Differences in pedalling technique between road cyclists of different competitive levels

The purpose of this study was to compare the pedalling technique in road cyclists of different competitive levels. Eleven professional, thirteen elite and fourteen club cyclists were assessed at the beginning of their competition season. Cyclists’ anthropometric characteristics and bike measurements were recorded. Three sets of pedalling (200, 250 and 300 W) on a cycle ergometer that simulated their habitual cycling posture were performed at a constant cadence (~90 rpm), while kinetic and kinematic variables were registered. The results showed no differences on the main anthropometric variables and bike measurements. Professional cyclists obtained higher positive impulse proportion (1.5–3.3% and P < 0.05), mainly due to a lower resistive torque during the upstroke (15.4–28.7% and P < 0.05). They also showed a higher ankle range of movement (ROM, 1.1–4.0° and P < 0.05). Significant correlations (P < 0.05) were found between the cyclists’ body mass and the kinetic variables of pedalling: positive impulse proportion (r = ?0.59 to ?0.61), minimum (r = ?0.59 to ?0.63) and maximum torques (r = 0.35–0.47). In conclusion, professional cyclists had better pedalling technique than elite and club cyclists, because they opted for enhancing pulling force at the recovery phase to sustain the same power output. This technique depended on cycling experience and level of expertise.     

Performance differences when using 26- and 29-inch-wheel bikes in Swiss National Team cross-country mountain bikers

The purpose of this study was to analyse the effect of bike type – the 26-inch-wheel bike (26“ bike) and the 29-inch-wheel bike (29“ bike) – on performance in elite mountain bikers. Ten Swiss National Team athletes (seven males, three females) completed six trials with individual start on a simulated cross-country course with 35 min of active recovery between trials (three trials on a 26“ bike and three trials on a 29“ bike, alternate order, randomised start-bike). The course consisted of two separate sections expected to favour either the 29“ bike (section A) or the 26“ bike (section B). For each trial performance, power output, cadence and heart rate were recorded and athletes’ experiences were documented. Mean overall performance (time: 304 ± 27 s vs. 311 ± 29 s; P < 0.01) and performance in sections A (P < 0.001) and B (P < 0.05) were better when using the 29“ bike. No significant differences were observed for power output, cadence or heart rate. Athletes rated the 29“ bike as better for performance in general, passing obstacles and traction. The 29“ bike supports superior performance for elite mountain bikers, even on sections supposed to favour the 26“ bike.     

A comparison of well-peer mentored and non-peer mentored athletes’ perceptions of satisfaction

The purpose of the present study was to compare well-peer mentored and non-peer mentored athletes’ perceptions of satisfaction. A total of 444 intercollegiate athletes (272 well-peer mentored and 172 non-peer mentored) from a variety of sport teams participated in the study. Athletes from both well-peer mentored and non-peer mentored groups reported their satisfaction levels using the Athlete Satisfaction Questionnaire. The results of a MANOVA and follow-up post hoc ANOVAs showed that well-peer mentored athletes were significantly more satisfied than their non-peer mentored counterparts in terms of individual performance, personal dedication, team task contribution, team social contribution, team integration, ethics, ability utilisation and training and instruction. Overall, the findings suggest that athletes who are well-peer mentored by a teammate perceive higher satisfaction levels with various aspects of their athletic experience than athletes who are not peer mentored by a teammate. Given these positive findings, practitioners (i.e., coaches, sport psychology consultants) should inform athletes on the benefits of peer-to-peer mentoring. The practical implications of the results and strategies to promote peer athlete mentoring relationships in sport are highlighted.     

Accelerometer data requirements for reliable estimation of habitual physical activity and sedentary time of children during the early years - a worked example following a stepped approach

This study presents a worked example of a stepped process to reliably estimate the habitual physical activity and sedentary time of a sample of young children. A total of 299 children (2.9 ± 0.6 years) were recruited. Outcome variables were daily minutes of total physical activity, sedentary time, moderate to vigorous physical activity and proportional values of each variable. In total, 282 (94%) provided 3 h of accelerometer data on ≥1 day and were included in a 6-step process: Step-1: determine minimum wear-time; Step-2: process 7-day-data; Step-3: determine the inclusion of a weekend day; Step-4: examine day-to-day variability; Step-5: calculate single day intraclass correlation (ICC) (2,1); Step-6: calculate number of days required to reach reliability. Following the process the results were, Step-1: 6 h was estimated as minimum wear-time of a standard day. Step-2: 98 (32%) children had ≥6 h wear on 7 days. Step-3: no differences were found between weekdays and weekend days (P ≥ 0.05). Step-4: no differences were found between day-to-day variability (P ≥ 0.05). Step-5: single day ICC’s (2,1) ranged from 0.48 (total physical activity and sedentary time) to 0.53 (proportion of moderate to vigorous physical activity). Step-6: to reach reliability (ICC = 0.7), 3 days were required for all outcomes. In conclusion following a 7 day wear protocol, ≥6 h on any 3 days was found to have acceptable reliability. The stepped-process offers researchers a method to derive sample-specific wear-time criterion.     

Cuba’s Challenges Hosting the 1991 Pan-American Games and the Spectacle of the Revolution’s ‘Soft Power’

Abstract

This paper examines the confluence of global, regional, and national politics in the lead up to the 1991 Pan-American Games hosted by Cuba. Cuba’s contentious selection as host was wholly underpinned by the international politics of the time. Once selected, the preparations for the Games in Havana were surrounded by an unprecedented domestic economic crisis fueled by shifts in global politics. This paper analyzes how international politics informed the hosting of the 1991 Pan-American Games, and shaped the political challenge the Cuban government faced in hosting such an event. The Revolution’s use of sport domestically and internationally came to the forefront in its efforts as host and the results of those efforts proved to be providential given the emerging political economic contexts during and in the ensuing years after the Games.     

The Structural Adjustment of Football in Zambia: Politics,Decline and Dispersal, 1991–1994

Abstract

This paper explores multiple and complex relationships between football (soccer), politics, and the economy in postcolonial Zambia. Based on archival and oral sources collected in Zambia, the paper argues that President Frederick Chiluba’s government failed to support football development when it came into power in 1991 because it was elected on a platform of liberalizing the collapsing national economy. Chiluba privatized state-owned companies that were sponsoring the game resulting in the plummeting of the local standards and migration of talented footballers abroad in search of better livelihoods. Furthermore, the paper argues that while the exodus of talented footballers led to the deterioration of the standards of the local league, their transnational experience boosted the performance of the Zambia national football team. This led to the emergence of one of the best national teams the country has ever had. Unfortunately, this particular team perished in the Gabon air disaster in 1993 following the government’s disinvestment in the game. However, a few months after the disaster, the country managed to rebuild a national football team, which emerged as runners up to Nigeria in the 1994 African Cup of Nations final as a result of a large pool of local and foreign-based football players.     

Equity in groupwork: the social process of creating justice in a science classroom

Cultural Studies of Science Education - Over the last few decades, there has been an international focus on productive talk in science classrooms, requiring teachers to use more dialogic practices...     

The kinematic differences between off-spin and leg-spin bowling in cricket

Spin bowling is generally coached using a standard technical framework, but this practice has not been based upon a comparative biomechanical analysis of leg-spin and off-spin bowling. This study analysed the three-dimensional (3D) kinematics of 23 off-spin and 20 leg-spin bowlers using a Cortex motion analysis system to identify how aspects of the respective techniques differed. A multivariate ANOVA found that certain data tended to validate some of the stated differences in the coaching literature. Off-spin bowlers had a significantly shorter stride length (p = 0.006) and spin rate (p = 0.001), but a greater release height than leg-spinners (p = 0.007). In addition, a number of other kinematic differences were identified that were not previously documented in coaching literature. These included a larger rear knee flexion (p = 0.007), faster approach speed (p < 0.001), and flexing elbow action during the arm acceleration compared with an extension action used by most of the off-spin bowlers. Off-spin and leg-spin bowlers also deviated from the standard coaching model for the shoulder alignment, front knee angle at release, and forearm mechanics. This study suggests that off-spin and leg-spin are distinct bowling techniques, supporting the development of two different coaching models in spin bowling.     

Physical fitness normative values for 6–18-year-old Greek boys and girls,using the empirical distribution and the lambda,mu, and sigma statistical method

The aim of the this study was to establish age- and gender-specific physical fitness normative values and to compare percentiles and Z scores values in a large, nationwide sample of Greek children aged 6–18 years. From March 2014 to May 2014, a total of 424,328 boys and girls aged 6–18 years who attended school in Greece were enrolled. The studied sample was representative, in terms of age–sex distribution and geographical region. Physical fitness tests (i.e. 20?m shuttle run test (SRT), standing long jump, sit and reach, sit-ups, and 10?×?5?m SRT) were performed and used to calculate normative values, using the percentiles of the empirical distributions and the lambda, mu, and sigma statistical method. Normative values were presented as tabulated percentiles for five health-related fitness tests based on a large data set comprising 424,328 test performances. Boys typically scored higher than girls on cardiovascular endurance, muscular strength, muscular endurance, and speed/agility, but lower on flexibility (all p values <0.001). Older boys and girls had better performances than younger ones (p?相似文献