Proactive and Reactive Mechanisms Play a Role in Stepping on Inverting Surfaces During Gait

Abstract

Ankle inversions have been studied extensively during standing conditions. However, inversion traumas occur during more dynamic conditions, like walking. Therefore in this study sudden ankle inversions were elicited in 12 healthy subjects who stepped on a trap door while walking on a treadmill. First, 10 control trials (0 degrees of rotation) were presented. Then, 20 stimulus (25 degrees of rotation) and control trials were presented randomly. EMG recordings were made of six lower leg muscles. All muscles showed a short-latency response (SLR) of about 40 ms and a late-latency response (LLR) of about 90 ms. The peroneal muscles showed the largest amplitudes in both responses. The functionally more important, larger, and more consistent LLR response was too late to resist the induced stretch during the inversion. The functional relevance of this response must lie after the inversion. During the first trial a widespread "startle-like" coactivation of the LLR was observed. The last trials showed only a recruitment of the peroneal muscles and, to a lesser extent, the gastrocnemius lateralis, which is seen as a switch from reactive control to more proactive adaptive strategies. These proactive strategies were investigated separately by comparing trials in which inversion was expected (but did not occur) with those in which subjects knew that no inversion would occur. Anticipation of a possible inversion was expressed in decreased tibialis anterior activity before initial contact, consistent with a more cautious and stable foot placement. Furthermore, immediately after landing, the peroneal muscles were activated to counteract the upcoming stretch.

Effects of Kinesio Tape Compared With Nonelastic Sports Tape and the Untaped Ankle During a Sudden Inversion Perturbation in Male Athletes

“…27 Our results demonstrated a significant increase in muscle activity of fibularis longus after the perturbation. As hypothesized, the group of athletes with less stability demonstrated greater muscle activation than those scoring higher on the SEBT, although this was only apparent immediately after the perturbation.…”

“…6,30 It has also been proposed that greater preactivation of the fibularis muscles prior to inversion stress may overcome the electromechanical delay (from activation to force production of the muscle), which could result in a larger spindle response. 11,27 Nonelastic adhesive tape has been used for injury prevention and during rehabilitation after ankle injury. This type of tape has been shown to be effective in restraining ankle inversion, and its use may decrease the incidence of ankle sprains.…”

“…Fibularis muscle response has been measured during simulated inversion injury and is reported to have an expected latency period of 50 to 90 milliseconds. 22,27,42 The time to peak and duration of the response is task dependent. The data were viewed across 4 time frames: baseline activity during the 500 milliseconds prior to the inversion perturbation, the 500 milliseconds immediately after the applied perturbation, and 2 additional 500-millisecond blocks during the recovery period after the inversion stress (time frames 3 and 4).…”

Neuromuscular Ankle Joint Stabilisation after 4-weeks WBV Training

“…refl ex activity of the stabilising ankle musculature could protect ankle joint from ligament injury. Further, it was recently suggested that refl ex activity of the stabilising ankle muscles could substantially reduce ankle joint loading in case of ankle sprain motion [15,30] . However, so far no data exist concerning the preventive eff ects of several weeks WBV training on refl ex activity of the stabilising ankle musculature during induced perturbed ankle inversion.…”

Post-effect of forward and backward locomotion on body orientation in space during quiet stance

“…The human locomotor system can react quickly to unpredictable conditions, but it can also produce predictive adjustments in response to persistent perturbations (Marigold and Patla 2005;Nieuwenhuijzen and Duysens 2007;Sorensen et al 2002). Adaptive mechanisms are therefore critical for optimising coordination patterns and allow individuals to maintain stability and eYciency of walking and balancing behaviours De Nunzio et al 2005;Diekmann et al 2004;Richards et al 2007).…”