Inertial Movement Research Articles

Features of the penetration of elements of the cumulative jet into a steel barrier

Based on numerical simulations carried out using numerical methods of continuum mechanics, the influence on the depth of craters, formed in steel barriers of various strengths, geometric and kinematic parameters of elongated cylindrical copper strikers, simulating elements of a cumulative jet, in the range from 0.3 to 8 km/s. For description the behavior of materials of the impactor and barrier, the model of a compressible elastic-plastic medium with a variable value of the yield strength. Determined that the classical hydrodynamic theory of the penetration of a cumulative jet into a barrier is not takes into account the effects of the inertial movement of the barrier after triggering separately taken element (aftereffect). The existence of three regimes is distinguished shock interaction-high-speed, when the elements behave like a liquid body, are worked out, but not inhibited; low speed, when the elements behave like solid body and are decelerated as a whole and intermediate, when the elements are decelerated and are deformed at the same time. It is shown that the braking mode of copper elements at high-speed impact on a steel armored barrier is realized at speeds smaller 0.8-1 km/s. It is shown that when interacting with an obstacle, high-speed fragmented cumulative jet, the total depth of armor penetration will be greater, than this is predicted by the classical hydrodynamic theory of penetration, and the more more, the higher the speed of the elements and the greater the distance between them on the one hand and less strength of the barrier on the other side. Keywords: High-velocity strike, elongated striker, cumulative jet, steel barrier, crater, inertial movement of the barrier, numerical modeling.

A new measure of realized volatility: Inertial and reverse realized semivariance

In this study, based on inertial and reverse price movements, a new measure of realized volatility, inertial realized semivariance (IRV) and reverse realized semivariance (RRV), was proposed. The limit property of the inertial and reverse realized semivariances is established from probability theory. Through the analysis on high frequency data, it shows that IRV and RRV both are effective measures of variation of asset prices and, that RRV and reverse jump variation (RJV) exhibited significant prediction capabilities for future returns. Empirical results of China Securities Index 300 (CSI 300) also show that this new measure of realized volatility has good prediction performance for future realized variances and returns.

Biomechanical Loads and Their Effects on Player Performance in NCAA D-I Male Basketball Games.

Basketball games and training sessions are characterized by quick actions and many scoring attempts, which pose biomechanical loads on the bodies of the players. Inertial Measurement Units (IMUs) capture these biomechanical loads as PlayerLoad and Inertial Movement Analysis (IMA) and teams collect those data to monitor adaptations to training schedules. However, the association of biomechanical loads with game performance is a relatively unexplored area. The aims of the current study were to determine the statistical relations between biomechanical loads in games and training with game performance. Biomechanical training and game load measures and player-level and team-level game stats from one college basketball team of two seasons were included in the dataset. The training loads were obtained on the days before gameday. A three-step analysis pipeline modeled: (i) relations between team-level game stats and the win/loss probabilities of the team, (ii) associations between the player-level training and game loads and their game stats, and (iii) associations between player-level training loads and game loads. The results showed that offensive and defensive game stats increased the odds of winning, but several stats were subject to positional and individual performance variability. Further analyses, therefore, included total points [PTS], two-point field goals, and defensive rebounds (DEF REB) that were less subject to those influences. Increases in game loads were significantly associated with game stats. In addition, training loads significantly affected the game loads in the following game. In particular, increased loads 2 days before the game resulted in increased expected game loads. Those findings suggested that biomechanical loads were good predictors for game performance. Specifically, the game loads were good predictors for game stats, and training loads 2 days before gameday were good predictors for the expected game load. The current analyses accounted for the variation in loads of players and stats that enabled modeling the expected game performance for each individual. Coaches, trainers, and sports scientists can use these findings to further optimize training plans and possibly make in-game decisions for individual player performance.

Practice versus Game External Load Measures in Starters and Non-Starters of a Men’s Collegiate Soccer Team

Monitoring external loads may minimize injury risk and improve physical performance. The purpose was to describe the external loads of a men’s collegiate soccer team during practice and games at the start of in-season play. In the first 2 weeks of the competitive season, National Collegiate Athletic Association Division I soccer athletes (n=19; mean±SD, age: 20.3±0.9 yr; body mass: 77.9±6.8kg; body height: 178.87±7.18cm; body fat: 10.0±5.0%; VO2max: 65.39±7.61mL/kg/min) wore a global positional system device (GPS/GNSS) during practices (n=8) and games (n=3). Starters were classified as players who maintained a minimum playing time of 45 minutes per game (n=10); other players were considered non-starters (n=9). External load metrics collected were: total distance (TD), player load (PL), high-speed distance (HSD, >13 mph (5.8 m/s)), high inertial movement analysis (IMA, >3.5m/s2), and repeated high intensity efforts (RHIE). Multivariate and repeated measures analyses of variance assessed differences in external load measures for practices and games in starters and non-starters. Relative to game loads, practices were quantified as high (>1 SD above the mean), medium (1 SD below the mean), low (2 SD below the mean) and very low (3 SD below the mean). For starters and non-starters, TD, PL, HSD, IMA, and RHIEs were lower in practices compared to games (p<0.001). No practices were classified as high or medium for any external load measure, with the majority of practices (75-100%) being classified as very low. Therefore, practice did not simulate game volumes or intensities. An individualized approach to monitoring is recommended to ensure starters receive adequate recovery and non-starters receive exposure to game-load physical stress.

Position-Specific Physical Workload Intensities in American Collegiate Football Training.

MamonJr, MA, Olthof, SBH, Burns, GT, Lepley, AS, Kozloff, KM, and Zernicke, RF. Position-specific physical workload intensities in American collegiate football training. J Strength Cond Res 36(2): 420-426, 2022-Quantifying player training loads allows football coaching staff to make informed adjustments to the volume and intensity of training. Physical workload intensity in American football practices have not been extensively quantified. The current study examined physical workload intensities across positions in American collegiate football during training. Data from player tracking technology (Catapult Vector) were collected from 72 American football players (National Collegiate Athletic Association Division I) during in-season practices. Players were involved in individualized skill (indy), team playbook (team), and special team (ST) drills during practice and analyzed for their specialist offensive or defensive role (e.g., linebacker or wide receiver). Player running (i.e., high-speed running and sprint) and accelerations (i.e., high-intensity PlayerLoad and high-intensity inertial movement analysis) per minute were of interest. Drill type and practice day had significant effects on all workload intensity metrics (p < 0.01), but not position. Greater running intensities were seen in ST drills compared with other drill types. Tuesday practice sessions had greater overall intensities compared with other days. Interaction effect of position and drill type was significant (p < 0.001) for all intensity metrics, indicating that position groups exhibited unique workload responses to the drill types. Drill type and practice day interaction effect was significant for all intensity metrics (p < 0.01). The findings may be informative for coaches to tailor physical workloads of practice drills for positional roles in preparation for games and practices. Player tracking technology can add value for strength and conditioning coaches to adjust training programs based on position-specific on-field demands of players.

Organization of Students and Total Task Time: External and Internal Load Recorded during Motor Activity

The organization of the students and the time taken to execute the learning tasks determine the physical (external load) and physiological (internal load) demands the students support during physical education classes. The aim of this study was to determine which organizational and pedagogical elements used to design different learning tasks for soccer provoke greater external (Player Load (PL)) and internal (Heart Rate (HR)) load and thus help the students to fulfil the adequate physical activity recommendations (moderate to vigorous physical activity for ≥50% of class time). The organizational elements studied were (1) the participation type and (2) total task time, and the pedagogical element of (3) the game situation. A total of 40 students from the fifth year of primary education participated in the study distributed into two class groups. The basic analysis units were the data on physical activity recorded in each of the tasks carried out by the students during the practical sessions (1500 records), and they were recorded using WIMU ProTM inertial movement devices. A descriptive and inferential analysis was performed with the Mann–Whitney U and Kruskal–Wallis H statistical tests. The results recommend the following types of tasks with simultaneous participation: individual games, numerical inequality SSG, numerical equality SSG lasting less than 6 min, numerical equality SSG, and full games lasting between 6 and 10 min. This type of learning task makes the students move more (medium Player Load between 0.80 and 1.20) and at greater intensities (Heart Rate zone 4, between 161 and 181 bpm). Therefore, physical education teachers must take into account the pedagogical and organizational elements studied to make the sessions more intense and associated with health benefits.

Physical Demands in Three Different Basketball Competitions Played By the Same Under-18 Players

The goal of this study was to compare the physical demands of the same team in three different basketball com- petitions (EBA league (EBA), U18 regional league (U18L), and a U18 international tournament (U18T)) during the same season. Data from eleven U18 players (age: 16.92 ± 0.67 years) were collected using inertial movement units. As external load variables, Player Load (PL), accelerations (ACC), decelerations (DEC), changes of direction (COD), and jumps (JUMP) were expressed in their total (t) and high intensity (h) values. The analysis of variances (ANOVA) and effect size (ES, Cohen’s d) with their respective 90% confidence intervals were applied to identify differences between the competitions. U18T showed the highest values in PL, tACC, tDEC, hDEC, tCOD, tJUMP, and hJUMP (small to moderate ES). However, the hACC and hCOD values were greater in EBA (small ES) than in U18L and U18T. In conclusion, all three competitions presented different external load demands for the same group of players. This data could help basketball coaches to optimize the training process based on the competition in which their team plays. Furthermore, data could also indicate the most suitable competition for players’ development.

Research of the stress-strain state of a workpiece under the double bending by the pulse loading

The object of research is the technology of metal processing by high-speed and high-energy methods, plastic deformation of layered metal compositions. Theoretical studies are based on the main provisions of the theory of joining metals in the solid phase, the theory of plasticity, explosion welding technology, plastic deformation of layered metal compositions, and their heat treatment. The main problem of creating layered metal compositions using explosion energy, including wear and corrosion resistant, electrical, materials with high ballistic resistance, etc., is that they have not yet taken their rightful place in the range of modern structural and functional materials. This can be explained by the limited application of this process, as well as the lagging behind the theory and experimental base in the field of joining various metals in the solid phase and providing the necessary performance properties according to the needs of modern industry. The process of deformation of the cladding blank during the explosion welding is considered. The process of the workpiece collision is considered in three stages: the movement of the element of the cladding workpiece before the collision, its inertial movement and deformation. The equations of motion and equilibrium of the elements of the workpiece are described. A joint solution of the equations of plasticity and equilibrium of the blank element in the double inflection zone is presented. The work is devoted to solving the problem of increasing the level of production and economic indicators of the manufacture of layered metal compositions through the development of methods for calculating and optimizing the technological parameters. Explosion welding, as the most versatile, promising, and economical method, which still has many possibilities for the application of mathematical modeling and process optimization, has been investigated for the production and subsequent processing of the main groups of industrial metal compositions. This makes it possible to solve the problem of replacing traditional materials with layered metal compositions. The results obtained are important from the point of view of the application of cost-effective materials with high mechanical, operational, and technological properties.

External and Internal Load Measures During Preseason Training in Men Collegiate Soccer Athletes.

Fields, JB, Merigan, JM, Gallo, S, White, JB, and Jones, MT. External and internal load measures during preseason training in men collegiate soccer athletes. J Strength Cond Res 35(9): 2572-2578, 2021-Collegiate athletes are exposed to high volume loads during preseason training. Monitoring training load can inform training and recovery periods. Therefore, the purpose was to examine changes in and bidirectional relationship between external and internal load metrics in men collegiate soccer athletes (n = 20; age, 20 ± 1 year). Internal load measures of heart rate variability (HRV), salivary testosterone (T) and cortisol (C), and self-assessment wellness and ratings of perceived exertion scales were collected daily. External load measures of total distance, player load, high-speed distance, high inertial movement analysis, and repeated high-intensity efforts were collected in each training session using global positioning system/global navigation satellite system technology. A 1-way analysis of variance determined weekly changes in external load, physiological, hormonal, and subjective self-assessment measures of internal load. Bidirectional prediction of external load markers and self-assessment measures on physiological and hormonal markers of internal load were assessed by hierarchical linear regression models (p < 0.05). External load measures, C, energy, sleep, and rate of perceived exertion (RPE) decreased (p < 0.01), whereas T, T:C ratio, anger, depression, and vigor increased (p < 0.01) from week 1 to week 2. Morning C positively predicted afternoon external load and post-training RPE (p < 0.05); T:C ratio negatively predicted afternoon external load and post-training RPE (p < 0.05); and morning HRV negatively predicted post-training RPE (p = 0.031). Despite reduced hormonal stress and external load across weeks, negative perceptions of fatigue increased, suggesting fatigue patterns may have a delayed response. Load may have a more belated, chronic effect on perceptions of fatigue, whereas hormonal changes may be more immediate and sensitive to change. Practitioners may wish to use a variety of external and internal load measures to understand athletes' stress responses to training.

Modern technology against falls – A description of the MoTFall project

To meet future challenges from an older and physically less active population innovative solutions are needed. Modern Technology against Falls (MoTFall) aims to prevent falls, increase physical activity and improve self-rated health among older people by means of an information and communication technology based system. The project has developed technology-based solutions, focusing on person-centred care. A participatory research design was applied in the development of a mobile application, a wearable inertial movement measurement unit (IMMU), called the Snubblometer ('snubbla' is 'stumble' in Swedish) and a web-based education programme for health care professionals. The mobile application includes a fall risk index, exercises and information related to falls prevention. By linking the app to the IMMU, person-centred interventions can be developed and implemented in various health care settings and with different target populations. The IMMU has shown good validity and reliability for measuring postural sway and high sensitivity and specificity for measuring a near fall. The education programme is directed at non-graduate health care professionals in nursing homes and home care. The technical solutions have potential for use in research and in clinical practice.

Design and modeling of an improved bridge-type compliant mechanism with its application for hydraulic piezo-valves

Bridge-type compliant mechanisms have been frequently utilized as the micro displacement amplifier for a variety of precision manipulation applications. However, the inertial movement of internal actuators (e.g. piezo-stacks) limits the system’s dynamic bandwidth in some traditional design. This paper presents an improved bridge-type compliant mechanism with double output ports that can generate homodromous bi-motions actuated by only one group of piezo-stacks. The inertial motion of piezo-stacks is avoided and the dynamic bandwidth is enhanced. The two-port dynamic stiffness model is established to straightforwardly capture its kinetostatic and dynamic characteristics from the perspective of input and output ports. The displacement amplification ratio, input stiffness, fundamental frequency and dynamic response spectrum of the improved bridge-type compliant mechanism are curved against key geometric parameters, then the optimal performance can be confirmed. Of particular interest for the mechanism application is applying it to develop a new type of piezoelectric two-stage flow control valve with relatively fast dynamic response and large flow rate. The inner leakage and oil contamination is effectively overcome in contrast to traditional nozzle-flapper servovalves. The presented piezoelectric flow control valve is fabricated and experimentally measured with the step response time of 8.5 ms, frequency bandwidth of 120 Hz, and stroke of ±0.8 mm (corresponding to the flow rate of 180 L/min at the supply pressure of 210 bar).

Relationship Between External Load and Self-Reported Wellness Measures Across a Men's Collegiate Soccer Preseason.

Fields, JB, Lameira, DM, Short, JL, Merrigan, JM, Gallo, S, White, JB, and Jones, MT. Relationship between external load and self-reported wellness measures across a collegiate men's soccer preseason. J Strength Cond Res 35(5): 1182-1186, 2021-Monitoring athlete training load is important to training programming and can help balance training and recovery periods. Furthermore, psychological factors can affect athlete's performance. Therefore, the purpose was to examine the relationship between external load and self-reported wellness measures during soccer preseason. Collegiate men soccer athletes (n = 20; mean ± SD age: 20.3 ± 0.9 years; body mass: 77.9 ± 6.8 kg; body height: 178.87 ± 7.18cm; body fat: 10.0 ± 5.0%; V̇o2max: 65.39 ± 7.61ml·kg-1·min-1) participated. Likert scale self-assessments of fatigue, soreness, sleep, stress, and energy were collected daily in conjunction with the Brief Assessment of Mood (vigor, depression, anger, fatigue, and confusion). Total distance (TD), player load (PL), high-speed distance (HSD, >13 mph [5.8 m·s-1]), high inertial movement analysis (IMA, >3.5 m·s-2), and repeated high-intensity efforts (RHIEs) were collected in each training session using positional monitoring (global positioning system/global navigation satellite system [GPS/GNSS]) technology. Session rate of perceived exertion (sRPE) was determined from athlete's post-training rating (Borg CR-10 Scale) and time of training session. Multilevel models revealed the bidirectional prediction of load markers on fatigue, soreness, sleep, energy, and sRPE (p < 0.05). Morning ratings of soreness and fatigue were predicted by previous afternoon's practice measures of TD, PL, HSD, IMA, RHIE, and sRPE. Morning soreness and fatigue negatively predicted that day's afternoon practice TD, PL, HSD, IMA, RHIE, and sRPE. Morning ratings of negative mood were positively predicted by previous day's afternoon practice HSD. In addition, negative morning mood states inversely predicted HSD (p = 0.011), TD (p = 0.002), and PL (p < 0.001) for that day's afternoon practice. Using self-reported wellness measures with GPS/GNSS technology may enhance the understanding of training responses and inform program development.

Not All About the Effort? A Comparison of Playing Intensities During Winning and Losing Game Quarters in Basketball.

To compare peak and average intensities encountered during winning and losing game quarters in basketball players. Eight semiprofessional male basketball players (age = 23.1 [3.8]y) were monitored during all games (N = 18) over 1 competitive season. The average intensities attained in each quarter were determined using microsensors and heart-rate monitors to derive relative values (per minute) for the following variables: PlayerLoad, frequency of high-intensity and total accelerations, decelerations, changes of direction, jumps, and total inertial movement analysis events combined, as well as modified summated-heart-rate-zones workload. The peak intensities reached in each quarter were determined using microsensors and reported as PlayerLoad per minute over 15-second, 30-second, 1-minute, 2-minute, 3-minute, 4-minute, and 5-minute sample durations. Linear mixed models and effect sizes were used to compare intensity variables between winning and losing game quarters. Nonsignificant (P > .05), unclear-small differences were evident between winning and losing game quarters in all variables. During winning and losing game quarters, peak and average intensities were similar. Consequently, factors other than the intensity of effort applied during games may underpin team success in individual game quarters and therefore warrant further investigation.

Comparing Weekly Training and Game Demands According to Playing Position in a Semiprofessional Basketball Team.

To compare weekly training and game demands according to playing position in basketball players. A longitudinal, observational study was adopted. Semiprofessional, male basketball players categorized as backcourt (guards; n = 4) and frontcourt players (forwards/centers; n = 4) had their weekly workloads monitored across an entire season. External workload was determined using microsensors and included PlayerLoad™ (PL) and inertial movement analysis variables. Internal workload was determined using heart rate to calculate absolute and relative summated-heart-rate-zones workload and rating of perceived exertion (RPE) to calculate session-RPE workload. Comparisons between weekly training and game demands were made using linear mixed models and effect sizes in each positional group. In backcourt players, higher relative PL (P = .04, very large) and relative summated-heart-rate-zones workload (P = .007, very large) were evident during training, while greater session-RPE workload (P = .001, very large) was apparent during games. In frontcourt players, greater PL (P < .001, very large), relative PL (P = .019, very large), peak PL intensities (P < .001, moderate), high-intensity inertial movement analysis events (P = .002, very large), total inertial movement analysis events (P < .001, very large), summated-heart-rate-zones workload (P < .001, very large), RPE (P < .001, very large), and session-RPE workload (P < .001, very large) were evident during games. Backcourt players experienced similar demands between training and games across several variables, with higher average workload intensities during training. Frontcourt players experienced greater demands across all variables during games than training. These findings emphasize the need for position-specific preparation strategies leading into games in basketball teams.

ГОСУДАРСТВЕННАЯ АКАДЕМИЯ ХУДОЖЕСТВЕННЫХ НАУК: ТРАДИЦИИ И СОВРЕМЕННОСТЬ. ЧАСТЬ ВТОРАЯ: «ТЛЕЮЩИЕ ТРАДИЦИИ В ТЕЛЕ СОВРЕМЕННОСТИ»

The State Academy of Arts is a phenomenon of Russian culture at the beginning of the 20th century. Archival reconstructions of its history are still continuing. The scientific research task of the State Academy of Arts was a comprehensive study of the issues of art and artistic culture, the solution of the problem of the synthesis of arts, as well as the unification of domestic specialists who worked in this field. The emergence of State Academy of Arts was conditioned, on the one hand, by the building of the institutions of the young Soviet state, and, on the other hand, by aspirations for interdisciplinarity and creative synthesis as an inertial movement of the Silver Age culture. The uniqueness of State Academy of Arts was the integration of pre-revolutionary academic and emerging Soviet practices. However, at the turn of 1920-1930-ies in the Soviet Union, repressive tendencies intensified: searches for enemies, «purges» and mass arrests swept over scientific institutions. «Akademicheskoe Delo», «Delo Slavistov», «Pulkovskoe Delo», «Leningradskoe Delo» and others led to the death of many scientists and the loss of scientific directions, the defeat, above all, of the socio-humanitarian sciences. «Cold Civil War» as a Result of the Cultural and Psychological Traumas of the Twentieth Century carries the risks of the smoldering traditions of totalitarianism. What is needed is educational activities, responsible pedagogical and psychological work with historical memory, the restoration of forgotten names and the cultivation of attitudes towards social harmony in a complex and diverse modern society

Reflections on Rationality, Utility, University, Mass Culture and Unsustainable Society

Abstract This paper is an expression of gratitude, remembrance and honour the jubilee of Prof. Tomasz Żylicz. As I have been invited to write a paper for a special issue of the CEEJ journal, I sincerely wanted to express regarding my friendship and my research that have been binding me with Tomasz in my more than 40-year work in the Faculty of Economic Sciences, University of Warsaw. Our cooperation was varied and rich including joint articles, research projects and our work for the Ministry of the Environment. In this paper, after friendly acknowledgment, I decided to propose my polemical answer to the paper ‘Is reason valued now?’ written by Tomasz. The subject of my reply is primarily the rationality in general and in the institution of university in the context of teaching and practicing science, including first of all economics and ecological economics. The method applied in this paper is my descriptive and polemical reference to Tomasz's theses with the analytical use of literature, both classics and very current references. The basic topic of the paper focuses on the fact that modernity continues in an increasingly inertial movement towards mass culture and is dominated by three criteria in this mechanism namely usefulness, non-exclusion and accessibility. I analyse these three fetishes in our dynamic times and with particular emphasis on their negative role in academic education. In my conclusions I categorically state that scientific knowledge and education, perfectly represented by universities, were formed and developed in an alliance with usefulness and utility, but never only thanks to them and never only for them.

The Relationships Between External and Internal Workloads During Basketball Training and Games.

To investigate the relationships between external and internal workloads using a comprehensive selection of variables during basketball training and games. Eight semiprofessional, male basketball players were monitored during training and games for an entire season. External workload was determined as PlayerLoad™: total and high-intensity accelerations, decelerations, changes of direction, and jumpsand total low-intensity, medium-intensity, high-intensity, and overall inertial movement analysis events. Internal workload was determined using the summated-heart-rate zones and session rating of perceived exertion models. The relationships between external and internal workload variables were separately calculated for training and games using repeated-measures correlations with 95% confidence intervals. PlayerLoadwas more strongly related to summated-heart-rate zones (r = .88 ± .03, very large [training]; r = .69 ± .09, large [games]) and session rating of perceived exertion (r = .74 ± .06, very large [training]; r = .53 ± .12, large [games]) than other external workload variables (P < .05). Correlations between total and high-intensity accelerations, decelerations, changes of direction, and jumps and total low-intensity, medium-intensity, high-intensity, and overall inertial movement analysis events and internal workloads were stronger during training (r = .44-.88) than during games (r = .15-.69). PlayerLoadand summated-heart-rate zones possess the strongest dose-response relationship among a comprehensive selection of external and internal workload variables in basketball, particularly during training sessions compared with games. Basketball practitioners may therefore be able to best anticipate player responses when prescribing training drills using these variables for optimal workload management across the season.

Self-Powered Inertial Sensor Based on Carbon Nanotube Yarn

Inertial sensors are devices that can monitor inertial movements, such as linear acceleration and angular motions, in industrial and human systems. For portable and wearable applications, inertial sensors must be self-powered and miniaturized. In this article, we report a self-powered inertial sensor with high accuracy based on carbon nanotube (CNT) yarn. By harvesting the mechanical energy of a coiled CNT yarn, our inertial sensor can detect inertial movements without the need for external power. For practical applications, the sensor can monitor various inertial movements, such as vibrations, external impacts, tilting, and body motions (squatting, walking, running, and jumping motions). These findings suggest that the self-powered inertial sensor exhibits the advantages of portability and wearability in industrial and human system applications.

The Effects Of Practice On Maximal Force And Low-Frequency Fatigue In Collegiate Basketball Players

Low-Frequency Fatigue (LFF) refers to the disproportionate loss of force at low as compared to high firing frequencies. LFF is thought to manifest during high intensity, moderate-to high-force, repetitive eccentric, or stretch-shortening cycle activities, similar to the demands of basketball. PURPOSE: Therefore, the purpose of the present study was to examine the effects of basketball practice on maximal isometric force and LFF. METHODS: Eleven NCAA Division 1 basketball players (Males = 6 and Females = 5) performed a Maximal Voluntary Isometric Contraction (MVIC) and neuromuscular electrical stimulation of the knee extensors at a high and low frequency before (Pre), immediately after (Post) and 24-hours (24Post) following a basketball practice during the preseason. Athletes wore Inertial Measurement Units to capture the external training load (eTL) of the practice. The ratio of force produced during the low to high frequency muscle stimulation was used as an index of LFF. A one-way repeated measures analysis of variance was performed to determine differences in MVIC and LFF across time, with significance set at p ≤ 0.05. Effects sizes (Cohen’s d) were calculated for pairwise comparisons and interpreted as trivial (0-0.19), small (0.20-0.49), medium (0.50-0.79), and large (0.80 and greater). RESULTS: The average of the eTL parameters during practice were PlayerLoad = 636.5 ± 66.1 arbitrary units (au); PlayerLoad per Minute = 4.76 ± 0.69au; Total Jumps = 143.8 ± 53.0 count (ct); Inertial Movement Analysis (IMA)_High = 39 ± 20ct; IMA_Medium = 135 ± 53ct; IMA_Low = 582.8 ± 156ct. There was a significant time effect for MVIC (p = 0.031), but post-hoc pairwise comparisons revealed no significant difference across time (p > 0.05). There was a significant time main effect for LFF (Pre = 0.515 ± 0.025; Post = 0.483 ± 0.038; 24Post = 0.513 ± 0.033, p = 0.019), with post-hoc pairwise comparisons revealing no significant difference from Pre- to Post-practice (p = 0.104), but did exhibit a large negative effect (d = 1.0). There was a significant increase from Post- to 24Post-practice (p = 0.039, d = 0.84). CONCLUSIONS: Based on these preliminary findings it appears basketball practice induces LFF in collegiate basketball athletes that recovers back to baseline within 24 hours of the bout. Although LFF was present, MVIC appeared unaffected.

Online Gait Detection with an Automatic Mobile Trainer Inspired by Neuro-Developmental Treatment.

This paper demonstrates the development of an automatic mobile trainer employing inertial movement units (IMUs). The device is inspired by Neuro-Developmental Treatment (NDT), which is an effective rehabilitation method for stroke patients that promotes the relearning of motor skills by repeated training. However, traditional NDT training is very labor intensive and time consuming for therapists, thus, stroke patients usually cannot receive sufficient rehabilitation training. Therefore, we developed a mobile assisted device that can automatically repeat the therapists’ intervention and help increase patient training time. The proposed mobile trainer, which allows the users to move at their preferred speeds, consists of three systems: the gait detection system, the motor control system, and the movable mechanism. The gait detection system applies IMUs to detect the user’s gait events and triggers the motor control system accordingly. The motor control system receives the triggering signals and imitates the therapist’s intervention patterns by robust control. The movable mechanism integrates these first two systems to form a mobile gait-training device. Finally, we conducted preliminary tests and defined two performance indexes to evaluate the effectiveness of the proposed trainer. Based on the results, the mobile trainer is deemed successful at improving the testing subjects’ walking ability.