Assessing the validity of two-dimensional video analysis for measuring lower limb joint angles during fencing lunge.

Introduction: The fencing lunge (lunge), characterized by minimal body rotation, offers a movement well-suited for 2D video analysis. However, to the best of our knowledge, the validity of 2D video analysis for fencing has not been verified. This study aimed to validate 2D video analysis by comparing lower limb joints (hip, knee, and ankle joints) angles during lunge using both 2D video analysis and 3D motion analysis methods. Methods: Twenty-two male fencers performed lunge trials that were simultaneously recorded using eight motion capture cameras (Qualisys Miqus M1) and two digital video cameras (Sony AX-450 and AX450a). Results: The 2D video analysis results exhibited an extremely large correlation in knee joint angles of the front and rear legs in the sagittal with those from 3D motion analysis (r = 0.93-0.99). However, while a robust correlation was found between the ankle joint angles of the front and rear legs (r = 0.82-0.84), a large bias was also observed (-5.23° to -21.31°). Conversely, for the hip joints of the rear leg, a moderate correlation (r = 0.31) and a large bias (-10.89°) were identified. Conclusions: The results of this study will contribute to the development of coaching using 2D video analysis in competition settings because such analysis can be a useful alternative to 3D motion analysis when measuring the knee joint angle of the front leg and rear leg in the sagittal plane. However, for the ankle joint angle, further research on the optimal shooting position and height of the digital video camera is needed, whereas for the hip joint angle, 3D motion analysis is recommended at this time.

Relationships between Changes in Muscle Shear Modulus, Urinary Titin N- Terminal Fragment, and Maximum Voluntary Contraction Torque after Eccentric Exercise of the Elbow Flexors.

The study aimed to investigate the relationships between the shear modulus of the biceps brachii (BB) and brachialis muscle (BA) and the total of the two (BB+BA), and urinary titin N-terminal fragment (UTF), maximum voluntary isometric contraction (MVC), and other indirect markers. Fifteen healthy men performed five sets of 10 eccentric contractions using a dumbbell corresponding to 50% of MVC at 90° measured at baseline. The elbow joint of the left arm was extended from 90° to 180° (180° = full extension) in 5 s in the exercise, and was returned with support from the examiner to prevent concentric contraction. Shear modulus of BB and BA were measured by ultrasound shear wave elastography, and UTF, MVC, and range of motion of the elbow joint (ROM) were recorded before; immediately after; and 1, 24, 48, 72, 96, and 168 h after the exercise. After calculating the shear modulus of BB and BA, two values were added (BB+BA). The shear modulus peaked at 48 h, UTF peaked at 96 h, MVC and ROM changed largest at immediately, and muscle soreness peaked at 48 h post-exercise. Significant (p < 0.05) relationships were found between changes in BB shear modulus and BA shear modulus (r = 0.874), BB+BA shear modulus (r = 0.977), UTF (r = 0.681), and MVC (r = -0.538). Significant (p < 0.05) relationships were also observed between changes in BA shear modulus and BB+BA shear modulus (r = 0.957), UTF (r = 0.682), MVC (r = -0.522), and ROM (r = -0.600). Moreover, significant (p < 0.05) relationships were observed between changes in BB+BA shear modulus and UTF (r = 0.703), MVC (r = -0.549), and ROM (r = -0.547). These results indicate that shear modulus of each muscle (i.e., BB and BA) provide more precise information about muscle damage than UTF, MVC and ROM.

The Effect of Contrast Water Therapy on Dehydration during Endurance Training Camps in Moderate-Altitude Environments.

The effects of contrast water therapy (CWT) on dehydration at moderate altitudes during training camps remain unknown. We hypothesized that CWT reduces dehydration resulting from training at moderate altitudes and improves performance, akin to conditions at sea level. A 13-day endurance training camp was held at a moderate altitude of 1100 m and included 22 university athletes, who were divided into two groups (CWT group, n = 12; control (CON) group, n = 10). The sample size was calculated based on an α level of 0.05, power (1 ß) of 0.8, and effect size of 0.25 based on two-way ANOVA. Longitudinal changes over 13 days were compared using a two-group comparison model. Additionally, 16 athletes participated in an additional performance verification analysis. Subjective fatigue, body mass, and water content (total body water (TBW), extracellular water (ECW), and intracellular water) were measured using bioimpedance analysis every morning, and the titin N-terminal fragment in urine (UTF) was measured as an index of muscle damage. For performance verification, 10 consecutive jump performances (with the reactive strength index (RSI) as an indicator) were evaluated as neuromuscular function indices. The results indicated that the UTF did not significantly differ between the two groups. Moreover, the ECW/TBW values, indicative of dehydration, on days 4 and 5 in the CWT group were significantly lower than those in the CON group. However, there was no significant difference in RSI between the two groups. Therefore, although CWT reduces dehydration in the early stages of the training camp, it may not affect performance.

Associations of eccentric force variables during jumping and eccentric lower-limb strength with vertical jump performance: A systematic review.

The purpose of this systematic review was to summarize the associations of eccentric force variables during jumping and eccentric lower-limb strength with vertical jump performance. A literature search was conducted in September 2022 using PubMed, Web of Science, and Scopus. Thirteen cross-sectional studies investigating the relationship between eccentric force and strength variables, such as force, rate of force development (RFD), power, time, and velocity, and vertical jump performance, including the jump height, reactive strength index (RSI), and reactive strength index-modified (RSImod), were included in this systematic review. As eccentric strength, variables during the unloading-to-braking phase of countermovement jump (CMJ) (force, RFD, etc.) and the eccentric force of the squat movement and knee joint were included. The CMJ height, RSImod, and drop jump RSI were included to analyze the vertical jump performance. The modified form of the Downs and Black checklist was used to evaluate quality. Associations between the force and RFD during the descending phase of the CMJ and jump height were observed in some studies but not in others, with differences between the studies. Some studies reported associations between the force and/or RFD during the descending phase of the CMJ and RSImod of the CMJ, with no differences among their results. In addition, there are associations of the eccentric forces during squatting and knee extension with the CMJ and the drop jump heights and RSI of the drop jump. The eccentric force variables in the CMJ and RSImod are related; however, their relationship with jump height remains unclear. Furthermore, improved eccentric muscle strength may contribute to vertical jump height because of the associations of the eccentric strength during knee extension and squatting with jump height.

Ballistic Exercise Versus Heavy Resistance Exercise Protocols: Which Resistance Priming Is More Effective for Improving Neuromuscular Performance on the Following Day?

ABSTRACT: Nishioka, T and Okada, J. Ballistic exercise versus heavy resistance exercise protocols: which resistance priming is more effective for improving neuromuscular performance on the following day? J Strength Cond Res 37(10): 1939-1946, 2023-This study aimed to determine whether ballistic exercise priming (BEP) or heavy resistance priming (HRP) is more effective for improving ballistic performance after 24 hours. Ten resistance-trained men performed BEP and HRP conditions 72-144 hours apart in a randomized and counterbalanced order. Jumping performance was assessed before and 24 hours after the BEP and HRP sessions using 0 and 40% one-repetition maximum (1RM) squat jump (SJ), 0 and 40% 1RM countermovement jump (CMJ), and drop jump (DJ) reactive strength index (RSI). Statistical significance was accepted at p ≤ 0.05. In the BEP condition, 0% 1RM CMJ height (+3.62%) as well as theoretical maximum velocity (+5.14%) and theoretical maximum power (+2.55%) obtained from CMJ 24 hours after the priming session were significantly greater than those at the baseline ( p ≤ 0.05), but 0% 1RM SJ height and DJ RSI ( p > 0.05) were not greater than those at the baseline. In the HRP condition, the jump performances were not improved ( p > 0.05). The percentage change in 0% 1RM CMJ height in the BEP condition was significantly greater than that seen in the HRP condition ( p = 0.015) but did not differ for 0% 1RM SJ height and DJ RSI ( p > 0.05). These results suggest that the BEP is more effective than HRP in improving CMJ performance after 24 hours. Therefore, practitioners should consider prescribing resistance priming using low-load ballistic exercises rather than high-load traditional exercises when planning to enhance athlete performance on the following day.

Immunohistochemical characterization of transient receptor potential vanilloid types 2 and 1 in a trinitrobenzene sulfonic acid-induced rat colitis model with visceral hypersensitivity.

Transient receptor potential vanilloid type 2 (TRPV2) and type 1 (TRPV1) are originally identified as heat-sensitive TRP channels. We compared the expression patterns of TRPV2 and TRPV1 in the rat distal colon and extrinsic primary afferent neurons, and investigated their roles in visceral hypersensitivity in 2,4,6-trinitrobenzenesulfonic acid (TNBS)-induced colitis rats. Both TRPV2 and TRPV1 expressions in the colon, dorsal root ganglion (DRG), and nodose ganglion (NG) were significantly upregulated in the TNBS-induced colitis model. TRPV2 cell bodies co-localized with the intrinsic primary afferent marker NeuN and the inhibitory motor neuronal marker nNOS in the myenteric plexus. TRPV2 expressions were further detected in the resident macrophage marker ED2 in the mucosa. In contrast, no TRPV1-expressing cell bodies were detected in the myenteric plexus. Both TRPV2- and TRPV1-positive cell bodies in the DRG and NG were double-labeled with the neuronal retrograde tracer fluorescent fluorogold. Large- and medium-sized TRPV2-positive neurons were labeled with the A-fiber marker NF200, calcitonin gene-related peptide (CGRP), and substance P (SP) in the DRG while small-sized TRPV1-positive neurons were labeled with the C-fiber markers IB4, CGRP, and SP. TRPV2- and TRPV1-positive NG neurons were labeled with NF200 and IB4. TNBS treatment increased p-ERK1/2-positive cells in TRPV2 and TRPV1 neurons but did not affect the TRPV2 and TRPV1 subpopulations in the DRG and NG. Both TRPV2 and TRPV1 antagonists significantly alleviated visceral hypersensitivity in TNBS-induced colitis model rats. These findings suggest that intrinsic/extrinsic TRPV2- and extrinsic TRPV1-neurons contribute to visceral hypersensitivity in an experimental colitis model.

Associations of maximum and reactive strength indicators with force-velocity profiles obtained from squat jump and countermovement jump.

Understanding the properties associated with the vertical force-velocity (F-v) profiles is important for maximizing jump performance. The purpose of this study was to evaluate the associations of maximum and reactive strength indicators with the F-v profiles obtained from squat jump (SJ) and countermovement jump (CMJ). On the first day, 20 resistance-trained men underwent measurements for half squat (HSQ) one-repetition maximum (1RM). On the second day, jump performances were measured to calculate the drop jump (DJ) reactive strength index (RSI) and the parameters of F-v profiles (theoretical maximum force [F0], velocity [V0], power [Pmax], and slope of the linear F-v relationship [SFv]) obtained from SJ and CMJ. The DJ RSI was not significantly correlated with any parameter of the vertical F-v profiles, whereas the relative HSQ 1RM was significantly correlated with the SJ F0 (r = 0.508, p = 0.022), CMJ F0 (r = 0.499, p = 0.025), SJ SFv (r = -0.457, p = 0.043), and CMJ Pmax (r = 0.493, p = 0.027). These results suggest that maximum strength is a more important indicator than reactive strength in improving vertical F-v profiles. Furthermore, the importance of maximum strength may vary depending on whether the practitioner wants to maximize the performance of SJ or CMJ.

Validity of using perceived exertion to assess muscle fatigue during resistance exercises.

BACKGROUND: The rating of perceived exertion (RPE) is correlated with physiological variables. The purpose of this study was to assess the validity of using the Borg CR-10 scale and velocity to predict muscle fatigue assessed by surface electromyography during single joint resistance exercises. METHODS: Fifteen healthy males underwent different fatigue levels of unilateral elbow flexion (EF) and knee extension (KE), consisting of low, medium, and high volumes at 65% of their one-repetition maximum. The RPEs, spectral fatigue index (SFI), and mean velocity of the experimental exercises were assessed throughout the trials. RESULTS: Significant differences in overall RPE (p < 0.001) and average SFI (p < 0.001) were observed between the conditions in both exercises. Significant changes in RPE and SFI (p < 0.001) were observed throughout the EF, whereas a SFI increase (p < 0.001) was only observed at the end point of KE. Multiple regression analyses revealed two significant models (p < 0.001) for the prediction of muscle fatigue during EF (R2 = 0.552) and KE (R2 = 0.377). CONCLUSIONS: Muscle fatigue resulted in similar increases in perceptual responses, demonstrating that RPE is useful for assessing fatigue when resistance exercise is performed. However, velocity changes may not reflect muscle fatigue correctly when exercise is no longer performed in an explosive manner. We recommend combining RPE responses with velocity changes to comprehensively assess muscle fatigue during clinical and sports situations.

Influence of Strength Level on Performance Enhancement Using Resistance Priming.

ABSTRACT: Nishioka, T and Okada, J. Influence of strength level on performance enhancement using resistance priming. J Strength Cond Res 36(1): 37-46, 2022-The current study aimed to investigate (a) whether resistance priming was effective in enhancing jump performance for both stronger and weaker individuals and (b) how resistance priming influences the lower-body force-velocity profile. A total of 20 resistance-trained men performed priming and control conditions 72-144 hours apart in a randomized and counterbalanced order. Jump performances (0 and 40% 1 repetition maximum [1RM] squat jump, 0 and 40% 1RM countermovement jump [CMJ] and drop jump) were assessed before and 24 hours after the priming session, and before and 24 hours after rest (control). Priming session-induced percentage change in 0% 1RM CMJ height was positively correlated with the individual's relative half squat 1RM (r = 0.612, p ≤ 0.05). Using the median split method, subjects were divided into stronger (relative half squat 1RM = 1.93-2.67 kg·kg-1) and weaker (relative half squat 1RM = 1.37-1.92 kg·kg-1) groups and subsequently analyzed. The stronger group showed specific improvement in 0% 1RM CMJ performance 24 hours after the priming session (p ≤ 0.05), whereas the weaker group showed no improvement in any of their jump performances. Moreover, the priming session enhanced the theoretical maximum velocity (p ≤ 0.05), but not the theoretical maximum force during CMJ in the stronger group; whereas none of the force-velocity profile variables were enhanced in the weaker group. These results suggest that stronger individuals are more likely to experience performance enhancement using resistance priming, which may be movement- and velocity-specific.

The microscopic transition process from high-density to low-density amorphous state of SnI4.

A molecular crystalline SnI4undergoes pressure-induced solid-state amorphization via molecular dissociation to the high-density amorphous (HDA) state, which we call Am-I. In the present study, we examine the reverse transition process from Am-I to the low-density amorphous (LDA) state, called Am-II. We first measure the structure factor on decompression from 30 GPa down to 1.1 GPa at room temperature, usingin situangle-dispersive synchrotron x-ray measurement and a diamond anvil cell. We then estimate the density, which exhibits an abrupt change between 3.3 and 3.0 GPa, indicating the HDA(Am-I)-to-LDA(Am-II) transition. We use the density and the molecular configuration generated from a molecular dynamics simulation as input to a reverse Monte Carlo fit. The fit vividly visualizes gradual molecular reassociation between 18 and 14 GPa within the Am-I region. The Am-I state can thus be divided into two states: the high-pressure Am-I state containing isolated Sn atoms and the low-pressure Am-I state consisting of deformed molecules connected by metallic I2bonds. In the latter state, the molecular shape becomesC3v-like just before the transition to Am-II, in which molecules recover the originalTdsymmetry. This local symmetry change has been detected on the liquid-liquid transition of SnI4, suggesting the strong coupling between the local symmetry and the global order parameter of density.

Ultrasound radiation from a three-layer thermoacoustic transformation device.

A thermophone is a thermoacoustic transducer, which generates sound via time-varying Joule heating of an electrically conductive layer, which leads to expansion and contraction of a small pocket of air near the surface of the film. In this work, a 10-µm-thick Ag-Pd conductive film was coupled with heat-insulating and heat-releasing layers to fabricate a three-layer thermophone for generating ultrasound. The heat-insulating layer was 47 µm thick, and was made of glass. The heat-releasing layer was 594 µm thick, and was made of 94% alumina. Because of the simple sound-generation mechanism, which does not require mechanical moving parts, the Ag-Pd conductive film on the glass substrate can produce ultrasound radiation with broadband frequency characteristics, where exiting commercial electrode materials were used. We also demonstrate that the measured directivity patterns are in good agreement with theoretical predictions, assuming a rectangular diaphragm with the same size as the metallic film.

Sodium dodecyl sulfate polyacrylamide slab gel electrophoresis and hydroxyethyl cellurose gel capillary electrophoresis of luminescent lanthanide chelate-labeled proteins with time-resolved detection.

Proteins labeled with a luminescent lanthanide chelate, {{2,2',2'',2'''-{4'-{[(4,6-dichloro-1,3,5-triazin-2-yl)amino]biphenyl-4-yl}-2,2':6',2''-terpyridine-6,6''-diyl}bis(methylenenitrilo)}tetrakis(acetato)}europium(III) (DTBTA-Eu(3+)),were analyzed with sodium dodecyl sulfate-polyacrylamide gel (SDS-PAGE) slab gel electrophoresis and hydroxyethyl cellurose gel capillary electrophoresis with a time-resolved fluorometric detector. The metal ion of the luminescent lanthanide chelate did not dissociate from the ligand during electrophoresis, and the luminescence was retained. On a slab gel, the band of DTBTA-Eu(3+)-labeled streptavidin was apparently less broad than that of AlexaFluor 488-labeled streptavidin. DTBTA-Eu(3+) in SDS-PAGE slab gel is stable, and the gel after electrophoresis can be dried and stored for at least one year without luminescence fading. In capillary gel electrophoresis (CGE), five labeled proteins with different molecular weight were separated, and a good correlation was observed between the molecular weight and the migration time. Although the detection limits of these proteins determined in buffer solutions of the capillary electrophoresis were not better than those reported for CGE with laser-induced-detection, the detection limits of the same proteins in the present CGE system were not significantly deteriorated in serum solutions compared to those in buffer solutions, and the advantage of using time-resolved detection has been shown.

13C NMR longitudinal relaxation time studies of a molecular tweezers derived from a calixarene-porphyrin conjugate.

Zn(II)porphyrin-substituted calix[4]arene 1 serves as molecular tweezers for 1,4-diazabicyclo[2.2.2] octane (DABCO) selectively, which led to the formation of Ensemble I. The molecular segments composing the calixarene cavity change upon inclusion of DABCO as Ensemble I were evaluated through (13)C NMR longitudinal relaxation times (T(1)) for the first time. As for Ensemble I, the 1:1 complex should be formed. The T(1) values for Ensemble I are generally smaller than those for 1: in CDCl(2)CDCl(2), DT1 = 5.03 s for C-1, 5.31 s for C-2, 0.13 s for C-3, 0.7 s for C-4, and 0.16 s for C-5. This substantiates that the rings of Ensemble I are firmly freezed because of the two-point coordination by DABCO. In 1, the T1 values for C-3 are always greater than those for C-4, and the difference between C-3 and C-4 is slight. As for Ensemble I, on the other hand, the difference between C-3 and C-4 is large. We can suggest two different motions for phenol units in 1 and Ensemble I: a rotational motion around a C-1 to C-4 axis (A) and a seesaw motion around a C-2 to C-2' axis (B). The data indicate that in Ensemble I motion (A) is predominant over motion (B). This indicates that motion (B) is specifically suppressed because of the two-point coordination interactions in Ensemble I.

Application of a lanthanide fluorescent chelate label for detection of single-nucleotide mutations with peptide nucleic acid probes.

We developed the approach to detect single-nucleotide mutation with peptide nucleic acid (PNA) probes and time-resolved fluorometry using a fluorescence lanthanide chelate label, {2,2',2'',2'''-{4'-{[(4,6-dichloro-1,3,5-triazin-2-yl)amino]biphenyl-4-yl}-2,2': 6',2''-terpyridine-6,6''-diyl}bis(methylenenitrilo)}tetrakis(acetato)}europium(III) (DTBTA-Eu3+). Compared with DNA probes, PNA probes showed lower mismatch signals and gave higher signal/noise (S/N) ratios. Using the system, we examined the single-nucleotide mutations of codon 12 in the c-Ha-ras gene of PCR amplicons of genome DNAs isolated from human umbilical vein endothelial cells (HUVECs) and T24 cells.

New luminescent europium(III) chelates for DNA labeling.

The new europium(III) chelate [2,2',2'',2'''-[[4'-(aminobiphenyl-4-yl)-2,2':6',2''-terpyridine- 6,6''-diyl]bis(methylenenitrilo)]tetrakis(acetato)] europium(III) (ATBTA-Eu3+) and its 4,6-dichloro-1,3,5-triazinyl and succinimidyl derivatives (DTBTA and NHS-ATBTA, respectively) were synthesized and characterized. Both labeling complexes DTBTA-Eu3+ and NHS-ATBTA-Eu3+ are luminescent. Especially DTBTA-Eu3+ is strongly luminescent, with a luminescence quantum yield of 9.1%, molar extinction coefficient of 3.1 x 10(4) cm(-1) M(-1) (335 nm), and luminescence lifetime of 1.02 ms. The excitation and emission maximum wavelengths of DTBTA-Eu3+ are 335 and 616 nm, respectively. The complex is very stable in aqueous buffers, with a conditional formation constant log K(DTBTA-Eu) of 25.0 at pH 8, and can be conjugated to DNA and proteins. The chelates are also highly resistant to thermal decomposition, photodegradation, and ozone oxidation. These properties prove that DTBTA-Eu3+ is suitable as a luminescence label in DNA assays.

Detection of various platelet-associated immunoglobulins by flow cytometry in idiopathic thrombocytopenic purpura.

BACKGROUND: In 1975, Dixson reported that anti-platelet IgG on platelets from patients with idiopathic thrombocytopenic purpura (ITP) is greater than in normal people, by determining anti-platelet antibodies directly on the platelet surface with a quantitative complement lysis-inhibition-assay. Since then, platelet-associated IgG (PAIgG) has been thought of as evidence of ITP. Although platelets from ITP patients show significantly higher PAIgG values than from normal control individuals, PAIgG is not specific for autoantibody because it increases in other than immune ITP patients. METHODS: We analyzed positive platelet percentage with various platelet-associated immunoglobulins: IgG, IgM, IgA, and total immunoglobulins, in the blood from 17 normal donors and 23 ITP patients. RESULTS: The specificity for ITP disease was better in flow cytometry than in ELISA, because, other than ITP, only aplastic anemia was positive in flow cytometry; however, various disorders (aplastic anemia, chronic lymphocytic leukemia, acute myeloid leukemia, and myelodysplastic syndrome) showed positive in ELISA. Flow cytometry methods had the same sensitivity for ITP disease as ELISA. However, it is supposed that there was no nonimmune ITP in this study because the PAIgG negative patients (n = 1) showed positive results in flow cytometry. CONCLUSION: Flow cytometry method was effective for ITP screening, especially for specificity.

Tissue factor pathway inhibitor can interact with platelets.

Tissue factor pathway inhibitor (TFPI) regulates the extrinsic pathway of blood coagulation. However, there is no report on interaction between TFPI and platelets other than that by Tsuji, who found that whole blood anticoagulated with TFPI exhibited remarkable decrease in platelet count. Our study revealed that washed platelets suspended in modified Tyrode's buffer (8 mM CaCl2) containing TFPI exhibit platelet aggregation. However, platelets aggregation was observed without TFPI, but its increase and intensity were slow and weak, compared to that in the presence of TFPI. This aggregation was inhibited by anti-CD41 (anti-GPIIb) antibody. This finding suggested that TFPI promotes platelet aggregation.