Dept. of Integrative Physiology, Univ. of Colorado, Boulder, CO 80309-0354, USA.
J Neurophysiol. 2012 Sep;108(5):1501-10. doi: 10.1152/jn.01144.2011. Epub 2012 Jun 13.
The purpose of this study was to compare endurance time and accompanying neuromuscular adjustments when left- and right-handed subjects used the dominant and nondominant arms to sustain submaximal contractions that required either force or position control. Ten left-handed and 10 right-handed healthy adults (21 ± 5 yr) participated in the study. Each subject exerted a similar net torque about the elbow joint during the force and position tasks to achieve a target force of 20% maximal voluntary contraction (MVC) force (56 ± 18 N). MVC force declined to a similar level immediately after task failure for left- and right-handed subjects (27 ± 13 vs. 25 ± 15%, P = 0.9). Endurance time for the position task was similar for the dominant and nondominant arms (task × dominance interaction, P = 0.17). Although the difference in endurance time between the two tasks was similar for left-handed (136 ± 165 s) and right-handed individuals (92 ± 73 s, task × handedness interaction, P = 0.38), there was greater variance in the ratio of the endurance times for the force and position tasks for left-handed (0.77) than right-handed subjects (0.13, P < 0.001; see Fig. 2). Furthermore, endurance time for the force and position tasks was significantly correlated for right-handed subjects (r(2) = 0.62, P < 0.001), but not for left-handed subjects (r(2) = 0.004, P = 0.79). Multiple regression analyses identified sets of predictor variables for each endurance time, and these differed with handedness and task. Hand dominance, however, did not influence endurance time for either group of subjects. These findings indicate that endurance times for the elbow flexors when performing submaximal isometric contractions that required either force or position control were not influenced by hand dominance but did depend on handedness.
本研究旨在比较左、右手惯用人群在使用优势侧和非优势侧手臂进行次最大等长收缩时的耐力时间和伴随的神经肌肉调整，这些收缩需要力量或位置控制。10 名左利手和 10 名右利手健康成年人（21±5 岁）参与了这项研究。在力量和位置任务中，每位受试者在肘部关节处施加相似的净扭矩，以实现 20%最大自主收缩（MVC）力（56±18N）的目标力。任务失败后，左、右手惯用人群的 MVC 力迅速下降到相似水平（27±13%比 25±15%，P=0.9）。对于位置任务，优势侧和非优势侧手臂的耐力时间相似（任务×优势侧交互作用，P=0.17）。虽然左利手（136±165s）和右利手个体（92±73s，任务×利手交互作用，P=0.38）之间两个任务的耐力时间差异相似，但左利手的力量和位置任务耐力时间比（0.77）大于右利手（0.13，P<0.001；见图 2）。此外，对于右利手受试者，力量和位置任务的耐力时间显著相关（r²=0.62，P<0.001），但对于左利手受试者，两者不相关（r²=0.004，P=0.79）。多元回归分析确定了每组耐力时间的预测变量，这些变量因利手和任务而异。然而，手优势并不能影响两组受试者的耐力时间。这些发现表明，当执行需要力量或位置控制的次最大等长收缩时，肘部屈肌的耐力时间不受手优势的影响，但确实取决于利手。
