Journal of Applied Biomechanics最新文献

Changes in knee mechanics following anterior cruciate ligament (ACL) reconstruction are known to be magnified during more difficult locomotor tasks, such as when descending stairs. However, it is unclear if increased task difficulty could distinguish differences in forces generated by the muscles surrounding the knee. This study examined how knee muscle forces differ between individuals with ACL reconstruction with different graft types (hamstring tendon and patellar tendon autograft) and "healthy" controls when performing tasks with increasing difficulty. Dynamic simulations were used to identify knee muscle forces in 15 participants when walking overground and descending stairs. The analysis was restricted to the stance phase (foot contact through toe-off), yielding 162 separate simulations of locomotion in increasing difficulty: overground walking, step-to-floor stair descent, and step-to-step stair descent. Results indicated that knee muscle forces were significantly reduced after ACL reconstruction, and stair descent tasks better discriminated changes in the quadriceps and gastrocnemii muscle forces in the reconstructed knees. Changes in quadriceps forces after a patellar tendon graft and changes in gastrocnemii forces after a hamstring tendon graft were only revealed during stair descent. These results emphasize the importance of incorporating sufficiently difficult tasks to detect residual deficits in muscle forces after ACL reconstruction.

In the article Kawakami W, Takahashi M, Iwamoto Y, Shinkoda K. Coordination among shank, rearfoot, midfoot, and forefoot kinematic movement during gait in individuals with hallux valgus. J Appl Biomech. 2019;35(1):44–51, https://doi.org/10.1123/jab.2017-0319, an author name was spelled incorrectly. Koichi Shinkoda was spelled Koichi Shinakoda. The online version of this article has been corrected.

Observable scapular dyskinesis is associated with biomechanical deficits. Preventative interventions aimed at correcting these deficits may aid in preventing the development and resolution of shoulder pain. Our purpose was to investigate the effects of kinesio taping (KT) on common biomechanical deficits associated with scapular dyskinesis and shoulder pain. Participants (n = 51) with observable scapular dyskinesis, and without shoulder pain were randomized to KT, KT-placebo, or a no-treatment control group. Measurements taken before, immediately after taping, and 3 days later included pectoralis minor muscle length, lower trapezius muscle strength, scapular upward rotation angle at 0° to 120° in scapular plane humeral elevation and acromiohumeral distance. There were no changes in scapular upward rotation, lower trapezius strength, and acromiohumeral distance immediately after taping or 3 days later compared to baseline (P > .05). The pectoralis minor increased in length in the KT group on day 3 compared to directly after taping (P = .03), but no difference between groups or interaction between time and group were determined (P > .05). Scapular dyskinesis prevalence did not change over time in any group (P > .05). In people with scapular dyskinesis free from shoulder pain, KT applied to the shoulder cannot be recommended to ameliorate the biomechanical deficits associated with shoulder pain.

The electromyographic (EMG) normalization (often to maximum voluntary isometric contraction [MVIC]) is used to control for interparticipant and day-to-day variations. Repeated MVIC exertions may be inadvisable from participants' safety perspective. This study developed a technique to predict the MVIC EMG from submaximal isometric voluntary contraction EMG. On day 1, 10 participants executed moment exertions of 100%, 60%, 40%, and 20% of the maximum (biceps brachii, rectus femoris, neck flexors, and neck extensors) as the EMG data were collected. On day 2, the participants replicated the joint moment values from day 1 (60%, 40%, and 20%) and also performed MVIC exertions. Using the ratios between the MVIC EMGs and submaximal isometric voluntary contraction EMG data values established on day 1, and the day 2 submaximal isometric voluntary contraction EMG data values, the day 2 MVIC EMGs were predicted. The average absolute percentage error between the predicted and actual MVIC EMG values for day 2 were calculated: biceps brachii, 45%; rectus femoris, 27%; right and left neck flexors, 27% and 33%, respectively; and right and left neck extensors, both 29%. There will be a trade-off between the required accuracy of the MVIC EMG and the risk of injury due to exerting actual MVIC. Thus, using the developed predictive technique may depend on the study circumstances.

The study aim was to quantify the impact of a commercially available variable stiffness shoe (VSS) on 3-dimensional ankle, knee, and hip mechanics and estimated knee contact forces compared with a control shoe. Fourteen participants (10 females) with knee osteoarthritis completed gait analysis after providing informed consent. Shoe conditions tested were control shoe (New Balance MW411v2) and VSS (Abeo SMART3400). An OpenSim musculoskeletal model with static optimization was used to estimate knee contact forces. There were no differences in joint kinematics or in the knee adduction or flexion moments (P = .06; P = .2). There were increases in the knee internal and external rotation (P = .02; P = .03) and hip adduction and internal rotation moments for VSS versus control (P = .03; P = .02). The estimated contact forces were not different between shoes (total P = .3, medial P = .1, and lateral P = .8), but contact force changes were correlated with changes in the knee adduction moment (medial r2 = .61; P < .007). High variability in knee flexion moment changes and increases in the internal rotation moment combined with small decreases in the knee adduction moment did not lead to decreases in estimated contact forces. These results suggest that evaluation of VSS using only the knee adduction moment may not adequately capture its impact on osteoarthritis.