Extramuscular myofascial force transmission within the rat anterior tibial compartment: proximo‐distal differences in muscle force

Abstract

Intramuscular connective tissues are continuous to extramuscular connective tissues. If force is transmitted there, differences should be present between force at proximal and distal attachments of muscles. Extensor digitorum longus (EDL), tibialis anterior (TA), and extensor hallucis longus muscles (EHL) were excited simultaneously and maximally. Only EDL length was changed, exclusively by moving the position of its proximal tendon. Distal force exerted by TA + EHL complex was not affected significantly. Proximal and distal EDL isometric force were not equal for most EDL lengths: F prox ± F dist ranged from 0 to »+22.7% of F prox at higher lengths and from 0 to »±24.5% at the lowest lengths. It is concluded that extramuscular connections transmit force from muscle. Signi®cant proximo-distal differences of EDL force remained after repeated measurements, regardless of length order, although their length dependence was altered. Measurements of both proximal and distal EDL force were highly reproducible, if EDL did not attain higher lengths than target length. After being active at high lengths, proximal and distal length±force curves were altered at low lengths but not for the highest length range. Extensor digitorum longus length±active force hysteresis was present for proximal as well as distal EDL measurements with increasing and decreasing isometric length order. Further isolating EDL removed the proximo-distal difference for active EDL force. However a decreased difference for passive EDL force remained, which was ascribed to remaining extramuscular connective tissue linkages. It is concluded that extramuscular myofascial force transmission is an important feature of muscle that is not isolated from its surrounding tissues.

Myofascial force transmission in dynamic muscle conditions: effects of dynamic shortening of a single head of multi-tendoned rat extensor digitorum longus muscle

“…Such position effects have been explained in terms of force transmission out of the muscle via pathways other than the tendons, i.e. inter-and extramuscular myofascial force transmission (Huijing and Baan 2001a;Maas et al 2001). Previous studies (Huijing et al 1998;Jaspers et al 2002) on fully dissected multi-tendoned rat EDL muscle yielded clear evidence of transmission of force between muscle heads via connective tissue at their interface (i.e.…”

Effects of firing frequency on length-dependent myofascial force transmission between antagonistic and synergistic muscle groups

“…Before acquiring data, EDL and TA + EHL were preconditioned by isometric contractions at alternating high and low lengths, until forces at low length were Eur J Appl Physiol (2008) 104:501-513 503 reproducible (i.e. effects of previous activity at high length (Huijing and Baan 2001a) are removed). For the lengthforce curve, TA + EHL and EDL muscles were lengthened distally with 1 mm increments and isometric contractions were performed at different EDL and TA + EHL lengths.…”

“…Values are shown as mean ± SE (n = 6) Eur J Appl Physiol (2008) 104:501-513 505 to as intermuscular myofascial force transmission (Huijing and Baan 2001b;Maas et al 2001). Third, when force is transmitted between the epimysium of a muscle and a nonmuscular structure, such as connective tissues reinforcing nerves and blood vessels, intermuscular septa, the interosseal membrane, compartmental fascia and epitendinous tissues (Rijkelijkhuizen et al 2005), it is referred to as extramuscular myofascial force transmission (Huijing and Baan 2001a). Note that when muscle force is transmitted via the epimysium, it is generally referred to as epimuscular myofascial force transmission until further distinction of pathways is possible.…”

“…This means that the cytoskeleton is connected to connective tissue structures within and surrounding the muscle and force transmission will take place between these structures (i.e. myofascial force transmission, (Huijing and Baan 2001a;Huijing et al 1998;Maas et al 2001;Yucesoy et al 2003)). Epimuscular myofascial force transmission (i.e.…”

“…transmission trough the epimysium to other muscles or nonmuscular tissues) is indicated by a difference in force exerted at the origin and insertion of a muscle. This principle was demonstrated by Huijing and Baan (2001a), who showed that for rat extensor digitorum muscle (EDL) within an intact network of connective tissue, forces measured at the proximal tendon were usually not equal to force measured at the distal tendons. Via myofascial connections, a fraction of the muscle force can be transmitted from one muscle onto another, without passing one of its tendons.…”