| By studying the differences in body shape and quality of students of different ages,bone ages and development types,the changes in body shape and quality are analyzed to explore their development laws and characteristics.At the same time,studying the sudden increase period of body shape and physical quality of students of the same development type can provide the basis for physical education teaching,suggesting that strengthening physical education during this period plays an extremely important role in improving students’ physique,and also lays a solid foundation for improving the public physique,and also lays a foundation for the selection and development of excellent reserve talents in competitive sports.Research objectives:By testing the students’ body shape,physical quality and bone age,this paper discusses the relevance of bone age,body shape,physical quality and youth development period,and provides suggestions and countermeasures for students’ healthy growth and health promotion.Research Methods:The bone age,body shape and physical fitness of 160 boys aged 11-14 and 147 girls aged 9-12 were tested.Body shape indicators include height,weight and BMI,and physical quality indicators include grip strength,vertical jump,sit-ups,selective reaction time(hereinafter referred to as reaction time),dot test(Dot A,Dot B,Dot C),sitting forward bending(hereinafter referred to as forward bending),single-legged standing,30-second rope skipping,and stepping.The students were grouped according to age,bone age,development type,exercise habit and BMI,and the data were analyzed.Research results:(1)The bone age of male and female students in all age groups is greater than the actual age.The bone age of male was 0.39～0.81 years older than the actual age,and that of female was 0.43～0.72 years older than the actual age,the difference was statistically significant(P<0.05).(2)The body shape and physical quality of all students basically keep synchronous growth with the age of life and bone age,while the speed quality and flexibility of boys increase more significantly with bone age.(3)Compared with students with low bone development type,boys and girls with high bone development type have larger body size(height,weight,BMI)and stronger strength(such as upper and lower limb strength and core strength of boys and upper and lower limb strength of girls)(P<0.01).(4)The height and weight of the precocious group of 11-year-old boys were higher than that of the normal group.The height,weight,grip strength and vertical jump of the precocious 12-year-old boys were higher than those of the normal group;Sit-ups,standing on one leg,rope skipping in 30 seconds,and stepping were less than those in the normal group.The height and grip strength of the precocious group of 13-year-old boys were higher than those of the normal group.The BMI of the precocious group of14-year-old boys was higher than that of the normal group,and the sit-ups and reaction time were lower than that of the normal group,with a significant difference(P<0.05).The height,weight and BMI of the precocious group of 9-year-old girls were higher than those of the normal group.The height,weight and grip strength of the precocious group of 10-year-old girls were higher than that of the normal group,and the rope skipping in 30 seconds was lower than that of the normal group.The height,weight and grip strength of the precocious group of 11-year-old girls were higher than those of the normal group.The height,weight,grip strength,vertical jump,punch-point A and punch-point C of the precocious 12-year-old girls were significantly higher than those of the normal group(P<0.05).(5)Body sudden increase period: in terms of shape,the sudden increase period of boys’ height is between 13-14 years old,and the bone age increases significantly in this sudden increase period(P<0.01).There was no obvious sudden increase in body weight.The girls’ height and weight increased in a sudden period between 11-12 years old,and the bone age increased significantly in this sudden period(P<0.01).In terms of quality,boys’ core strength,action speed,balance ability,sensitivity,and endurance increased suddenly between the ages of 11-12,and their lower limb strength,reaction speed,and flexibility increased suddenly between the ages of 12-13.The girls’ balance ability,sensitivity and endurance increased between 9-10 years old,speed endurance and flexibility increased between 10-11 years old,and lower limb strength and reaction speed increased between 11-12 years old.(6)Boys with exercise habits have better performance in core strength,sensitivity and endurance than boys without exercise habits.Girls with exercise habits have better performance in height,strength(upper and lower limbs,core strength)and endurance than girls without exercise habits.There was no difference in bone age between male and female students with or without exercise habits.It shows that participating in sports during adolescence is helpful to improve body shape and quality,but has no effect on bone age.(7)The bone age of obese male and female students increased earlier than that of male and female students with normal BMI(P<0.05),indicating that the degree of obesity affected the growth and development of students.Obese boys are better than boys with normal BMI in height and upper limb strength,while core strength and endurance are the opposite.Girls with normal BMI are better than obese girls in lower limb strength,flexibility and endurance.Research conclusion:(1)The bone age of male and female students in all age groups was greater than the life age.With the increase of actual age and bone age,the height,weight,BMI,strength quality(upper and lower limbs)and speed quality of male and female students increased significantly,and the flexibility of male students also increased significantly.(2)Bone age is closely related to body shape and physical quality.Male and female students with high bone maturity have greater advantages in height,weight,physical quality,especially upper limb strength.(3)The sudden increase of body shape is shown in girls’ height and weight at 11-12 years old,boys’ height at 13-14 years old,and boys’ weight does not show obvious age sudden increase.The sudden increase of physical quality is shown in boys’ 11-12 years old and girls’ 9-10 years old.(4)Exercise habits have no obvious effect on bone age,but contribute to the growth of shape and quality.Obesity can lead to early bone development in children. |
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