Purpose The aim of the present study was to evaluate the trunk strength capacity of alpine ski racers aged 10-18 years,who were tested during the last 15 years,to identify reference values for trunk flexor to extensor...Purpose The aim of the present study was to evaluate the trunk strength capacity of alpine ski racers aged 10-18 years,who were tested during the last 15 years,to identify reference values for trunk flexor to extensor strength ratios according to age and sex.Methods In total,2841 participants(1605 males,1236 females;10-18 years)were included,who were pupils of a famous skiing-specific secondary modern school or members of the provincial ski team between 2006 and 2020.The maximum isometric trunk flexion and extension strength was measured using the slightly modified Back Check.Sex-specific differ-ences were assessed with Student’s t test or Mann-Whitney-U test.Univariate analyses of variance or Kruskal-Wallis-H tests were used to assess differences between age groups.Descriptive sex-and age-specific reference values were calculated(norm area:mean±½standard deviation).Results Sex-specific differences were found for both flexion(starting at 11 years)and extension strength(starting at 12 years)(P<0.001).Lower flexion to extension strength ratios were identified for males(0.89±0.18)compared with females(0.82±0.15),but the ratios remained constant across age groups for both sexes.Conclusion The present study provides age-and sex-specific reference values for trunk flexion to extension strength ratios for 10-to 18-year old youth and adolescent ski racers.The data of the present study represent a large data pool of youth ski racers at a high-performance level;thus,coaches can use the reference values for comparing the ratios of their athletes.展开更多
Purpose To compare anthropometric and physical performance profiles of Japanese 11th and 12th grade American football players within each positional group.Methods Fifty-two 11th and 12th grade American football player...Purpose To compare anthropometric and physical performance profiles of Japanese 11th and 12th grade American football players within each positional group.Methods Fifty-two 11th and 12th grade American football players from two Japanese high schools participated in the study during the summer pre-season period.They performed anthropometric(height and body mass)and physical(vertical jump,broad jump,40-yard dash,pro-agility shuttle 4-kg medicine ball chest throw,front throw,and back throw)testing.Vertical jump momentum and 10-yard sprint momentum were also calculated by multiplying the velocity and body mass.Athletes were divided into two groups by playing positions:skill players and linemen.Results Skill players in the 12th grade were better at medicine ball chest throw(d=0.73,P=0.04)and vertical jump momen-tum(d=0.75,P=0.03)than those in the 11th grade.However,there were no differences in any measurements(P>0.05)between linemen from the two grades.Conclusion The current study suggests that upper and lower body absolute power and momentum production can be improved for skill players even over 17 years old.On the other hand,body size and speed,attributes that did not change between 11th and 12th grades,seem to be essential talent identification criteria in the current environment.Further study is needed to monitor longitudinal performance improvements in implementing talent development programs by focusing on the quality of speed,agility and power development at the youth level.展开更多
文摘Purpose The aim of the present study was to evaluate the trunk strength capacity of alpine ski racers aged 10-18 years,who were tested during the last 15 years,to identify reference values for trunk flexor to extensor strength ratios according to age and sex.Methods In total,2841 participants(1605 males,1236 females;10-18 years)were included,who were pupils of a famous skiing-specific secondary modern school or members of the provincial ski team between 2006 and 2020.The maximum isometric trunk flexion and extension strength was measured using the slightly modified Back Check.Sex-specific differ-ences were assessed with Student’s t test or Mann-Whitney-U test.Univariate analyses of variance or Kruskal-Wallis-H tests were used to assess differences between age groups.Descriptive sex-and age-specific reference values were calculated(norm area:mean±½standard deviation).Results Sex-specific differences were found for both flexion(starting at 11 years)and extension strength(starting at 12 years)(P<0.001).Lower flexion to extension strength ratios were identified for males(0.89±0.18)compared with females(0.82±0.15),but the ratios remained constant across age groups for both sexes.Conclusion The present study provides age-and sex-specific reference values for trunk flexion to extension strength ratios for 10-to 18-year old youth and adolescent ski racers.The data of the present study represent a large data pool of youth ski racers at a high-performance level;thus,coaches can use the reference values for comparing the ratios of their athletes.
基金funded by JSPS KAKENHI,Grant Number 16K16557 and JSC High Performance Center Total Conditioning Research Project.
文摘Purpose To compare anthropometric and physical performance profiles of Japanese 11th and 12th grade American football players within each positional group.Methods Fifty-two 11th and 12th grade American football players from two Japanese high schools participated in the study during the summer pre-season period.They performed anthropometric(height and body mass)and physical(vertical jump,broad jump,40-yard dash,pro-agility shuttle 4-kg medicine ball chest throw,front throw,and back throw)testing.Vertical jump momentum and 10-yard sprint momentum were also calculated by multiplying the velocity and body mass.Athletes were divided into two groups by playing positions:skill players and linemen.Results Skill players in the 12th grade were better at medicine ball chest throw(d=0.73,P=0.04)and vertical jump momen-tum(d=0.75,P=0.03)than those in the 11th grade.However,there were no differences in any measurements(P>0.05)between linemen from the two grades.Conclusion The current study suggests that upper and lower body absolute power and momentum production can be improved for skill players even over 17 years old.On the other hand,body size and speed,attributes that did not change between 11th and 12th grades,seem to be essential talent identification criteria in the current environment.Further study is needed to monitor longitudinal performance improvements in implementing talent development programs by focusing on the quality of speed,agility and power development at the youth level.
