominant and non-dominant legs. The Pearson correlation coefficient and Paired Samples t-test were utilized. Results While no significant differences were found in several isokinetic strength measurements, notable differences in running kinematics were observed. Specifically, pelvic drop at midstance (MS) was significantly lower in the DL (5.79 ± 3.00°) compared to the NDL (8.71 ± 1.39°) with a large effect size (t=-4.04, p

Background: The relationship between hip strength deficiency in various planes and musculoskeletal injuries within the movement system has been well-established in numerous studies. The present study sought to explore the relationships between hip strength and specific aspects of lower extremity running kinematics. Methodology: To achieve this objective, the three-dimensional running kinematics of 21 male elite middle-distance runners (mean age: 19.7 ± 1.2 years; mean experience 6.5 ± 1.0 years) were assessed using nine high-speed cameras on a treadmill at a speed of 16 km·h⁻¹. Concurrently, isokinetic hip strength was measured at a speed of 60 deg·s⁻¹ in both the dominant and non-dominant legs. The Pearson correlation coefficient and Paired Samples t-test were utilized. Results: While no significant differences were found in several isokinetic strength measurements, notable differences in running kinematics were observed. Specifically, pelvic drop at midstance (MS) was significantly lower in the DL (5.79 ± 3.00°) compared to the NDL (8.71 ± 1.39°) with a large effect size (t=-4.04, p < 0.001, Cohen's d = 1.25). Additionally, knee adduction at maximum showed a moderate effect size difference, with the DL at 2.99 ± 1.13° and the NDL at 3.81 ± 1.76° (t=-2.74, p = 0.03, Cohen's d = 0.55). Results indicated a moderate to highly positive association between running knee adduction in the dominant leg and hip external rotation (r = 0.67, p < 0.05), concentric extension (r = 0.77, p < 0.05), and concentric abduction (r = 0.78, p < 0.05). Additionally, the running tibial external rotation angle in the dominant leg exhibited an inverse relationship with all strength measurements, with statistical significance observed only for concentric extension force (r=-0.68, p < 0.05). Furthermore, hip internal rotation force demonstrated a highly inverse correlation with foot pronation in the dominant leg (r=-0.70, p < 0.05) and anterior pelvic tilt in the non-dominant leg (r=-0.76, p < 0.05). Conclusions: These findings underscore the interrelation between hip strength and running kinematics, particularly on the dominant side. In light of these observations, it is imperative to consider hip strength exercises as integral components for correcting running kinematics. Coaches should also be mindful that kinematic deviations contributing to running injuries may manifest unilaterally or specifically in the dominant leg. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the post-activation performance enhancement effects of drop jumps (DJs) on lower limb stiffness [leg stiffness (Kleg); vertical stiffness (Kvert)] and the related mechanical [maximal ground reaction force (Fmax), vertical displacement of the centre of mass (Δy), and lower limb length (ΔL)] and kinematic parameters [step length (SL), step frequency (SF), flight time (FT), and contact time (CT)] during high-speed treadmill running. For this purpose, 18 male physical education students performed 10 s running bouts on a treadmill at a speed of 6.67 m·s−1 in an experimental condition (EC) or in a control condition (CC). During the EC, following a 5 min treadmill running warm-up at 2.22 m·s−1, the participants were tested pre and 3 min post five DJs, while during the CC, the participants did not perform DJs. The study results revealed that EC significantly increased Fmax, Δy, SL, and FT, while SF decreased after performing drop jumps (mean differences: 0.026 ± 0.007 kN, p = 0.003; 0.001 ± 0.001 m, p = 0.025; 0.034 ± 0.013 m, p = 0.019; 0.05 ± 0.001 s, p = 0.005 and −0.057 ± 0.023 Hz, p = 0.026, respectively). Kleg and Kvert showed no significant differences (p > 0.05) following the preconditioning exercise. The findings suggest that a plyometric stimulus of low volume and a short recovery period prior to high-speed treadmill running may be beneficial to acutely improve running mechanical and kinematic parameters without affecting lower limb stiffness.

The assessment of leg asymmetries is gaining scientific interest due to its potential impact on performance and injury development. Athletes around puberty exhibit increased gait variability due to a non-established running pattern. This study aims to describe the asymmetries in the spatiotemporal running parameters in developmentally aged athletes. Forty athletes under 14 (U14) (22 females and 18 males) were assessed running on a treadmill at constant speeds of 12 and 14 km·h−1 for 3 min. Step length, step frequency, along with contact (CT) and flight time, both in absolute values and as a percentage of step time, were recorded using a RunScribe sensor attached to the laces of each shoe. U14 runners exhibited high bilateral symmetry in the spatiotemporal parameters of running, with mean asymmetry values (1–5.7%) lower than the intra-limb coefficient of variation (1.7–9.6%). Furthermore, bilateral asymmetries did not vary between the two speeds. An individual-based interpretation of asymmetries identified subjects with consistent asymmetries at both speeds, particularly in terms of CT and contact ratio (%, CT/step time). This study confirms the high symmetry of pubertal runners and paves the way for the application of portable running assessment technology to detect asymmetries on an individual basis. [ABSTRACT FROM AUTHOR]

Background: Prior studies investigated selected discrete sagittal‐plane outcomes (e.g., peak knee flexion) in relation to running economy, hereby discarding the potential relevance of running technique parameters during noninvestigated phases of the gait cycle and in other movement planes. Purpose: Investigate which components of running technique distinguish groups of runners with better and poorer economy and higher and lower weekly running distance using an artificial neural network (ANN) approach with layer‐wise relevance propagation. Methods: Forty‐one participants (22 males and 19 females) ran at 2.78 m∙s−1 while three‐dimensional kinematics and gas exchange data were collected. Two groups were created that differed in running economy or weekly training distance. The three‐dimensional kinematic data were used as input to an ANN to predict group allocations. Layer‐wise relevance propagation was used to determine the relevance of three‐dimensional kinematics for group classification. Results: The ANN classified runners in the correct economy or distance group with accuracies of up to 62% and 71%, respectively. Knee, hip, and ankle flexion were most relevant to both classifications. Runners with poorer running economy showed higher knee flexion during swing, more hip flexion during early stance, and more ankle extension after toe‐off. Runners with higher running distance showed less trunk rotation during swing. Conclusion: The ANN accuracy was moderate when predicting whether runners had better, or poorer running economy, or had a higher or lower weekly training distance based on their running technique. The kinematic components that contributed the most to the classification may nevertheless inform future research and training. [ABSTRACT FROM AUTHOR]

Abstract Purpose Overhead squat assessment (OHSA) is a pre-activity dynamic movement analysis tool used to define deviations from an ideal motion pattern which known as compensation. Compensatory movements may result from abnormality in myofascial activity, length-tension relationships, neuro-motor control strategies, osteokinematics and arthrokinematics. The aim of this study is to identify the association between selected biomechanical variables of the ankle, knee, hip, pelvis, torso during OHSA and 16 km/h treadmill running tasks. Methods Thirteen national long distance male runners (17.3 ± 0.5 age (years); 5.89 ± 1.95 experience (years), 57.9 ± 3.7 body mass (kg); 175.4 ± 5.7 height (cm)) participated in this 2controlled laboratory study. Three-dimensional kinematics were collected at 250 Hz using a 9-camera Qualisys motion analysis system (Qualisys AB, Goteborg, Sweden) while participants performed 16 km/h treadmill running and OHSA tasks. Results Correlation coefficients demonstrated that OHSA pelvic anterior tilt angle was in a positive association with foot strike (FS), mid-stance (MS), and toe-off (TO) pelvic anterior tilt angles and MS tibial internal rotation on talus, MS ankle pronation, MS hip internal rotation. OHSA pelvic anterior tilt angle was in a negative association with TO hip extension. OHSA maximal hip adduction was positively correlated with MS and stance maximal knee adduction. FS, MS, stance maximal angular dorsiflexion values were positively correlated with OHSA dorsiflexion. Increased OHSA dorsiflexion angle was negatively associated with TO plantar flexion. OHSA pronation was positively associated with MS and stance pronation. MS hip internal rotation, MS hip adduction angles were increased, and MS ankle dorsiflexion was significantly decreased with the increase of trunk forward lean relative to tibia during OHSA. Conclusions OHSA was associated with some important and dysfunction-related hip, knee and ankle kinematics. Running coaches, may use OHSA as an assessment tool before the corrective training plan to detect injury-related compensation patterns to reduce the risk of injury and improve running technique.

A regular endurance training program may elicit different adaptations compared to an isolated training method. In this study, we analyzed the effects of 8 weeks of a regular endurance training program on running economy (RE), particularly neuromuscular and biomechanical parameters, in runners of different athletic abilities. Twenty-four male runners were divided into two groups: well-trained (n= 12) and recreational (n =12). Both groups completed a 4-min running bout at 13 and 17 km·h-1 , respectively, for the recreational and well-trained group, and a 5-jump plyometric test pre-post intervention. During the training program, participants completed low-intensity continuous sessions, high-intensity interval training sessions, and auxiliary strength training sessions. RE, measured as oxygen cost and energy cost, decreased by 6.15% (p=0.006) and 5.11% (p=0.043), respectively, in the well-trained group. In the recreational group, energy cost of running, respiratory exchange ratio, and leg stiffness decreased by 5.08% (p=0.035), 7.61% (p=0.003), and 10.59% (p=0.017), respectively, while ground contact time increased by 3.34% (p=0.012). The maximum height of the 5-jump plyometric test decreased by 4.55% (p=0.018) in the recreational group. We suggest that 8 weeks of regular endurance training leads to an improvement of ~5% in RE in recreational and well-trained runners with different physiological adaptations between groups and few changes in biomechanical and neuromuscular parameters only in recreational runners. [ABSTRACT FROM AUTHOR]

Introduction Wearable motion tracking technology often focuses on reducing the number of sensors to simplify design and lower costs. Research has shown that single IMUs can reconstruct leg kinematics (Gholami et al., 2020; Hossain et al., 2022; Lim et al., 2020) and ground reaction forces (Jiang et al., 2020) effectively. Additionally, model-based methods have demonstrated the feasibility of using fewer gyroscopes to estimate stride length and motion range in healthy individuals and patients with coxarthritis (Salarian et al., 2013). In this study, we aim to assess the precision of sagittal joint angle estimations using strain sensors while minimizing sensor count. Methods We conducted a study with ten participants based on our previous work that involved collecting single-leg treadmill running data to monitor lower limb joint angles with piezoresistive strain sensors. Subjects ran on an instrumented treadmill at 8-10 km/h, wearing athletic pants embedded with nine strain sensors located on the hip, knee, and ankle. Optical motion capture provided reference kinematics. Our prior research achieved less than 1.5° error in the sagittal plane using a machine-learning approach. The current study explores the extent to which sensor reduction is possible without meaningful loss of accuracy. Three evaluation measures were used for assessment: Pearson correlation, dynamic time warping, and root-mean-squared error. Results The results from our correlation analysis will be used to develop a model that optimally balances between accuracy and minimizing the number of sensors. This has practical implications in sports science, where athletes could benefit from less intrusive and more comfortable performance monitoring, and in healthcare, for remote monitoring of patients with mobility issues. References Gholami, M., Napier, C., & Menon, C. (2020). Estimating lower extremity running gait kinematics with a single accelerometer: A deep learning approach. Sensors, 20(10), Article 2939. https://doi.org/10.3390/s20102939 Hossain, M. S., Bin, Dranetz, J., Choi, H., & Guo, Z. (2022). DeepBBWAE-Net: A CNN-RNN based deep superlearner for estimating lower extremity sagittal plane joint kinematics using shoe-mounted IMU sensors in daily living. IEEE Journal of Biomedical and Health Informatics, 26(8), 3906-3917. https://doi.org/10.1109/jbhi.2022.3165383 Jiang, X., Napier, C., Hannigan, B., Eng, J. J., & Menon, C. (2020). Estimating vertical ground reaction force during walking using a single inertial sensor. Sensors, 20(15), Article 4345. https://doi.org/10.3390/s20154345 Lim, H., Kim, B., & Park, S. (2020). Prediction of lower limb kinetics and kinematics during walking by a single IMU on the lower back using machine learning. Sensors, 20(1), Article 130. https://doi.org/10.3390/s20010130 Salarian, A., Burkhard, P. R., Vingerhoets, F. J. G., Jolles, B. M., & Aminian, K. (2013). A novel approach to reducing number of sensing units for wearable gait analysis systems. IEEE Transactions on Biomedical Engineering, 60(1), 72–77. https://doi.org/10.1109/TBME.2012.2223465

Purpose: Overhead squat assessment (OHSA) is a pre-activity dynamic movement analysis tool used to define deviations from an ideal motion pattern which known as compensation. Compensatory movements may result from abnormality in myofascial activity, length-tension relationships, neuro-motor control strategies, osteokinematics and arthrokinematics. The aim of this study is to identify the association between selected biomechanical variables of the ankle, knee, hip, pelvis, torso during OHSA and 16 km/h treadmill running tasks. Methods: Thirteen national long distance male runners (17.3 ± 0.5 age (years); 5.89 ± 1.95 experience (years), 57.9 ± 3.7 body mass (kg); 175.4 ± 5.7 height (cm)) participated in this 2controlled laboratory study. Three-dimensional kinematics were collected at 250 Hz using a 9-camera Qualisys motion analysis system (Qualisys AB, Goteborg, Sweden) while participants performed 16 km/h treadmill running and OHSA tasks. Results: Correlation coefficients demonstrated that OHSA pelvic anterior tilt angle was in a positive association with foot strike (FS), mid-stance (MS), and toe-off (TO) pelvic anterior tilt angles and MS tibial internal rotation on talus, MS ankle pronation, MS hip internal rotation. OHSA pelvic anterior tilt angle was in a negative association with TO hip extension. OHSA maximal hip adduction was positively correlated with MS and stance maximal knee adduction. FS, MS, stance maximal angular dorsiflexion values were positively correlated with OHSA dorsiflexion. Increased OHSA dorsiflexion angle was negatively associated with TO plantar flexion. OHSA pronation was positively associated with MS and stance pronation. MS hip internal rotation, MS hip adduction angles were increased, and MS ankle dorsiflexion was significantly decreased with the increase of trunk forward lean relative to tibia during OHSA. Conclusions: OHSA was associated with some important and dysfunction-related hip, knee and ankle kinematics. Running coaches, may use OHSA as an assessment tool before the corrective training plan to detect injury-related compensation patterns to reduce the risk of injury and improve running technique. [ABSTRACT FROM AUTHOR]

The assessment of leg asymmetries is gaining scientific interest due to its potential impact on performance and injury development. Athletes around puberty exhibit increased gait variability due to a non-established running pattern. This study aims to describe the asymmetries in the spatiotemporal running parameters in developmentally aged athletes. Forty athletes under 14 (U14) (22 females and 18 males) were assessed running on a treadmill at constant speeds of 12 and 14 km·h−1 for 3 min. Step length, step frequency, along with contact (CT) and flight time, both in absolute values and as a percentage of step time, were recorded using a RunScribe sensor attached to the laces of each shoe. U14 runners exhibited high bilateral symmetry in the spatiotemporal parameters of running, with mean asymmetry values (1–5.7%) lower than the intra-limb coefficient of variation (1.7–9.6%). Furthermore, bilateral asymmetries did not vary between the two speeds. An individual-based interpretation of asymmetries identified subjects with consistent asymmetries at both speeds, particularly in terms of CT and contact ratio (%, CT/step time). This study confirms the high symmetry of pubertal runners and paves the way for the application of portable running assessment technology to detect asymmetries on an individual basis.

Background Female collegiate cross-country (XC) runners have a high incidence of running-related injury (RRI). Limited reports are available that have examined potential intrinsic factors that may increase RRI risk in this population. Purpose To examine the relationships between RRI, hip muscle strength, and lower extremity running kinematics in female collegiate XC runners. Study Design Prospective observational cohort. Methods Participants included twenty female NCAA collegiate XC runners from Southern California universities who competed in the 2019-20 intercollegiate season. A pre-season questionnaire was used to gather demographic information. Hip muscle strength was measured with isokinetic dynamometry in a sidelying open-chain position and normalized by the runner's body weight (kg). Running kinematic variables were examined using Oualisys 3D Motion Capture and Visual 3D analysis. RRI occurrence was obtained via post-season questionnaires. Independent t-tests were used to determine mean differences between injured and non-injured runners for hip abductor muscle strength and selected running kinematics. Pearson correlation coefficients were calculated to examine relationships between hip muscle performance and kinematic variables. Results End-of-the-season RRI information was gathered from 19 of the 20 participants. During the 2019-20 XC season, 57.9% (11 of 19) of the runners sustained an RRI. There were no significant differences between mean hip abductor normalized muscle strength (p=0.76) or mean normalized hip muscle strength asymmetry (p=0.18) of injured and non-injured runners during the XC season. Similarly, no significant differences were found between mean values of selected kinematic variables of runners who did and who did not report an RRI. Moderate relationships were found between hip abductor strength variables and right knee adduction at footstrike (r=0.50), maximum right knee adduction during stance (r=0.55), left supination at footstrike (r=0.48), right peak pronation during stance (r=-0.47), left supination at footstrike (r=0.51), and right peak pronation during stance (r=-0.54) (all p≤0.05). Conclusions Hip abduction muscle strength, hip abduction strength asymmetry, and selected running kinematic variables were not associated with elevated risk of RRI in female collegiate XC runners. [ABSTRACT FROM AUTHOR]

Background: Pes Planus or Flat feet is one of the most common lower limb abnormalities. When runners with this abnormality participate in recreational running, interventional therapies could help in pain alleviation and enhance performance. To determine the most effective treatment, however, a biomechanical examination of the effects of each treatment modality is required.Research Question: The aim of the present study was to investigate the effects of Foot Orthoses (FOs) and Low-Dye Tape (LDT) on lower limb joint angles and moments during running in individuals with pes planus.Methods: kinematic and kinetic data of 20 young people with pes planus were measured during running in three conditions: (1) SHOD (2) with shoes and FOs (3) with shoes and LDT. One-way repeated measure ANOVA was used to investigate the impacts of the FOs and LDT on the lower limb joint angles and moments throughout the stance phase of the running cycle.Results: The results showed that FOs reduced ankle eversion compared to SHOD and LDT (P < 0.001) and decreased the dorsiflexion angle (P = 0.005) and the plantarflexor moment compared to the SHOD (P < 0.001). FOs increased knee adduction angle (P = 0.021) and knee external rotator moment (P < 0.001) compared to both conditions and increased knee extensor and abductor moments compared to SHOD (P < 0.001). At the hip joint, FOs only increased hip external rotation compared with the LDT condition (P = 0.031); and LDT increased hip extensor moment compared to SHOD and FOs (P = 0.037) and also increased hip adduction angle compared to SHOD (P = 0.037).Significance: FOs with a medial wedge appears to increase the external knee adduction moment and knee adduction angles, which are risk factors for the development and progression of knee osteoarthritis. Further, usage of FOs seems to reduce the ankle joint role in propulsion as it impacts the ankle sagittal angles and moments. [ABSTRACT FROM AUTHOR]

The feasibility of prediction of same-limb kinematics using a single inertial measurement unit attached to the same limb has been demonstrated using machine learning. This study was performed to see if a single inertial measurement unit attached to the tibia can predict the opposite leg's kinematics (cross-leg prediction). It also investigated if there is a minimal or smaller data set in a convolutional neural network model to predict lower extremity running kinematics under other running conditions and with what accuracy for the intra- and inter-participant situations. Ten recreational runners completed running exercises under five conditions, including treadmill running at speeds of 2, 2.5, 3, and 3.5 m/s and level-ground running at their preferred speed. A one-predict-all scheme was adopted to determine which running condition could be used to best predict a participant's overall running kinematics. Running kinematic predictions were performed for intra- and inter-participant scenarios. Among the tested running conditions, treadmill running at 3 m/s was found to be the optimal condition for accurately predicting running kinematics under other conditions, with R2 values ranging from 0.880 to 0.958 and 0.784 to 0.936 for intra- and inter-participant scenarios, respectively. The feasibility of cross-leg prediction was demonstrated but with significantly lower accuracy than the same leg. The treadmill running condition at 3 m/s showed the highest intra-participant cross-leg prediction accuracy. This study proposes a novel, deep-learning method for predicting running kinematics under different conditions on a small training data set. [ABSTRACT FROM AUTHOR]

Understanding the relationship between footwear features and their potential influence on running performance can inform the ongoing innovation of running footwear, aimed at pushing the limits of humans. A notable shoe feature is hollow structures, where an empty space is created in the midsole. Presently, the potential biomechanical effect of the hollow structures on running performance remains unknown. We investigated the role of hollow structures through quantifying the magnitude and timing of foot and footwear work. Sixteen male rearfoot runners participated in an overground running study in three shoe conditions: (a) a shoe with a hollow structure in the forefoot midsole (FFHS), (b) the same shoe without any hollow structure (Filled-FFHS) and (c) a shoe with a hollow structure in the midfoot midsole (MFHS). Distal rearfoot power was used to quantify the net power generated by foot and footwear together. The magnitude and timing of distal rearfoot work and ankle joint work were compared across shoe conditions. The results indicated that MFHS can significantly (p = 0.024) delay distal rearfoot energy return (3.4 % of stance) when compared to Filled-FFHS. Additionally, FFHS had the greatest positive (0.425 J/kg) and negative (−0.383 J/kg) distal rearfoot work, and the smallest positive (0.503 J/kg) and negative (−0.477 J/kg) ankle joint work among the three conditions. This showed that the size and location of the midsole hollow structure can affect timing and magnitude of energy storage and return. The forefoot hollow shoe feature can effectively increase distal rearfoot work and reduce ankle joint work during running. [ABSTRACT FROM AUTHOR]

This study explores the cardiorespiratory and muscular fatigue responses to downhill (DR) vs uphill running (UR) at similar running speed or similar oxygen uptake (⩒O2). Eight well-trained, male, trail runners completed a maximal level incremental test and three 15-min treadmill running trials at ±15% slope: i) DR at ~6 km·h−1 and ~19% ⩒O2max (LDR); ii) UR at ~6 km·h−1 and ~70% ⩒O2max (HUR); iii) DR at ~19 km·h−1 and ~70% ⩒O2max (HDR). Cardiorespiratory responses and spatiotemporal gait parameters were measured continuously. Maximal isometric torque was assessed before and after each trial for hip and knee extensors and plantar flexor muscles. At similar speed (~6 km·h−1), cardiorespiratory responses were attenuated in LDR vs HUR with altered running kinematics (all p < 0.05). At similar ⩒O2 (~3 l·min−1), heart rate, pulmonary ventilation and breathing frequency were exacerbated in HDR vs HUR (p < 0.01), with reduced torque in knee (−15%) and hip (−11%) extensors and altered spatiotemporal gait parameters (all p < 0.01). Despite submaximal metabolic intensity (70% ⩒O2max), heart rate and respiratory frequency reached maximal values in HDR. These results further our understanding of the particular cardiorespiratory and muscular fatigue responses to DR and provide the bases for future DR training programs for trail runners. [ABSTRACT FROM AUTHOR]

Abstract Background Previous studies have suggested that distinct and homogenous sub-groups of gait patterns exist among runners with patellofemoral pain (PFP), based on gait analysis. However, acquisition of 3D kinematic data using optical systems is time consuming and prone to marker placement errors. In contrast, axial segment acceleration data can represent an overall running pattern, being easy to acquire and not influenced by marker placement error. Therefore, the purpose of this study was to determine if pelvic acceleration patterns during running could be used to classify PFP patients into homogeneous sub-groups. A secondary purpose was to analyze lower limb kinematic data to investigate the practical implications of clustering these subjects based on 3D pelvic acceleration data. Methods A hierarchical cluster analysis was used to determine sub-groups of similar running profiles among 110 PFP subjects, separately for males (n = 44) and females (n = 66), using pelvic acceleration data (reduced with principal component analysis) during treadmill running acquired with optical motion capture system. In a secondary analysis, peak joint angles were compared between clusters (α = 0.05) to provide clinical context and deeper understanding of variables that separated clusters. Results The results reveal two distinct running gait sub-groups (C1 and C2) for female subjects and no sub-groups were identified for males. Two pelvic acceleration components were different between clusters (PC1 and PC5; p

The purpose of this study was to determine the validity of the Garmin fēnix® 3 HR fitness tracker. Methods: A total of 34 healthy recreational runners participated in biomechanical or metabolic testing. Biomechanics participants completed three running conditions (flat, incline, and decline) at a self-selected running pace, on an instrumented treadmill while running biomechanics were tracked using a motion capture system. Variables extracted were compared with data collected by the Garmin fēnix 3 HR (worn on the wrist) that was paired with a chest heart rate monitor and a Garmin Foot Pod (worn on the shoe). Metabolic testing involved two separate tests; a graded exercise test to exhaustion utilizing a metabolic cart and treadmill, and a 15-min submaximal outdoor track session while wearing the Garmin. 2 × 3 analysis of variances with post hoc t tests, mean absolute percentage errors, Pearson's correlation (R), and at test were used to determine validity. Results: The fēnix kinematics had a mean absolute percentage errors of 9.44%, 0.21%, 26.38%, and 5.77% for stride length, run cadence, vertical oscillation, and ground contact time, respectively. The fēnix overestimated (p < .05) VO2max with a mean absolute percentage error of 8.05% and an R value of .917. Conclusion: The Garmin fēnix 3 HR appears to produce a valid measure of run cadence and ground contact time during running, while it overestimated vertical oscillation in every condition (p < .05) and should be used with caution when determining stride length. The fēnix appears to produce a valid VO2max estimate and may be used when more accurate methods are not available. [ABSTRACT FROM AUTHOR]

Objectives: We determined whether perceptually-regulated, high-intensity intermittent runs in hypoxia and normoxia induce similar running mechanics adjustments within and between intervals.Design: Within-participants repeated measures.Methods: Nineteen trained runners completed a high-intensity intermittent running protocol (4×4-min intervals at a perceived rating exertion of 16 on the 6-20 Borg scale, 3-min passive recoveries) in either hypoxic (FiO2=0.15) or normoxic (FiO2=0.21) conditions. Running mechanics were collected over 10 consecutive steps, at constant velocity (∼15.0±2.0km.h-1), at the beginning and the end of each 4-min interval. Repeated measure ANOVA were used to assess within intervals (onset vs. end of each interval), between intervals (interval 1, 2, 3 vs. 4) and FiO2 (0.15 vs. 0.21) main effects and any potential interaction.Results: Participants progressively reduced running velocity from interval 1-4, and more so in hypoxia compared to normoxia for intervals 2, 3 and 4 (P<0.01). There were no between intervals (across all intervals P>0.298) and FiO2 (across all intervals P>0.082) main effects or any significant between intervals×within intervals×FiO2 interactions (all P>0.098) for any running mechanics variables. Irrespective of interval number or FiO2, peak loading rate (+10.6±7.7%; P<0.001) and duration of push-off phase (+2.0±3.1%; P=0.001) increased from the onset to the end of 4-min intervals, whereas peak push-off force decreased (-4.0±4.0%; P<0.001).Conclusions: When carrying out perceptually-regulated interval treadmill runs, runners adjust to progressively slower velocities in hypoxia compared to normoxia. However, only subtle constant-velocity modifications of their mechanical behaviour occurred within each set, independently of FiO2 or interval number. [ABSTRACT FROM AUTHOR]

Purpose: We determined the effect of custom foot orthotics manufactured from ethyl-vinyl acetate (EVA) and expanded thermoplastic polyurethane (TPU) materials, both compared to a control condition (CON; shoes only) during repeated sprints on running mechanical alterations.Methods: Eighteen males performed eight, 5-s sprints with 25-s recovery on an instrumented sprint treadmill in three footwear conditions (EVA, TPU and CON). Mechanical data consisted of continuous (step-by-step) measurement of running kinetics and kinematics, which were averaged for each sprint for further analysis.Results: Distance ran in 5 s decreased from first to last sprint (P < 0.001), yet with higher sprints 1-8 values for both EVA (P = 0.004) and TPU (P = 0.018) versus CON. Regardless of footwear condition, mean horizontal forces, step frequency, vertical and leg stiffness decreased from sprint 1 to sprint 8 (all P < 0.001). Duration of the propulsive phase was globally shorter for both EVA (P = 0.002) and TPU (P = 0.021) versus CON, while braking phase duration was similar (P = 0.919). In the horizontal direction, peak propulsive (P < 0.001), but not braking (P = 0.172), forces also decreased from sprint 1 to sprint 8, independently of conditions.Conclusion: Compared to shoe only, wearing EVA or TPU custom foot orthotics improved repeated treadmill sprint ability, yet provided similar fatigue-induced changes in mechanical outcomes. [ABSTRACT FROM AUTHOR]

Acute ergogenic effects of wearing occlusal splints have been reported for aerobic and anaerobic exercises, but the literature centered on performance improvement by using jaw repositioning splints is scarce. We aimed to analyze the effect of wearing a 50% lower jaw advancement splint on biophysical and perceptual responses at low to severe running intensities. Sixteen middle- and long-distance runners performed twice a 7 × 800 m intermittent running protocol (with 1 km·h−1 increments and 30 s rest periods) in an outdoor track field using two lower intraoral splints (a placebo and a lower jaw advancer). These devices were custom manufactured for each participant and a randomized and repeated measure design was used to compare conditions. No differences between placebo and lower jaw advancer were found (e.g., 52.1 ± 9.9 vs. 53.9 ± 10.7 mL·kg−1·min−1 of oxygen uptake, 3.30 ± 0.44 vs. 3.29 ± 0.43 m of stride length and 16 ± 3 vs. 16 ± 2 Borg scores), but small effects were sometimes observed (e.g., 109.2 ± 22.5 vs. 112.7 ± 25.2 L·min−1 of ventilation, ES = −0.42). Therefore, this jaw advancement splint had no substantial ergogenic effect on biophysical and perceptual responses when running at different intensities.

This study aimed to examine the effect of running velocity on spatiotemporal parameters and lower-body stiffness of endurance runners, and the influence of the performance level on those adaptations. Twenty-two male runners (novice [NR], n = 12, and elite runners [ER], n = 10) performed an incremental running test with a total of 5 different running velocities (10, 12, 14, 16, 18 km/h). Each condition lasted 1 min (30 s acclimatization period, and 30 s recording period). Spatiotemporal parameters were measured using the OptoGait system. Vertical (Kvert) and leg (Kleg) stiffness were calculated according to the sine-wave method. A repeated measures ANOVA (2 x 5, group x velocities) revealed significant adaptations (p < 0.05) to increased velocity in all spatiotemporal parameters and Kvert in both NR and ER. ER showed a greater flight time (FT) and step angle (at 18 km/h) (p < 0.05), longer step length (SL) and lower step frequency (SF) (p < 0.05), whereas no between-group differences were found in contact time (CT) nor in the sub-phases during CT at any speed (p ≥ 0.05). ER also showed lower Kvert values at every running velocity (p < 0.05), and no differences in Kleg (p ≥ 0.05). In conclusion, lower SF and Kvert and, thereby, longer FT and SL, seem to be the main spatiotemporal characteristics of high-level runners compared to their low-level counterparts. [ABSTRACT FROM AUTHOR]

This study aimed to analyze the influence of muscular performance parameters on spatiotemporal gait characteristics during running when gradually increasing speed. Fifty-one recreationally trained male endurance runners (age, 28 ± 8 years) voluntarily participated in this study. Subjects performed a battery of jumping tests (squat jump, countermovement jump, and 20-cm drop jump), and after that, the subjects performed an incremental running test (10-20 km⋅h-1) on a motorized treadmill. Spatiotemporal parameters were measured using the OptoGait system. Cluster k-means analysis grouped subjects according to the jumping test performance, by obtaining a group of good jumpers (n = 19) and a group of bad jumpers (n = 32). With increased running velocity, contact time was shorter and flight time and step length were longer, whereas cadence and stride angle were greater (p < 0.001). No significant differences between groups (p ≤ 0.05) were found at any running speed. The results obtained indicate that increased running velocity produced no differences in spatiotemporal adaptations between those runners with good jumping ability and those with poor jumping ability. Based on that, it seems that muscular performance parameters do not play a key role in spatiotemporal adaptations experienced by recreational endurance runners with increased velocity. However, taken into consideration the well-known relationship between running performance and neuromuscular performance, the authors suggest that muscular performance parameters would be much more determinant in the presence of fatigue (exhausted condition) or in the case of considering other variables such as running economy or kinetic. [ABSTRACT FROM AUTHOR]

Objectives: While several cross-sectional studies have investigated the acute effects of shoe drop on running biomechanics, the long-term consequences are currently unknown. This study aimed to investigate if the drop of standard cushioned shoes induces specific adaptations in running technique over a six-month period in leisure-time runners.Design: Double-blinded randomised controlled trial.Methods: The participants (n=59) received a pair of shoes with a heel-to-toe drop of 10mm (D10), 6mm (D6) or 0mm (D0) and were followed-up regarding running training over 6 months or 500km, whichever came first. Spatio-temporal variables and kinematics (foot/ground, ankle and knee joint angles) were investigated while running at preferred speed on a treadmill before and after the follow-up.Results: The participants ran 332±178km in the study shoes between pre- and post-tests. There was no shoe version by time interaction for any of the spatio-temporal variables nor for lower limb angles at initial ground contact. A small but significant shoe drop effect was found for knee abduction at mid-stance (p=0.032), as it decreased for the D0 version (-0.3±3.1 vs. -1.3±2.6°) while it increased for the D6 (0.3±2.7 vs. 1.3±3.1°) and D10 version (-0.2±3.2 vs. 0.5±3.1°). However, none of the pairwise comparisons was significant in the post-hoc analysis.Conclusions: Apart from knee abduction at mid-stance, no specific adaptation in spatio-temporal variables and kinematics was found between the three shoe versions during this 6-month follow-up. Thus, shoe drop of standard cushioned shoes does not seem to influence running biomechanics in the long term. [ABSTRACT FROM AUTHOR]

Despite an intuitive relationship between technique and both running economy (RE) and performance, and the diverse techniques used by runners to achieve forward locomotion, the objective importance of overall technique and the key components therein remain to be elucidated. Purpose: This study aimed to determine the relationship between individual and combined kinematic measures of technique with both RE and performance. Methods: Ninety-seven endurance runners (47 females) of diverse competitive standards performed a discontinuous protocol of incremental treadmill running (4-min stages, 1-km⋅h-1 increments). Measurements included three-dimensional full-body kinematics, respiratory gases to determine energy cost, and velocity of lactate turn point. Five categories of kinematic measures (vertical oscillation, braking, posture, stride parameters, and lower limb angles) and locomotory energy cost (LEc) were averaged across 10-12 km⋅h-1 (the highest common velocity < velocity of lactate turn point). Performance was measured as season's best (SB) time converted to a sex- specific z-score. Results: Numerous kinematic variables were correlated with RE and performance (LEc, 19 variables; SB time, 11 variables). Regression analysis found three variables (pelvis vertical oscillation during ground contact normalized to height, minimum knee joint angle during ground contact, and minimum horizontal pelvis velocity) explained 39% of LEc variability. In addition, four variables (minimum horizontal pelvis velocity, shank touchdown angle, duty factor, and trunk forward lean) combined to explain 31% of the variability in performance (SB time). Conclusions: This study provides novel and robust evidence that technique explains a substantial proportion of the variance in RE and performance. We recommend that runners and coaches are attentive to specific aspects of stride parameters and lower limb angles in part to optimize pelvis movement, and ultimately enhance performance. [ABSTRACT FROM AUTHOR]

Objectives: To examine mechanical alterations during interval-training treadmill runs in high-level team-sport players.Design: Within-participants repeated measures.Methods: Twenty high-level male field-hockey players performed six 30-s runs at 5.53±0.19ms-1 corresponding to 115% of their velocity associated with maximal oxygen uptake (vVO2max) with 30-s passive recovery on an instrumented treadmill. Continuous measurement of running kinetics/kinematics and spring-mass characteristics were performed and values were subsequently averaged over 20s (8th-28ths) for comparison.Results: Contact time (+1.1±4.3%; p=0.044), aerial time (+4.1±5.3%; p=0.001), step length (+2.4±2.2%; p<0.001) along with mean loading rates (+7.1±10.6%; p=0.026) increased from the first to the last interval, whereas step frequency (-2.3±2.1%; p<0.001) decreased. Both centre of mass vertical displacement (+3.0±6.0%; p<0.001) and leg compression (+2.8±9.7%; p=0.036), but not peak vertical forces (0.0±4.1%; p=0.761), increased with fatigue. Vertical stiffness decreased (-2.8±6.9%; p=0.012), whereas leg stiffness did not change across intervals (p=0.149).Conclusions: During interval-training treadmill runs, high-level team-sport players modified their mechanical behaviour towards lower vertical stiffness while preserving a constant leg stiffness. Maintenance of running velocity induced longer step lengths and decreased step frequencies that were also accompanied by increased impact loading rates. These mechanical alterations occurred early during the set. [ABSTRACT FROM AUTHOR]

Despite the growing interest in minimalist shoes, no studies have compared the efficacy of different types of minimalist shoe models in reproducing barefoot running patterns and in eliciting biomechanical changes that make them differ from standard cushioned running shoes. The aim of this study was to investigate the acute effects of different footwear models, marketed as “minimalist” by their manufacturer, on running biomechanics. Six running shoes marketed as barefoot/minimalist models, a standard cushioned shoe and the barefoot condition were tested. Foot–/shoe–ground pressure and three-dimensional lower limb kinematics were measured in experienced rearfoot strike runners while they were running at 3.33 m · s−1on an instrumented treadmill. Physical and mechanical characteristics of shoes (mass, heel and forefoot sole thickness, shock absorption and flexibility) were measured with laboratory tests. There were significant changes in foot strike pattern (described by the strike index and foot contact angle) and spatio-temporal stride characteristics, whereas only some among the other selected kinematic parameters (i.e. knee angles and hip vertical displacement) changed accordingly. Different types of minimalist footwear models induced different changes. It appears that minimalist footwear with lower heel heights and minimal shock absorption is more effective in replicating barefoot running. [ABSTRACT FROM PUBLISHER]

Background: Female collegiate cross-country (XC) runners have a high incidence of running-related injury (RRI). Limited reports are available that have examined potential intrinsic factors that may increase RRI risk in this population., Purpose: To examine the relationships between RRI, hip muscle strength, and lower extremity running kinematics in female collegiate XC runners., Study Design: Prospective observational cohort., Methods: Participants included twenty female NCAA collegiate XC runners from Southern California universities who competed in the 2019-20 intercollegiate season. A pre-season questionnaire was used to gather demographic information. Hip muscle strength was measured with isokinetic dynamometry in a sidelying open-chain position and normalized by the runner's body weight (kg). Running kinematic variables were examined using Qualisys 3D Motion Capture and Visual 3D analysis. RRI occurrence was obtained via post-season questionnaires. Independent t-tests were used to determine mean differences between injured and non-injured runners for hip abductor muscle strength and selected running kinematics. Pearson correlation coefficients were calculated to examine relationships between hip muscle performance and kinematic variables., Results: End-of-the-season RRI information was gathered from 19 of the 20 participants. During the 2019-20 XC season, 57.9% (11 of 19) of the runners sustained an RRI. There were no significant differences between mean hip abductor normalized muscle strength (p=0.76) or mean normalized hip muscle strength asymmetry (p=0.18) of injured and non-injured runners during the XC season. Similarly, no significant differences were found between mean values of selected kinematic variables of runners who did and who did not report an RRI. Moderate relationships were found between hip abductor strength variables and right knee adduction at footstrike (r=0.50), maximum right knee adduction during stance (r=0.55), left supination at footstrike (r=0.48), right peak pronation during stance (r=-0.47), left supination at footstrike (r=0.51), and right peak pronation during stance (r=-0.54) (all p≤0.05)., Conclusions: Hip abduction muscle strength, hip abduction strength asymmetry, and selected running kinematic variables were not associated with elevated risk of RRI in female collegiate XC runners., Competing Interests: The authors affirm that they have no financial affiliation (including research funding) or involvement with any commercial organization that has a direct financial interest in any matter included in this manuscript.

Abstract: Several studies have used variability of continuous relative phase (CRP) to investigate overuse injuries, since low variability is thought to be related to running injuries. This study investigates whether the analysis of CRP variability leads to additional information about possible differences or similarities between healthy and injured runners. Further, a decision about future applications of CRP variability should be based on the ability to implement and interpret data. 18 healthy female runners (CO) and 18 female runners who suffered from iliotibial band syndrome (ITBS) were evaluated by calculating CRP variability for 4 coupling pairs. Besides analyzing continuous variability of CRP, we also averaged it for the whole stance phase and for four predefined stance phase intervals. Confidence intervals were displayed and independent t-tests for comparing the two groups were conducted. During initial and terminal stance phase as well as after heel-off an increase in CRP variability was detected for both groups of runners. In contrast, the foot flat period was characterized by stable joint coordination and a decrease in variability. This paper presents possible interpretations of CRP variability but no statistically significant differences in CRP variability were found between the two groups of runners. Despite the missing statistical significance, a relationship between high CRP variability and injury seems to be conceivable, since the injured runners demonstrated an increased variability for all couplings in the first half of the stance phase. Further application of CRP variability in biomechanical research is essential to determine whether a relationship exists between injury and coordination variability. [Copyright &y& Elsevier]

The purpose of the present study was to evaluate the effect of three pacing strategies upon performance of the 400-m sprint. Eight healthy male physical education students participated in this study. Each participant performed a 200-m maximal test (200(MAX)) and three 400-m running tests in a random counterbalanced design. The 400-m tests were run with the first 200-m pace set at 98% (400(98%)), 95% (400(95%)), and 93% (400(93%)), respectively, of the effort for 200(MAX). The stimulation of the lactate system was assessed by post-test blood lactate concentration (BLa). Running speed (RS) was controlled with time-keeping devices. Stride frequency (SF), stride length (SL) and lower extremity kinematics were acquired with video cameras operating at 100 fps at the 125 and 380-m marks of the tests. A two-way analysis of variance (ANOVA) with repeated measures was used to identify modifications caused by the pacing strategies used. Non-significant differences were revealed for BLa. The fastest 400-m race was run in 400(93%), but performance was not significantly different (p > 0.05) among the examined pacing strategies. RS, SF and SL had significantly (p < 0.05) lower values in the 380-m mark when compared with the 125-m mark. In 400(98%), both SF and SL decreased by approximately 13%, while SF and SL dropped 2.4 and 9.2%, respectively, in 400(93%). In conclusion, lower peak BLa and less unfavorable modifications of running mechanics were recorded in 400(93%), where time differential between the halves of the 400-m race was smaller, which eventually resulted in better performance. [ABSTRACT FROM AUTHOR]

Abstract: In order to compare gait patterns, a common procedure is to normalize strides both in time and magnitude. The stride duration is usually normalized to a time percentage before averaging curves. As the timing of event occurrences may shift across strides, the shape of the averaged curves is distorted and therefore the standard deviation is overvalued. Stride magnitude normalization is performed by means of dimensionless numbers. However, there is little agreement on which body size correction methods should be used. The Procrustes method describes curve shape and shape change in a mathematical and statistical framework, independently of time and size factors. The present study aims to explore how this technique may be used for time- and magnitude-stride normalization to reflect individual and group mean responses. The Procrustes method, which combines quantitative and visual features, is applied to the shape of the ankle and knee cyclograms. Superimposition of 25 cyclograms (10 for sprinters (SP) and 15 for middle-distance runners (MDR)) was supplemented by statistical procedures (principal component analysis, discriminant function) to extract the main key events, which vary according to the athletic specialities. In comparison with the MDR (poulaine-shaped cyclogram), the ovoid cyclogram of SP reveals the following gait indicators: a short braking phase, a rapid initial lower limb swing in the forward direction, a fast upward movement of the knee and ankle, and an active foot contact. The Procrustes approach could be used to describe other quasi-periodic movements through relative motion plots (e.g., cyclograms, angle–angle diagrams, phase plane portraits). [Copyright &y& Elsevier]

The purpose of this study was to test the hypothesis that runners having different running economies show differences in the mechanical and morphological properties of their muscle-tendon units (MTU) in the lower extremities. Twenty eight long-distance runners (body mass: 76.8±6.7 kg, height: 182±6 cm, age: 28.1±4.5 years) participated in the study. The subjects ran on a treadmill at three velocities (3.0, 3.5 and 4.0 m s-1) for 15 min each. The ...O2 consumption was measured by spirometry. At all three examined velocities the kinematics of the left leg were captured whilst running on the treadmill using a high-speed digital video camera operating at 250 Hz. Furthermore the runners performed isometric maximal voluntary plantarflexion and knee extension contractions at eleven different MTU lengths with their left leg on a dynamometer. The distal aponeuroses of the gastrocnemius medialis (GM) and vastus lateralis (VL) were visualised by ultrasound during plantarflexion and knee extension, respectively. The morphological properties of the GM and VL (fascicle length, angle of pennation, and thickness) were determined at three different lengths for each MTU. A cluster analysis was used to classify the subjects into three groups according to their ...O2 consumption at all three velocities (high running economy, N=10; moderate running economy, N=12; low running economy, N=6). Neither the kinematic parameters nor the morphological properties of the GM and VL showed significant differences between groups. The most economical runners showed a higher contractile strength and a higher normalised tendon stiffness (relationship between tendon force and tendon strain) in the triceps surae MTU and a higher compliance of the quadriceps tendon and aponeurosis at low level tendon forces. It is suggested that at low level forces the more compliant quadriceps tendon and aponeurosis will increase the force potential of the muscle while running and therefore the volume of active muscle at a given force generation will decrease. [ABSTRACT FROM AUTHOR]

The aim of the study was to verify whether an overloaded training (OT) in triathlon deteriorates running kinematics (RK) and running economy (RE). Thirteen well-trained male long-distance triathletes (age: 28.1 ± 4.3 yrs; V̇O2max: 65.0 ± 3.1 ml O2·min-1·kg-1) were divided into two groups: completed an individualized OT program (OG; n = 7) or maintained a normal level of training (NT) (CG; n=6) for a duration of 3 weeks. Every week, each triathlete completed a standardized questionnaire to quantify the influence of training loads on mood state. To reach OT, total training load (h·3 wk-1) was increased by 24%; swimming and cycling total volumes were increased by 46 and 57%, respectively, but the distance run was not modified in order to limit the risk of injuries. RK and RE were determined on treadmill test at 12 km·h-1 before and after the 3 weeks. The 3-week swimming and cycling OT in triathlon was sufficiently stressful to alter mood state but not to deteriorate the running kinematics and economy parameters in our previously well-trained male long-distance triathletes. [ABSTRACT FROM AUTHOR]

Abstract: This study compared the effect of load distribution using two different webbing designs on oxygen consumption and running kinematics of soldiers. It was hypothesised that running with webbing that distributes the load closer to the body (M83 Assault Vest) would expend less energy compared to running with conventional webbing (CON). Seven soldiers randomly completed three treadmill trials; an unloaded VO2max test, and two loaded (8kg) efficiency tests using either the M83 or CON webbing. The VO2max test and the loaded efficiency tests had 4-min stages at 5, 8, 10 and 12kmh−1. Energy expenditure was measured via indirect calorimetry and video analysis was used to determine stride frequency (SF) and stride length (SL) during each trial. Participants using the M83 webbing expended significantly () less energy at all four running velocities compared to the CON trials. The M83 webbing resulted in smaller changes to SL and SF from the unloaded trial when compared to the CON trial. These results indicate that the M83 vest that is designed to distribute the load closer to the body may have an energy efficiency advantage over conventional webbing when soldiers are running. [Copyright &y& Elsevier]

Acute ergogenic effects of wearing occlusal splints have been reported for aerobic and anaerobic exercises, but the literature centered on performance improvement by using jaw repositioning splints is scarce. We aimed to analyze the effect of wearing a 50% lower jaw advancement splint on biophysical and perceptual responses at low to severe running intensities. Sixteen middle- and long-distance runners performed twice a 7 × 800 m intermittent running protocol (with 1 km·h−1 increments and 30 s rest periods) in an outdoor track field using two lower intraoral splints (a placebo and a lower jaw advancer). These devices were custom manufactured for each participant and a randomized and repeated measure design was used to compare conditions. No differences between placebo and lower jaw advancer were found (e.g., 52.1 ± 9.9 vs. 53.9 ± 10.7 mL·kg−1·min−1 of oxygen uptake, 3.30 ± 0.44 vs. 3.29 ± 0.43 m of stride length and 16 ± 3 vs. 16 ± 2 Borg scores), but small effects were sometimes observed (e.g., 109.2 ± 22.5 vs. 112.7 ± 25.2 L·min−1 of ventilation, ES = −0.42). Therefore, this jaw advancement splint had no substantial ergogenic effect on biophysical and perceptual responses when running at different intensities. [ABSTRACT FROM AUTHOR]

Running ability is critical to maintaining activity participation with peers. Children and adolescents with cerebral palsy (CP) are often stated to run better than they walk, but running is not often quantitatively measured. The purpose of this study was to utilize overall gait deviation indices to determine if children with diplegic CP run closer to typically developing children than they walk. This retrospective comparative study utilized 3D running kinematics that were collected after walking data at two clinical motion analysis centers for children with diplegic cerebral palsy. Separate walking and running Gait Deviation Indices (GDI Walk and GDI* Run), overall indices of multiple plane/joint motions, were calculated and scaled for each participant so that a typically developing mean was 100 with standard deviation of 10. An analysis of variance was used to compare the variables Activity (walking vs running) and Center (data collected at two different motion analysis laboratories). Fifty participants were included in the study. The main effect of Activity was not significant, mean GDI Walk = 76.4 while mean GDI* Run = 77.1, p = 0.84. Mean GDI scores for walking and running were equivalent, suggesting children with diplegic cerebral palsy as a group have similar walking and running quality. However, individual differences varied between activities, emphasizing the need for individual assessment considering specific goals related to running.

To examine the influence of sex and anthropometric characteristics of recreationally-trained endurance athletes on spatiotemporal parameters during running at a constant velocity. In all, 97 runners (52 men and 45 women) performed a running protocol on a treadmill at 12 km.h−1. Spatiotemporal parameters were measured using the OptoGait system and anthropometric characteristics were assessed by determining body mass, height, leg length and torso length. Partial correlation analysis, adjusted by sex, revealed some significant correlations between anthropometric and spatiotemporal characteristics. Cluster k-means analysis grouped participants according to the body height, leg length and body mass. A 1-way Anova showed no between sex differences (P ≥ 0.05) in any spatiotemporal parameters; whereas some differences were found between created sub-groups. Shorter contact time (CT) and step length (SL) and higher step frequency (SF) were obtained by the shorter group (P < 0.01, compared to the taller group) and by shorter leg length group (P < 0.01). As for the body mass, shorter CT were found in the lighter group compared to those heavier (P < 0.05). A linear regression analysis showed a significant association between CT and body height, leg length and body mass (R2 = 0.202, P < 0.001). In conclusion, at a given running velocity, differences in body proportions seem to determine CT in amateur endurance runners, with higher values reported in taller and heavier runners. Nevertheless, although does exist a relationship between anthropometric characteristics and spatiotemporal parameters during running, the role of the somatic parameters measured in this study does not seem to be determinant in the spatiotemporal characteristics of amateur endurance runners. [ABSTRACT FROM AUTHOR]