Contraction of knee flexors and extensors in skiing related to the backward fall mechanism of injury to the anterior cruciate ligament

Abstract

Contraction of knee flexors and extensors in skiing related to the backward fall mechanism of injury to the anterior cruciate ligament Aune AK, Schaff P, Nordsletten L. Contraction of knee flexors and extensors in skiing related to the backward fall mechanism of injury to the anterior cruciate ligament. Scand J Med Sci Sports 1995: 5: 165-169. 0 Munksgaard, 1995 The purpose of this study was to examine the motion pattern and muscle activity during jumping and landing in downhill skiing to estimate the muscular involvement during the jump-landing-backward fall-anterior cruciate ligament (ACL) injury. A digitized 2-D video motion analysis and a synchronous %channel electromyography registration was performed over ajump on a downhill slope during 3 runs by 2 skiers and during 6 control jumps in the laboratory. The knee flexors (lateral gastrocnemius and biceps femoris) were recruited before touchdown and mean 60 ms earlier than the extensors (vastus lateralis and rectus femoris). Extensors and flexors reached peak activity simultaneously at the instant of landing. The knee flexion angle at the instant of landing was mean 36". As the landing was stabilized, the extensor activity persisted during eccentric work at increasing knee flexion as a corresponding flexor relaxation took place. The control jump in the laboratory showed a similar order of recruitment and timing of muscle contraction. The gastrocnemius was recruited mean 96 ms earlier and the biceps femoris mean 63 ms earlier than the extensors. This recruitment pattern during the landing movement suggest a learned motor program engaging the kinetic chain of the lower extremity to intercept the landing energy. The results also indicate that the knee flexor activity may protect the ACL at the instant of landing but that it is minimal shortly thereafter and probably not able to protect the ACL when a backward fall occurs. The knee was flexed substantially as the extensors became the dominating muscles. Thus, their ability to apply any anterior drawer force able to rupture the ACL is questioned.

Knee joint neuromuscular activation performance during muscle damage and superimposed fatigue

“…From the current data it is not possible to discern the relative contributions of these mechanisms, yet from a functional perspective, it is interesting to note a possible down-regulation of knee extensor performance commensurate with peak impairments to knee flexor performance (48h). Given that activation of the knee extensors at vulnerable joint angles may be associated with anterior tibio-femoral shear forces and a susceptibility to ACL injury (Aune., Schaff, Nordsletten, 1995), the observed reduction in RFDy might be favourable for knee joint stabilisation in circumstances where knee flexor activation performance is impaired.…”

Studying Force Patterns in an Alpine Ski Boot and Their Relation to Riding Styles and Falling Mechanisms

“…Research on the skier's body position, muscular stress and ground reaction forces (GRF) (Müller, 1994;Aune et al, 1995;Färber et al, 2018;Seifert et al, 2020) as well as studies on the influence of the boot's geometry (Benoit et al, 2005) and material properties (Petrone et al, 2013) can support product development, injury prevention and the development of skiing technique. Hereby, the utilization of pressure insoles is part of present day methods to measure forces within a ski boot or generally in orthopedics (Babiel et al, 1997;Stricker et al, 2010;Nakazato et al, 2011;Adelsberger, 2014).…”

Is it possible to voluntarily increase hamstring muscle activation during landing from a snow jump in alpine skiing? - a pilot study

“…In this situation two specific injury mechanisms can be described. First, ACL injuries are common in unbalanced landings when the bodyweight is shifted backwards -"landing back weighted" (Aune, Schaff, & Nordsletten, 1995;Barone et al, 1999;T Bere et al, 2014;Gerritsen et al, 1996). In this situation, the ski ends make the first contact with the snow and the stiff ski-binding-boot system leads to a considerable torque that produces an "anterior drawer".…”

“…However, the ACL is one of several structures crossing the knee joint. Particularly, both the quadriceps and the hamstring muscle-tendon units cross the knee joint and are activated during landing from a jump (Aune et al, 1995;De Britto, Carpes, Koutras, & Pappas, 2014;Peng, Kernozek, & Song, 2011). Thus, it has been discussed whether their activation might contribute to or alleviate the ACL injury risk (Oberhofer et al, 2017).…”

“…Whether quadriceps activation contributes to ACL loads seems to strongly depend on the knee flexion angle (Withrow, Huston, Wojtys, & Ashton-Miller, 2006). For the specific situation of landing from a jump in alpine skiing one previous study concluded that quadriceps activation plays an insignificant role in ACL loading (Aune et al, 1995). In contrast, for the hamstring muscle-tendon units cadaver studies (Li et al, 1999;More et al, 1993) as well as simulation studies (Gerritsen et al, 1996) suggested that an increased activation reduces ACL loads and increasing the hamstring/quadriceps strength ratio has been considered in several ACL injury prevention programs (Myer et al, 2009;Renstrom et al, 2008;Zebis, Andersen, Bencke, Kjaer, & Aagaard, 2009).…”