Similar muscles contribute to horizontal and vertical acceleration of center of mass in forward and backward walking: implications for neural control

Abstract

Leg kinematics during backward walking (BW) are very similar to the time-reversed kinematics during forward walking (FW). This suggests that the underlying muscle activation pattern could originate from a simple time reversal, as well. Experimental electromyography studies have confirmed that this is the case for some muscles. Furthermore, it has been hypothesized that muscles showing a time reversal should also exhibit a reversal in function [from accelerating the body center of mass (COM) to decelerating]. However, this has not yet been verified in simulation studies. In the present study, forward simulations were used to study the effects of muscles on the acceleration of COM in FW and BW. We found that a reversal in function was indeed present in the muscle control of the horizontal movement of COM (e.g., tibialis anterior and gastrocnemius). In contrast, muscles' antigravity contributions maintained their function for both directions of movement. An important outcome of the present study is therefore that similar muscles can be used to achieve opposite functional demands at the level of control of the COM when walking direction is reversed. However, some muscles showed direction-specific contributions (i.e., dorsiflexors). We concluded that the changes in muscle contributions imply that a simple time reversal would be insufficient to produce BW from FW. We therefore propose that BW utilizes extra elements, presumably supraspinal, in addition to a common spinal drive. These additions are needed for propulsion and require a partial reconfiguration of lower level common networks.

Control of propulsion and body lift during the first two stances of sprint running: a simulation study

“…To further elucidate the role of biarticular muscles, the analysis was extended to include individual muscle contributions. Several papers already documented the role of individual muscles in COM control during walking and running (Hamner et al, 2010;Jansen et al, 2012;Liu, Anderson, Pandy, & Delp, 2006;Liu, Anderson, Schwartz, & Delp, 2008;Neptune, Kautz, & Zajac, 2001;Neptune, Zajac, & Kautz, 2004). In sprinting, only descriptive studies documenting kinematics, kinetics and EMG are available (Bezodis, Kerwin, & Salo, 2008;Charalambous et al, 2012;Debaere et al, 2013;Guissard, Duchateau, & Hainaut, 1992;Johnson & Buckley, 2001;Kugler & Janshen, 2010;Morin, Edouard, & Samozino, 2011;.…”

Altering length and velocity feedback during a neuro-musculoskeletal simulation of normal gait contributes to hemiparetic gait characteristics

“…The marker protocol consisted of six technical clusters and 16 anatomical markers [34]. Surface EMG data (Zero-wire EMG, Aurion, Italy) were recorded bilaterally at 1000 Hz from 7 muscles: tibialis anterior (TA), lateral gastrocnemius (LGAS), soleus (SOL), lateral vastus (LVAS), rectus femoris (RF), biceps femoris (BF) and semitendinosus (ST).…”

Selective bilateral activation of leg muscles after cutaneous nerve stimulation during backward walking

“…In the cTA, reflex activity is most pronounced during its single-stance phase. In this period the TA resists the horizontal acceleration of the CoM (Jansen et al 2012). To evaluate the effect of reflex activity in the TA during single stance during BW we analyzed the induced accelerations due to middlelatency responses, using a set of kinematic pilot data (A. L. Hof, unpublished observation).…”