BLOCKING THE QUICK ATTACK IN VOLLEYBALL: A 3D KINEMATIC ANALYSIS

The importance of the volleyball block against the quick attack is more important in the modern volleyball with new scoring system. Two types of tactics are used normally: the Read Block System (RBS) and the Commit Block System (CBS). A preliminary study was conducted to identify variables that quantified the differences between these two techniques. Four young players performing the RBS and the CBS were acquired by means of stereo-photogrammetry and kinematic variables were identified. The quantified analysis confirms coaches experience: in the RBS the hands arrive over the net in a shorter time, the feet start “naturally” wider but the jump performed has a lower height with respect to the CBS. Further longitudinal and transversal studies will be conducted with more subjects of different level and gender

KINEMATICS OF THE SPRINGBOARD PHASE IN YURCHENKO-STYLE VAULTS

The object of this study is the kinematics analysis of the center of mass (COM) in the springboard phase of the Yurchenko-style vault performed by 14 female gymnasts during the 2006 Italian Championship for Clubs. The purpose was to widen the biomechanics knowledge about this phase. Temporal, horizontal and vertical spatial, horizontal and vertical velocity and body’s angle parameters were estimated. A representative kinematics analysis of the Yurchenko’s springboard phase was compiled based on these parameters. The results indicated that the gymnasts use the board to avoid a large decrease in the COM horizontal velocity and increase their COM vertical velocity. These were realizing by a great body’s angle at the board impact, reducing the amount of the downward motion in the gathering and maximizing the successive upward lift of the COM

Remineralization strategies in oral hygiene: a position paper of Italian Society of Oral Hygiene Sciences-S.I.S.I.O. working group

Background/Objective: The clinical conditions that lead to an alteration of the enamel structure are numerous. The diet high in sugars and acidifying substances, psychological stress that triggers parafunctional behaviors, the reduced intake of fiber-rich foods or alkalizing substances, together with other factors, contribute to demineralization of the tooth enamel. Dental mineralizing products on the current market are distinguished according to the dosage form, the active ingredient, the release technology, clinical indications and patient choice. Currently, it is necessary to propose to oral health professionals a guide to orient themselves in this chaotic choice, in order to prefer the most effective product for their own clinical target. Methods: Italian Society of Oral Hygiene Sciences-S.I.S.I.O. is one of the leading scientific Italian societies representing those dental hygienists working with high-quality standards and in agreement with scientific evidence: in the last year, the SISIO working group has carried out a study focused on remineralizing agents in dentistry, in order to give an authoritative point of view to indicate a guideline in the decision process of the choice of a remineralizing agent. We will report the results pointed out from the last consensus meeting in 2017. Results: We have reported the good the bad and the ugly have been discussed in a critical discussion of such topic. Conclusion: The SISIO experience has been reported in this position paper with the aim to serve as a useful aid in the daily choice of the clinical steps to perform, when dental professionals need to treat demineralized teeth. Keywords: Dental Hygiene, Oral health, Dental Remineralizing, Enamel, Toothpaste, Mouthwash

Path Linearity of Elite Swimmers in a 400 m Front Crawl Competition

none6noIn the frontal crawl, the propulsive action of the limbs causes lateral fluctuations from the straight path, which can be theoretically seen as the best time saving path of the race. The purpose of the present work was to analyze the head trajectory of 10 elite athletes, during a competition of 400 m front crawl, in order to give information regarding the path linearity of elite swimmers. The kinematic analysis of the head trajectories was performed by means of stereo-photogrammetry. Results showed that the forward speed and lateral fluctuations speed are linearly related. Multiple regression analysis of discrete Fourier transformation allowed to distinguish 3 spectral windows identifying 3 specific features: strokes (0.7-5 Hz), breathings (0.4-0.7 Hz), and voluntary adjustments (0-0.4 Hz), which contributed to the energy wasting for 55%, 10%, and 35%, respectively. Both elite swimmers race speed and speed wastage increase while progressing from the 1st to the 8th length during a 400 m front crawl official competition. The main sources of the lateral fluctuations that lead to the increasing speed wastage could be significantly attributed to strokes and voluntary adjustments, while breathings contribution did not reach statistical significance. In conclusion, both strokes and voluntary adjustments are the main energy consuming events that affect path linearity.PubMed ID: 25729292 [PMID]openGatta, Giorgio; Cortesi, Matteo; Lucertini, Francesco; Benelli, Piero; Sisti, Davide; Fantozzi, SilviaGatta, Giorgio; Cortesi, Matteo; Lucertini, Francesco; Benelli, Piero; Sisti, Davide; Fantozzi, Silvi

CENTRE OF MASS TRAJECTORY IN SNOWBOARD GIANT SLALOM USING INERTIAL SENSORS: LABORATORY AND IN-FIELD PRELIMINARY EVALUATION

The purpose of the present study was to evaluate the reconstruction accuracy of the centre of mass during snowboard giant slalom using inertial sensors (Opal, APDM, 128 Hz). Two approaches were implemented and tested: i) a multi-segment model using 7 inertial sensors on the trunk, the pelvis, the thighs, the shanks, and the board; and ii) a double integration of the acceleration at L5 level measured with one inertial sensor. The accuracy of the algorithms was verified in two laboratory conditions: a) the multi-segment model approach was tested indoor during controlled movements using stereo-photogrammetry as gold standard, and b) the double integration of acceleration approach was tested outdoor in simulated movements on a longboard using GPS as gold standard. Successively, to verify the application in real conditions, an in-field acquisition of a forerunner athlete during a snowboard world cup competition was performed. The position of the centre of mass estimated indoor with multi-segmental model approach reported in the local reference frame of the board showed high correlation with respect to stereo-photogrammetry (r=0.87) and a RMS error of 3.8 [%] expressed as percentage of the range of motion during the trial (1.32m). For the simulated movements test in outdoor conditions on the longboard applying the double integration approach, high correlation was found with respect to the GPS data (r=0.95) on the trajectory but , for the 4 turns trial, a RMS difference on the distance equal to 15.3 [%] expressed as percentage of the whole distance covered (46m). Finally, the in-field acquisition showed how using inertial sensors is a viable option for collecting centre of mass data during training session useful for coaches and athletes. The approach using one sensors at L5 level showed low level of accuracy with respect to the one using a multi-segment model. Further developments should be performed in the direction of a better estimation of the orientation of the inertial sensors and of the boundary conditions for the integration algorithm

EFFECTS OF FATIGUE ON KINEMATICS AND SHOCK ATTENUATION DURING DOWNHILL TRAIL RUNNING

This study assessed the effects of a competitive trail run on running kinematics and shock attenuation in well-trained trail runners. Nine male runners performed a simulated short trail running race. Prior and 5-min after the race, participants completed a 290-m downhill run at pre-determined preferred speed. Inertial measurement units were used to assessselected kinematic parameters. The contact time showed a moderate increase in the fatigued condition (pre: 0.215 (0.024) s vs. post: 0.226 (0.219) s; p2vs. post: 49.1 (11.9) m/s2; p=0.038; d=0.56), while peak tibial acceleration and shock attenuation showed no change (p\u3e0.05). These findings confirm that running-induced fatigue impacts running kinematics, although shock attenuation was unaltered with the present fatiguing protocol. This study assessed the effects of a competitive trail run on running kinematics and shock attenuation in well-trained trail runners. Nine male runners performed a simulated short trail running race. Prior and 5-min after the race, participants completed a 290-m downhill run at pre-determined preferred speed. Inertial measurement units were used to assessselected kinematic parameters. The contact time showed a moderate increase in the fatigued condition (pre: 0.215 (0.024) s vs. post: 0.226 (0.219) s; p2vs. post: 49.1 (11.9) m/s2; p=0.038; d=0.56), while peak tibial acceleration and shock attenuation showed no change (p\u3e0.05). These findings confirm that running-induced fatigue impacts running kinematics, although shock attenuation was unaltered with the present fatiguing protocol

Asymmetric posterior reversible encephalopathy syndrome in patient with hyperplastic anterior choroidal artery

We describe a case of asymmetric PRES due to the presence of hyperplastic anterior choroidal artery (AChA) in a man affected by sever hypertension. Posterior reversible encephalopathy syndrome (PRES) has become synonymous with a unique pattern of brain vasogenic edema and predominates in the parietal and occipital regions, accompanied by clinical neurological alterations. Sever hypertension is a risk factor that exceeds the limits of brain autoregulation, leading to breakthrough brain edema. In our knowledge this is the first case reported in literature, in which a similar vascular abnormality is linked to a PRES syndrome

Detection of hidden vertical root fracture by stereomicroscope

The vertical root fractures resulting as from trauma, as from the “cracked tooth syndrome”, are spotted within the “iatrogenic periodontal lesions” according to the Al-Fouzan (1) classification. The stereo microscope, an optical microscope variant typically exploiting the light reflected from the surface of an object rather than that transmitted through it (2), in the reported case has revealed the best tool to perform the resolving three-dimensional examination of the tooth. Aim of this paper is to describe a vertical root fracture, not otherwise detectable. A second upper molar, has been endodontically treated, because of the presence of an endo-periodontal lesion. Even though the treatment was performed according the standard protocol, after two years the lesion persisted and the tooth was extracted. After the extraction, the tooth was diaphanized to be observed with the stereomicroscope (Leica LED2000). The investigation clearly showed a vertical fracture, starting directly from the cervical line and a small hole on the distal surface of the root palatal cone. Mean values of measurements taken in 15 randomly points at 1x, 4x and 8x magnification were made. The fracture resulted to be long 9,79 mm and to have a mean width of 0,37 + 0,07 mm externally, and 0,15 + 0,02 mm internally. The mean area of the hole resulted of 0,85 mm2. All the analytical procedure was validated by t-student test, showing a p value < 0,0001. This vertical root fracture represented the unexpected pathway between the pulp and periodontal tissues and sure it caused the endodontic treatment failure, with tooth loss. It appears clear that a good diagnosis, following exactly the proto- col stated in the literature, together with the patient’s compliance, are crucial basis to face such clinical challenge

Markerless analysis of front crawl swimming

a b s t r a c t Research on motion analysis of swimmers is commonly based on video recordings of the subject's motion, which are analyzed by manual digitization of feature points by an operator. This procedure has two main drawbacks: it is time-consuming, and it is affected by low repeatability. Therefore, the application of video-based, automatic approaches to motion analysis was investigated. A video-based, markerless system for the analysis of arm movements during front crawl swimming was developed. The method proposed by was modified in order to be used into water environment. Three dimensional coordinates of shoulder, elbow and wrist joints centers of 5 sprint swimmers performing front crawl swimming were determined. Wrist joint velocity was also calculated. Accuracy and reliability of the proposed technique were evaluated by means of comparison with traditional manual digitization (SIMI Reality Motion Systems GmbH). Root mean square distance (RMSD) values between trajectories estimated with the two techniques were determined. Results show good accuracy for wrist joint (RMSD o 56 mm), and reliability, evaluated on one subject, comparable to the inter-operator variability associated with the manual digitization procedure. The proposed technique is therefore very promising for quantitative, wide-scale studies on swimmers' motion

ISB recommendations on the reporting of intersegmental forces and moments during human motion analysis

The International Society of Biomechanics (ISB) has charged this committee with development of a standard similar in scope to the kinematic standard proposed in Wu et al., 2002, Wu et al., 2005. Given the variety of purposes for which intersegmental forces and moments are used in biomechanical research, it is not possible to recommend a particular set of analysis standards that will be acceptable in all applications. Instead, it is the purpose of this paper to recommend a set of reporting standards that will result in an understanding of the differences between investigations and the ability to reproduce the research. The end products of this standard are 1) a critical checklist that can be used during submission of manuscripts and abstracts to insure adequate description of methods, and 2) a web based visualization tool that can be used to alter the coordinate system, normalization technique and internal/external perspective of intersegmental forces and moments during walking and running so that the shape and magnitude of the curves can be compared to one’s own data