Faulkner J A, Opiteck J A, Brooks S V
Department of Physiology, University of Michigan, Ann Arbor 48109-0622.
Int J Sports Med. 1992 Oct;13 Suppl 1:S160-2. doi: 10.1055/s-2007-1024626.
A contracting skeletal muscle will shorten, remain isometric, or lengthen depending on the interaction between external load and the force developed by the muscle. Most physical activities involve shortening, isometric and lengthening contractions. The fluctuations in terrain encountered at altitude, increase both the likelihood that lengthening contractions will occur and the severity of the stretches. When performing a given amount of work, muscles lengthened during contractions expend less energy and fatigue less rapidly than muscles that shorten. Conversely, with equal activation, displacement, and velocity, the work done on a muscle during lengthening contractions is greater than the work performed by a muscle during shortening contractions, but force decreases more rapidly during lengthening. Furthermore, muscles are more likely to be injured during lengthening contractions than during shortening or isometric contractions. The occurrence of contraction-induced injury can be eliminated, or minimized, by prior training specific for the performance of lengthening contractions.
收缩的骨骼肌会缩短、保持等长或拉长,这取决于外部负荷与肌肉产生的力量之间的相互作用。大多数体育活动都涉及缩短、等长和拉长收缩。在海拔高度遇到的地形起伏,增加了拉长收缩发生的可能性以及拉伸的强度。当完成一定量的工作时,收缩时拉长的肌肉比缩短的肌肉消耗的能量更少,疲劳也更慢。相反,在相同的激活、位移和速度下,拉长收缩时作用于肌肉的功大于缩短收缩时肌肉所做的功,但在拉长过程中力量下降得更快。此外,肌肉在拉长收缩过程中比在缩短或等长收缩过程中更容易受伤。通过针对拉长收缩表现的预先训练,可以消除或最小化收缩引起的损伤的发生。