Dynamic knee valgus in competitive alpine skiers: Observation from youth to elite and influence of biological maturation

Abstract

Numerous studies investigated the association between dynamic knee valgus and injury risk in post‐pubertal and elite athletes; however, normative reference scores for competitive alpine skiers and observations on the development process throughout and beyond athletes' growth spurt are lacking. Thus, the aim of this study was to describe the dynamic knee valgus of competitive alpine skiers during drop jump landings (DJ) and single‐leg squats (SLS) with respect to sex, sportive level, and biological maturation. Thirty‐seven elite and 104 youth competitive alpine skiers around the growth spurt (U15) were examined for their maximal medial knee displacement (MKD) during DJ and SLS by a marker‐based 3D motion analysis evaluating dynamic knee valgus. Additionally, skiers' age, anthropometry and biological maturation were assessed. MKD of youth and elite alpine skiers during DJ was comparable and did not improve with increasing training age. Female U15 skiers (on average further matured) had significantly larger MKD values during DJ than male U15 skiers (less matured) (P < .01). Moreover, MKD during DJ was directly associated with the athlete's individual biological maturation status. MKD values obtained from DJ significantly differed from those obtained during SLS (P < .01). The gender‐specific difference in MKD values during DJ and their relationship with maturity offset highlight the fundamental changes to the neuromuscular control system during the growth spurt. Thus, biological maturation needs to be considered as a confounding factor for knee valgus screening. Caution is required when evaluating MKD by using high‐ and low‐dynamic tasks, as corresponding information can differ.

Thigh muscle activation patterns and dynamic knee valgus at peak ground reaction force during drop jump landings: Reliability, youth competitive alpine skiing-specific reference values and relation to knee overuse complaints

“…the rectangular medial distance [mm] of the knee joint centre relative to a reference plane formed by the hip, knee and ankle joint centres one frame before the initial ground contact. 20 However, in contrast to our previous study, 20 MKD at the moment of maximum vertical ground reaction force (MKD GRF ) (and not the maximum MKD amplitude) was considered being the most relevant metric for further analysis. The corresponding values were averaged over the two landings and both legs.…”

“…Generally, MKD GRF appears before the maximum MKD (File 2), which explains the lower values compared to a previous study reporting maximum MKD. 20 Regarding the increased QH GRF of male skiers, it can be seen from the supplementary material (File 1) that the increased ratio in males does not result from pronounced quadriceps activity, but rather from reduced activity of the hamstring muscles. This indicates that male skiers might use a less conservative landing strategy than females, putting them at supposedly higher risk for overuse injuries.…”

“…The modified PlugIn-Gait marker set used, as well as the joint centre determination and customized Matlab Scripts (Matlab, The MathWorks, Inc, US), corresponded to the procedure described in a previous study. 20 Additionally, two force plates (SP Sportdiagnosegeräte GmbH, Austria) as well as an eight electrode electromyographic system (Aktos, Myon AG, Switzerland) recorded the DJ tasks at 2000 Hz. All systems were integrated into the Vicon system and thus synchronised.…”

“…18 Since there is evidence that males and females differ in neuromuscular development from puberty onward, a sexspecific analysis appears to be warranted. 19,20 Concerning the second aspect, it is known that the quadriceps (Q) and hamstring (H) muscles serve as the main stabilizers of the knee, 21 and that thigh muscle strength deficits and imbalances (i.e. H:Q strength ratios below normal range) may favour the occurrence of overuse injuries in the knee.…”

The acute effects of one session reactive neuromuscular training on balance and knee joint position sense in female athletes with dynamic knee valgus

“…In the high-risk sports such as handball, volleyball, basketball, and soccer, increased knee valgus or medial knee displacement due to weak neuromuscular control during dynamic movement tasks have been identified as the major risk factors for ACL injuries (Alentorn--Geli et al, 2009;Hewett et al, 2005;Krosshaug et al, 2016). It has been previously reported that core muscle activation, hip external rotators and abductors strength, and neuromuscular activation methods of the thigh muscles can play a major role in the reduction and prevention of the DKV (Ellenberger et al, 2020;Jamison, McNally, Schmitt, & Chaudhari, 2013;Malloy, Morgan, Meinerz, Geiser, & Kipp, 2016;Stickler, Finley, & Gulgin, 2015).…”