Isometric preactivation before active lengthening increases residual force enhancement
Isometric preactivation before active lengthening increases residual force enhancement
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DOI：
10.1111/sms.13454
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发表时间：
2019-08-01
影响因子：
4.1
通讯作者：
Isaka, Tadao
中科院分区：
文献类型：
--
作者：
Fukutani, Atsuki;Shimoho, Kento;Isaka, Tadao
主动拉伸后获得的等长力大于纯粹等长收缩中获得的等长力。这种现象被称为残余力增强（RFE）。目的是检查主动伸展前进行的等长预激活对跖屈肌RFE幅度的影响。方法在对照条件下，受试者进行15 °背屈等长收缩。在无预激活条件下，在从0 °到15 °背屈的离心收缩之后进行15 °背屈的等长收缩。在等长预激活条件下，在进行与无预激活条件下相同的程序之前进行等长收缩预激活。在15度背屈的等长收缩结束时的等长扭矩进行了比较，以检查等长预激活是否影响RFE的大小。超声记录腓肠肌内侧肌束的运动行为。结果预激活状态下获得的等长扭矩大于对照状态（P = 0.017）。无预激活和对照条件之间无显著差异（P = 0.744）。在主动拉伸过程中，预激活的肌束伸长幅度大于无预激活条件下的肌束伸长幅度（P = 0.002）。结论与对照组相比，激活前条件下的等长扭矩更大，表明激活前条件下才能诱发大量的RFE。这种差异可以解释为在无预激活条件下主动拉伸期间束伸长程度较低。
Introduction The isometric force attained after active stretch is greater than that attained in a purely isometric contraction. This phenomenon is called residual force enhancement (RFE). The purpose was to examine the influence of isometric preactivation conducted just before active stretch on the magnitude of RFE in plantar flexors. Methods In the control condition, subjects conducted isometric contraction at 15 degrees of dorsiflexion. In the no preactivation condition, the isometric contraction at 15 degrees of dorsiflexion was conducted after an eccentric contraction from 0 degrees to 15 degrees of dorsiflexion. In the isometric preactivation condition, an isometric contraction was conducted for preactivation before conducting the same routine as in the no preactivation condition. Isometric torque at the end of isometric contraction at 15 degrees of dorsiflexion was compared among conditions to examine whether isometric preactivation affects the magnitude of RFE. The fascicle behaviors of the medial gastrocnemius were recorded by ultrasonography. Results The isometric torque attained in the preactivation condition was greater than that in the control condition (P = 0.017). There was no significant difference between no preactivation and control conditions (P = 0.744). The magnitude of fascicle elongation during active stretch was greater in the preactivation than in the no preactivation condition (P = 0.002). Conclusion Compared to the control condition, greater isometric torque was observed only in the preactivation condition, indicating that substantial RFE was induced only in the preactivation condition. This difference would be explained by the lesser degree of fascicle elongation during active stretch in the no preactivation condition.