ABSTRACT
Objective@#To explore the effect of breastfeeding duration on age at adiposity rebound, and provide a scientific theoretical basis for identifying early life factors of obesity in children and adolescents, while promoting early intervention.@*Methods@#In September 2019, first graders from a primary school in Minhang District, Shanghai, were selected to participate in this study, and their growth information was retrospectively collected. The natural cubic spline function was used to fit the body mass index trajectory of the subjects from 1 to 80 months, and age at adiposity rebound was calculated. A total of 6 148 subjects were selected, and complete data of adiposity rebound timing and breastfeeding duration were obtained. A multiple linear regression model was used to analyze the relationship between these two variables.@*Results@#The average breastfeeding duration of all children included in the study was (3.71±3.28) months, and most of the subjects (69.63% for male and 70.45% for female) were breastfed for less than 4 months. A positive linear relationship was found between them [male, B =0.16(0.02-0.30), female, B =0.34(0.18- 0.51 ), total, B =0.23(0.12-0.34), P <0.05]. The linear relationship was determined using the multivariate model.@*Conclusion@#Breastfeeding duration independently affected age at adiposity rebound. Prolonging the duration of breastfeeding within 24 months of age may help to delay the timing of adiposity rebound,and thus reduce later risks of overweight and obesity.
ABSTRACT
Objective To compare biomechanical characteristics of the knee joint during forward walking and backward walking. Methods Temporal-spatial, kinematics, kinetics parameters of 13 healthy young male volunteers were collected and compared by 3D motion capture system Vicon T40 and force platforms AMTI OR6-7. Results Compared with forward walking, the speed, cadence and stride length significantly decreased, while the gait cycle and stance phase percentage in gait cycle significantly increased during backward walking. In the sagittal plane, the range of motion (ROM), the maximum flexion/extension moment of the knee were smaller during backward walking. In the frontal plane, the ROM of knee varus/valgus during backward walking decreased, and the peak value of knee adduction moment significantly reduced in the early stance phase while significantly increased in the late stance phase of backward walking. The peak value of ground reaction force (GRF) was significantly larger in the early stance phase while smaller in the late stance phase during backward walking than that during forward walking. Conclusions The biomechanical characteristics of the knee joint during forward walking and backward walking are significantly different. Compared with forward walking, backward walking is helpful to reduce the medial compartment load in the early stance phase. Further study will be needed to investigate the effects of backward walking on knee joint loading in the late stance phase.
ABSTRACT
Objective To assess the injury risks and affecting factors of spinal loads at L5/S1 joint for caregivers during manual patient-handling tasks, so as to find a suitable handling way to effectively reduce such risks. Methods Kinetic data were collected from nine female caregivers performing six patient handling tasks on three agent ‘patients’ with different weight. Peak L5/S1 force was calculated based on a multi-segment three-dimensional model to investigate the characteristics of injury risks, and the correlations between the peak L5/S1 force and six affecting factors were specifically analyzed. Results Peak compression of the tasks all exceeded the safe thresholds of 3.4 kN; Peak anterior-posterior force for those repositioning tasks were above the threshold of 0.5 kN. Different tasks showed different biomechanical characteristics for risk of injury and affecting factors, and there was a significant correlation between the L5/S1 loads and the moving distance of center of gravity, and the ground reaction force as well (P<0.01). Conclusions Manual patient handling tasks could cause different injury risks by high loads on spinal low back. Decreasing the range of motion of the whole body and avoiding jerk movement during the patient handling tasks would help caregiver to reduce the injury risks.