10 research outputs found
Differences in run-up, take-off, and flight characteristics: successful vs. unsuccessful high jump attempts at the IAAF world championships
Studies previously conducted on high jump have yielded important information regarding successful performance. However, analyses in competitive scenarios have often disregarded athletesâ unsuccessful attempts. This study aimed to investigate the biomechanical differences between successful and unsuccessful jumps during competition. High-speed video footage (200â
Hz) was obtained from 11 athletes during the 2018 Men's World Athletics Indoor Championship Final. From each athlete, one successful (SU) and one unsuccessful (UN) jump at the same bar height were included in the analysis, leaving seven athletes in total. Following whole-body 3D manual digitization, several temporal and kinematic variables were calculated for the run-up, take-off, and flight phases of each jump. During SU jumps, athletes raised the center of mass to a greater extent (pâ<â0.01) from take-off. Touchdown in SU jumps was characterized by a faster anteroposterior velocity (pâ<â0.05), lower backward lean (pâ<â0.05), and changes in joint angles for the stance and trail limbs (pâ<â0.05). Athletes also shortened the final contact time during SU jumps (pâ<â0.01) after producing a longer flight time in the final step of the run-up (pâ<â0.05). Elite-level high jumpers undertake a series of adjustments to successfully clear the bar after UN jumps. These adjustments reinforce the importance of the run-up in setting the foundations for take-off and bar clearance. Furthermore, the findings demonstrate the need for coaches to be mindful of the adjustments required in stance and trail limbs when looking to optimize feedback to athletes during training and competition
The Association Between Hip-Shoulder Separation Angles and Technique Characteristics in World-Class High Jumpers
Hip-shoulder separation (H-Ssep) has been widely researched in many sporting activities (e.g., golf) to provide information on the contribution of torso rotation to performance and injury. Although it is necessary for high jumpers to generate significant long-axis rotation to successfully clear the bar, limited information exists on H-Ssep for high jump athletes. As such, this study aimed to (a) characterize the H-Ssep of world-class high jump athletes during competition, (b) determine if differences exist between male and female athletes and (c) to examine the relationship between H-Ssep and the biomechanical parameters used to describe high jump technique. Twenty-nine world-class high jumpers (17 males, 12 females) were video recorded (frame rate: 120â200 Hz) during the 2017 and 2018 World Athletics Championship finals. H-Ssep was quantified at touchdown (TD) and take-off (TO) following manual digitizing (SIMI motion) and a number of other common biomechanical parameters were computed. The observed levels of H-Ssep at TD (â46±12°) and TO (16 ±11°) were in line with those reported previously for other sports. The magnitude of H-Ssep varied between individuals and showed significant associations with other approach and take-off characteristics. Significant differences in H-Ssep were not evident between male and female athletes despite significant differences in other performance- and technique-related parameters. These findings highlight the divergent take-off characteristics of world-class performers and their reliance on hip-shoulder interactions when generating long axis rotation. Coaches should be mindful of the mechanical and physical consequences of H-Ssep when developing technical models, conditioning interventions and coaching strategies
Changes in running biomechanics during the 2017 IAAF World Championships men's 1500m final
The aim of this study was to analyse key kinematic, spatiotemporal, and global mechanical characteristics in world-class middle-distance racing. Eight men were recorded halfway along the home straight on the second, third and final laps in the 2017 IAAF World Championship 1500m final. Video data (150 Hz) from three high-definition camcorders were digitised to calculate relevant variables, subsequently analysed in relation to running speed and finishing position. Better-placed finishers had greater hip extension at initial contact and through late stance, greater knee excursion throughout stance, and longer overstriding distances. Step length did not change with faster speeds as runners relied on increasing step frequency, but the highest-finishing athletes had longer contact phases and greater fluctuations in speed through the step cycle, which were related to higher normalised peak horizontal forces. The best athletes also had lower leg stiffnesses and vertical stiffnesses. The extended contact phase and greater compression could allow for more sustained force production, enabling better acceleration and maintenance of sprinting speed, indicating a trade-off between aerobic energetic efficiency and anaerobic power capacity. Coaches should note that these factors, as well as the best athletes' greater overstriding distances, show that elite 1500m runners might prioritise a technique that favours running speed over economy
Urotensin II(4-11) Azasulfuryl Peptides: Synthesis and Biological Activity
Cyclic azasulfuryl (As) peptide analogs of the urotensin II (UII, 1, H-Glu-Thr-Pro-Asp-c[Cys-Phe-Trp-Lys-Tyr-Cys]-Val-OH) fragment 4-11 were synthesized to explore the influences of backbone structure on biological activity. N-Aminosulfamides were inserted as surrogates of the Trp(7) and Lys(8) residues in the biologically relevant Trp-Lys-Tyr triad. A combination of solution- and solid-phase methods were used to prepare novel UII((4-11)) analogs 6-11 by routes featuring alkylation of azasulfuryl-glycine tripeptide precursors to install various side chains. The pharmacological profiles of derivatives 6-11 were tested in vitro using a competitive binding assay and ex vivo using a rat aortic ring bioassay. Although the analogs exhibited weak affinity for the urotensin II receptor (UT) without agonistic activity, azasulfuryl-UII((4-11)) derivatives 7-9 reduced up to 50% of the effects of UII and urotensin II-related peptide (URP) without affecting their potency
Kinematic factors associated with start performance in World-class male sprinters
The aim was to investigate the kinematic factors associated with successful performance in the initial acceleration phase of a sprint in the best male athletes in the World at the 2018 World Indoor Athletics Championships. High speed video (150 Hz) was captured for eight sprinters in the men's 60 m final. Spatio-temporal and joint kinematic variables were calculated from the set position to the end of the first ground contact post-block exit (GC1). Normalised average horizontal external power (NAHEP) defined performance and was the dependent variable for a series of regression analyses. Clear relationships were found between GC1 NAHEP and 10-m time, 60-m time, change in velocity, acceleration and contact time in the first ground contact (r = â0.74, â0.64, 0.96, 0.91 and â0.56, respectively). Stepwise multiple linear regression of joint kinematic variables in the first ground contact revealed that trunk angle at take-off and thigh separation angle at take-off explained nearly 90% of variation in GC1 NAHEP (R2 = 0.89). The athletesâ projection at take-off with a forward leaning trunk and large thigh separation is characteristic therefore of excellent initial acceleration performance and this will be a good visual guide for technical coaching instruction. This was the first study of its kind to adopt such a research design in a World-class sample in a representative environment. Future studies that combine detailed kinematic and kinetic data capture and analysis in such a setting will add further insight to the findings of this investigation.</p
Long-Term Anatomical and Hearing Outcomes of Canal Wall down Tympanoplasty for Tympano-Mastoid Cholesteatoma: A 20-Year Retrospective Study
Background: to evaluate the residual rate and the functional results after ten years from canal wall down tympanoplasty (CWD) for tympano-mastoid cholesteatoma. Methods: All the patients undergoing CWD for chronic otitis media with cholesteatoma at our ENT University Department between January 2002 and December 2022 were initially assessed. We performed clinical and diagnostic evaluation at baseline, 6 months, and then every year until an average follow-up of 10 years was obtained. Patients were consequently divided into two groups according to the presence (group A) or absence (group B) of the stapes superstructure. Results: After the selection process, 176 ears were included. The presence of the stapes superstructure was associated with better hearing outcomes (rate of patients p = 0.001) and 10 years (74.46% vs. 24.11%; p p = 0.993). The recurrent cholesteatoma rate was respectively 1/35 (2.85%) vs. 3/141 (2.18%) (p = 0.516). Conclusions: the CWD approach to cholesteatoma allows for effective long-term anatomical disease control and good hearing results when the stapes superstructure is preserved
Type 1 Tympanoplasty Outcomes between Cartilage and Temporal Fascia Grafts: A Long-Term Retrospective Study
Background: To compare the functional and anatomical results of two different types of grafts in type 1 tympanoplasty (TPL I). Methods: A retrospective comparative bicentric study was conducted on patients treated with TPL I using temporal fascia or tragal cartilage. We evaluated the functional and anatomical results with intergroup and intragroup analyses. Variables predicting long-term success were also evaluated. Results: A total of 142 patients (98 fascia graft vs. 44 cartilage) were initially assessed, with a mean follow-up of 67.1 ± 3.2 months. No significant differences were observed between the two groups on the intergroup analysis of age, gender, ear side, or pre-operative hearing data (all p > 0.05). At the intragroup analysis of auditory outcomes, both groups demonstrated a significant improvement in post-operative air conduction, with greater gain for the fascia group at 6 months follow-up (p p p p = 0.04). On the contrary, the cartilage group at long-term follow-up at 5 years maintained greater outcomes (10 ± 1.6 dB vs. 6.4 ± 2 dB; p p = 0.036) and higher size of perforation (F = 4.820; p = 0.030) were predictors of long-term functional success. Conclusions: The graft material selection should consider several factors influencing the surgical outcome. At long-term follow-up, the use of a cartilage graft could result in more stable audiological outcomes, especially in younger patients or in case of wider perforations