Load-dependent movement regulation of lateral stretch shortening cycle jumps

Abstract

The classical stretch shortening cycle (SSC) describes sagittal joint flexion-extensions in motions like running or hopping. However, lateral movements are integral components of team sports and are associated with frontal plane joint displacements. The purpose of this study is to identify neuromuscular and kinematical mechanisms determining motor control and performance of reactive laterally conducted SSCs. Lateral jumps were performed from four distances in order to investigate the influence of lateral stretch loads on the lower extremity. Electromyographic (EMG) data of nine lower extremity muscles were collected. Foot, ankle, knee, and hip kinematics were recorded by 3-D motion analysis. High stretch loads were characterized by a greater foot exorotation during the initial phase of contact. In the sagittal plane knee and hip joint, displacements increased, whereas in the frontal plane only the hip joint displacement was significantly raised. In particular, frontal peak joint moments increased with stretch load. Thigh muscles' mean pre-activity amplitude was enhanced. It was possible to detect stretch reflexes in the thigh muscles, whereas in particular the short-latency reflex (SLR) was stretch load-dependently modulated. The results of the present study suggest that the foot exorotation seems to play a decisive role in the movement control of lateral jumps. The association between exorotation and increased sagittal joint displacements may be seen as a compensation strategy to shift load from the frontal to the sagittal plane. Lateral load compensation seems to strongly depend on upper leg's kinematic and neuromuscular adjustments, rather than on the ankle joint complex.

Multi-segment foot landing kinematics in subjects with chronic ankle instability

“…Fleischmann et al [35] found no differences in angular displacement at the ankle joint during landing jumps at different distances, so for now we could consider that submaximal jumps may well have revealed the same group effects, yet this still needs to be seen. Furthermore, given the exploratory nature of the current study, the alpha level in the SPM analyses was not corrected for the dependent planes of joint motion, as in a previous paper [17].…”

Pelvic floor muscle electromyography during different running speeds: an exploratory and reliability study

“…100 % of EMG equals the average of the two peak amplitude values during the two 5-s sessions of MVC. Third, EMG variables were calculated as RMS values within each 30-ms interval [10,15,16], averaged over 10 steps and normalized to peak MVC (%EMG). The different activity variables are described in Table 1.…”

“…According to Komi [9], the stretch-shortening cycle proceeds in three phases, namely pre-activity, eccentric lengthening and concentric contraction. Because of the eccentric lengthening a reactive and stronger contraction can follow, which allows the muscle to generate more strength in shorter time [9,10]. Stretch reflexes can be classified according to their latencies-i.e., reflex peaks-and are characterized by slow, mid and long latency responses and long latency succeeding responses in relation to an impact, e.g., the initial ground contact during running [10].…”

Trunk extensor fatigue decreases jump height similarly under stable and unstable conditions with experienced jumpers

“…Integrated EMG (iEMG) parameters of lateral jumps were analyzed between -30 -0 ms, 0-30 ms, 30 -60 ms, 60-90 ms, and 90-120 ms epochs. All testing was performed in one session and electrodes were not removed, therefore normalization of iEMG and MAV was not necessary (Fleischmann et al 2010).…”

“…To the authors' knowledge, there is no study available that investigated the influence of unstable surfaces on activity of lower limb as well as trunk muscles during maximal jumping and cutting tasks. During cutting (i.e., lateral jumps) and jumping, it seems that EMG activity in lower limb muscles is preprogrammed during the preactivation phase (Dyhre-Poulsen et al, 1991;Avela et al, 1996) and affected by stretching loads (Avela et al 1996, Komi & Gollhofer 1997, Fleischmann et al, 2010Hoffrén et al, 2011) during the braking phase. In fact, it has been shown that muscle preactivation is related to the appearance and magnitude of spinal stretch reflexes during ground contact of drop jumps (Avela et al 1996).…”