Muscle fascicle and series elastic element length changes along the length of the human gastrocnemius during walking and running

Abstract

Ultrasound imaging has recently been used to distinguish the length changes of muscle fascicles from those of the whole muscle tendon complex during real life movements. The complicated three-dimensional architecture of pennate muscles can however cause heterogeneity in the length changes along the length of a muscle. Here we use ultrasonography to examine muscle fascicle length and pennation angle changes at proximal, distal and midbelly sites of the human gastrocnemius medialis (GM) muscle during walking (4.5 km/h) and running (7.5 km/h) on a treadmill. The results of this study have shown that muscle fascicles perform the same actions along the length of the human GM muscle during locomotion. However the distal fascicles tend to shorten more and act at greater pennation angles than the more proximal fascicles. Muscle fascicles acted relatively isometrically during the stance phase during walking, however during running the fascicles shortened throughout the stance phase, which corresponded to an increase in the strain of the series elastic elements (SEEs) (consisting of the Achilles tendon and aponeurosis). Measurement of the fascicle length changes at the midbelly level provided a good approximation of the average fascicle length changes across the length of the muscle. The compliance of the SEE allows the muscle fascicles to shorten at a much slower speed, more concomitant with their optimal speed for maximal power output and efficiency, with high velocity shortening during take off in both walking and running achieved by recoil of the SEE.

Human medial gastrocnemius force–velocity behavior shifts with locomotion speed and gait

“…2). This is in good agreement with studies using similar measurement techniques (19,20) and modeling studies (12,21) at normal walking speeds. There was a trend for increases in fascicle-shortening velocity with walking speed ( Fig.…”

“…Gastrocnemius is important in providing power for propulsion during walking, which involves rapid shortening of the whole MTU to produce high angular velocities of the ankle. Although the compliant Achilles tendon has been shown to lower the required shortening velocity of muscle fascicles during push-off at preferred walking speeds (19,20), it may be unable to do so sufficiently at fast walking speeds.…”

In vivo maximal fascicle-shortening velocity during plantar flexion in humans

“…Interestingly, it has been demonstrated that the ankle joint could reach the equivalent or even higher velocity in ballistic multijoint movements (e.g., vertical jump) than in monoarticular movements such as those the current study explores (25,26,51). Performance in multijoint movements is clearly enhanced by prestretching or the stretch-shortening cycle that involves an even larger contribution of tendinous tissues to angular velocity (34,42). Therefore, it would be interesting to compare the maximal fascicle-shortening velocity obtained during both dynamic single-joint and multijoint tasks to appraise the respective roles of the different muscle-tendon unit components and to investigate the influence of V Fmax on explosive performance.…”

Muscle fascicle shortening behaviour of vastus lateralis during a maximal force–velocity test

“…These interactions have been well described in animal (Astley and Roberts 2012;Biewener and Baudinette 1995;Wilson et al 2003) and human locomotion (e.g., walking and running; Cronin and Lichtwark 2013;Fukunaga et al 2001;Ishikawa et al 2007;Lichtwark et al 2007). During exercises involving stretch-shortening cycles, these interactions have been demonstrated to enhance the work produced by the muscle-tendon unit (Ishikawa and Komi 2004;Kawakami et al 2002;Finni et al 2001), to improve the efficiency (Lichtwark and Barclay 2010) and to reduce muscle fibre elongation during the eccentric phase, thereby limiting the risk of strain induced injury (Guilhem et al 2016;Konow et al 2012).…”