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

Abstract

Activation of the hamstrings has been discussed as a measure for reducing strain on the ACL during jump landings in alpine skiing. The current study tested the hypothesis that hamstring and quadriceps activation can be voluntarily increased by the athlete. Specifically, two different instructions - to increase hamstring activation or to increase upper-leg co-contraction - were compared to normal landings. Eight members of the German national and junior national squad in freestyle skiing (age 19.6 ± 3.8 years; weight 66.1 ± 13.2 kg; height 172.2 ± 7.7 cm) performed 12 jump landings on a prepared run, 4 with no specific instruction, 4 with the instruction to generally activate the thigh muscles, and 4 with the instruction to specifically activate the hamstrings. Electromyographic (EMG) signals were recorded on the biceps femoris (BF), semitendinosus (ST), vastus lateralis (VL), rectus femoris (RF) and vastus medialis (VM). EMG activation levels were integrated over three landing phases and analysed with a repeated measures ANOVA. The instruction produced a significant main effect in ST (p = .026), VM (p = .032) and RF (p = .001). Contrary to previous research, the current study suggests that hamstring muscle activation levels can be voluntarily increased during jump landing, particularly in co-activation with its antagonists.

Maximal Eccentric Hamstrings Strength in Competitive Alpine Skiers: Cross-Sectional Observations From Youth to Elite Level

“…Competitive alpine skiers are known to be subject to substantial risks of injury (Spörri et al, 2017). Although the rates for some injuries have been recently reported to show a decline as stated by Färber et al (2018), the possibility for skiers to sustain an anterior cruciate ligament (ACL) injury during their sportive career is still very high (Pujol et al, 2007; Flørenes et al, 2009, 2012; Westin et al, 2012, 2018; Bere et al, 2013a; Stenroos and Handolin, 2014; Haaland et al, 2016; Müller et al, 2017b). Most of the ACL-injuries occur while the skier is turning or landing from a jump (i.e., before or without falling) (Bere et al, 2011, 2014).…”

“…Considering that both quadriceps and hamstrings muscle groups are significantly activated during jump landings (Färber et al, 2018), it is reasonable to enquire whether enhanced co-activation of such muscle groups contributes to prevention strategies (Oberhofer et al, 2017). However, previous research and opinion targeting quadriceps functional features and ACL-injuries has been controversial, as Färber et al (2018) pointed out.…”

“…Considering that both quadriceps and hamstrings muscle groups are significantly activated during jump landings (Färber et al, 2018), it is reasonable to enquire whether enhanced co-activation of such muscle groups contributes to prevention strategies (Oberhofer et al, 2017). However, previous research and opinion targeting quadriceps functional features and ACL-injuries has been controversial, as Färber et al (2018) pointed out. Instead, hamstrings strength capacity may be of importance for many typical injury situations (e.g., jump landings or backward falls) (Read and Herzog, 1992; Herzog and Read, 1993; Gerritsen et al, 1996; DeMorat et al, 2004; Koyanagi et al, 2006; Semadeni and Schmitt, 2009; Bere et al, 2011, 2014; Yeow et al, 2011; Heinrich et al, 2018).…”

“…Instead, hamstrings strength capacity may be of importance for many typical injury situations (e.g., jump landings or backward falls) (Read and Herzog, 1992; Herzog and Read, 1993; Gerritsen et al, 1996; DeMorat et al, 2004; Koyanagi et al, 2006; Semadeni and Schmitt, 2009; Bere et al, 2011, 2014; Yeow et al, 2011; Heinrich et al, 2018). In fact, if hamstrings are pre-activated fast and high enough (Färber et al, 2018), tibial anterior translation relative to the femur might be reduced, consequently diminishing the risk of ACL-injury.…”

Monitoring the Return to Sport Transition After ACL Injury: An Alpine Ski Racing Case Study

“…Consequently, the neuromuscular tests that are proposed may be insufficient for evaluating the physical capacities of alpine skiers with ACL injury. To this end, wearable technologies such as inertial measurement units that can be worn during skiing may provide additional information to the IPT, including the ability to assess the relationship between off-snow neuromuscular testing indices and on-snow neuromuscular strategies that may be involved in ACL reinjury (Färber et al, 2018;Bessone et al, 2019). Finally, it is recognized that psychological readiness is an important determinant of return to sport readiness after ACL injury (McPherson et al, 2019).…”