The aim of this study was to determine the influence of schoolbag carriage on pattern changes in plantar pressure during walking among schoolchildren of first grade. The sample consisted of 127 schoolchildren, 48.8% male (n = 62) and 51.2% female (n = 65), aged 6.7 (±0.5) years. The mean schoolbag weight was 4.2 kg (±0.7), which represented 16.9% (±3.9) of children’s body weight, thus exceeding the upper limit of the recommended 15% of the body weight and generally affecting their posture. The study has shown the statistically significant influence of the schoolbag on changes in plantar pressure pattern when walking in relation to walking without the schoolbag. Using a t-test for large dependent samples and by setting statistical significance at p≤.05, the significant increase was noticed in peak pressure for the forefoot (p=.000; 17.1%), midfoot (p=.000; 5.7%) and hindfoot (p=.004; 3.9%) as well as in average pressure for the midfoot (p=.005; 6.2%). Also, due to the compensatory mechanisms activated while the bag was being carried, the statistically significant increase in the contact surface at the forefoot (p=.000; 3.6%) and midfoot (p=.000, 8.8%) occurred. Changes in the distribution of pressure between different parts of the foot are a source of potential foot problems which is why the results of this study have a high applicability in the prevention of foot pathology in the future
Ball velocity is considered an important performance measure in baseball pitching. Proper pitching mechanics play an important role in both maximising ball velocity and injury-free participation of baseball pitchers. However, an individual pitcher’s characteristics display individuality and may contribute to velocity imparted to the ball. The aim of this study is to predict ball velocity in baseball pitching, such that prediction is tailored to the individual pitcher, and to investigate the added value of the individuality to predictive performance. Twenty-five youth baseball pitchers, members of a national youth baseball team and six baseball academies in The Netherlands, performed ten baseball pitches with maximal effort. The angular velocity of pelvis and trunk were measured with IMU sensors placed on pelvis and sternum, while the ball velocity was measured with a radar gun. We develop three Bayesian regression models with different predictors which were subsequently evaluated based on predictive performance. We found that pitcher’s height adds value to ball velocity prediction based on body segment rotation. The developed method provides a feasible and affordable method for ball velocity prediction in baseball pitching.
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