Abstract
Not only twitch torque but also the maximal voluntary concentric torque increases after a high-intensity contraction (conditioning contraction). The purpose of this study was to test the hypothesis that the increase in the maximal voluntary concentric torque induced by a conditioning contraction is prominent when tested at fast angular velocities conditions. Twelve healthy male participants performed the maximal voluntary isometric plantar flexion for six seconds as a conditioning contraction. Before and after the conditioning contraction, peak torques during the maximal voluntary concentric plantar flexions were measured at 30°/s (slow) and 180°/s (fast), each of which was carried out in a separate condition. Isometric twitch torque was also recorded before and after the conditioning contraction in each of the two velocity conditions to confirm the extent of the positive effect of the conditioning contraction. The extent of increase in isometric twitch torque was similar between the two velocity conditions, whereas the maximal voluntary concentric torque increased significantly only in the fast velocity condition (p = 0.003). These results support the hypothesis and indicate that the maximal voluntary concentric torque can be potentiated by the conditioning contraction if the joint angular velocity during the maximal voluntary concentric contraction is sufficiently high.Electronic supplementary materialThe online version of this article (doi:10.1186/2193-1801-2-554) contains supplementary material, which is available to authorized users.
Highlights
The twitch force generated by isolated muscle fibers increases shortly after a high-intensity contraction of the same muscle (MacIntosh et al 2008); (Manning and Stull 1982)
One of the possible reasons for this discrepancy is that the type of contraction used to test the effect of the conditioning contraction varied among these studies
We investigated the effects of a conditioning contraction on the increase in the maximal voluntary concentric torque at fast (180°/s) and slow (30°/s) joint angular velocities
Summary
The twitch force generated by isolated muscle fibers increases shortly after a high-intensity contraction of the same muscle (MacIntosh et al 2008); (Manning and Stull 1982) This phenomenon is called posttetanic potentiation (Abbate et al 2000). The underlying mechanism of the increase in twitch torque is considered to be the phosphorylation of the myosin regulatory light chain, which leads an It has been under debate whether the conditioning contraction increases the force or torque generated by highintensity contractions. Some studies reported that the electrically-evoked maximal isometric force was not increased by a conditioning contraction (Vandenboom et al 1993; 1995; 1997) whereas others observed increases in the maximal voluntary concentric torque (Fukutani et al 2012); (Miyamoto et al 2011).
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