length-tension relationship

(A) Force generated at different sarcomere lengths. (B) Arrangement of filaments at different sarcomere lengths.

length-tension relationship

the relation between a muscle's length and the isometric tension (force) which it generates when fully activated. During normal muscular activity, particularly at the longer lengths, tension partly depends on passive stretch of the connective tissue within the muscle, acting in parallel with active force generation by the muscle fibres themselves. When this contribution is subtracted, and only the actively generated force considered, the relation between force and length depends predominantly on the number of actin-myosin cross-bridges (XB) which can be formed. Diagram A shows the relationship for skeletal muscle in terms of sarcomere length. Diagram B illustrates how this is accounted for by variations in overlap between thick and thin filaments, and therefore in the formation of cross-bridges. Over the range of decreasing sarcomere length (I-II) progressively more XB can form but when the shortest length (IV) is approached, correctly oriented XB formation diminishes as the thin filaments begin to overlap and force declines. Most muscles in the body operate only over the central, high force, part of the curve shown in A. See also muscle contraction, myofibrils, sliding filament mechanism.
References in periodicals archive ?
They found that the length-tension relationship of the erector spinae increases linearly up to 45 degrees of trunk flexion.
The length-tension relationship of the erector spinae seems to be supported by studies that have investigated the effect of lumbar posture on the ratio of extensor torque production to levels of erector spinae muscle activation (neuromuscular efficiency ratio) (Roy et al 2003, Tan et al 1993).
A change in lumbar curvature can alter fascicle obliquity, lever arm distance, and the length-tension relationships of the erector spinae (McGill et al 2000, Raschke and Chaffin 1996, Singh et al 2011, Tveit et al 1994).
The first is the length-tension relationship of the muscle.
HHD testing can also be performed at several points in the ROM, if necessary for interpreting functional movements; however, the optimal length-tension relationship may be lost in certain positions and these positions may not be easily repeated or standardized for follow-up tests.