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Background: In rhythmic gymnastics, balance represents a key element in achieving optimal performance. However, there is a lack of data on the modalities with which postural control is impaired by fatigue originated by actual competitive performance. Aims: This study aims to analyze the effect of fatigue consequent to a competitive performance on static balance of rhythmic gymnasts (quantitatively assessed by means of postural sway analysis) for several sport-specific positions. Methods: Fifteen rhythmic gymnasts (mean age 12.7 years) who compete at national and regional levels participated in the study. Their balance was assessed before and after a 90 s performance for 4 unipedal positions (i.e., "ring with hand support", "back split without hand support", "arabesque", and "split with hand support") using a pressure platform. Center-of-pressure (COP) time series acquired for 10 s was processed to calculate sway area, COP path length, and COP displacements in the antero-posterior and medio-lateral directions. Results: After the performance, a generalized increase in postural sway was detected for all the positions tested, with the exception of "arabesque". Sway area doubled for most positions after the performance, while fatigue appears to have a reduced effect on COP displacements in the ML direction, which were found significantly increased only for the "split with hand support" position. Conclusions: The physical effort associated with the performance influences the effectiveness of the postural control system. Coaches could include specific balance exercises even when gymnasts are fatigued to improve their adaptations to competitive conditions and reduce the risk of injuries. [ABSTRACT FROM AUTHOR]

The article discusses the longitudinal retrospective study regarding the interaction of foot and ground on individual with down syndrome when standing, wherein it states the hypotonia and ligament laxity as the characteristic features. It mentions the use of pedobarography inassessing thirteen participants with DS in a time range of 17 years, from childhood to adulthood and compare them to healthy participants.

Gears perform their main task, namely load transmission, by means of very small contact areas originated by tooth interaction and thus, the analysis of phenomena occurring at the interface between mating teeth represents a critical issue in ensuring the optimal functioning of such devices. Nevertheless, while literature proposes a huge amount of numerical tooth contact analyses (TCA), a lack of experimental validation of such approaches is to be noted, since it is extremely difficult to inspect a contact interface which is, by its own nature, closed towards the outside world. One of the most promising techniques employed in investigating contact in metallic interfaces is based on the use of high frequency ultrasonic waves; their reflection from the interface (which is known to be related to contact conditions) can be graphically processed to build maps from which it is possible to assess geometrical features of the nominal contact area and, after a suitable calibration procedure, contact pressure distribution. This study proposes the application of the ultrasonic method to investigate the contact of a tooth belonging to a spur gear with a plane, thus reproducing the case of a gear-rack system. Experimental tests were carried out under different conditions, including regular contacts, misalignments and excessive waviness of the teeth; in all cases analyzed, this technique exhibited interesting capabilities in faithfully reproducing the contact features, thus allowing us to state that it may represent a useful tool in arriving at a deeper insight into contact problems in gears and, above all, in effectively validating numerical TCA and wear models. [ABSTRACT FROM AUTHOR]