School of Kinesiology, Arthur and Sonia Labatt Health Sciences Building, University of Western Ontario, London, Ontario, N6A 5B9, Canada.
Muscle Nerve. 2014 Feb;49(2):218-24. doi: 10.1002/mus.23888. Epub 2013 Oct 12.
Both voluntary and evoked conditioning contractions will potentiate muscle twitch contractile properties. The response of a voluntary contraction to each condition type is not well understood but it may be a more functional model than evoked twitch potentiation.
Baseline measurements from tibialis anterior included: maximal isometric twitch torque and rate of torque development (RTD); maximal evoked 50-Hz torque; and maximal voluntary ballistic RTD. Potentiation was induced by a 10-s voluntary or tetanic contraction (∽78% MVC), followed by 2 twitches and 2 ballistic contractions.
Twitch properties (torque and RTD) were potentiated equally after each conditioning contraction. Ballistic RTD was greater post-tetanus (390.2 ± 59.3 Nm/s) than post-voluntary (356.4 ± 69.1 Nm/s), but both were reduced from baseline (422.0 ± 88.9 Nm/s).
Twitch potentiation was similar between conditioning contraction types, but ballistic RTD was lower after post-tetanus than post-voluntary. The results indicate central inhibition or fatigue concurrent with peripheral potentiation.
自愿和诱发的条件反射收缩都会增强肌肉抽搐的收缩特性。对于每种条件类型的自愿收缩反应尚不清楚，但它可能是比诱发的抽搐增强更具功能性的模型。
胫骨前肌的基线测量包括：最大等长抽搐扭矩和扭矩发展速率（RTD）；最大诱发的 50-Hz 扭矩；以及最大自愿弹道 RTD。通过 10 秒的自愿或强直收缩（约 78%MVC）诱导增强，随后进行 2 次抽搐和 2 次弹道收缩。
在每次条件反射收缩后，抽搐特性（扭矩和 RTD）均相等地增强。弹道 RTD 在强直后（390.2±59.3 Nm/s）大于自愿后（356.4±69.1 Nm/s），但均低于基线（422.0±88.9 Nm/s）。
两种条件反射收缩类型的抽搐增强相似，但强直后弹道 RTD 低于自愿后。结果表明，在周围增强的同时存在中枢抑制或疲劳。
