Core stability and core strength have been subject to research since the early 1980s. Research has highlighted benefits of training these processes for people with back pain and for carrying out everyday activities. However, less research has been performed on the benefits of core training for elite athletes and how this training should be carried out to optimize sporting performance. Many elite athletes undertake core stability and core strength training as part of their training programme, despite contradictory findings and conclusions as to their efficacy. This is mainly due to the lack of a gold standard method for measuring core stability and strength when performing everyday tasks and sporting movements. A further confounding factor is that because of the differing demands on the core musculature during everyday activities (low load, slow movements) and sporting activities (high load, resisted, dynamic movements), research performed in the rehabilitation sector cannot be applied to the sporting environment and, subsequently, data regarding core training programmes and their effectiveness on sporting performance are lacking. There are many articles in the literature that promote core training programmes and exercises for performance enhancement without providing a strong scientific rationale of their effectiveness, especially in the sporting sector. In the rehabilitation sector, improvements in lower back injuries have been reported by improving core stability. Few studies have observed any performance enhancement in sporting activities despite observing improvements in core stability and core strength following a core training programme. A clearer understanding of the roles that specific muscles have during core stability and core strength exercises would enable more functional training programmes to be implemented, which may result in a more effective transfer of these skills to actual sporting activities.

Measures of internal load derived from perceived exertion and heart rate show consistently positive associations with running- and accelerometer-derived external loads and intensity during team-sport training and competition, but the magnitude and uncertainty of these relationships are measure and training mode dependent.

BackgroundMusculoskeletal injuries during initial military training are a significant medical problem facing military organisations globally. In order to develop an injury management programme, this study aims to quantify the incidence and rehabilitation times for injury specific diagnoses.MethodsThis was a prospective follow-up study of musculoskeletal injuries in 6608 British Army recruits during a 26-week initial military training programme over a 2-year period. Incidence and rehabilitation times for injury specific diagnoses were recorded and analysed.ResultsDuring the study period the overall incidence of musculoskeletal injuries was 48.6%, and the most common diagnosis was iliotibial band syndrome (6.2%). A significant proportion of the injuries occurred during the first 11 weeks of the programme. The longest rehabilitation times were for stress fractures of the femur, calcaneus and tibia (116 ± 17 days, 92 ± 12 days, and 85 ± 11 days, respectively). The combination of high incidence and lengthy rehabilitation indicates that medial tibial stress syndrome had the greatest impact on training, accounting for almost 20% of all days spent in rehabilitation.ConclusionWhen setting prevention priorities consideration should be given to both the incidence of specific injury diagnoses and their associated time to recovery.

The inconsistencies of published data on the Young's modulus of dental enamel, the parameter used to quantify stiffness, have, for a long time, restricted our understanding of the biomechanical behavior of teeth. With the use of modeling techniques, the aim of this paper is to investigate which of the data may be more reliable. In this way, the possible causes of the discrepancies in data will be addressed. Two different structural levels are considered within the model. At an ultrastructural (i.e., crystalline) level, the model considers enamel to behave as a simple composite, being made up of long, parallel crystals held together by an organic matrix. At this level, the stiffness of enamel is predicted by simple composite theory, and the model indicates that stiffness is dependent on chemical composition and crystal orientation. At a microstructural (i.e., prismatic) level, the model considers enamel to behave as a hierarchical composite, being made up of prisms, in which the crystal orientation is heterogeneous. At this level, the stiffness of enamel is predicted by finite element stress analysis, and values of predicted stiffness are found to be dependent on both chemical composition and prism orientation. Within a realistic compositional range, predicted values of Young's modulus along the direction of prisms are comparable with the corresponding experimental values of 77.9 +/- 4.8 GPa obtained by Craig et al. (1961) and 73 GPa obtained by Gilmore et al. (1970), but not with those low values of 9.65 +/- 3.45 obtained by Stanford et al. (1960). Predictions of Young's modulus values across the direction of prisms are also made, and the model is less stiff in this direction. These findings indicate that human prismatic enamel is almost certainly anisotropic with respect to stiffness.

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Repeated-sprint training can induce small to large improvements in power, speed, repeated-sprint ability and endurance, and may have relevance for training in team sports.

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