Do accelerometers mounted on the back provide a good estimate of impact loads in jumping and landing tasks?

Artistic gymnasts are frequently exposed to both low- and high-magnitude loads through impacts with the apparatus. These impact loads are thought to be associated with the high injury rates observed in gymnastics. Due to the variable apparatus and surfaces in gymnastics, impact loads during training are difficult to quantify. This study aimed to use triaxial accelerometers mounted on the back to assess impact loading during jumping and landing tasks. Twelve participants were fitted with an accelerometer on their upper and lower back, before performing a continuous hopping task, as well as drop landings and rebound jumps from various heights (37.5, 57.5, and 77.5 cm) onto a force platform. Peak resultant acceleration (PRA) was low-pass filtered with four cut-off frequencies (8, 15, 20, and 50 Hz). Filtering of PRA with the 20 Hz cut-off frequency showed the highest correlations between ground reaction force (GRF) and PRA. PRA recorded at the upper back, filtered with a 20 Hz cut-off frequency, appears to provide a good estimate of impact loading for continuous hopping and rebound jumps, but less so for drop landings since correlations between GRF and PRA were only significant when landing from 57.5 cm.     

Do the effects of high intensity 40 km cycling upon left ventricular function and cardiac biomarker during recovery vary with time of day?

Abstract

Twelve healthy participants performed two identical high-intensity 40 km cycling trials (morning and evening) under controlled laboratory conditions. Echocardiograms and venous blood samples were collected before and after each exercise bout. Cardiac electro-mechanical-delay (cEMD) was measured as QRS-complex onset to peak systolic (S’) and early diastolic (E’) tissue velocities. Myocardial strain and strain rates were assessed in longitudinal, circumferential and radial planes at the left ventricular apex and base. Cardiac troponin I (cTnI) and N-terminal Pro-Brain Natriuretic Peptide (NT-proBNP) were assessed as biomarkers of cardiomyocyte damage and wall stress. cEMD was lengthened after both morning (S’: 160 ± 30 vs. 193 ± 27; E’: 478 ± 60 vs. 620 ± 87, P < 0.05) and evening (S’: 155 ± 29 vs. 195 ± 31; E’: 488 ± 42 vs. 614 ± 61, P < 0.05) trials. A reduction in peak S’ (morning: 6.96 ± 1.12 vs. 6.66 ± 0.89; evening: 7.09 ± 0.94 vs. 7.02 ± 0.76) was correlated with cEMD (r = ?0.335, P < 0.05). Peak longitudinal strain was reduced, atrial strain rates were sporadically increased in both trials post-cycling. cTnI was elevated in only two participants (0.04 µg · L^?1, 0.03 µg · L^?1), whilst NT-proBNP was below the clinical cut-off point in all participants. Prolonged-cycling resulted in a lengthening of cEMD, small changes in aspects of left ventricular deformation and sporadic increases in cardiac biomarkers. None of these effects were moderated by time-of-day.     

Missing in Action? New Perspectives on the Origins and Diffusion of Women's Football in Australia during the Great War

Previous work on female participation in Australian Rules football has highlighted the seemingly discontinuous character of the women's game as it spread from Western Australia to Victoria during the period of the Great War. In this paper, an overview of the current literature on the topic is provided, and there is a focus on hitherto ‘missing links’ in the existing sequence of events – the knowledge of which has the potential to create a more integrated narrative of the code. In particular, the photographic, filmic and textual evidence for matches of women's football played in South Australia during the Great War is discussed. These games, with proceeds directed to such charities as the ‘Workers' Memorial Fund’ as well as ‘comforts for the Anzacs’, attracted sizeable crowds and were sometimes played under the patronage of the governor of the state, the mayor of Adelaide and senior military officers. The paper concludes with a reflection on how the availability (or unavailability) of particular digitised sources, and the serendipitous nature of research itself, can have a problematic influence on investigations associated with marginalised sports such as women's football.     

Do they make a difference? Professional team sports clubs’ effects on migration and local growth: Evidence from Denmark

It is a common argument in Denmark that municipal involvement in professional team sports can be justified on the grounds of local impact. The use of public funds to directly or indirectly subsidise local professional team sports clubs (PTSCs) is often seen as warranted due to the PTSCs’ positive effects on local economic growth or (inbound) municipal migration. However, can PTSCs be associated with tangible effects at all? This question has never been answered properly in a European context. Based on data covering the 2008–2013 period, and using spatial panel regression models, this article examines this issue in relation to three dominant professional sports in Denmark: football (soccer), handball and ice hockey. The study finds effects for only one of the sports examined, with Danish handball clubs exercising a marginal effect on average income. Ice hockey’s effect is negative and football remains insignificant in all models deployed. Concerning migration, negative effects are found in relation to female handball clubs. These findings are consistent with previous research and have implications for local sport policies and managers. Municipal politicians, public authorities or sport managers should no longer rationalise the use of public funds for local PTSCs on the assumption of (tangible) economic effects or population growth, as it appears to be an inefficient use of public money. If policy makers want to increase municipal income or inbound migration, they should engage themselves in developing more appropriate strategies.     

Do PON1-Q192R and PON1-L55M polymorphisms modify the effects of hypoxic training on paraoxonase and arylesterase activity?

Background:Low levels of antioxidant paraoxonase 1(PON 1) enzyme activity,PON1-Q192R polymorphism(a glutamine(Q) to arginine(R)substitution at position 192),PON1-L55M polymorphism(a leucine(L) to methionine(M) substitution at position 55),and oxidized low-density lipoprotein(oxLDL) are risk factors for coronary heart disease.Aerobic exercise improves PON1 activity,but the effects of hypoxic exercise are yet unclear.The aim of this study was to determine the effects of hypoxic underwater rugby tr...     

‘Do I have a choice?’ The influences of family values and investments on Chinese migrant young people's lifestyles and physical activity participation in Australia

This paper examines Chinese migrant young people's lifestyles and physical activity experiences in relation to the values and cultural investments of their families in Australia. The data in this paper were taken from a larger-scale study underpinned by a critical and interpretive ethnographic method conducted in two school sites. The young people's lives were significantly shaped by dominant Chinese cultural norms and traditional notions of gender. Bourdieuian concepts are drawn upon to explain the (re)production of the Chinese young people's habitus cultivated at home. Based on the young people's pursuit of cultural capital as a consequence of familial values, discussion also focuses on the agency of these young people in relation to their lifestyle choices. Dominant discourses in the ‘talk’ of these young people included their notions of excelling, hyper-investment in academic success and, especially for the girls, skin colour and safety. Traditional Chinese family power relations limited the choices these young people had regarding physical activity which was complicated by the cultural and social fluidity of their lived experiences. The inter-generational flow of habitus and capital of these Chinese migrant young people's families tended to privilege a particular set of discourses based on gender, race, social class and hierarchical practices that resonated with traditional Confucian philosophy.     

Do expert swimmers have expert technique? Comment on "Arm coordination and performance level in the 400-m front crawl" by Schnitzler, Seifert, and Chollet (2011)

In a recent article by Schnitzler, Seifert, and Chollet (2011), they used an index of coordination (IdC) to quantify arm synchronization in swimming, which has become a practical standard to measure gaps (negative IdC) and overlaps (positive IdC) in arm propulsion. Their previous work supported an increase in IdC as swimming velocity and performance level increase, consistent with mechanics and physiology. Their recent study showed a lower IdC for expert swimmers than for recreational swimmers and concluded "catch-up coordination can be an efficient coordination mode. "In the hopes of preventing coaches and swimmers from using this finding to justify "catch-up stroke", other explanations are suggested.     

Does intensity really matter regarding aerobic exercise reductions in wave reflection and central hemodynamics? Commentary on "The effect of acute aerobic exercise on central arterial stiffness,wave reflections,and hemodynamics in adults with diabetes: A randomized cross-over design"by Way et al.

We read with great interest the study by Way et al.1 pub-lished in this journal, which described and compared the acute changes in central arterial stiffness (A...