The influence of hand positions on biomechanical injury risk factors at the wrist joint during the round-off skills in female gymnastics

The aim of this study was to examine the biomechanical injury risk factors at the wrist, including joint kinetics, kinematics and stiffness in the first and second contact limb for parallel and T-shape round-off (RO) techniques. Seven international-level female gymnasts performed 10 trials of the RO to back handspring with parallel and T-shape hand positions. Synchronised kinematic (3D motion analysis system; 247 Hz) and kinetic (two force plates; 1235 Hz) data were collected for each trial. A two-way repeated measure analysis of variance (ANOVA) assessed differences in the kinematic and kinetic parameters between the techniques for each contact limb. The main findings highlighted that in both the RO techniques, the second contact limb wrist joint is exposed to higher mechanical loads than the first contact limb demonstrated by increased axial compression force and loading rate. In the parallel technique, the second contact limb wrist joint is exposed to higher axial compression load. Differences between wrist joint kinetics highlight that the T-shape technique may potentially lead to reducing these bio-physical loads and consequently protect the second contact limb wrist joint from overload and biological failure. Highlighting the biomechanical risk factors facilitates the process of technique selection making more objective and safe.     

Acute effects of walking on inflammatory and cardiovascular risk in sedentary post-menopausal women

Biochemical markers of inflammation are emerging as new predictors of risk of cardiovascular disease (CVD) and may alter acutely with exercise. Few studies have been conducted on the effects of walking on these markers or whether different walking intensities elicit varied effects. As there is growing interest in modifiable lifestyle factors such as walking to reduce CVD risk, these inflammatory responses warrant investigation. The aim of this study was to compare the effects of walking at 50% versus 70% of predicted maximal heart rate on C-reactive protein (CRP), plasma fibrinogen, and triglycerides in sedentary post-menopausal women. Twelve post-menopausal women (mean age 58 years, s +/-6; stature 1.62 m, s+/-0.06; body mass 66.8 kg, s +/-6.2) completed two 30-min treadmill walks in a randomized cross-over design. Fasted blood samples were taken (for the determination of plasma fibrinogen, CRP, and lipids) before, immediately after, and 1 and 24 h after exercise. Triglyceride concentrations decreased from pre-exercise to 24 h post exercise at both walking intensities (time x group interaction, P < 0.05). No significant effects were observed for plasma fibrinogen, CRP, total cholesterol, low-density or high-density lipoprotein cholesterol (time x group interaction, P > 0.05). The results of this study suggest that fasting plasma triglycerides are decreased on the morning after 30 min of brisk walking at either 50% or 70% of maximal heart rate (moderate and vigorous intensity).     

Musculoskeletal demands of progressions for the longswing on high bar

Kinetic analyses of the chalked bar longswing on high bar and its associated progressions were used to explain musculoskeletal contributions during the performance of these skills. Data on four international male gymnasts performing three series of chalked bar longswings and eight progressions were recorded. Customized body segment inertia parameters, two-dimensional kinematics (50 Hz), and bar forces (1000 Hz) were used as input to inverse dynamic modelling. The analysis focused on the relative contributions of the knees, hips, and shoulders with root mean squared differences between the chalked bar longswing and the progressions being used to rank the progressions. Seventy per cent of the total work occurred between 200 degrees and 240 degrees of angular rotation in the longswing, 67% of which was contributed by the shoulders. The shoulders were also dominant in all progressions, with the largest such contribution occurring in the looped bar longswing with "no action". The least similar progression was the looped bar pendulum swing, while the most similar was the chalked bar bent knee longswing. This study provides a useful means for ranking progressions based on their kinetic similarity to the chalked bar longswing and builds on earlier research in identifying that progressions can be classified into those similar in physical demand (kinetics) and those similar in geometry (kinematics).