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TRUNK KINEMATICS IN THE SLIDING FOREHAND ON CLAY COURTS: A COMPARISON OF ELITE AND SUB-ELITE TENNIS PLAYERS
No full textThis study compares the trunk kinematics of elite and sub-elite male tennis players during the sliding forehand stroke on clay courts. A total of 24 highly skilled players participated in this study. Their stroke execution was recorded using a 3D high-speed infrared motion capture system. Independent sample t-tests (p \u3c 0.05) were used to compare trunk kinematics between groups. Elite players outperformed their sub-elite counterparts across all measured points, including greater right lateral bending at the Ground Contact and End Backswing points, enhanced anterior tilt at the Impact and Racket Extension points, and superior left lateral bending at the Completion of Swing point. Additionally, their greater maximum trunk displacement reflects superior trunk control and movement efficiency throughout the stroke sequence. This study underscores the importance of trunk rotational control and sliding techniques in optimizing forehand performance on clay courts
VALIDATING A MARKERLESS MOTION CAPTURE APPLICATION IN SIMULTAED SNOWBOARDING
No full textThe purpose of the present pilot study was to validate the timing and position accuracy of the centre of mass (COM) during a replicative snowboarding training session using a previously validated motion capture system (Simi Motion®) and a mobile markerless monocular motion capture application (SPLYZA Motion). The positional timing of the two-dimensional (2D) COM motion between the two systems were validated in an indoor laboratory condition as two elite snowboarders performed three individual movements, namely a static (isometric) pose as a proxy method for ground truth validation followed by a vertical jump and a single rotation. The position of the COM was reported in a local reference frame. High levels of agreement were found in both the x (anteroposterior) and y (vertical) axis. The approach of using motion capture and video footage to validate the raw timing data showed a moderate level of correlation in the x axis (r = 0.84) and a very high correlation in the y axis (r = 1.0). While reasons for the moderate correlation in the x axis remain unclear, further research should be performed to obtain a greater estimation of the COM positional trajectory to further refine the mobile application’s algorithm
THEORETICAL ANALYSIS OF THE ADDITION EFFECT OF KNEE FLEXION AND EXTENSION MOVEMENT OF THE SWINGING LEG ON HORIZONTAL VELOCITY IN MEN-UCHI: COMPARISON WITH EXPERIMENTAL DATA
No full text剣道は日本の伝統武道一つであり、最も基本的な技は面打ちである。 この動作において踏み出し足となる右足の動作に関する研究はほとんど行われていない。 本研究は、右膝の適切な屈曲のタイミングと角度を見極めることを目的とする。体験者3名が面打ち動作の測定のために採用され、右膝の角度と両足の間の角度が測定された
INTEGRATING SYSTEM DYNAMICAL PRINCIPLES OF MOTOR LEARNING IN A BIOMECHANIC TRAINING SYSTEM IN ROWING
No full textMeasurement and information technologies for the optimization of movement technique are well established in high performance sports. While measurement technologies and biomechanical aspects of sport performance are well investigated, the underlying models for technique training do not represent the state of research in motor learning and therefore have been criticized. The aim of this study was to evaluate the effects of a biomechanic training device based on system-dynamics principles of motor learning in high-performance rowing. Eight elite rowers completed a three-week training experiment in which the intervention group had to replicate varying strength curves. All subjects in the intervention group showed significantly lower proportions of force in the final phase and all but one showed higher proportions in the initial phase of the stroke, while the control group showed an opposite trend. The SPM analysis also revealed that changes occurred primarily at the beginning and end of the force progression. Observed changes in the intervention group in particular were rated positively by coaches and experts. Feedback training with varying target curves therefore appears to be a promising alternative to coach-led technical training in rowing
INTRODUCING ‘SLIDE’ - A PORTABLE DEVICE FOR ASSESSING SKIN-SURFACE INJURY RISK VIA THE MAXWELL TRIBO INDEX
No full textSynthetic turf enhances sports participation through durability, high usage, and low maintenance, but some systems increase the risk of skin abrasions compared to natural grass. This study presents the SLIDE - a portable, cost-effective device that replicates skin-surface interactions and applies the Maxwell Tribo Index (MTI) to quantify skin injury risk per surface. The initial prototype achieved target velocities and pressures, supporting its relevance for on-site testing. Ongoing validation aims to establish correlation between SLIDE and SID outputs across a representative range of MTI values
ISBS 2025 CONFERENCE PROCEEDINGS
No full textThese are the proceedings of the 43rd Conference of the International Society of Biomechanics in Spor
The Effect of Ischemic Preconditioning on Rock Climbing Performance
No full textRock climbing involves isometric contractions of the finger flexors, limiting forearm blood flow and causing ischemia-induced fatigue. Ischemic preconditioning (IPC) has been shown to improve time to failure (TTF) during climbing-specific tasks, though its mechanisms remain unclear. The purpose of this study was to assess the effects of IPC on hemodynamics and muscle oxygenation during a finger flexor endurance test. This study assessed the effects of IPC on TTF, brachial artery blood flow (BF), vessel diameter (VD), and tissue saturation index (TSI). Variables were measured before (BL1) and after intervention (BL2), and throughout a finger-flexor fatiguing task (FT), including TSI during contractions (ΔTSIwork), and rest periods (ΔTSIrest). In a randomized, crossover design, 24 climbers performed the FT after either IPC or sham in a random order separated by at least 48 hours. The FT consisted of 7:3-second work-to-rest ratio handgrip contractions at 55% of maximal voluntary isometric contraction force until failure. TTF was not different between IPC (225±98s) and sham (223±97s; p = .924). Change in TSI from BL1 to BL2 was greater in IPC than sham (mean difference 4.686, p = .005, CI 1.606-7.766). No differences were observed in BF (p = .843, ηp2 = .002), VD (p = .343, ηp2 = .041), TSI (p = .938, ηp2 = .000), ΔTSIwork (p = .425, ηp2 = .028), or ΔTSIrest (p = .452, ηp2 = .025) between IPC and sham at any time point during the FT. In conclusion, IPC had no impact on finger flexor endurance, muscle oxygenation, or hemodynamics in rock climbers
EFFECTS OF SIGMA-1 RECEPTOR AGONISTS ON COMPULSIVE BEHAVIOR AND NEUROPLASTICITY
No full textCompulsivity is a feature of many psychiatric disorders, resulting in distressing and challenging to treat symptoms. Compulsivity is a key feature of obsessive compulsive disorder, which can hinder a person\u27s life and ability to work. Selective serotonin reuptake inhibitors are the current treatments for these disorders, which take 8-12 weeks to take effect and leave many patients without adequate treatment gains. Delayed treatment effects may be due to neuronal proliferation involving mammalian target of rapamycin (mTOR). Preclinical studies suggest that sigma-1 receptor agonists produce antidepressant-like drug effects and affect the mTOR pathway. Other mechanisms include serotonin neurotransmission and N-methyl-D-aspartate (NMDA) receptors. This study evaluated drugs acting as sigma-1 agonists, NMDA receptor antagonists, and serotonin reuptake inhibitors in preclinical animal behavior models for assessing treatments for obsessive compulsive disorder, the marble burying test, and depression, the novelty suppressed feeding test. Further, a Western blot assessment was conducted with dextromethorphan, which is a compound that exhibits all three pharmacological actions of interest for this study. The NMDA receptor antagonist S-ketamine, the sigma 1 receptor agonist SA4503, dextromethorphan (after subcutaneous, but not intraperitoneal, administration), the sigma 1 agonist and serotonin reuptake inhibitor fluvoxamine, and the serotonin reuptake inhibitor paroxetine significantly reduced marbles buried, but did not affect response latency in the novelty suppressed feeding test. Only fluvoxamine exhibited reduced marbles buried up to 72 hrs post treatment. Dextromethorphan did not affect levels of phosphorylated mTOR. Overall, these findings lend support for novel pharmacological actions to treat obsessive compulsive disorder. Methodological considerations are discussed
TEMPERATURE VARIATION IN MARQUETTE, MICHIGAN, CONCERNING SKELETAL MUSCLE DEGRADATION PATTERNS FOR POSTMORTEM INTERVAL DETERMINATION
No full textPostmortem interval (PMI), or time since death, is regularly estimated in criminal investigations. Biochemistry methods can estimate PMI by analyzing changes in protein breakdown within muscle tissue. Observing protein degradation has been proposed as a new method of PMI estimation due to specific proteins degrading in a predictable and time-dependent manner. This study examined the effect of temperature on the degradation patterns of vinculin, a skeletal protein, and the levels of essential metals in human skeletal muscle. Calcium concentrations were also observed for evidence of calpain activation, which degrades vinculin. Once observations of vinculin degradation and calpain activation were seen and the patterns of vinculin degradation were observed in the controlled temperature studies, the controlled temperature data were used to identify the PMI range of human muscle samples with unknown PMI. For the PMI estimation, human muscle samples were donated from the Paris Lodron Universität Salzburg and compared to controlled samples to evaluate the potential for PMI estimation. The study was conducted in three temperature-controlled lab environments and at the Forensic Research Outdoor Station (FROST) during spring/summer. Muscle samples underwent western blotting and ICP-MS analysis. Ambient temperatures were continuously recorded using the onsite weather station at FROST. Analysis of the western blot results showed that temperature affects the degradation rate of skeletal muscle and that it is possible to estimate PMI using controlled temperature data. Analysis of ICP-MS results indicated that metal concentration patterns vary between spring and summer, along with evidence of calpain activation related to calcium concentrations
QUOTIENTS, EQUIVALENCE RELATIONS, AND NORMALITY IN NON-ASSOCIATIVE ALGEBRA WITH REGARDS TO LOOPS AND QUASIGROUPS
Full text linkThis thesis will contain a detailed overview of relations, quotients, normality, loops, quasigroups, and related theorems and varieties. Nonassociative algebra is a relatively new area of mathematics, it came about in the past hundred years, and has started making progress in the past 60 years. In nonassociative algebra, varieties do not necessarily satisfy associativity. Several interesting problems with relations, quotients, and normality arise from the setting of nonassociative algebra. In the language of equivalence relations, quotients, and subsets what are the conditions of normality, or existence of a subalgebra in quasigroups and loops? A quasigroup, Q, is defined to be algebra (Q, ·,\,/) that takes two elements from the quasigroup, under one of the operations ·,\,/, and maps the combination to another element of the quasigroup. The three quasigroup binary operations must satisfy axioms that guarantee left and right inverses; additionally the inverses are unique. A loop, typically denoted (L, ·), is a quasigroup with a two-sided identity element e. For e to be a two sided identity element, e · x = x · e = x for any x in L. In order for a relation to be an equivalence relation it must be reflexive, symmetric, and transitive