Alpine Ski Technique Observation Instrument: Reliability and Validity

The aim of the study was to design an accurate and useful observational instrument for evaluating basic turn techniques in alpine skiing, and to determine its validity and reliability. A multi-step approach was used to design and validate the instrument: a literature revision; an expert meeting; a pilot test; the assessment of intra- and inter-observer reliability; a convergent validity test; and the responsiveness calculation with a pre- post-test. Results showed adequate values of intra-rater (P=0.80-0.83) and inter-rater reliability (P=0.86- 0.97). For the convergent validity, a moderate statistically significant correlation for the speed and trajectory control dimensions were achieved (rho=0.58-0.65, p<0.001), but not for the balance position dimension (rho=0.24, p=0.166). The responsiveness was also acceptable (p<0.05, r=0.46-0.60). In conclusion, the Alpine Ski Technique Observation Instrument is a useful, reliable, valid, and responsive observational tool.El objetivo del estudio fue diseñar un instrumento de observación preciso y útil para evaluar la técnica de cambios de dirección básicos en el esquí alpino, y determinar su validez y fiabilidad. Para diseñar y validar el instrumento se siguieron los siguientes pasos: revisión de la literatura, valoración por comité de expertos, prueba piloto, evaluación de la fiabilidad intra e inter-evaluador, prueba de validez convergente, y cálculo de sensibilidad con una prueba pre y post-intervención. Los resultados mostraron valores adecuados de fiabilidad intra-evaluador (P=0,80-0,83) e inter-evaluador (P=0,86-0,97). Respecto a la validez convergente se obtuvo una correlación moderada para las dimensiones de control de la velocidad y de la trayectoria (rho=0,58-0,65, p<0,001), pero no para la dimensión de posición de equilibrio (rho=0,24, p=0,166). La sensibilidad fue aceptable (p<0,05, r=0,46-0,60). En conclusión, el Instrumento de Observación de la Técnica en Esquí Alpino es una herramienta útil, fiable, válida y sensible.This work was supported by the Spanish Ministry of Universities [FPU16/03314 (Carolina Casado-Robles)]

Development and Evaluation of a Low-Drift Inertial Sensor-Based System for Analysis of Alpine Skiing Performance

This research has been funded by Junta de Andalucía (Spain) under project B-TIC-468- UGR18. The project was partially supported by European Regional Development Funds (ERDF).In skiing it is important to know how the skier accelerates and inclines the skis during the turn to avoid injuries and improve technique. The purpose of this pilot study with three participants was to develop and evaluate a compact, wireless, and low-cost system for detecting the inclination and acceleration of skis in the field based on inertial measurement units (IMU). To that end, a commercial IMU board was placed on each ski behind the skier boot. With the use of an attitude and heading reference system algorithm included in the sensor board, the orientation and attitude data of the skis were obtained (roll, pitch, and yaw) by IMU sensor data fusion. Results demonstrate that the proposed IMU-based system can provide reliable low-drifted data up to 11 min of continuous usage in the worst case. Inertial angle data from the IMU-based system were compared with the data collected by a video-based 3D-kinematic reference system to evaluate its operation in terms of data correlation and system performance. Correlation coefficients between 0.889 (roll) and 0.991 (yaw) were obtained. Mean biases from -1.13 degrees (roll) to 0.44 degrees (yaw) and 95% limits of agreements from 2.87 degrees (yaw) to 6.27 degrees (roll) were calculated for the 1-min trials. Although low mean biases were achieved, some limitations arose in the system precision for pitch and roll estimations that could be due to the low sampling rate allowed by the sensor data fusion algorithm and the initial zeroing of the gyroscope.Junta de Andalucia European Commission B-TIC-468UGR18European Commissio

Evaluation of Adipose Tissue Zinc-Alpha 2-Glycoprotein Gene Expression and Its Relationship with Metabolic Status and Bariatric Surgery Outcomes in Patients with Class III Obesity

Zinc-α2 glycoprotein (ZAG) is an adipokine involved in adipocyte metabolism with potential implications in the pathogenesis of metabolic disorders. Our aim was to evaluate the relationship between visceral (VAT) and subcutaneous adipose tissue (SAT) ZAG expression and metabolic parameters in patients with class III obesity, along with the impact of basal ZAG expression on short- and medium-term outcomes related to bariatric surgery. 41 patients with class III obesity who underwent bariatric surgery were included in this study. ZAG gene expression was quantified in SAT and VAT. Patients were classified into two groups according to SAT and VAT ZAG percentile. Anthropometric and biochemical variables were obtained before and 15 days, 45 days, and 1 year after surgery. The lower basal SAT ZAG expression percentile was associated with higher weight and waist circumference, while the lower basal VAT ZAG expression percentile was associated with higher weight, waist circumference, insulin, insulin resistance, and the presence of metabolic syndrome. Basal SAT ZAG expression was inversely related to weight loss at 45 days after surgery, whereas no associations were found between basal VAT ZAG expression and weight loss after surgery. Additionally, a negative association was observed between basal SAT and VAT ZAG expression and the decrease of gamma-glutamyl transferase after bariatric surgery. Therefore, lower SAT and VAT ZAG expression levels were associated with an adverse metabolic profile. However, this fact did not seem to confer worse bariatric surgery-related outcomes. Further research is needed to assess the clinical significance of the role of ZAG expression levels in the dynamics of hepatic enzymes after bariatric surgeryThis study has been co-funded by FEDER funds (“A way to make Europe”). M.M. and L.G.S. are also supported by UMA18-FEDERJA-285 and UMA20-FEDERJA-144, co-funded by Malaga University, Junta de Andalucía and FEDER funds, CB06/03/0018, PI-0297-2018 and PI-0194-2017, co-funded by FEDER funds and Consejería de Salud y Familias, Junta de Andalucía, and CP17/00133, Instituto de Salud Carlos III (ISCIII), Ministry of Science, Innovation and Universities, Spain Partial funding for open access charge: Universidad de Málag

Efecto de un programa de formación inicial encaminado a la autonomía sobre las competencias del profesor de esqui alpino y su evolución del conocimiento práctico

Estudia el proceso de formación inicial del profesor de esquí alpino, su evolución y su pensamiento docente orientado a su autonomíaEstudia el proceso de formación inicial del profesor de esquí alpino, su evolución y su pensamiento docente orientado a su autonomíaUniv. de Granada, Departamento de Educación Física y Deportiva. Leída el 29/10/0

Effect of learning to ski with an indoor skiing carpet compared to the real snow setting on alpine skiing technique, autotelic experience, and anxiety levels in university students: A pilot randomized controlled trial

The aim was to compare the effects of an alpine skiing learning intervention initiated in an indoor carpet setting (ICS) with the snow setting (SS) on the alpine skiing turn technique, state of anxiety, and autotelic experience. Thirty-four students (4 females) aged 18-37 years were randomly divided into indoor carpet skiing (ICSG; first two classes in an ICS, and the two last classes in the SS) or snow (all classes in the SS) groups. Statistically significant differences were only detected in the cognitive anxiety levels between both groups for the second day of the program and in the alpine skiing turn technique at the first day of practice in the SS for both groups, in favor of the ICSG in both cases (p < 0.05). The ICS seems to be a useful and effective setting for learning to ski in relation to motor learning and anxiety than THE SS

Upper limbs asymmetries in young competitive paddle-tennis players

Existe escasa literatura sobre las asimetrías en el pádel, un deporte de naturaleza asimétrica. Para estudiar el desarrollo de asimetrías en este deporte se evaluó, con bioimpedancia, la masa magra de ambos miembros superiores de 96 jugadores de pádel jóvenes y de 76 esquiadores (grupo control) y se calculó el índice de simetría. Los jugadores de pádel tuvieron una asimetría entre ambos miembros superiores mayor que los esquiadores, cuando se consideró toda la muestra (7.2 ± 5 % vs. 1.4 ± 3.2 %; p < 0.001), en jugadores con un estado de madurez negativo (5,7 ± 3,2 % vs. 1,5 ± 3,8 %; p < 0,001) y en aquellos con un estado de madurez positivo (8,3 ± 5,8 % vs. 1,3 ± 2,4 %; p < 0,001). Este estudio revela que el pádel genera asimetrías de masa magra en los miembros superiores, incluso antes de la edad de crecimiento pico.There is little literature on asymmetries in paddle tennis, a sport of an asymmetrical nature. To study the development of upper limb asymmetries, 96 young paddle players and 76 skiers (control group) were evaluated via bioimpedance. The lean mass symmetry index was then compared, considering the sport (paddle tennis players and skiers) and the maturity offset (positive or negative). Paddle-tennis players had a systematically greater upper limbs asymmetry than skiers (7.2 ± 5 % vs. 1.4 ± 3.2 %; p < 0.001). This also occurs when comparing only the subsamples with a negative maturity offset (5.7 ± 3.2 % vs. 1.5 ± 3.8 %; p < 0.001) or with a positive maturity offset (8.3 ± 5.8 % vs. 1.3 ± 2.4 %; p < 0.001). The study reveals that paddle tennis generates asymmetries of lean mass in upper limbs, even before growth spurt.Spanish Government FPU15/0294

Development and Evaluation of a Low-Drift Inertial Sensor-Based System for Analysis of Alpine Skiing Performance.

In skiing it is important to know how the skier accelerates and inclines the skis during the turn to avoid injuries and improve technique. The purpose of this pilot study with three participants was to develop and evaluate a compact, wireless, and low-cost system for detecting the inclination and acceleration of skis in the field based on inertial measurement units (IMU). To that end, a commercial IMU board was placed on each ski behind the skier boot. With the use of an attitude and heading reference system algorithm included in the sensor board, the orientation and attitude data of the skis were obtained (roll, pitch, and yaw) by IMU sensor data fusion. Results demonstrate that the proposed IMU-based system can provide reliable low-drifted data up to 11 min of continuous usage in the worst case. Inertial angle data from the IMU-based system were compared with the data collected by a video-based 3D-kinematic reference system to evaluate its operation in terms of data correlation and system performance. Correlation coefficients between 0.889 (roll) and 0.991 (yaw) were obtained. Mean biases from -1.13° (roll) to 0.44° (yaw) and 95% limits of agreements from 2.87° (yaw) to 6.27° (roll) were calculated for the 1-min trials. Although low mean biases were achieved, some limitations arose in the system precision for pitch and roll estimations that could be due to the low sampling rate allowed by the sensor data fusion algorithm and the initial zeroing of the gyroscope

Development and Evaluation of a Low-Drift Inertial Sensor-Based System for Analysis of Alpine Skiing Performance

In skiing it is important to know how the skier accelerates and inclines the skis during the turn to avoid injuries and improve technique. The purpose of this pilot study with three participants was to develop and evaluate a compact, wireless, and low-cost system for detecting the inclination and acceleration of skis in the field based on inertial measurement units (IMU). To that end, a commercial IMU board was placed on each ski behind the skier boot. With the use of an attitude and heading reference system algorithm included in the sensor board, the orientation and attitude data of the skis were obtained (roll, pitch, and yaw) by IMU sensor data fusion. Results demonstrate that the proposed IMU-based system can provide reliable low-drifted data up to 11 min of continuous usage in the worst case. Inertial angle data from the IMU-based system were compared with the data collected by a video-based 3D-kinematic reference system to evaluate its operation in terms of data correlation and system performance. Correlation coefficients between 0.889 (roll) and 0.991 (yaw) were obtained. Mean biases from −1.13° (roll) to 0.44° (yaw) and 95% limits of agreements from 2.87° (yaw) to 6.27° (roll) were calculated for the 1-min trials. Although low mean biases were achieved, some limitations arose in the system precision for pitch and roll estimations that could be due to the low sampling rate allowed by the sensor data fusion algorithm and the initial zeroing of the gyroscope