Physiotherapy - Theses
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ItemEffects of athletic footwear design features on running and landing biomechanics in adolescent and young adult females: Implications for anterior cruciate ligament injury and development of patellofemoral pain syndrome( 2023-12)Emerging evidence indicates that adolescent and young adult females experience a notably higher incidence of non-contact anterior cruciate ligament (ACL) injury and patellofemoral pain (PFP) in comparison to their male and pre- and mid-pubertal counterparts. The increased risk of ACL injury and development of PFP in girls and young women is thought to be associated with their aberrant knee (i.e., increased tri-planar knee kinematics and kinetics) during running and landing tasks. Indeed, excessive tri-planar (i.e., knee flexion, knee valgus and internal tibial rotation) knee biomechanics have been found to increase loads on the ACL and patellofemoral joint (PFJ). For this reason, shoes with a lower shoe pitch and/or medial arch may mitigate loads on the ACL and PFJ as these footwear design features can attenuate tri-planar knee kinematics and kinetics. Whilst previous footwear studies have reported independent effects of shoe pitch and medial arch support on knee joint biomechanics, no previous study has investigated the combined effects of shoe pitch and medial arch support on ACL and PFJ contact forces. With respect to current commercially-available footwear, the influence of their design features - such as the degree of shoe pitch and amount of foot support - on in-vivo knee loads during sports-specific tasks remains largely unknown. To determine the most effective load-modifying footwear design features, it is critical to quantify in-vivo muscle forces and the resultant loads on knee joint structures during sports-specific tasks. However, direct measurement of these forces in-vivo is impractical due to the methodological complexities and ethical concerns. Advanced electromyography (EMG)-informed neuromusculoskeletal (NMSK) computational model provides the alternative approach to directly estimate in-vivo loads on ACL and PFJ. In light of these considerations, this thesis incorporated a series of studies that evaluated the effects of athletic footwear design features on knee and lower limb biomechanics in adolescent and young adult females during sport-specific tasks using advanced computational modelling. Biomechanical datasets for the footwear studies in this thesis were derived from two Australian Research Council-funded projects. Both projects used healthy late/post-pubertal females (Project 1: n = 50, age = 22.0 years; Project 2: n = 24, age = 20.0 years) and evaluated two different sets of footwear during drop-lateral-jump (DLJ) and running tasks. Specifically, Studies 2 and 3 used prototype athletic shoes with modifiable footwear features, including shoe pitch (4mm, 7mm and 10mm) and medial arch support (no support, low support and high support). Study 4 used commercially-available high- and low-support athletic shoes. An EMG-informed NMSK computational model was used to estimate in-vivo muscle forces and resultant loads on the knee joint and soft tissues. Study 1 validated the accuracy of predicted knee joint contact forces obtained from the novel EMG-informed NMSK computational modelling pipeline using in-vivo measurements obtained from the Grand Challenge Competition dataset (2010-2012). Specifically, root-mean-squared error (RMSE) between model-predicted and in-vivo measurements of tibiofemoral joint contact forces were comparable with those reported by previous winners of the Grand Challenge Competitions, with differences less than 10%. In addition, significant (p<0.05) associations were found between (i) model-predicted and EMG-derived muscle activity, and (ii) model-predicted and inverse-dynamics-derived joint moments. Together, these findings demonstrated that the novel NMSK computational model was valid and sufficiently accurate for assessing the effects of athletic footwear design features on in-vivo muscle forces and the resultant loads on knee joint structures during dynamic tasks. Study 2 investigated the effects of modifiable footwear design features on ACL force during the DLJ task, using the biomechanical dataset from Project 1. Results indicated no significant (p<0.05) interaction or main effect of shoe pitch or medial arch support on peak ACL force. Although modifiable footwear design features had no effect on the primary outcome measures, an independent main effect of shoe pitch was found for time-to-peak (TTP) ACL force. Specifically, the 4mm shoe pitch condition resulted in a delayed TTP by 8-12%, compared to 7mm and 10mm pitch conditions. Whilst a delayed TTP observed in the 4mm shoe pitch is representative of a lower ACL loading rate, the magnitude of the absolute reduction (i.e., 3-4 ms) was small and, coupled with the fact that peak ACL forces were similar across pitch variants, these findings likely have negligible practical and real-world implications. Study 3 evaluated the effects of modifiable footwear features on PFJ contact forces and Achilles tendon (AT) force parameters (i.e., peak force, loading rate and cumulative force) during running, using the biomechanical dataset from Project 1. Achilles tendon force was measured because previous studies have demonstrated that certain shoe design features reduce PFJ contact forces but concurrently elevate AT force and vice versa. Results indicated no significant (p<0.05) interaction effect between shoe pitch and medial arch support for any of the temporal or magnitude-related PFJ contact force and AT force parameters. However, an independent main effect of shoe pitch was found for PFJ contact forces parameters. Specifically, the 4mm shoe pitch produced a reduction in all temporal and magnitude-related PFJ contact force parameters by 2-3%, compared to 7mm and 10mm pitch conditions. However, it is important to highlight that the magnitude of reduction in PFJ contact force parameters was relatively small and consequently, shoes with a 4mm pitch are unlikely to confer substantial benefit with respect to lowering the risk of developing PFP. Independent main effects of shoe pitch and medial arch support were also found for AT force parameters. Specifically, the 10mm shoe pitch condition reduced all temporal and magnitude-related AT force parameters by 4-7%, compared with 4mm and 7mm pitch conditions. Also, both low and high medial arch support reduced all the temporal and magnitude-related AT force parameters by 2-5%, compared with the no medial arch support condition. Given the association between elevated AT load and pathological changes, physically active individuals seeking the management or prevention of AT tendinopathy may benefit by wearing shoes with a higher pitch and/or medial arch support. Study 4 compared the effects of commercially-available ASICS footwear on PFJ contact forces and AT force parameters during running, using the biomechanical dataset from Project 2. For PFJ contact forces parameters, no significant (p<0.05) difference was found for peak PFJ contact forces and PFJ cumulative force between high- and low-support shoes. By contrast, results suggested that PFJ loading rate was 8% lower in high-support shoes compared with low-support shoes. For AT force, differences were found for peak force, loading rate and cumulative force between high- and low-support shoes. Specifically, results demonstrated that wearing high-support shoes was associated with a decrease in all AT force parameters by 4-10% compared with low-support shoes. Given the aforementioned association between elevated AT load and development of Achilles tendinopathy, high-support footwear may offer advantages for runners predisposed to or experiencing Achilles tendinopathy. In conclusion, it is important to highlight that whilst several results from the three footwear studies reached statistical significance, the magnitude of the observed footwear-related changes was relatively small. Hence, the footwear design features investigated in this thesis likely have negligible practical benefits for girls and young women participating in netball or other court sports. For this reason, future studies should explore other footwear design features to identify which are most effective in mitigating detrimental loads imposed on the ACL and PFJ during sports-specific tasks.