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The unique action of bi-articular muscles in complex movements

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Abstract

Actions of muscles that pass over more than one joint are mainly described with respect to movements in the joints that are crossed. In a previous study of push-off without plantar flexion it was shown that the transformation of knee angular velocity into translation of the body is constrained by the fact that velocity difference between hip and ankle has to reach its peak value a long time before the knee is extended. The present study was meant to test the hypothesis that the action of the gastrocnemius can be understood in the light of this constraint. Vertical jumps of ten subjects were analysed cinematographically. Electromyographic signals were derived from knee extensors and plantar flexors simultaneously. The results show that the peak velocity difference between hip and ankle is reached at a mean knee angle of 132 degrees. At that instant a rapid plantar flexion starts, reinforced by a strong increase of activation of gastrocnemius. It is suggested that the bi-articular character of the gastrocnemius muscle enables the knee extensors to continue to deliver work which is transported to the ankle where it is used for plantar flexion. This optimal use of the capabilities of proximally located muscles would not be possible if man had mono-articular muscles only.
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... The muscles of limbs also have their own issues including a paradox that has been debated in biomechanical science ( van Ingen Schenau et al. 1987 ;van Ingen Schenau 1989 ). In our hindlimbs and forelimbs, there is a pair of muscles that cross two joints in series, called bi-articular muscles. ...
... Through his analysis of bi-articular muscles ( van Ingen Schenau et al. 1987 ) and his view of multi-joint movements ( van Ingen Schenau 1989 ), van Ingen Schenau (1990) has focused on the important concepts that our present review discusses below ( Fig. 1 ). These include the joint link segment; forces and directions that a pair of bi-articular muscles exerts and determines; the coordination of mono-and bi-articular muscles; co-activation of an antagonistic pair of muscles; control position and force at the distal end of the link; and ground reaction forces. ...
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Synopsis We review the two-joint link model of mono- and bi-articular muscles in the human branchium and thigh for applications related to biomechanical studies of tetrapod locomotion including gait analyses of humans and non-human tetrapods. This model has been proposed to elucidate functional roles of human mono- and bi-articular muscles by analyzing human limb movements biomechanically and testing the results both theoretically and mechanically using robotic arms and legs. However, the model has not yet been applied to biomechanical studies of tetrapod locomotion, in part since it was established based mainly on mechanical engineering analyses and because it has been applied mostly to robotics, fields of mechanical engineering, and to rehabilitation sciences. When we discovered and published the identical pairs of mono- and bi-articular muscles in pectoral fins of the coelacanth fish Latimeria chalumnae to those of humans, we recognized the significant roles of mono- and bi-articular muscles in evolution of tetrapod limbs from paired fins and tetrapod limb locomotion. Therefore, we have been reviewing the theoretical background and mechanical parameters of the model in order to analyze functional roles of mono- and bi-articular muscles in tetrapod limb locomotion. Herein, we present re-defined biological parameters including 3 axes among 3 joints of forelimbs or hindlimbs that the model has formulated and provide biological and analytical tools and examples to facilitate applicable power of the model to our on-going gait analyses of humans and tetrapods.
... And it is beneficial for the knee to have external assistance. First, some of the muscles that actuate the knee joint are multi-articular, meaning the muscle crosses and actuates multiple joints simultaneously [45][46][47]. Augmenting the knee joint will affect the muscle biomechanics of the biand tri-articular muscles, which could improve muscle efficiency or network efficiency done at the joint. Second, studies have found that altering dynamics at one lower limb joint can modify the dynamics of the non-assisted joints, such that a knee exoskeleton may be able to improve walking or muscle efficiency not only at the knee joint but also at the ankle and hip joints [15,48,49]. ...
Article
State-of-the-art exoskeletons are typically limited by the low control bandwidth and small-range stiffness of actuators, which are based on high gear ratios and elastic components (e.g., series elastic actuators). Furthermore, most exoskeletons are based on discrete gait phase detection and/or discrete stiffness control, resulting in discontinuous torque profiles. To fill these two gaps, we developed a portable, lightweight knee exoskeleton using quasi-direct-drive (QDD) actuation that provides 14 N·m torque (36.8% biological joint moment for overground walking). This article presents 1) stiffness modeling of torque-controlled QDD exoskeletons and 2) stiffness-based continuous torque controller that estimates knee joint moment in real-time. Experimental tests found that the exoskeleton had a high bandwidth of stiffness control (16 Hz under 100 N·m/rad) and high torque tracking accuracy with 0.34 N·m root mean square error (6.22%) across 0–350 N·m/rad large-range stiffness. The continuous controller was able to estimate knee moments accurately and smoothly for three walking speeds and their transitions. Experimental results with eight able-bodied subjects demonstrated that our exoskeleton was able to reduce the muscle activities of all eight measured knee and ankle muscles by 8.60%–15.22% relative to the unpowered condition and two knee flexors and one ankle plantar flexor by 1.92%–10.24% relative to the baseline (no exoskeleton) condition.
... Furthermore, the trunk muscles are used to generate rotational torques around the spine [90][91][92]. For example, greater gluteus and trapezius muscle activation resulted in increased ankle (26%) [93] and rotator cuff (23-24%) [94,95] activation, respectively. Potentially, greater trunk muscle strength, and/or stability, may optimize transfer, control, and production of force and kinetic energy during sport-specific movements. ...
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Background The role of trunk muscle training (TMT) for physical fitness (e.g., muscle power) and sport-specific performance measures (e.g., swimming time) in athletic populations has been extensively examined over the last decades. However, a recent systematic review and meta-analysis on the effects of TMT on measures of physical fitness and sport-specific performance in young and adult athletes is lacking. Objective To aggregate the effects of TMT on measures of physical fitness and sport-specific performance in young and adult athletes and identify potential subject-related moderator variables (e.g., age, sex, expertise level) and training-related programming parameters (e.g., frequency, study length, session duration, and number of training sessions) for TMT effects. Data Sources A systematic literature search was conducted with PubMed, Web of Science, and SPORTDiscus, with no date restrictions, up to June 2021. Study Eligibility Criteria Only controlled trials with baseline and follow-up measures were included if they examined the effects of TMT on at least one measure of physical fitness (e.g., maximal muscle strength, change-of-direction speed (CODS)/agility, linear sprint speed) and sport-specific performance (e.g., throwing velocity, swimming time) in young or adult competitive athletes at a regional, national, or international level. The expertise level was classified as either elite (competing at national and/or international level) or regional (i.e., recreational and sub-elite). Study Appraisal and Synthesis Methods The methodological quality of TMT studies was assessed using the Physiotherapy Evidence Database (PEDro) scale. A random-effects model was used to calculate weighted standardized mean differences (SMDs) between intervention and active control groups. Additionally, univariate sub-group analyses were independently computed for subject-related moderator variables and training-related programming parameters. Results Overall, 31 studies with 693 participants aged 11–37 years were eligible for inclusion. The methodological quality of the included studies was 5 on the PEDro scale. In terms of physical fitness, there were significant, small-to-large effects of TMT on maximal muscle strength (SMD = 0.39), local muscular endurance (SMD = 1.29), lower limb muscle power (SMD = 0.30), linear sprint speed (SMD = 0.66), and CODS/agility (SMD = 0.70). Furthermore, a significant and moderate TMT effect was found for sport-specific performance (SMD = 0.64). Univariate sub-group analyses for subject-related moderator variables revealed significant effects of age on CODS/agility ( p = 0.04), with significantly large effects for children (SMD = 1.53, p = 0.002). Further, there was a significant effect of number of training sessions on muscle power and linear sprint speed ( p ≤ 0.03), with significant, small-to-large effects of TMT for > 18 sessions compared to ≤ 18 sessions (0.45 ≤ SMD ≤ 0.84, p ≤ 0.003). Additionally, session duration significantly modulated TMT effects on linear sprint speed, CODS/agility, and sport-specific performance ( p ≤ 0.05). TMT with session durations ≤ 30 min resulted in significant, large effects on linear sprint speed and CODS/agility (1.66 ≤ SMD ≤ 2.42, p ≤ 0.002), whereas session durations > 30 min resulted in significant, large effects on sport-specific performance (SMD = 1.22, p = 0.008). Conclusions Our findings indicate that TMT is an effective means to improve selected measures of physical fitness and sport-specific performance in young and adult athletes. Independent sub-group analyses suggest that TMT has the potential to improve CODS/agility, but only in children. Additionally, more (> 18) and/or shorter duration (≤ 30 min) TMT sessions appear to be more effective for improving lower limb muscle power, linear sprint speed, and CODS/agility in young or adult competitive athletes.
... A comparison of single-joint and multi-joint assistance would also provide scientific insights into the biomechanics of walking. A large portion of human leg musculature is biarticular (van Ingen Schenau et al., 1987), comprising muscles that span two joints. Biarticular muscles might be more effectively assisted by multi-joint exoskeletons, leading to a total benefit beyond the sum of assisting each joint individually. ...
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Exoskeletons that assist the hip, knee, and ankle joints have begun to improve human mobility, particularly by reducing the metabolic cost of walking. However, direct comparisons of optimal assistance of these joints, or their combinations, have not yet been possible. Assisting multiple joints may be more beneficial than the sum of individual effects, because muscles often span multiple joints, or less effective, because single-joint assistance can indirectly aid other joints. In this study, we used a hip–knee–ankle exoskeleton emulator paired with human-in-the-loop optimization to find single-joint, two-joint, and whole-leg assistance that maximally reduced the metabolic cost of walking. Hip-only and ankle-only assistance reduced the metabolic cost of walking by 26 and 30% relative to walking in the device unassisted, confirming that both joints are good targets for assistance ( N = 3). Knee-only assistance reduced the metabolic cost of walking by 13%, demonstrating that effective knee assistance is possible ( N = 3). Two-joint assistance reduced the metabolic cost of walking by between 33 and 42%, with the largest improvements coming from hip-ankle assistance ( N = 3). Assisting all three joints reduced the metabolic cost of walking by 50%, showing that at least half of the metabolic energy expended during walking can be saved through exoskeleton assistance ( N = 4). Changes in kinematics and muscle activity indicate that single-joint assistance indirectly assisted muscles at other joints, such that the improvement from whole-leg assistance was smaller than the sum of its single-joint parts. Exoskeletons can assist the entire limb for maximum effect, but a single well-chosen joint can be more efficient when considering additional factors such as weight and cost.
... The human ankle plantar-flexors however consist of two types; the mono-articular soleus, and the biarticular gastrocnemius in which the upper end is connected to the lower section of the femur. Different studies have shown benefits of the bi-articular gastrocnemius, especially for power transfer from knee to ankle during explosive activities such as upward jumping or running [13], [14], [15]. The possibility to transfer power allows to reduce the mass and workload of the distal muscles [16]. ...
Chapter
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Chapter
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