Step Frequency Research Articles

Influence of Running Surface Using Advanced Footwear Technology Spikes on Middle- and Long-Distance Running Performance Measures

Objective: This study evaluated the effects of advanced footwear technology (AFT) spikes on running performance measures, spatiotemporal variables, and perceptive parameters on different surfaces (track and grass). Methods: Twenty-seven male trained runners were recruited for this study. In Experiment 1, participants performed 12 × 200 m at a self-perceived 3000 m running pace with a recovery of 5 min. Performance (time in each repetition), spatiotemporal, and perceptive parameters were measured. In Experiment 2, participants performed 8 × 5 min at 4.44 m/s while energy cost of running (W/kg), spatiotemporal, and perceptive parameters were measured. In both experiments the surface was randomized and mirror order between spike conditions (Polyether Block Amide (PEBA) and PEBA + Plate) was used. Results: Experiment 1: Runners were faster on the track (p = 0.002) and using PEBA + Plate spike (p = 0.049). Experiment 2: Running on grass increased energy cost (p = 0.03) and heart rate (p < 0.001) regardless of the spike used, while PEBA + Plate spike reduced respiratory exchange ratio (RER) (p = 0.041). Step frequency was different across surfaces (p < 0.001) and spikes (p = 0.002), with increased performance and comfort perceived with PEBA + Plate spikes (p < 0.001; p = 0.049). Conclusions: Running on the track surface with PEBA + Plate spikes enhanced auto-perceived 3000 m running performance, showed lower RER, and improved auto-perceptive comfort and performance. Running on grass surfaces increased energy cost and heart rate without differences between spike conditions.

Hybrid filter for lock-in amplifiers.

Lock-in amplifiers are instrumental in the precise measurement of extremely small AC signals within high-noise environments. Traditionally, noise reduction in these instruments relies on infinite impulse response (IIR) filters, which can necessitate prolonged settling times to ensure the acquisition of accurate, statistically independent data. While moving average filters offer faster settling times, their non-monotonic frequency response may not be optimal for noise reduction. Conversely, IIR filters frequently realized as N-pole RC filters exhibit a monotonic frequency response conducive to effective noise reduction. This study presents a hybrid filter architecture that combines a short IIR filter with a longer moving average finite impulse response filter. The objective is to enhance noise reduction as quantified by the filter's equivalent noise bandwidth (ENBW). Theoretical analysis is provided to derive the step response, settling time, frequency response, and ENBW of the hybrid filter configuration. Design methodologies are outlined for hybrid filters that either match the settling time of an N-pole RC filter while achieving a lower ENBW or maintain the ENBW of an N-pole RC filter but with significantly faster settling time. The performance of the hybrid filter is validated through noise measurements of low-value resistors and thermal noise of larger resistors, with results compared to theoretical predictions.

Research on miniaturized frequency steering system based on atomic clock

In order to generate a high-performance RF signal, by analyzing the traditional frequency steering system, and aiming at the goal of miniaturization and engineering, this paper designs a miniaturized frequency steering system based on dual-atomic clock. In addition, we have carried out research on key technologies such as high-precision frequency deviation measurement and precision frequency regulation. On this basis, a frequency deviation measurement and correction system is designed. And according to the theoretical analysis, the measuring accuracy of the frequency deviation measurement approach can reach 1.0 × 10-14, besides, the step frequency tuning can also reach 1.125 × 10-14. What's more, some related experiments, the RF signal synthesized from a Rb clock and a master has an accuracy of 2.26 × 10-13, and also the frequency stability of 104 s in terms of the Allan deviation reaches 2.36 × 10-14, suggesting that the overall performance of the rubidium atomic clock has been greatly improved.

The Effect of Step Frequency and Running Speed on the Coordination of the Pelvis and Thigh Segments During Running.

This study investigates the specific influence of step frequency (SF) and speed on the coordination between pelvic and thigh movements. Eight recreational male runners ran at different SFs and speeds on an instrumented treadmill. The coordination between the pelvis and thigh segments was analyzed using modified vector coding in the sagittal and frontal planes (FPs). Our findings show that hip range of motion increases as a function of SF in the sagittal plane. Pelvic tilt plays a compensatory role in hip extension, particularly at lower SFs. In the FP, pelvic roll increased at lower SFs, whereas the thigh abduction angle was participant dependant. Coordination analysis showed that thigh movements dominated the sagittal plane motion, which was simplified at higher SF. At low SF, the pelvic movements were increased and anticipated, playing a more dominant role in explaining motion. In the FP, pelvic movements dominated the motion. The increase in pelvic motion at low SFs stretches the hip flexors further and for a longer period. The link between SF, pelvic motion, and the risks of running-related injuries in the sagittal and FP is considered. Understanding these could help athletes and sports professionals optimize performance and reduce injury risk.

Effects of longitudinal bending stiffness and midsole foam on running energetics

Advanced footwear technology has become commonplace in the competitive running world. However, a systematic exploration of the effects of each of the primary components has not yet been presented. Our goal was to quantify running economy and step parameters in four different shoe conditions: PEBA shoes with plate, PEBA shoes without plate, EVA shoes with plate and EVA shoes without plate. Participants ran at 14 km/h (n = 8 males) or 12 km/h (n = 6 females) on a treadmill. The shoe order was randomly assigned for the four shoe conditions, where the participants wore each shoe twice in a mirrored order. There was a significant reduction in metabolic power (1.0%) associated with the presence of a plate, as well as a similar reduction based on foam type (1.0%). However, there was no significant interaction between presence of plate and foam type. Adding a plate significantly reduced metabolic power for EVA by 1.3% but not for PEBA. PEBA foam significantly reduced metabolic power by 1.3% in shoes without a plate, but not for the shoes with a plate. Step frequency and contact time were similar between shoes and not correlated to running economy improvements. Starting from a baseline condition with traditional foam without a plate, either adding a plate or using PEBA foam improved running economy with a similar amount (1.3%). Adding the alternate second feature non-significantly improved running economy with an additional 0.6%. The benefit of both technologies combined (1.9%) was smaller than the sum of its parts (1.3% each).

Biomechanical analysis of balance control in the elderly By Ba Duan Jin

This study aims to evaluate the biomechanical effects of Ba Duan Jin on balance control in the elderly, seeking effective fitness methods to enhance their balance capabilities and reduce the risk of falls. Methods: Participants were randomly assigned to an experimental group (EG) and a control group (CG), with 25 individuals in each. The Berg Balance Scale (BBS) and mechanical measurements were utilized to evaluate the participants’ balance abilities and biomechanical performance. Statistical analyses were performed to compare the outcomes between the EG and CG, ensuring a comprehensive assessment of the differences. Results: The experimental group demonstrated a significant improvement in the Berg Balance Scale (BBS) scores (p < 0.01), with a notable increase in the eyes-closed standing task (BBS6), which reached significance (p < 0.05), indicating a consistent advantage for the experimental group in this area. Biomechanical measurements revealed that the experimental group exhibited significantly higher parameters compared to the control group, including stability index (EG: 0.7 ± 0.1/2.2 ± 0.4, CG: 0.6 ± 0.1/1.9 ± 0.3), power (EG: 3.2 ± 0.5/3.8 ± 0.6, CG: 2.9 ± 0.4/3.5 ± 0.5), energy expenditure (EG: 20.1 ± 3.8/25.0 ± 4.3, CG: 16.5 ± 3.2/20.3 ± 3.8), and step frequency (EG: 95.0 ± 5.5/105.0 ± 6.0, CG: 85.0 ± 5.0/100.0 ± 5.5). Additionally, peak force (EG: 345.2 ± 30.1/412.6 ± 35.8, CG: 310.4 ± 28.5/310.4 ± 28.5), impact force (EG: 68.3 ± 7.2/85.7 ± 8.9, CG: 55.8 ± 6.7/72.4 ± 8.1), average force (EG: 280.5 ± 25.6/320.7 ± 30.2, CG: 245.3 ± 22.8/280.1 ± 26.4), and direction of force (EG: 10.0 ± 2.0/15.0 ± 2.5, CG: 8.5 ± 1.5/12.0 ± 2.0) also exhibited significant differences (p < 0.05). Notably, the static single-leg stance (EG: 3.38 ± 0.39, CG: 2.38 ± 0.50), dynamic sit-to-stand (EG: 3.77 ± 0.34, CG: 2.85 ± 0.37), turning movements (EG: 3.88 ± 0.27, CG: 2.58 ± 0.56), and double-leg step-ups (EG: 4.00 ± 0.02, CG: 2.69 ± 0.49) displayed extremely significant differences (p < 0.01). These results indicate that Ba Duan Jin training effectively enhances balance control and reduces the risk of falls among the elderly. Conclusion: As a traditional form of physical exercise, Ba Duan Jin effectively enhances balance control and reduces the risk of falls among older adults, providing valuable practical evidence for health management in this population. Future research should focus on conducting more long-term studies with larger sample sizes to verify the applicability and long-term effects of Ba Duan Jin across various age groups and health conditions in older individuals.

Acute effects of different loading protocols upon performance and kinematics of 180 degrees change of direction

ABSTRACT This study examined the acute effects of different loading protocols on 180° change of direction (COD) performance in eleven male handball players. Participants performed a 10-0-5 COD test under seven conditions: without an external load, and with 3, 6, and 9 kg loads applied under two modes—assisted into the COD and resisted out of it and resisted into the COD and assisted out of it. While total COD time was not affected (p = 0.098; η2 = 0.16), significant phase effects were observed (p < 0.001; η2 ≥ 0.55). Loading protocols significantly influenced velocity, acceleration, and their distances from COD (p < 0.001; η2 ≥ 0.37). Significant phase effects were observed for all step kinematic variables (p ≤ 0.037; η2 ≥ 0.67), except contact time, and significant interaction (phase*condition) effects for all variables (p ≤ 0.004; η2 ≥ 0.08), except for step frequency. Assisted-resisted protocols increased deceleration demands through higher COD entry velocities, displaying fewer but longer steps in the acceleration phase and greater steps taken during the deceleration phase. Resisted-assisted protocols decreased deceleration demands due to lower COD entry velocities, displaying shorter, but more steps taken in the acceleration phase, and fewer steps taken in the deceleration phase. These findings suggest that assisted-resisted and resisted-assisted loading protocols can be used to selectively overload specific phases of COD performance.

Exploring the influence of body movements on spatial perception in landscape and interior design

This study investigates the influence of body movements on spatial perception in both landscape and interior design environments, focusing on how physical interactions shape spatial understanding beyond visual perception alone. Grounded in the theory of embodied cognition, the research examines how gait, posture, and movement dynamics affect spatial awareness. The study captures detailed data on movement patterns and visual engagement across different spatial contexts using a combination of real-world observations and Virtual Reality (VR) simulations, motion-tracking systems, wearable sensors, and eye-tracking technology. A total of 157 participants, aged 20 to 65, navigated both outdoor landscapes and indoor environments, with key variables such as surface materials, spatial layout, and lighting conditions manipulated to assess their effects on spatial perception. The study measured gait speed, step frequency, path deviations, time to destination, visual attention, and subjective ratings of perceived openness, ease of movement, and emotional response. Key findings include that surface materials significantly influenced gait speed and step frequency. For example, participants walking on concrete had a significantly faster gait speed (mean difference = 0.5220, p = 0.001) than those walking on gravel. In terms of spatial layout, the two-way Analysis of variance (ANOVA) results showed that winding paths led to more path deviations (F-statistic = 350.00, p = 3.19 × 10−8) and longer times to destination (F-statistic = 1744.00, p = 2.39 ´ 10−11) compared to straight paths. The environment type (landscape vs. interior) also significantly affected navigation, with landscape participants showing a more significant deviation from direct paths (F-statistic = 19.60, p = 2.37 × 10−3). Visual engagement data, analyzed through a chi-square test, indicated that vertical elements like walls approached significance in attracting visual attention (Chi-square = 2.88, p = 0.0896), while other elements like trees and benches had less impact. The Wilcoxon signed-rank test results showed significant differences between real-world and VR experiences in perceived openness (W-statistic = 0.0, p = 0.001953), ease of movement (W-statistic = 0.0, p = 0.001953), and comfort (W-statistic = 0.0, p = 0.001953), highlighting VR’s limitations in replicating the full embodied experience of physical spaces.

Effects of Plyometric Training on Running Biomechanics and Jumping Ability of U14 Athletes.

Cardiel-Sánchez, S, Rubio-Peirotén, A, Molina-Molina, A, García-Cebadera Gómez, C, Almenar-Arasanz, A, Ráfales-Perucha, A, Roche-Seruendo, LE, and Cartón-Llorente, A. Effects of plyometric training on running biomechanics and jumping ability of U14 athletes. J Strength Cond Res 38(11): e656-e663, 2024-Children under the age of 14 years (U14) are particularly susceptible to musculoskeletal disorders because of growth spurts. Plyometric training has been shown to be beneficial for both injury reduction and performance enhancement. The aim of this study was to evaluate the effects of plyometric training on the jumping ability and running biomechanics of U14 track-and-field athletes. A single-blind randomized controlled trial was conducted. Thirty-five (18 female and 17 male) U14 athletes (age: 12.5 ± 1.2 years; height: 152.3 ± 7.7 cm; body mass: 47.3 ± 6.9 kg) were randomized into experimental and control groups. All subjects completed their usual training for 4 weeks, and those in the intervention group added a low-volume plyometric program twice a week. Preintervention and postintervention assessments included a countermovement jump (CMJ) to determine maximum jump height, 10-second repeated jumps to assess reactive strength index (RSI), and a 3-minute run at 12 km·h -1 to analyze running kinematics contact time, flight time, step length (SL), step frequency (SF), mean power output, vertical spring stiffness, and leg spring stiffness (LSS). The results revealed no main effect of time for any of the variables. A group-by-time interaction was found for RSI ( p = 0.045) in the intervention group, whereas a significant increase in LSS was also found after the intervention ( p = 0.031). However, no changes in CMJ height or other running parameters were observed. The significance level for the study was set at ρ ≤ 0.05. Plyometric-jump training may improve the stretch-shortening cycle in U14 athletes by increasing RSI and LSS. Athletes and coaches in running-related sports should be aware of these short-term effects when aiming to optimize the energy storage and release mechanism.

Experiment on Measuring Lake Ice Thickness Using a SFCW Ground Penetrating Radar System

Abstract To ensure transportation safety and for other purposes, it becomes necessary to measure the thickness of the ice layer on natural water bodies during winter. As an efficient and non-destructive subsurface detection tool, Ground Penetrating Radar (GPR) can achieve rapid and accurate measurements of ice thickness. For this experiment, we utilize a stepped frequency continuous wave (SFCW) GPR system based on a Vector Network Analyzer (VNA) system to measure the thickness of ice layers. Additionally, based on the scenario of detecting ice layer structures with ground-penetrating radar, the formula for calculating the thickness of ice layers was revised to achieve more accurate measurements of ice thickness. Finally, we compared the calculated results with the ice thickness detection results from ice layer drilling experiments to verify the effectiveness of the system in detecting ice layer thickness.

A compact air-coupled SFCW ground penetrating radar and its application in the earthen sites

Abstract As a non-destructive testing technology, ground-penetrating radar (GPR) has been widely used in archaeological investigations of the earthen sites. Traditionally, a GPR antenna is ground-couple. It is attached to the measured object and thus may cause damage to the earthen sites. This paper develops a lightweight and compact air-coupled stepped frequency continuous waveform (SFCW) GPR system with frequency range from 1GHz up to 6GHz. We suppress the nonlinear variables of the radar system by calibration. And we perform tests on different weathering samples from the earthen sites. Our system is verified that can discriminate layered structures in samples and the results of tests are consistent with the simulations of the gprMax model. In general, this radar system can assess the weathering degree and provide technical support for the preservation of the earthen sites.

Global vibration serviceability assessment of human-induced vibration of high-frequency floors considering the layout of indoor building items

The higher-order harmonics of crowd loading can induce resonance in high-frequency floors, leading to significant amplification of vibrations and potentially causing serviceability or safety issues. Additionally, differences in item layouts on indoor floor spaces are a major factor affecting pedestrian step frequency and itineraries, which cause changes in floor vibrations. This study aimed to analyze the influence of different layouts of indoor items on human-induced vibrations of high-frequency floors. Firstly, a random high-frequency floor load model was established by combining a social force model and a pedestrian load model. A high-frequency floor with a fundamental frequency of 10.3540 Hz was used for testing to verify the soundness of the model when applied to different layout forms. Secondly, a global vibration serviceability assessment method was proposed to establish human-induced vibrations. Finally, the serviceability probability of floors with different layouts under random walking conditions was calculated, and the assessment results were provided. The results indicate that, based on the layout configurations adopted in this study, the discussion room layout is most prone to issues related to human-induced vibration serviceability under the influence of five pedestrians walking randomly, with a probability of occurrence reaching 80 %. The next most vulnerable layout is that of the classroom, where the probability is 70 %. In contrast, the meeting room layout exhibits the lowest probability of experiencing vibration serviceability issues, at 50 %, demonstrating a significant advantage in mitigating human-induced vibrations. Furthermore, an analysis of the floor's dynamic response Fourier spectra reveals that when assessing human-induced vibration serviceability, it is crucial to account for the contributions of higher-order modal shapes of the floor. The present research provides references to design and implement improved layouts for indoor items.

KINEMATIC CHARACTERISTICS OF THE APPROACH RUN ON HANDSPRING VAULT BY HIGH LEVEL MALE GYMNASTS HIGH LEVEL MALE GYMNASTS

The approach run is a fundamental precondition for successful vault performance, as it enables the gymnast to develop maximum controlled horizontal velocity. The purpose of this study was to investigate the length, frequency, and velocity of steps during the run-up phase (approach run) in the execution of the handspring vault on the vaulting table. Nine high-level male artistic gymnasts, who performed the handspring vault under training conditions, volunteered to participate in the study. Five video cameras—four stationary and one scanning—were used to record the run-up phase, the hurdle step, and the take-off from the springboard. The gymnasts performed six trials of the handspring vault with a three-minute rest between each trial. Results showed that the final step was shorter than the penultimate step, and the penultimate step was longer than the preceding step. Additionally, the gymnasts demonstrated a gradual increase in their run-up velocity, a key requirement for a successful jump, up to the penultimate step. The average step frequency among gymnasts ranged from 3.20 to 4.88 steps per second, while the average step velocity across the six attempts was between 4.03 and 7.37 m/sec. Finally, a gradual increase in the gymnast’s velocity was observed up until the last step, with the final step being shorter than the penultimate step and the penultimate step being longer than the one before it.

Comparative Study of GPR Acquisition Methods for Shallow Buried Object Detection

This paper investigates the use of ground-penetrating radar (GPR) technology for detecting shallow buried objects, utilizing an air-coupled stepped frequency continuous wave (SFCW) radar system that operates within a 2 GHz bandwidth starting at 500 MHz. Different GPR data acquisition methods for air-coupled systems are compared, specifically down-looking, side-looking, and circular acquisition strategies, employing the back projection algorithm to provide focusing of the acquired GPR data. Experimental results showed that the GPR can penetrate up to 0.6 m below the surface in a down-looking mode. The developed radar and the back projection focusing algorithm were used to acquire data in the side-looking and circular mode, providing focused images with a resolution of 0.1 m and detecting subsurface objects up to 0.3 m below the surface. The proposed approach transforms B-scans of the GPR-based data into 2D images. The provided approach has significant potential for advancing shallow object detection capabilities by transforming hyperbola-based features into point-like features.

On the fractionation of lignin oligomers by stepwise gradient reversed-phase liquid chromatography

With the increased interest in lignin valorization, the analytical challenge to separate a complex mixture of a vast number of phenolics has made chromatography an indispensable step in lignin analysis. High-resolution separations, such as gas chromatography, reversed-phase liquid chromatography and supercritical fluid chromatography have typically been targeting low-molecular-weight compounds, while larger lignin oligomers have received less attention. These compounds have proven to be difficult to separate due to the inherent complexity of the high-molecular-weight fraction of lignins, in fact, even high-resolving linear reversed-phase gradients elute them as one wide zone. To tackle this, in this study we show that a crude fractionation of lignin oligomers can be achieved by applying stepwise reversed-phase gradients. A commonly employed reversed-phase system with water:acetonitrile mobile phase is evaluated for this task. Special attention was devoted to uncovering the molecular level explanation of the retention phenomenon. Our results indicate that separation is mainly governed by reversed-phase retention phenomena without any major exclusion or viscosity-related effects, shown by great fits to linear retention models (R2avg = 0.9599 for five different oligomers) and apparent differences in retentivity between different stationary phases. The influence of the gradient shape was demonstrated by the comparison of stepwise gradients with different number and frequency of steps, leading to the conclusion that gradients with a low number of steps yield fewer, but better resolved fractions, while finer multi-step gradients can be used to distinguish more fractions.

Efficacy of high-frequency rTMS in the treatment of gait disorder and cognition in patients with Parkinson's disease based on wearable devices and eye-movement assessments.

Postural instability and gait disorder and cognitive dysfunction are common symptoms of Parkinson's disease (PD). Scale assessment is frequently used in the clinic to evaluate PD, but this technique is limited by its lack of sensitivity to changes in disease progression and its difficulty in capturing subtle movements and changes in cognitive function. It is currently believed that high-frequency repetitive transcranial magnetic stimulation (rTMS) can improve motor and cognitive dysfunction in patients with PD, though it remains controversial. Therefore, it is imperative to monitor and dynamically identify changes in postural instability and gait disorder, as well as those in cognitive dysfunction, in PD to develop targeted interventions. In this study, we observed the effect of high-frequency rTMS on gait disorders and cognitive functions in patients with PD by comparing data from wearable devices and eye-tracking devices before and after treatment. A total of 159 patients with PD were included in this study. A GYENNO MATRIX wearable gait analyzer was used to monitor the objective gait data (including the timed up-and-go, narrow-track, and turning tests), the Eyeknow eye-tracking evaluation system was used to monitor the patient's eye movement cognition data (including the smooth pursuit, pro-saccade, and anti-saccade tests), and gait and cognitive function-related scales, including the Tinetti Balance Scale, Tinetti Gait Scale, Berg Balance Scale, Mini-Mental State Examination, and Montreal Cognitive Assessment (MoCA), were evaluated at the same time before and after high-frequency rTMS treatment. The mean step length, mean stride velocity, stride length, and mean step frequency of patients with PD in the timed up-and-go test all increased compared with those before rTMS treatment, whereas the mean stride time and double support decreased. In the narrow-track test, the mean stride velocity increased and the mean stride time decreased. In the turning test, the turning left duration, turning right duration, mean duration, mean number of steps, and average step duration decreased, while the mean angular velocity increased after rTMS treatment. Compared with those before rTMS treatment, the latency period of patients with PD in overlapping saccades decreased, the completion time of overlapping saccades decreased, and the average saccade speed increased. In the anti-saccade test, the completion time decreased and the average saccade speed increased after rTMS treatment. Compared with those before rTMS treatment, the Tinetti Balance Scale, Tinetti Gait Scale, Berg Balance Scale, Mini-Mental State Examination, and MoCA scores increased, and the MoCA sub-items improved in terms of visual-spatial and executive function, language, abstraction, delayed recall, and orientation after rTMS treatment. High-frequency rTMS may be an effective therapy for improving gait disorders and cognitive functions in patients with PD.

Analysis of Biomechanical Gait Parameters in Patients after Total Hip Replacement in the Early Recovery Period

INTRODUCTION. The widespread use of total hip arthroplasty (THA) places high demands on the restoration of a normal gait pattern and is one of the key goals of rehabilitation. AIM. Determination of key parameters of walking in patients after THA to assess the effectiveness of restoration of the physiological gait pattern. MATERIALS AND METHODS. In a control prospective study, the main group consisted of 23 patients (11 men, 12 women, aged from 41 to 75 years, mean age 63.9 ± 9.4 years), who in the first 8 weeks after planned THA, moved with the help of assistive devices. supports (two crutches or walkers) who underwent stage II of medical rehabilitation; control group — 27 healthy people (12 men and 15 women, aged from 42 to 73 years, average age 60.9 ± 9.9 years). Spatiotemporal and kinematic gait parameters were recorded before and after the rehabilitation course using a gait simulator with biofeedback equipped with three sensors. For each leg, spatiotemporal and kinematic biomechanical parameters were separately recorded. RESULTS. All spatiotemporal gait parameters on both limbs and pelvic mobility in the sagittal plane in patients in the early recovery period after THA before the start of the rehabilitation course are significantly different from healthy people. After a course of rehabilitation, the studied gait parameters approach physiological values. The main asymmetry is observed in the single support phase from 16 % at the beginning of the course, to 10 % at the end; sagittal pelvic mobility are 2 times higher than the physiological normal meaning at the beginning of the course, without significant changes in dynamics. DISCUSSION. Disturbances in the gait pattern are observed in the majority of patients undergoing THA. Step symmetry is one of the significant parameters of walking, according to which the primary global assessment of its quality is carried out. Asymmetry of the single support phase of the limbs is a natural development of compensatory motor reactions after endoprosthetics. CONCLUSION. The gait parameters “step frequency” and “step cycle” quickly change after a course of rehabilitation and can be used to assess the locomotor activity of patients during short courses of medical rehabilitation in the early recovery period. Indicators of stance and swing phases, their symmetry changes much more slowly, can serve as criteria for assessing the effectiveness of measures taken at the stages of rehabilitation in the dynamics of gait restoration.

Relationship between Repeated Sprint Ability and Force–Velocity Profile in Elite and Subelite Female Field Hockey Players

This study aimed to compare two female field hockey teams of different competitive levels by analyzing kinematic variables in repeated sprint ability (RSA) tests and the force-velocity profile (FVP). Twenty-five female hockey players representing the elite and subelite levels from the same club volunteered to participate. The RSA protocol included six 30 m maximal sprints with a 30 s recovery. Kinematic variables, such as sprint time, step frequency, and step length, were analyzed for each sprint. Additionally, players performed counter-movement jumps (CMJs) and CMJs with 50% body weight (CMJ50s) to calculate the FV50 using the Bosco Index. The elite players showed better (≈2%; p &lt; 0.05) fatigue indexes in sprint time (0–30 m and 0–10 m sections), step length (0–10 m, 10–20 m, and 20–30 m sections), and step frequency (20–30 m section) during the RSA test, as well as greater values (&gt;10%; p &lt; 0.05) in the CMJ50 and FV50 tests. In addition, these RSA (sprint time, step frequency, and step length) and jumping (CMJ, CMJ50, and FV50) variables showed a moderate, significant, or very significant relationship with each other. Therefore, it seems that both strength and speed capacities can be used either in conjunction or as a complementary approach to enhance the overall RSA performance.

Triple Jump Performance Parameters and Inter-Limb Asymmetry in the Kinematic Parameters of the Approach Run in International and Paralympic-Level Class T46/T47 Male Athletes

Background/Objectives: The triple jump is included in the Paralympic Athletics competition. The aim of the research was to examine the relationship of the phase ratios and the inter-limb asymmetry in the spatiotemporal parameters of the approach run in Paralympic and international-level Class T46/T47 triple jumpers. Methods: Eleven Class T46/T47 male athletes were recorded during the examined competitions. Step length (SL), frequency (SF), and average velocity (ASV) for the late approach run as well as the length and the percentage distribution of each jumping phase (hop, step, jump) were measured using a panning video analysis method. The inter-limb asymmetry was estimated using the symmetry angle. Results: No significant inter-limb asymmetry was found (p &gt; 0.05). In addition, SL, SF, and ASV were not different (p &gt; 0.05) between the steps initiated from the ipsilateral and the contralateral leg regarding the impaired arm. However, the direction of asymmetry for SF was towards the ipsilateral leg to the impaired arm in the majority of the examined athletes. The maximum speed of the approach was correlated with the triple jump distance and the magnitude of asymmetry for AVS was correlated with the vertical take-off velocity and angle for the step. Conclusions: Since the distance of the triple jump related with the peak approach speed added the negative correlation of peak approach speed with the magnitude of the symmetry angle for SL, it is suggested to minimize the asymmetries in the step characteristics during the approach run to improve triple jump performance in Class T46/T47 jumpers.

Design and Implementation of a Ka-Band Frequency Source Based on DS+DDS Hybrid Method

Abstract This article proposes a design scheme for a broadband agile frequency conversion Ka-band frequency source, which adopts a mixed frequency synthesis method of DS+DDS. This method combines the advantages of DDS such as fast frequency switching speed, small frequency step, and wide DS frequency bandwidth, and uses segmented filtering to effectively suppress the disadvantage of DDS spurious error. DS adopts an up conversion and double frequency doubling scheme to broaden the frequency band, with simple design and low cost. The deterioration of phase noise is offset by selecting a low phase noise PLL. Actual measurement shows that the output bandwidth of the frequency source is 8GHz, with spurious suppression ≤ −61dBc, frequency switching time ≤ 140ns, output power ≥ 15dBm, step frequency of 1MHz, and phase noise ≤ −100dBc/Hz@1kHz, meet the design requirements.