Magid A, Law D J
Science. 1985 Dec 13;230(4731):1280-2. doi: 10.1126/science.4071053.
The tension that develops when relaxed muscles are stretched is the resting (or passive) tension. It has recently been shown that the resting tension of intact skeletal muscle fibers is equivalent to that of mechanically skinned skeletal muscle fibers. Laser diffraction measurements of sarcomere length have now been used to show that the exponential relation between resting tension and sarcomere length for whole frog semitendinosus muscle is similar to that of single fibers. Slack sarcomere lengths and the rates of stress relaxation in these muscles were similar to those in skinned fibers, and sarcomere length remained unchanged during stress relaxation, as in skinned fibers. Thus, in intact semitendinosus muscle of the frog up to a sarcomere length of about 3.8 micrometers, resting tension arises, not in the connective tissue as is commonly thought, but in the elastic resistance of the myofibrils.
放松的肌肉被拉伸时产生的张力即为静息（或被动）张力。最近的研究表明，完整骨骼肌纤维的静息张力与机械去膜骨骼肌纤维的静息张力相当。现在已通过激光衍射测量肌节长度来表明，青蛙半腱肌整体的静息张力与肌节长度之间的指数关系与单根纤维的类似。这些肌肉的松弛肌节长度和应力松弛速率与去膜纤维的相似，并且在应力松弛过程中肌节长度保持不变，这与去膜纤维的情况相同。因此，在青蛙完整的半腱肌中，直至肌节长度约为3.8微米时，静息张力并非如通常所认为的那样产生于结缔组织，而是产生于肌原纤维的弹性阻力。
