Oscillations in neural drive and age-related reductions in force steadiness with a cognitive challenge.
Oscillations in neural drive and age-related reductions in force steadiness with a cognitive challenge.
复制标题
神经驱动力的振荡和与年龄相关的力量稳定性的降低以及认知挑战。
DOI：
10.1152/japplphysiol.00821.2018
复制
发表时间：
2019
期刊：
影响因子：
--
通讯作者：
Hunter,SandraK
中科院分区：
文献类型：
--
作者：
Pereira,HugoM;Schlinder-DeLap,Bonnie;Keenan,KevinG;Negro,Francesco;Farina,Dario;Hyngstrom,AllisonS;Nielson,KristyA;Hunter,SandraK
当在低力等长收缩期间施加认知挑战时，会加剧与性别和年龄相关的力稳定性下降，但其机制尚不清楚。我们确定了振荡的作用，在共同的突触输入到运动单位的力量稳定性在肌肉收缩与并发的认知挑战。49名年轻人（19 - 30岁; 25名女性，24名男性）和36名老年人（60 - 85岁; 19名女性，17名男性）在5%最大随意收缩的等长肘关节屈曲任务期间进行认知挑战（向后计数13）。从高密度表面肌电图记录中分解出单运动单位。对于一个亚组的参与者，运动单位在控制和认知挑战试验中匹配，因此在不同条件下分析了相同的运动单位。在控制和认知挑战试验中，力稳定性降低与运动单位突触输入的振荡增加相关（r = 0.45-0.47，P <0.01）。老年人和年轻女性在施加认知挑战时，运动单位的共同突触输入表现出更大的振荡，力的稳定性降低，但年轻男性在不同条件下没有变化（会话×年龄×性别，P <0.05）。当年轻女性和老年人在低力收缩过程中施加认知挑战时，运动单位共同突触输入的振荡是改变力稳定性的潜在机制。新&值得注意的是，我们发现，当在低力收缩过程中施加认知挑战时，运动单位共同突触输入的振荡与力稳定性的降低有关。在年轻女性和老年男性和女性中肘部屈肌肌肉的力量收缩，而不是年轻男性。年龄和性别相关的肌肉无力与这些变化有关。
A cognitive challenge when imposed during a low-force isometric contraction will exacerbate sex- and age-related decreases in force steadiness, but the mechanism is not known. We determined the role of oscillations in the common synaptic input to motor units on force steadiness during a muscle contraction with a concurrent cognitive challenge. Forty-nine young adults (19–30 yr; 25 women, 24 men) and 36 old adults (60–85 yr; 19 women, 17 men) performed a cognitive challenge (counting backward by 13) during an isometric elbow flexion task at 5% of maximal voluntary contraction. Single-motor units were decomposed from high-density surface EMG recordings. For a subgroup of participants, motor units were matched during control and cognitive challenge trials, so the same motor unit was analyzed across conditions. Reduced force steadiness was associated with greater oscillations in the synaptic input to motor units during both control and cognitive challenge trials (r= 0.45–0.47,P< 0.01). Old adults and young women showed greater oscillations in the common synaptic input to motor units and decreased force steadiness when the cognitive challenge was imposed, but young men showed no change across conditions (session × age × sex,P< 0.05). Oscillations in the common synaptic input to motor units is a potential mechanism for altered force steadiness when a cognitive challenge is imposed during low-force contractions in young women and old adults.NEW & NOTEWORTHYWe found that oscillations in the common synaptic input to motor units were associated with a reduction in force steadiness when a cognitive challenge was imposed during low-force contractions of the elbow flexor muscles in young women and old men and women but not young men. Age- and sex-related muscle weakness was associated with these changes.