Abstract：
Acute sleep restriction (SR) reduces strength through an unknown mechanism.
OBJECTIVE: To determine how SR affects quadriceps contractile function and recruitment.
METHODS: Eighteen healthy subjects (9 M, 9F, age 23.8 ± 2.8y) underwent isometric (maximal and submaximal), isokinetic (300-60°·s-1), and interpolated twitch (ITT) assessment of knee extensors following 3d of adequate sleep (SA; 7-9 h·night-1), 3d of SR (5 h·night-1), and 7d of washout (WO; 7-9 h·night-1).
RESULTS: Compared to SA (227.9 ± 76.6Nm) and WO (228.19 ± 62.9Nm), MVIC was lesser following SR (209.9 ± 73.9Nm; p = 0.006) and this effect was greater for males (- 9.8 v. - 4.8%). There was no significant effect of sleep or sleep x speed interaction on peak isokinetic torque. Peak twitch torque was greater in the potentiated state, but no significant effect of sleep was noted. Males displayed greater potentiation of peak twitch torque (12 v. 7.5%) and rate of torque development (16.7 v. 8.2%) than females but this was not affected by sleep condition. ITT-assessed voluntary activation did not vary among sleep conditions (SA: 81.8 ± 13.1% v. SR: 84.4 ± 12.6% v. WO 84.9 ± 12.6%; p = 0.093). SR induced a leftward shift in Torque-EMG relationship at high torque output in both sexes. Compared to SA, females displayed greater y-intercept and lesser slope with SR and WO and males displayed lesser y-intercept and greater slope with SR and WO.
CONCLUSIONS: Three nights of SR decreases voluntary isometric knee extensor strength, but not twitch contractile properties. Sex-specific differences in neuromuscular efficiency may explain the greater MVIC reduction in males following SR.
OBJECTIVE: To determine how SR affects quadriceps contractile function and recruitment.
METHODS: Eighteen healthy subjects (9 M, 9F, age 23.8 ± 2.8y) underwent isometric (maximal and submaximal), isokinetic (300-60°·s-1), and interpolated twitch (ITT) assessment of knee extensors following 3d of adequate sleep (SA; 7-9 h·night-1), 3d of SR (5 h·night-1), and 7d of washout (WO; 7-9 h·night-1).
RESULTS: Compared to SA (227.9 ± 76.6Nm) and WO (228.19 ± 62.9Nm), MVIC was lesser following SR (209.9 ± 73.9Nm; p = 0.006) and this effect was greater for males (- 9.8 v. - 4.8%). There was no significant effect of sleep or sleep x speed interaction on peak isokinetic torque. Peak twitch torque was greater in the potentiated state, but no significant effect of sleep was noted. Males displayed greater potentiation of peak twitch torque (12 v. 7.5%) and rate of torque development (16.7 v. 8.2%) than females but this was not affected by sleep condition. ITT-assessed voluntary activation did not vary among sleep conditions (SA: 81.8 ± 13.1% v. SR: 84.4 ± 12.6% v. WO 84.9 ± 12.6%; p = 0.093). SR induced a leftward shift in Torque-EMG relationship at high torque output in both sexes. Compared to SA, females displayed greater y-intercept and lesser slope with SR and WO and males displayed lesser y-intercept and greater slope with SR and WO.
CONCLUSIONS: Three nights of SR decreases voluntary isometric knee extensor strength, but not twitch contractile properties. Sex-specific differences in neuromuscular efficiency may explain the greater MVIC reduction in males following SR.
摘要：
急性睡眠限制（SR）通过未知的机制降低强度。
目的：确定SR如何影响股四头肌收缩功能和募集。
方法：18名健康受试者（9M，9F,年龄23.8±2.8岁)接受等距(最大和次最大)，等速(300-60°·s-1)，和插值抽搐（ITT）评估膝关节伸肌3d充足的睡眠（SA；7-9h·night-1），SR的3d（5h·night-1），和7d的冲洗（WO；7-9h·night-1）。
结果：与SA（227.9±76.6Nm）和WO（228.19±62.9Nm）相比，在SR之后，MVIC较小（209.9±73.9Nm；p=0.006），男性的这种影响更大（-9.8v-4.8％）。睡眠或睡眠x速度相互作用对峰值等速扭矩没有显着影响。峰值抽搐扭矩在增强状态下更大，但没有注意到睡眠的显著影响。男性比女性显示出更大的峰值抽搐扭矩（12v.7.5％）和扭矩发育率（16.7v.8.2％），但不受睡眠条件的影响。ITT评估的自愿激活在睡眠条件之间没有变化（SA：81.8±13.1％v.SR：84.4±12.6％v.WO84.9±12.6％；p=0.093）。在两性的高扭矩输出下，SR引起扭矩-EMG关系向左移动。与SA相比，女性在SR和WO时显示出更大的y截距和更小的斜率，男性在SR和WO时显示出更小的y截距和更大的斜率。
结论：三晚SR降低了自愿性等距膝关节伸肌强度，但不是抽搐收缩特性。神经肌肉效率的性别特异性差异可能解释了SR后男性MVIC降低的原因。
目的：确定SR如何影响股四头肌收缩功能和募集。
方法：18名健康受试者（9M，9F,年龄23.8±2.8岁)接受等距(最大和次最大)，等速(300-60°·s-1)，和插值抽搐（ITT）评估膝关节伸肌3d充足的睡眠（SA；7-9h·night-1），SR的3d（5h·night-1），和7d的冲洗（WO；7-9h·night-1）。
结果：与SA（227.9±76.6Nm）和WO（228.19±62.9Nm）相比，在SR之后，MVIC较小（209.9±73.9Nm；p=0.006），男性的这种影响更大（-9.8v-4.8％）。睡眠或睡眠x速度相互作用对峰值等速扭矩没有显着影响。峰值抽搐扭矩在增强状态下更大，但没有注意到睡眠的显著影响。男性比女性显示出更大的峰值抽搐扭矩（12v.7.5％）和扭矩发育率（16.7v.8.2％），但不受睡眠条件的影响。ITT评估的自愿激活在睡眠条件之间没有变化（SA：81.8±13.1％v.SR：84.4±12.6％v.WO84.9±12.6％；p=0.093）。在两性的高扭矩输出下，SR引起扭矩-EMG关系向左移动。与SA相比，女性在SR和WO时显示出更大的y截距和更小的斜率，男性在SR和WO时显示出更小的y截距和更大的斜率。
结论：三晚SR降低了自愿性等距膝关节伸肌强度，但不是抽搐收缩特性。神经肌肉效率的性别特异性差异可能解释了SR后男性MVIC降低的原因。
