High-speed Running Research Articles

Target Before Shooting: Accurate Anomaly Detection and Localization Under One Millisecond via Cascade Patch Retrieval.

In this work, by re-examining the "matching" nature of Anomaly Detection (AD), we propose a novel AD framework that simultaneously enjoys new records of AD accuracy and dramatically high running speed. In this framework, the anomaly detection problem is solved via a cascade patch retrieval procedure that retrieves the nearest neighbors for each test image patch in a coarse-to-fine fashion. Given a test sample, the top-K most similar training images are first selected based on a robust histogram matching process. Secondly, the nearest neighbor of each test patch is retrieved over the similar geometrical locations on those "most similar images", by using a carefully trained local metric. Finally, the anomaly score of each test image patch is calculated based on the distance to its "nearest neighbor" and the "non-background" probability. The proposed method is termed "Cascade Patch Retrieval" (CPR) in this work. Different from the previous patch-matching-based AD algorithms, CPR selects proper "targets" (reference images and patches) before "shooting" (patch-matching). On the well-acknowledged MVTec AD, BTAD and MVTec-3D AD datasets, the proposed algorithm consistently outperforms all the comparing SOTA methods by remarkable margins, measured by various AD metrics. Furthermore, CPR is extremely efficient. It runs at the speed of 113 FPS with the standard setting while its simplified version only requires less than 1 ms to process an image at the cost of a trivial accuracy drop. The code of CPR is available at https://github.com/flyinghu123/CPR.

Do all matches require the same effort? Influence of contextual factors on physical demands during official female handball competitions.

Understanding the influence of contextual factors on physical demands is essential to maximize performance in handball. The purpose of this study was to explore and compare the influence of contextual factors (halves of the match, level of the opponent, match outcome and player role) on external load during official matches in women's handball. Twenty-two semi-professional female players from the Spanish 2nd Division were monitored across 13 official home matches. Total distance covered (TDC), high-speed running distance (HSR), high-intensity breaking distance (HIBD), accelerations (ACC), decelerations (DEC) and PlayerLoad (PL) were collected in absolute and relative values (normalized by playing time) using a local positioning system (WIMU PRO, Realtrack Systems S.L., Almería, Spain). HSR, HSR/min and HIBD/min decreased during the second half (p < 0.05; small effects). Regarding the level of the opponent, high-level and middle-level teams elicited higher TDC/min, HIBD/min and PL/min than low-level teams (p < 0.05; small-moderate effects). Additionally, starter players exhibited higher absolute values of external load (TDC, HSR, HIBD, ACC, DEC and PL) compared to non-starters (p < 0.05; moderate-large effects). Match outcome did not affect the physical demands (p > 0.05). The study indicated that halves of the match, level of the opponent, and player role influenced external load experienced by players during official matches; specifically, starter players showed higher absolute values of external load compared to non-starters. This information should be considered in managing load and developing strategies to minimize fatigue and enhance performance during matches.

External Training Loads and Soft-Tissue Injury Occurrence During Congested Versus Noncongested Periods in Football.

To analyze the influence of congested and noncongested fixture periods during 2 seasons in a professional male football team on soft-tissue injury incidence and external load. Thirty-three professional football players from a Portuguese Liga I team participated in this study. Weekly external load and soft-tissue injury rate and burden of 2 consecutive seasons (2021-22 and 2022-23) were analyzed. Total soft-tissue injury rate and burden for the 2 seasons were 3.9 and 3.2 injuries per 1000hours and 71.8 and 60.5days per 1000hours for congested and noncongested periods, respectively. No significant differences were observed between congested and noncongested periods. Total high-speed running, sprint distance, distance above 80% and 90% of maximal velocity, and meters accelerating and decelerating above 2m/s2 were significantly higher for noncongested weeks. Match accelerations and decelerations above 3m/s2 were higher during congested periods and training during noncongested periods. No differences between the 2 periods were observed for the total number of accelerations and decelerations above 3m/s2. Overall, physical outputs per week were higher for training during noncongested weeks, whereas matches during congested periods registered higher external load. No effect of a congested schedule was observed on soft-tissue injury rates and injury burden. Higher match exposure during congested periods increased external load performed per week, and during noncongested periods, training load was superior to congested weeks.

Weekly external load distribution in football teams of different competitive levels.

This study aimed to compare the microcycle load distribution between teams from different competitive levels. A total of 22 microcycles from one team of each competitive level (first division, 1st DIV, n = 32 players; second division, 2nd DIV, n = 23 players; third division, 3rd DIV, n = 23 players) were monitored using GPS (10 Hz, Catapult). During the match, a higher number of high accelerations (i.e., > 3 m/s, per min) were found in the 3rd DIV team compared to the 1st and 2nd DIV teams. On match day (MD) +1&+2, the 1st DIV team covered more total (per min, p < 0.001) and high-speed running distance (HSR per min, p < 0.001 and p = 0.042, respectively) than both the 2nd and 3rd DIV teams. The 2nd DIV team showed lower values in most distance-related variables (total distance covered per min, p < 0.001; running distance per min, p < 0.001; HSR per min, p < 0.001; and sprinting distance per min, p < 0.001) for both MD-4 and MD-3 compared to the 1st and 3rd DIV teams. In contrast, it showed higher sprinting distance per min (p < 0.001) on MD-2. In general, the 3rd DIV team showed higher values in the number of high accelerations (per min, p < 0.001) across all sessions. These results suggest that distance-related variables may be a priority when planning microcycles for the 1st DIV team, while accelerations are relevant for the 3rd DIV team. A higher emphasis on external load during MD-2 by the 2nd DIV team may explain the lower external loads across the microcycle.

The relationships between distances covered above generic and relative speed thresholds by male soccer players in English Premier League matches across two competitive seasons. The effects of positional demands and possession.

The aims of this study were to: a) examine the relationships between high-intensity distances covered above generic and relative speed thresholds in English Premier League (EPL) matches across two consecutive seasons and b) analyze the effects of playing position and team possession. Sixteen elite male soccer players (seven defenders, six midfielders and three forwards) participated in this study (age 27.8 ± 3.5 years, height 183.7 ± 5.4 cm, body mass 83.9 ± 7.1 kg). An Optical Tracking System was used to collect the following variables: total distance covered; high-speed running distance (HSRD) (> 5.5 m/s); high-intensity running distance (HIRD) (5.5-7 m/s); sprint distance (> 7 m/s); total distance covered above Maximal Aerobic Speed (MAS); distance covered > 85% peak speed (PS); and distance > 30% Anaerobic Speed Reserve (ASR). All measures were analyzed as whole match totals and as distances covered in the periods of the team in possession (TIP), opponent team in possession (OTIP), and ball out of play (BOP). Analysis by position based on defenders, midfielders and forwards was also performed. Distance > 30% ASR was almost perfectly correlated with HSRD (r = 0.98), while distances > MAS were highly correlated with both HIRD (r = 0.91) and HSRD (r = 0.91), and distance > 85% PS were highly correlated with SD (r = 0.70). Although the generic and relative speed thresholds show almost perfect correlation, the differences between HSRD, HIRD and distance > MAS indicate that players may be exposed to more HIRD when using relative thresholds.

Same Training for Everyone? Effects of Playing Positions on Physical Demands During Official Matches in Women’s Handball

The purpose of this study was to analyze and compare the differences between playing positions on physical demands during official matches in women’s handball. Twenty-two semi-professional female players (4 wings, 14 backs and 4 pivots) from the Spanish 2nd Division were monitored across 13 official home matches. Total distance covered (TDC), high-speed running distance (HSR), high-intensity breaking distance (HIBD), accelerations (ACC), decelerations (DEC) and PlayerLoad™ (PL) were collected in absolute and relative values (normalized by playing time) using a local positioning system (WIMU PRO™, Realtrack Systems S.L., Almería, Spain). Playing positions differences were determined by variance analysis one-way ANOVA with partial Etasquared (ηp2) or epsilon-squared (ε²) and Cohen’s effect size (ES). Wings covered more TDC (3414.5±1710.1 m), HSR (492.7±280.0 m) and HIBD (171.2±104.7 m) compared to backs and pivots (p&lt;0.05; moderate-large effects). Wings also registered more total number of ACC (750.5±362.2) and PL (85.0±7.8 a.u.) compared to backs and pivots (p&lt;0.05; moderate-large effects), whereas backs performed more ACC/min (19.9±1.1 n·min−1) than wings (18.9±1.4 n·min−1) and pivots (18.4±3.9 n·min−1) (p&lt;0.05; moderate effects). In conclusion, physical demands differ between playing positions during official female competitions and these differences should be considered by practitioners to better prescribe and periodize training load and to design more individualized training programs.

External training load and performance recovery after small-sided games in soccer: Insights for return-to-play management.

The return-to-play process' characteristics can vary by injury and sport type but are typically composed of phases of different durations, training targets, and intensities that gradually increase the physiological and mechanical load. In team sports, contact drills are a necessary part of the last phases of this process, and they should be planned using the optimal mechanical load. The present study investigated the external load and kinetic recovery in U19 soccer players performing 6vs6 and 3vs3 small-sided games. A global positioning system (GPS) measured external load metrics. The rate of perceived exertion (RPE) was registered at the end. Total quality of recovery (TQR) was collected at the beginning of the training session and after 24 h. Moreover, before and after the small-sided games (SSGs) and at 24 h, delayed-onset muscle soreness (DOMS) of the legs, sprinting time, and vertical jump height (CMJ) were collected. 6vs6 presented higher values in total distance low-, moderate-, high, and very-high-speed distance, and maximum speed (p < 0.05). However, 3vs3 showed higher number of sprints, acceleration, and deceleration at different intensities. Furthermore, no difference was shown in RPE. The effect of fatigue on sprint seems greater for 6vs6, showing an impairment persistent at 24 h (p < 0.05). Moreover, CMJ height was impaired after 6vs6 and at 24 h (p < 0.05) but did not change after 3vs3 (p > 0.05). DOMS values after SSGs and at 24 h were higher than baseline for both conditions (p < 0.05), while TQR decreased at 24 h in both conditions (p < 0.05). Based on our results, it seems that 6vs6, leading to a greater high-speed running distance, might cause a training load that needs more time to recover. This point may be crucial in a return-to-play process, especially when hamstring muscles are involved.

Measures Contributing to the Prevention of Hamstring Strain in Sprinters

One of the most typical injuries among sportsmen is hamstring injury. Extreme muscle stretching or high-speed running activities make athletes more vulnerable to hamstring injuries. Especially for sprinters, hamstring injuries rank among the most frequent in sports and cause a large amount cost of time. Despite its frequency, it is still unclear how hamstring injuries occur. It is crucial to keep sprinters injury-free because they also have a high rate of re-injury, which makes it difficult for athletes to heal entirely from injuries. It is important to use a variety of techniques to help athletes avoid hamstring injuries if they want to prevent sprinters from suffering them. This article is a review of the essays focus on methods to prevent hamstring injuries, which aims to provide scientific and comprehensive methods to instruct athletes and coaches to better deal with hamstring injuries.

Indicators of Fatigue during a Soccer Match Simulation Using GPS-Derived Workload Values: Which Metrics Are Most Useful?

Research into women's competitive soccer matches has shown distance and high-speed running (HSR) reductions over time, but the effects on some GPS-derived metrics have not been investigated. The purpose of this project was to examine the utility of common GPS metrics for indicating fatigue from the T-SAFT90 match simulation in collegiate soccer players. Unlike in competitive matches, changes to these metrics occurred as early as 15 min, with HSR, average and max speed, and speed intensity (SI) exhibiting significant declines. HSR and SI were even further decreased in later periods, with HSR lower in minutes 30-40 (T30-35 and T35-40) than T15-20 and lower in T70-85 than T45-60. SI showed a similar pattern of continued decline, reaching its lowest value in the last three time segments. Accelerations and decelerations were also decreased beginning at T15-20 and T20-25, respectively, but the fatigue index (FI), dynamic stress load (DSL), and step balance (SB) were unchanged. It can be concluded that in contrast to competitive matches where players can dictate their own intensity, a match simulation may result in a quicker onset of fatigue, but not all GPS-derived values change as expected in fatiguing environments. Coaches and sports scientists may use these findings to properly monitor fatigue in real time.

Relating external load variables with individual tactical actions with reference to playing position: an integrated analysis for elite futsal

ABSTRACT The purpose of this study was to contextualise players’ high-intensity activities (HIA) with individual tactical actions during match play with reference to playing positions. Tracking data was obtained using local positioning system devices from 19 male elite futsal players (28.8 ± 2.4 years). The HIA measures included high-intensity acceleration (ACC; ≥3 m · s−2), deceleration (DEC; ≤−3 m · s−2), and high-speed running (HSR; ≥18 km · h−1). Tracking data and match footage were synchronised using the SPRO™ to code players’ physical performance and technical-tactical actions. A small statistically significant association was observed between HIA and players’ actions with or without the ball (χ 2 = 183.27 (2, N = 4234), p<.001; Cramer’s V = 0.21). When players have the ball, the number of DEC efforts tends to increase with a corresponding decrease in ACC and HSR. When the players do not have the ball, ACC and HSR running tend to increase with a corresponding decrease in DEC. A comparison between HIA revealed that futsal performance requires greater mechanical efforts (ACC + DEC) than kinematic efforts (HSR). This underscores the importance of mechanical efforts within short space for futsal performance. Moreover, the diverse tactical actions associated with different player positions contribute to distinct activity profiles and physical requirements.

Worst Case Scenarios in Soccer Training and Competition: Analysis of Playing Position, Congested Periods, and Substitutes

ABSTRACT Aim: To understand mean (WCSmean) and peak (WCSpeak) worst case scenarios within training and game play in male professional soccer. Methods: Thirty-one (n = 31) first team players were monitored across 37 matches and 14 MD-3 sessions. Playing status was distinguished, football drills analyzed, and performance explored in long-period: >6 days, moderate-period: 5–6 days, and congested-period: ≤4 days. Relative total distance (TD), high-speed running distance (HSRD, >19.8 km·h−1), sprint distance (SD, >25.2 km·h−1), accelerations/decelerations (A+D, >3 m·s−2), accelerations (Acc, >3 m·s−2), and decelerations (Dec, >−3 m·s−2) were measured as well as Maximum acceleration (Max Acc; m·s−2) and deceleration (Max Dec; m·s−2). Results: Analysis of variance found differences between matches and training in WCSmean for TD, HSRD, SD, and Max Dec in all positions (p < .001; partial η2 > .275). Fullbacks displayed differences between match and training in Max Acc (moderate ESs; p < .001), while center backs and central midfielders in Max Dec (large ESs; p > .05). Main effects of playing status were discovered for all metrics except Max Dec (p < .001; partial η2 > .124). Analysis showed differences between long- and congested-period for A+D and Dec (large ESs; p ≤ .05). Conclusions: Findings provide more insights into short peak intensity demands of soccer showing that the maximum high velocity action of acceleration and deceleration is not being replicated in training. Nonstarters lack maximum intensity exposure in matches (WCSpeak) increasing the gap between training and competition even higher during congested fixture periods.

Match Exposure, Consecutive Match Number, and Recovery Days Affect Match Running During International Women's Soccer Tournaments.

Brown, G, Massard, T, Wignell, T, McCall, A, and Duffield, R. Match exposure, consecutive match number, and recovery days affect match running during international women's soccer tournaments. J Strength Cond Res 38(3): 577-583, 2024-To determine the influence of tournament-specific factors (match exposure, consecutive matches, and days between matches) on match running in women's international soccer players (footballers), 28 players from 1 national team were observed over 4 international tournaments using 10 Hz global positioning system units. Linear mixed models with a forward selection approach were used to analyze the collective effect of tournament-specific factors of match exposure (playing time), consecutive matches (count), days between matches (count) and time on pitch on relative (min -1 ) match running metrics (total distance, high-speed running, very high-speed running, accelerations, and decelerations), and the change in these metrics between halves. The significance level was set at p < 0.05. Days between matches were included in the final models for total distance ( p < 0.0001), high-speed running ( p = 0.002), very high-speed running ( p = 0.025), and change in accelerations ( p < 0.0001) and decelerations ( p = 0.002). Prior match exposure was included in the models for total distance ( p = 0.021), change in total distance ( p < 0.0001), and change in high-speed running ( p = 0.0008). Consecutive match number was included in the model for deceleration ( p = 0.030), change in very high-speed running ( p = 0.016), change in acceleration ( p < 0.0001), and change in deceleration ( p < 0.0001). Time on pitch was included in the final total distance ( p = 0.044), high-speed running ( p < 0.0001), acceleration ( p < 0.0001), and deceleration ( p = 0.0003) models. Overall, reduced match running throughout tournaments was associated with increased time on pitch and ≤3 days between matches. Increasing match exposure and more time between matches minimizes reductions in match running between halves. Practitioners can use these variables to inform player monitoring during international soccer tournaments and on return to clubs.

Validity of Inertial Measurement Units to Measure Lower-Limb Kinematics and Pelvic Orientation at Submaximal and Maximal Effort Running Speeds

Inertial measurement units (IMUs) have been validated for measuring sagittal plane lower-limb kinematics during moderate-speed running, but their accuracy at maximal speeds remains less understood. This study aimed to assess IMU measurement accuracy during high-speed running and maximal effort sprinting on a curved non-motorized treadmill using discrete (Bland–Altman analysis) and continuous (root mean square error [RMSE], normalised RMSE, Pearson correlation, and statistical parametric mapping analysis [SPM]) metrics. The hip, knee, and ankle flexions and the pelvic orientation (tilt, obliquity, and rotation) were captured concurrently from both IMU and optical motion capture systems, as 20 participants ran steadily at 70%, 80%, 90%, and 100% of their maximal effort sprinting speed (5.36 ± 0.55, 6.02 ± 0.60, 6.66 ± 0.71, and 7.09 ± 0.73 m/s, respectively). Bland–Altman analysis indicated a systematic bias within ±1° for the peak pelvic tilt, rotation, and lower-limb kinematics and −3.3° to −4.1° for the pelvic obliquity. The SPM analysis demonstrated a good agreement in the hip and knee flexion angles for most phases of the stride cycle, albeit with significant differences noted around the ipsilateral toe-off. The RMSE ranged from 4.3° (pelvic obliquity at 70% speed) to 7.8° (hip flexion at 100% speed). Correlation coefficients ranged from 0.44 (pelvic tilt at 90%) to 0.99 (hip and knee flexions at all speeds). Running speed minimally but significantly affected the RMSE for the hip and ankle flexions. The present IMU system is effective for measuring lower-limb kinematics during sprinting, but the pelvic orientation estimation was less accurate.

On the Surface Waves Retrieved from High-speed Trains Running on Viaducts and Ground Surface

The high-speed train (HST) generates strong ground vibrations when it runs on the railroad. However, little attention has been paid to retrieving surface wave from these vibrations. Here, we try to retrieve surface waves from HST-induced vibrations using field data. There are two kinds of HST tracks, one is built on the viaduct and the other is built on the ground. We acquired the signals generated by the HST running on the two kinds of tracks in Huzhou, China. In the original noise records, the HST signals can be obviously observed. In terms of a single HST event, the signals generated by the HST on the ground surface decay quickly and the signals generated by the HST running on the viaduct have broadband energy. We calculated the noise crosscorrelations in the HST-induced segments and stacked the results. Surface-wave dispersion energy were generated and compared with the results from the segments without HST. A significant improvement of the retrieval of surface waves were observed with signals generated by the HST running on viaducts while less obviously when on the ground surface.

Within-Subject Principal Component Analysis of External Training Load and Intensity Measures in Youth Soccer Training.

Marynowicz, J, Lango, M, Horna, D, Kikut, K, Konefał, M, Chmura, P, and Andrzejewski, M. Within-participant principal component analysis of external training load and intensity measures in youth soccer training. J Strength Cond Res 37(12): 2411-2416, 2023-The aim of this study was to identify which combination of external training load (EL) and external intensity (EI) metrics during youth soccer training sessions captured similar or unique information. Data were collected from 18 youth soccer players during an 18-week in-season competition period using a 10-Hz global positioning system, rating of perceived exertion (RPE), and session-RPE (sRPE). External training load measures included total distance (TD, in meters), PlayerLoad (PL, in arbitrary units), high-speed running distance (HSR, in meters), and number of accelerations (ACC, n). All EL metrics were also divided by session duration (minutes) to obtain EI values. A total of 804 training observations were undertaken (43 ± 17 sessions per player). The analysis was performed by use of the principal component analysis technique. The first principal component (PC) captured 49-70% and 68-89% of the total variance in EI and EL, respectively. The findings show that from the 5 EI metrics, most of the information can be explained by either TD per minute or PL per minute, with a loading from 0.87 to 0.98 and from 0.76 to 0.95, respectively. The majority of EL information can be explained by PL (loading: 0.93-0.98), TD (loading: 0.95-0.99), ACC (loading: 0.71-0.91), or sRPE (loading: 0.70-0.93). The second PC for EL metrics is most strongly correlated with HSR, with loadings from 0.53 to 0.84. The results suggest that the majority of the information contained in the EL variables can be captured in 1 PC without losing much information. The findings suggest that stakeholders who intend to provide a fast and holistic view of EL information in a daily training environment should report TD, PL, ACC, or sRPE plus HSR to coaching staff as a metrics that provides additional unique information.

Weekly Training Load Differences between Starting and Non-Starting Soccer Players.

The aim of this study was to examine the differences in the weekly training load between starters and non-starters classified based on the match starting line-up, with respect to the playing position and a training day. Notably, 31 young adult soccer players (age: 18.79 ± 1.04 years) competing in the 3rd Czech division were monitored across the season. The weekly training load was measured using a GPS system as follows: total distance covered (TD), high-speed running distance (HSR), sprint running distance (SR), and acceleration and deceleration distance (ACDC). We found higher values in three out of four observed variables (HSR, SR, and ACDC, excluding TD) for starters compared to non-starters (p < 0.05), with small to moderate effect sizes (d = 0.40-0.49). Differences were observed especially in players who were fullbacks, offensive midfielders, and forwards. Moreover, the largest differences were found in training prior to a match day for HSR, SR, and ACDC (p < 0.05). Non-starters experienced lower weekly external loads in offensive player positions, predominantly in high-intensity variables, which are essential for their physical performance. It seems that non-starters may experience potential under-loading in the training process. Coaches and practitioners should be aware of this potential risk and find an appropriate method to compensate for load discrepancies, particularly in terms of high-intensity activities.

Comparison of Different Coach Competition Micro-Cycle Planning Strategies in Professional Soccer

Background: Coaches propose training strategies to develop their playing model, but the impact on the conditional demand of players is unknown. The objective of this study aimed to assess the conditional demands associated with five competitive micro-cycle (Mi) planning strategies put forth by professional soccer coaches. The dependent locomotor variables were: total distance traveled (TD, in m), high-speed running distance (TD21, &gt;21 km·h−1, in m), sprint distance (TD27, &gt;27 km·h−1, in m), acceleration load (aLoaD, in AU) and number of accelerations (ACC2, &gt;2 m·s−2 in n) and decelerations (DEC2, &lt;−2 m·s−2 in n). The activity profile of the players was monitored during each training session using a global positioning system (GPS) during four seasons (2018–2019 to 2021–2022). Regardless of the coach, the sessions furthest from Mi (MD+1, MD-4 and MD-3) were the most conditionally demanding, where TD27 was especially stimulated on MD-3 (ES = 0.7, 0.2/1.2, mean and range; p &lt; 0.05); furthermore, MD-2 was the least demanding session of all the trainers (ES = −2.4, −2.6/−1.5, mean and range; p &lt; 0.01). However, there were nuances regarding the conditional demand among the coaches: Co1 and Co2 proposed a higher conditional demand in the MD-2 and MD-1 sessions (p &lt; 0.05). The conclusion was twofold: elite soccer coaches proposed a horizontal alternation in the weekly distribution of training stimuli; nevertheless, the differences in the style of play of each coach affected the week-planning strategy.

Research on a Wire Rope Breakage Detection Device for High-Speed Operation Based on the Multistage Excitation Principle

Wire rope breakage, as damage easily produced during the service period of wire rope, is an important factor affecting the safe operation of elevators. Especially in the high-speed elevator operation process, the problem of magnetization unsaturation caused by speed effects can easily lead to deformation of the magnetic flux leakage detection signal, thereby affecting the accuracy and reliability of wire breakage quantitative detection. Therefore, this article focuses on the problem that existing wire rope detection methods cannot perform non-destructive testing on high-speed elevator wire ropes and conducts design and experimental research on a high-speed running wire rope breakage detection device based on the principle of multi-stage excitation. The main research content includes simulation research on the multistage excitation, structural design, and simulation optimization of open–close copper sheet magnetizers and the building of a detection device for wire rope breakage detection experimental research. The simulation and experimental results show that the multistage magnetization method can effectively solve the problem of magnetization unsaturation caused by the velocity effect. The multistage excitation device has a good wire breakage recognition effect for speeds less than or equal to 3 m/s. It can detect magnetic leakage signals with a minimum of four broken wires and has good detection accuracy. It is a new and effective wire breakage detection device for high-speed elevator wire rope, providing important technical support for the safe and reliable operation of high-speed elevators.

Speed-specific optimal contractile conditions of the human soleus muscle from slow to maximum running speed.

The soleus is the main muscle for propulsion during human running but its operating behavior across the spectrum of physiological running speeds is currently unknown. This study experimentally investigated the soleus muscle activation patterns and contractile conditions for force generation, power production and efficient work production (i.e. force-length potential, force-velocity potential, power-velocity potential and enthalpy efficiency) at seven running speeds (3.0 m s-1 to individual maximum). During submaximal running (3.0-6.0 m s-1), the soleus fascicles shortened close to optimal length and at a velocity close to the efficiency maximum, two contractile conditions for economical work production. At higher running speeds (7.0 m s-1 to maximum), the soleus muscle fascicles still operated near optimum length, yet the fascicle shortening velocity increased and shifted towards the optimum for mechanical power production with a simultaneous increase in muscle activation, providing evidence for three cumulative mechanisms to enhance mechanical power production. Using the experimentally determined force-length-velocity potentials and muscle activation as inputs in a Hill-type muscle model, a reduction in maximum soleus muscle force at speeds ≥7.0 m s-1 and a continuous increase in maximum mechanical power with speed were predicted. The reduction in soleus maximum force was associated with a reduced force-velocity potential. The increase in maximum power was explained by an enhancement of muscle activation and contractile conditions until 7.0 m s-1, but mainly by increased muscle activation at high to maximal running speed.

Neuromuscular and perceptual-cognitive response to 4v4 small-sided game in youth soccer players.

The physical and psychological load of small-sided games (SSGs) can affect players' neuromuscular and cognitive functions. Yet, little is known about the acute performance changes after such a specific exercise in young soccer players and their association with exercise load applied. This study investigates i) the neuromuscular and perceptual-cognitive response to the SSG exercise load, and ii) the relationship between pre- and post-SSG changes in variables of performance and the respective exercise load in youth soccer players. Sixteen participants (13.6 ± 0.5years) underwent a 30-min SSG 4v4 + GK protocol. Prior to and after the SSG they performed countermovement jump (CMJ), planned and reactive Y-shaped agility tests (PA, RA), and go/no-go task (GNG). Their subjective perception of fatigue was evaluated by visual analog scale. Fatigue induced by SSG (perception of fatigue increased by 41.56%, p = .001, g = 4.15) increased PA time (4.04%, p = .002, g = .97), RA time (6.45%, p = .003, g = 1.16), and number of errors in the response inhibition task (87.1%, p = .023, rc = .57), whilst decreased CMJ height (-6.65%, p = .014, g = .56). These performance deteriorations were not significantly associated with neither internal nor external load variables. However, a less pronounced drop in performance was related to external load variables, i.e., ∆CMJ height and ∆RA time correlated with very high-speed running (rs = .66, p = .006; rs = -.50, p = .022; respectively) and maximal speed (r = .54, p = .032; r = -.52, p = .037; respectively), whilst ∆PA time was associated with high-intensity accelerations (rs = -.76, p = .002). These findings indicate that fatigue induced by SSG affects both planned and reactive agility, decision-making in response inhibition task, and explosive strength in youth soccer players regardless of significant contribution of any robust internal or external load variables. Nonetheless, high-intensity actions within SSG partially compensate for the decrements in their agility performance and explosive strength. The load variables encountered during SSG do not fully reflect youth players' neuromuscular and perceptual-cognitive responses to sport-specific exercise.