Simultaneous quantification of ankle, muscle, and tendon impedance in humans

Objective: Regulating the impedance of our joints is essential for the effective control of posture and movement. The impedance of a joint is governed mainly by the mechanical properties of the muscle-tendon units spanning it. Many studies have quantified the net impedance of joints but not the specific contributions from the muscles and tendons. The inability to quantify both muscle and tendon impedance limits the ability to determine the causes underlying altered movement control associated with aging, neuromuscular injury, and other conditions that have different effects on muscle and tendon properties. Therefore, we developed a technique to quantify joint, muscle, and tendon impedance simultaneously and evaluated this technique at the human ankle. Methods: We used a single degree of freedom actuator to deliver pseudorandom rotations to the ankle while measuring the corresponding torques. We simultaneously measured the displacement of the medial gastrocnemius muscle-tendon junction with B-mode ultrasound. From these experimental measurements, we were able to estimate ankle, muscle, and tendon impedance using non-parametric system identification. Results: We validated our estimates by comparing them to previously reported muscle and tendon stiffness, the position-dependent component of impedance, to demonstrate that our technique generates reliable estimates of these properties. Conclusion: Our approach can be used to clarify the respective contributions from the muscle and tendon to the net mechanics of a joint. Significance: This is a critical step forward in the ultimate goal of understanding how muscles and tendons govern ankle impedance during posture and movement.

Effect of Integrated Training on Balance and Ankle Reposition Sense in Ballet Dancers

Objective: To investigate the effects of a 6-week integrated training program on the ankle joint reposition sense and postural stability in ballet dancers. Methods: Sixteen female ballet dancers participated in the study and underwent a 6-week integrated training program consisting of plyometric, proprioception and core stability exercises along with a home program involving additional ankle muscle strengthening and stretching. The ankle joint reposition tests and the parameters of the center of pressure (COP) while performing grand-plie (deep squatting) and releve en demi-pointe (standing on balls of foot) movements were measured before and after training. Results: After 6 weeks, participants showed significantly smaller absolute ankle joint reposition errors in dorsiflexion (p = 0.031), plantarflexion (p = 0.003) and eversion (p = 0.019) compared to the pre-training measurement. Furthermore, after training, a significantly slower average COP speed at pre-equilibrium during grand-plie movement (p = 0.003) and pre-equilibrium phase of releve en demi-pointe (p = 0.023) were observed. In addition, the maximum COP displacement in the medial-lateral direction was significantly smaller at pre-equilibrium phase during grand-plie (p = 0.044) and releve en demi-pointe movements (p = 0.004) after training. Conclusions: The 6-week integrated training program improved the ankle joint reposition sense and postural control in the medial-lateral direction during grand-plie and releve en demi-pointe movements.

Observe Athlete’s Ankle Pain and Ankle Joint Muscle Characteristics Based on Microscope Images

Objective. To observe the characteristics of ankle pain and ankle joint muscle by microscope. Methods. In a sports university, 15 athletes above grade 2 were randomly selected as the experimental group, and 15 nonathletes were randomly selected as the control group. The experiment mainly included foot shape test, standard scaphoid height test, ankle range of motion test, ankle muscle emg test, and other experimental procedures. Medical microscopic image processing is a new technology developed in the past thirty years, which has brought great progress for mankind to understand and transform nature. Among them, the image processing and recognition of tumor cell microscopic images are one of the research focuses on the use of computers to process and recognize medical images. Results. In the test of ankle range of motion, when the angular velocity was the same as 60°/s, compared with the control group, the difference value of bilateral flexor peak moment in the experimental group was large, and the difference between the two groups was significant ( P < 0.05 ), with statistical significance. As the angular velocity dropped from 240°/s to 60°/s, 30 members of the experimental group and control group also experienced a decrease in the bilateral ankle isokyclic muscles, reflecting their lack of ankle strength. On the other hand, the muscle strength of the ankle joint in the experimental group was relatively small, and the difference between the two groups was significant ( P < 0.05 ). During the exercise, some members of the experimental group suffered from ankle pain, which resulted in insufficient strength of the muscles of the ankle joint, resulting in the interruption of the experiment. In the emg test of ankle muscles, the effective discharge values of preexcitation current of tibial anterior muscle before and after exercise were 104.6 ± 26.5 and 129.2 ± 38.1 , respectively, with significant difference and statistical significance. In the foot morphology test and the standard scaphoid height test, the difference between the two groups was not significant ( P > 0.05 ), and there was no statistical significance. Conclusion. Microscope based on athlete’s foot and ankle pain and ankle muscle characteristics to improve the accuracy of the observation, with the help of a microscope, you can see the details of a doctor are invisible to the naked eye and can record the relevant data in time in order to observe the late, for athlete’s foot and ankle pain relief and enhanced ankle muscles provide data support.

COMPARATIVE EFFECTIVENESS OF ROBOT-INTERACTIVE GAIT TRAINING WITH AND WITHOUT ANKLE ROBOTIC CONTROL IN PATIENTS WITH BRAIN DAMAGE

Although ankle robotic control has emerged as a critical component of robot-interactive gait training (RIGT), no study has investigated the neurophysiological and biomechanical effects on ankle muscle activity and joint angle kinematics in healthy adults and participants with brain damage, including stroke and cerebral palsy (CP). This study compared the effects of RIGT, with and without ankle control actuator, on ankle muscle activity and joint angle kinematics in healthy adults and participants with brain damage. Ten patients ([Formula: see text], left hemiparetic [Formula: see text], [Formula: see text]) underwent standardized surface electromyography (EMG) neurophysiological and kinematics biomechanical tests under the RIGT with and without ankle control actuator conditions. Outcome measures included the EMG amplitudes of the tibialis anterior and gastrocnemius muscle activity, and ankle movement angles recorded with a two-axis digital inclinometer. Descriptive statistical analysis demonstrated that RIGT with ankle control actuator showed superior effects on EMG (30%) and kinematics angles (25%) than RIGT without ankle control actuator. Our results provided novel, promising clinical evidence that RIGT with ankle control actuator can more effectively improve the neurophysiological EMG data and ankle dorsiflexion and plantarflexion movements than RIGT without ankle control actuator in participants with stroke and CP.

Reduced Achilles Tendon Stiffness Disrupts Calf Muscle Neuromechanics in Elderly Gait

Older adults walk slower and with a higher metabolic energy expenditure than younger adults. In this review, we explore the hypothesis that age-related declines in Achilles tendon stiffness increase the metabolic cost of walking due to less economical calf muscle contractions and increased proximal joint work. This viewpoint may motivate interventions to restore ankle muscle-tendon stiffness, improve walking mechanics, and reduce metabolic cost in older adults.

Ankle Muscle Activations during Different Foot-Strike Patterns in Running

This study analysed the landing performance and muscle activity of athletes in forefoot strike (FFS) and rearfoot strike (RFS) patterns. Ten male college participants were asked to perform two foot strikes patterns, each at a running speed of 6 km/h. Three inertial sensors and five EMG sensors as well as one 24 G accelerometer were synchronised to acquire joint kinematics parameters as well as muscle activation, respectively. In both the FFS and RFS patterns, according to the intraclass correlation coefficient, excellent reliability was found for landing performance and muscle activation. Paired t tests indicated significantly higher ankle plantar flexion in the FFS pattern. Moreover, biceps femoris (BF) and gastrocnemius medialis (GM) activation increased in the pre-stance phase of the FFS compared with that of RFS. The FFS pattern had significantly decreased tibialis anterior (TA) muscle activity compared with the RFS pattern during the pre-stance phase. The results demonstrated that the ankle strategy focused on controlling the foot strike pattern. The influence of the FFS pattern on muscle activity likely indicates that an athlete can increase both BF and GM muscles activity. Altered landing strategy in cases of FFS pattern may contribute both to the running efficiency and muscle activation of the lower extremity. Therefore, neuromuscular training and education are required to enable activation in dynamic running tasks.

Effects of Shoes That Can Be Tightened Using Wire and Dial on the Dynamic Balance Following Ankle Muscle Fatigue: A Crossover Study

Ankle muscle fatigue causes joint instability and increased postural sway, which triggers imbalance, leading to injury. The purpose of this study was to investigate the immediate effects of wearing shoes that can be tightened using wire and dial (SWD) compared to being barefoot and wearing lace shoes of the slip-on type (LSS) on the dynamic balance of the ankle after muscle fatigue. Twenty-two healthy individuals were enrolled in this study. Muscle fatigue in the ankle was induced using Biodex, an isokinetic equipment. The participants were randomly allocated to the barefoot, LSS, and SWD groups, and the dynamic balance immediately after inducing muscle fatigue in each participant was measured using BIORescue, the Y-Balance test, and the side-hop test. The results showed that after inducing ankle muscle fatigue, wearing SWD leads to a more significant increase in dynamic balance than barefoot and wearing LSS (p < 0.05). Hence, to improve the dynamic balance of the ankle after muscle fatigue, wearing SWD is suggested as it allows the tightening of the ankle and dorsum of the foot using the wire and dial.