An Experimental Study On The Effects Of Brief High-impact Exercise On Bone Mineral Density,Physical Fitness And Mental Health Of Junior High School Students

Research purpose:Although there is sufficient evidence to support high-impact exercise as an effective intervention to promote the health of children and adolescents,there is no research report on whether increasing the intensity of short-term high-impact exercise and adjusting load distribution can improve health benefits.Therefore,this study aims to evaluate the direct impact of 12-week short-term jumping exercises with different intensities and different load distributions on the bone mineral density and physical fitness of adolescents.Research method:220 participants were divided into 5 groups and received medium-intensity and vertical jump（MV）,medium-intensity and odd jump（MO）,vigorous-intensity and vertical jump（VV）,vigorous-intensity and odd jump（VO）and stretching exercise intervention（CON）.Assessing the bone mineral density and physical fitness of the participants before and after 12-week intervention.At the same time,in order to exclude the influence of lifestyle on the results of the intervention,this study also investigated the participants’ extracurricular exercise and daily dietary intake.Research results:（1）The increase in bone mineral density of MO,MV,VO,and VV are better than CON（P<0.05）.Compared with MV,Bone mineral density improvement of MO is higher than MV（P<0.05）,while VV is lower than MV（P<0.05）.（2）The increase in body fat percentage,waist-to-hip ratio and 1-minute squat up,MV,VO,VV are also greater than CON（P<0.05）,the MV,VV and VO had better 1-minute squat increments than the CON.The improvement in vital capacity of VV and VO are higher than CON.In terms of endurance running,the performance improvement of MV,VO,and VV are higher than CON in boys（P<0.05）.The improvement of VO and VV are higher than CON in girls.（3）Improved emotional stability of boys in MO,MV,VO,VV are better than CON（P<0.05）.Conclusions:（1）12 weeks,3 times/week,10 minutes of high-impact exercise can effectively improve the bone mineral density,physical fitness and emotional stability of adolescents.（2）Changing the direction of landing after airborne will induce more mechanical stimulation to amplifying the bone gain of high-impact exercise,while increasing exercise intensity per unit time will weaken the adaptive response of bone.（3）Body composition,muscular endurance,and cardiorespiratory endurance are more sensitive to high-impact exercises with vigorous-intensity.,Vertical jumping with medium-intensity is an efficient way to improve muscle strength.