서강대학교

초록/요약

Humans are able to naturally adapt the mechanical load of their bio-mechanical system to different requirements of functional tasks, to ensure safe locomotion. Depending on the mechanical load, lower extremity joints generate and absorb the biomechanical energy using their soft tissue and bones. While this biomechanical energy of lower extremity joints are shown as the positive or negative energy of the ankle, knee and hip joints during locomotion, the mechanical load of each joint can be adjusted and distributed according to environmental and human physical condition. The knee joint is a relatively unstable joint compared with ankle and hip joint; it is non-congruent and partially stabilized by menisci and ligaments as well as muscles. Improper adjustment and distribution of loads during locomotion can substantially increase the mechanical load on the knee, and it may lead to injury. Energetic analysis of locomotion combines kinematic and kinetic parameters across the locomotion period; therefore, Energetic analysis of locomotor adaptation provides a comprehensive description of the load distribution of lower extremity joints. The purpose of this investigation was to utilize this form of analysis to 1) evaluating the upslope and backpack load carriage effects, which were treated as individual variables in previous studies, as a combined effect on biomechanical energy; 2) evaluating the new approach to load distribution depending on the arch type; 3) exploring relationships between ankle plantar-flexion angle at initial contact and biomechanical energy; 4) elucidating new knowledge of ankle landing strategies that contribute to factors related to high-risk landing biomechanics on ACL damage. 82 volunteer subjects (part 1: 14 males, part2: 22 female, part3: 17 male and 10 female, part 4: 15 males and 7 females; age = 22.05 ± 2.7 years; height = 1.71 ± 0.31m; mass = 69.2 ± 13.4 kg) were included in this dissertation. Subjects walked on downstairs with backpack load, upslope or landed on a 0.3m platform. All kinematic and kinetic data was sampled using the same motion analysis system and force plate. In part 1), subjects who walk uphill with backpack load carriage demonstrated 64% greater knee positive joint work during early stance phase and 45% greater ankle positive joint work during late stance phase. It was also demonstrated 65% greater knee negative joint work during late stance phase in the uphill walking with backpack load carriage compared with the uphill walking without backpack load carriage. These results suggest that the effect of uphill and load carriage combination is given a relatively excessive load on the knee, unlike the single effect of uphill and load carriage presented in previous studies. In part 2), lower arch group absorbed the less energy in foot and arch from initial contact to first peak vertical ground reaction force, but there was no significant difference in energy absorption in foot and arch between arch types. This result indicates that despite foot arch types, people absorb a similar amount of energy, but their ankle and foot energy absorption strategies differ depending on the type of foot arch. In part 3) and 4), the subjects who naturally choose large ankle plantar-flexion angle at initial contact demonstrate greater ankle and total energy absorption, and lesser hip energy absorption compared to subjects who naturally choose lower ankle plantar-flexion angle at initial contact. Further, subjects who naturally choose large ankle plantar-flexion angle at initial contact decrease peak knee valgus moment, peak combined knee valgus-internal rotation moment and peak hip extension moment. These finding indicates that increasing ankle plantar-flexion angle at initial contact reduce the load that is directly transferred to the knee frontal plane, which reduces injury risk to the ACL. As a whole, the results of this investigation provide meaningful information that locomotor adaptation of lower limb joints during uphill-walking, stair descending and landing quantified using biomechanical energy analyses affects knee joint loading.