The reliability of accelerometry to measure weightlifting performance

The purposes of the study were to track weightlifters' barbell acceleration with a portable accelerometer over three training sessions to examine test–retest reliability and to compare peak barbell acceleration at different training intensities. Twelve nationally ranked weightlifters volunteered for this study. The portable accelerometer was attached to the right side of the barbell to measure barbell resultant acceleration during the snatch lift at a sampling frequency of 100 Hz. The data were collected over three training sessions at intensity levels of 80%, 85%, and 90% of one repetition maximum. The data were analyzed using intra-class correlation coefficients (ICCs) for the three training sessions and one-way repeated measure ANOVA to compare the difference in peak barbell acceleration at three intensities. Results showed that the device was highly reliable with an ICC of 0.88 and 95% confidence interval of 0.81–0.93. There were significant differences in peak barbell acceleration at various lifting intensities, indicating a decline of the acceleration as the mass of the barbell became heavier. The portable accelerometer seems useful in measuring barbell acceleration data, which can be analyzed in future studies to monitor a weightlifter's performance in a practical setting instead of testing at a laboratory.     

Biomechanical analysis of the sidearm throwing motion for distance of a flying disc: A comparison of skilled and unskilled Ultimate players

Joint angles of the throwing limb were examined from the acceleration phase up until release for the sidearm throwing motion when using a flying disc. 17 individuals (ten skilled, seven unskilled) threw a disc as far as possible ten times. Throwing motions were recorded using three-dimensional high-speed videography. The initial condition of disc release and joint angle kinematics of the upper limb during the throwing motion were obtained. Mean ( ± standard deviation) throwing distance and disc spin rate were significantly greater for skilled throwers (51.4 ± 6.6 m, 12.9 ± 1.3 rps) than for unskilled throwers (29.5 ± 7.6 m, 9.4 ± 1.3 rps), although there was no significant difference in initial velocity of the disc between the two groups (skilled: 21.7 ± 1.7 m/s; unskilled: 20.7 ± 2.5 m/s). A marked difference in motion of supination/pronation of the forearm before disc release was identified, with the forearm supinated in the final acceleration phase leading up to disc release for the unskilled participants, while the forearm was pronated in the same phase for the skilled participants. These differences in joint kinematics could be related to differences in disc spin rate, and thus led to the substantial differences in throwing distance.     

Validity and reliability of body composition assessed by the sulphur hexafluoride dilution method

The aims of this study were to assess the validity and reliability of body volume and percent body fat determined by sulphur hexafluoride dilution, using underwater weighing as the criterion method, and to determine the influence of the magnitude of body volume. Thirty-one healthy Japanese individuals aged 18-27 years (16 males: height 1.70 +/- 0.06 m, mass 64.8 +/- 7.7 kg; 15 females: height 1.60 +/- 0.05 m, mass 55.2 +/- 6.2 kg; mean +/- s) participated in the study. Sulphur hexafluoride dilution measures the concentration of sulphur hexafluoride gas in the chamber (BSF-200, Shimazu Corp.). Underwater weighing was performed five times using a weight scale (AD-6204, A&D) after residual volume had been determined (System9, Minato Medical Corp.). There were no significant differences in the mean between two trials for body volume, body density or percent body fat determined by sulphur hexafluoride dilution. The intra-class correlation coefficient of these variables ranged from 0.985 to 0.999. The results suggest that sulphur hexafluoride dilution is a reliable method for assessing body composition. There was no significant difference in body volume or percent body fat between sulphur hexafluoride dilution (males: 61.3 +/- 7.6 litres, 18.4 +/- 6.7%; females: 52.8 +/- 6.9 litres, 21.0 +/- 8.9%) and underwater weighing (males: 60.6 +/- 7.0 litres, 15.6 +/- 3.5%; females: 53.0 +/- 6.5 litres, 23.7 +/- 6.1%) and there was a high correlation between the two (r = 0.997, P < 0.05). A Bland-Altman plot of the difference between percent body fat estimated by underwater weighing and sulphur hexafluoride dilution versus average percent body fat by the two methods showed no systematic difference (mean difference = -0.12 +/- 6.6 kg). The upper and lower limits of agreement were 13.2% and -13.4%, respectively. Determination by sulphur hexafluoride dilution resulted in both over- and underestimations in body volume and the difference between the two body volumes (determined by underwater weighing and by sulphur hexafluoride dilution) was inversely proportional to the mean body volume by the two methods. This suggests that improvements need to be made to the device or to the technique to maintain a constant volume of sulphur hexafluoride in the chamber.     

The classroom observations of Vietnamese teachers: mediating underlying values to understand student learning

This study uses the grounded theory approach (GTA) to investigate the value and characteristics of teacher observations, when used to understand student learning. Earlier studies have analysed the act of observation, defining it as a combination of joint observation and interpretation activities. By contrast, this analysis of 28 primary school teachers in remote areas of Vietnam reveals that the act of observation is mediated by underlying values. This study develops a discussion about the way in which the inherent ‘compliance-with-a-plan’ value restricts teachers’ ability to develop knowledge, as proposed in the literature, while the value of ‘exploration’ encourages teachers to develop a broader interpretation of classroom interactions. Figures and tables illustrate these GTA-based results.     

Multi-segment trunk models used to investigate the crunch factor in golf and their relationship with selected swing and launch parameters

The use of multi-segment trunk models to investigate the crunch factor in golf may be warranted. The first aim of the study was to investigate the relationship between the trunk and lower trunk for crunch factor-related variables (trunk lateral bending and trunk axial rotation velocity). The second aim was to determine the level of association between crunch factor-related variables with swing (clubhead velocity) and launch (launch angle). Thirty-five high-level amateur male golfers (Mean ± SD: age = 23.8 ± 2.1 years, registered golfing handicap = 5 ± 1.9) without low back pain had kinematic data collected from their golf swing using a 10-camera motion analysis system operating at 500 Hz. Clubhead velocity and launch angle were collected using a validated real-time launch monitor. A positive relationship was found between the trunk and lower trunk for axial rotation velocity (r(35) = .47, P < .01). Cross-correlation analysis revealed a strong coupling relationship for the crunch factor (R² = 0.98) between the trunk and lower trunk. Using generalised linear model analysis, it was evident that faster clubhead velocities and lower launch angles of the golf ball were related to reduced lateral bending of the lower trunk.     

Social mapping and environmental education: dialogues from participatory mapping in the Pantanal,Mato Grosso,Brazil

Abstract

This article illustrates the steps taken to enact a new methodology for participatory social mapping by the Environmental Education, Communications and the Arts (GPEA) Research Group of the Federal University of Mato Grosso (UFMT). The aim of Social Mapping is to record the identities, territories and socio-environmental conflicts experienced by social groups, based on their own namings and narratives, rather than relying on those more typically generated or provided by researchers or theorists. As such, it offers an important dialogical pathway for environmental education practices, in that it highlights the intrinsic relationship between culture and nature, and reinforces the understanding that the loss of one implies the disappearance of the other.     

Kinematic repeatability of a multi-segment foot model for dance*

The purpose of this study was to determine the intra and inter-assessor repeatability of a modified Rizzoli Foot Model for analysing the foot kinematics of ballet dancers. Six university-level ballet dancers performed the movements; parallel stance, turnout plié, turnout stance, turnout rise and flex-point-flex. The three-dimensional (3D) position of individual reflective markers and marker triads was used to model the movement of the dancers’ tibia, entire foot, hindfoot, midfoot, forefoot and hallux. Intra and inter-assessor reliability demonstrated excellent (ICC ≥ 0.75) repeatability for the first metatarsophalangeal joint in the sagittal plane. Intra-assessor reliability demonstrated excellent (ICC ≥ 0.75) repeatability during flex-point-flex across all inter-segmental angles except for the tibia-hindfoot and hindfoot-midfoot frontal planes. Inter-assessor repeatability ranged from poor to excellent (0.5 > ICC ≥ 0.75) for the 3D segment rotations. The most repeatable measure was the tibia-foot dorsiflexion/plantar flexion articulation whereas the least repeatable measure was the hindfoot-midfoot adduction/abduction articulation. The variation found in the inter-assessor results is likely due to inconsistencies in marker placement. This 3D dance specific multi-segment foot model provides insight into which kinematic measures can be reliably used to ascertain in vivo technical errors and/or biomechanical abnormalities in a dancer’s foot motion.     

Long-term impact of the Tokyo 1964 Olympic Games on sport participation: A cohort analysis

The sport participation rate has been shown to decrease with age in many countries. In Japan, however, the elderly sport participation rate has increased over the last decade and is the highest among all Japanese. This study investigated whether the cohort effect generated by the shared experience of hosting the Tokyo 1964 Olympic Games during their youth can explain the increased sport participation of elderly Japanese. Data from the Japanese National Sport-Life Survey over 20 years were analyzed through regression analysis. The results show that, after controlling for demographics and other determinants of sport participation, individuals who experienced the Tokyo 1964 Olympic Games participated in sport more frequently than other generations.     

金属间化合物Nd_3Co的比热测定

我们对金属门化合物Nd3Co的比热在2K～35K的温度范围内进行了测量．观察到在8.5K、14K和25K．有三个磁性转变点。     

The continuous measurement of the springboard reaction force in gymnastic vaulting

A new method was established for the continuous measurement of force applied from a springboard to a gymnast in vaulting (board reaction force). Male gymnasts performed a handspring vault using a springboard mounted on force platforms. A high-speed video camera sampled the springboard motion at 500 Hz. The springboard was initially partitioned into 29 segments. The force due to the accelerative motion of the springboard was determined by summing the forces of the individual segments. The board reaction force acting on the gymnast was calculated by subtracting the force due to the accelerative motion of the springboard and weight from the force recorded by the force platform. The new method succeeded in illustrating transient changes of the board reaction force. The horizontal and vertical components of the peak values of the board reaction force were three and two times greater respectively than the average values. A series of tests was conducted to determine whether the number of segments of the springboard model could be reduced without affecting accuracy. A model consisting of only four segments produced almost the same accuracy as the 29-segment model. The simplified model is recommended as a more efficient method to measure board reaction force.