Journal of sports sciences
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Clinical Trial
Correlation of axial impact forces with knee joint forces and kinematics during simulated ski-landing.
Anterior cruciate ligament (ACL) rupture, during ski-landing, is caused by excessive knee joint forces and kinematics, like anterior tibial translation, internal tibial rotation, and valgus rotation. It is not well understood how these forces/kinematics are directly related to ski-landing impact. In the present study, we applied simulated ski-landing impact to knee specimens, and examined joint force/kinematic responses and their correlations with impact force. ⋯ We found positive correlations of axial impact force with anterior tibial force, medial tibial force, anterior tibial translation, internal tibial rotation, and valgus joint rotation. Axial impact forces were more strongly correlated with anterior tibial forces (R(2) = 0.937 ± 0.050), anterior tibial translation (R(2) = 0.916 ± 0.059), and internal tibial rotation (R(2) = 0.831 ± 0.141) than medial tibial force (R(2) = 0.677 ± 0.193) and valgus joint rotation (R(2) = 0.630+0.271). During ski-landing, these joint forces/kinematics can synergistically act to increase ACL injury risk, whereby the failure mechanism would be dominated by anterior tibial forces, anterior tibial translation, and internal tibial rotation.
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Although triathlon is growing in popularity at a remarkable rate, it has not been extensively studied. The aims of this research were to identify preparation strategies used by triathletes and to categorize these strategies according to gender and consultation with triathlon coaches. Survey data collected from 401 triathletes (207 males, 194 females) revealed training, nutritional, and mental preparation habits. ⋯ More male triathletes reported using nutritional supplements during training than their female counterparts. These findings add to the limited research base on triathletes' training habits, and hopefully will help guide practitioners who work with this group. The results provide guidance for collaborative efforts among training, nutrition, and mental health professionals to best support triathletes.
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In this review, we examine the original obesity paradox phenomenon (i.e. in cardiovascular disease populations, obese patients survive better), as well as three other related paradoxes (pre-obesity, "fat but fit" theory, and "healthy" obesity). An obesity paradox has been reported in a range of cardiovascular and non-cardiovascular conditions. Pre-obesity (defined as a body mass index of 25.0-29.9 kg · m⁻²) presents another paradox. ⋯ The final paradox under consideration is the presence of a sizeable subset of obese individuals who are otherwise healthy. Consequently, a large segment of the overweight and obese population is not at increased risk for premature death. It appears therefore that low cardiorespiratory fitness and inactivity are a greater health threat than obesity, suggesting that more emphasis should be placed on increasing leisure time physical activity and cardiorespiratory fitness as the main strategy for reducing mortality risk in the broad population of overweight and obese adults.
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The aim of this study was to determine whether triceps brachii muscle volume can be adequately estimated from a single anatomical cross-sectional area (ACSA) and can the same model be used for prediction after training. Thirty-five healthy male non-athletes (age 21.6 ± 2.5 years, body mass index 24.8 ± 3.5 kg · m(-2)) volunteered for this study. The volumes of the upper arm extensors were calculated from magnetic resonance imaging (MRI) sequence scans and regression models were developed, which were used to predict muscle volumes from single MRI cross-sectional scans taken at different points along the humerus length. ⋯ Thesame prediction formula can be used for the left arm (r = 0.904). If a single ACSA is used for triceps brachii volume prediction, the best fit is with Model CSA(60%) and HL, both before and after training (r = 0.941). By introducing humerus length into the calculation, we simplify the procedure for volume measurement, since it can be obtained during MRI scanning.
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Clinical Trial
The effects of an increasing versus constant crank rate on peak physiological responses during incremental arm crank ergometry.
We examined the effects of concomitant increases in crank rate and power output on incremental arm crank ergometry. Ten healthy males undertook three incremental upper body exercise tests to volitional exhaustion. The first test determined peak minute power. ⋯ Test duration was shorter for the increasing than for the constant crank rate protocol. The relationship between local RPE and heart rate differed between tests. The results of this study show that increasing cadence during incremental arm crank ergometry provides a valid assessment of peak responses over a shorter duration but alters the heart rate-local RPE relationship.