8—17岁儿童少年股外肌肌纤维组成最大等长伸膝力量、相对肌力及肌围的研究

本文用活检一组化方法对153名8～17岁儿童少年(男80人,女73人)做了股外肌快肌纤维%(FT%)的研究,并同时测定了最大等长伸膝力量(MVC)、相对肌力(RMVC)及肌围(活检处腿围,C)。实验发现男、女儿童及全体FT%均呈近似常态分布。且性别间也无显著差异(P>0.05)。还发现8～17岁儿童少年的MVC、RMVC及C均随年龄增长而增大。肌力(MVC及RMVC)与股外肌FT%间只有低度相关(r=0.23,r=0.30;P<0.05),而肌力(MVC)与肌围间却有密切相关(r=0.69,P<0.01)。     

Effect of vibration on static force sensation in man

To study the role of peripheral muscle receptors in sensing force, five subjects matched static contractions of one quadriceps with simultaneous contractions of the opposite quadriceps. Input to the central nervous system from the active muscles was disturbed by applying high-frequency vibration (～ 160 Hz) to the patellar tendon. When the force of a vibrated muscle was matched to the force of its nonvibrated control, vibrated force was always about 30% less (P < 0.01). Conversely, when a nonvibrated muscle matched the force of a vibrated muscle, vibrated force was always about 25% greater (P < .05). Vibration, therefore, intensifies the sensation of intramuscular tension. There was a small, significant, difference in matching force (5%, P < 0.05) between vibrated and nonvibrated trials in the sham experiment, but there was no measurable effect of vibration on either quadriceps or hamstrings EMG during contraction. The EMG experiments indicate that vibration exerts its effect directly on the agonist muscle rather than through a reflex contraction of the antagonist muscles. The data do not permit specific inference about a peripheral muscle receptor that mediates this response.