Muscle Torque

5 Key excerpts on "Muscle Torque"

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  eBook - ePub

  Applied Sport Mechanics

  • Brendan Burkett(Author)
  • 2018(Publication Date)
  • Human Kinetics

    (Publisher)

  figure 2.6 . The principles followed by the athlete in applying torque to a bolt apply to all lever situations that occur in sport (Kageyama et al. 2014). In essence, what happens is a battle between the turning effect of two opposing torques—torque produced by an athlete’s muscular forces and torque produced by any type of resistance, such as the weight of the athlete’s limbs plus whatever the athlete is holding (e.g., a discus or a barbell). In a sport such as wrestling or judo, an opponent can also generate resistance and torque.

  Figure 2.6 An example of the relationship in a baseball bat, torque, and force. If the bat is swung at a constant velocity and the ball makes contact with the bat at point 1, the force on the ball would be, say, 50 units. But if the ball makes contact with the bat at point 2, which is twice the distance of r1 , the force on the ball is double, or 100 units.

  Adapted from S.J. Hall, Basic Biomechanics, 4th ed. (Boston: McGraw-Hill, 2003), 370.

  At a Glance Human Anatomy–Mechanics Connection

  • For humans, bones rotate at the joints, so an athlete’s muscles, bones, and joints work together and work like a mechanical lever system
  • All human movement is a consequence of force and resistance battling each other.
  • In an athlete’s body, force is primarily produced by muscular contraction. The weight of the athlete’s limbs plus the weight of whatever the athlete is trying to move creates resistance.
  • Because the human bones rotate at the joints they always produce a turning effect, called torque.

  Lever Systems

  From this understanding of the term torque , we can then explore how various torque scenarios can exist within the human body. This mechanism is best described as a human lever system. Using the familiar bicycle pedal as an example, the mechanical principle for rotation requires an axis of rotation

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  eBook - PDF

  Industrial Engineering Applications in Emerging Countries

  • Ihsan Sabuncuoglu, Bahar Y. Kara, Bopaya Bidanda(Authors)
  • 2015(Publication Date)
  • CRC Press

    (Publisher)

  For example, applying force on the handle of a wrench connected to a bolt generates a torque (turning force) that tightens or loosens the bolt. Torque varies throughout joint motion due to change in moment arm and/or change in muscle force production. Not a single muscle but the muscle group interacts as a group to produce torque at a joint. Workers apply force or torque to produce physical work. Mathematically (in both physics and human activity), Work Force Displacement or Work Torque Angular displacement = × = × For example, a worker lifting a 10 kg load vertically from floor to a 1 m high shelf does 98 J of work (10 kg × 9.81 m/s 2 × 1 m = 98.1 N m = 98.1 J). Hand torque strength is important over a broad range of manual tasks because in many industrial work situations and also in daily life, human frequently encounters handle and knob turning tasks such as rotating a door knob to enter a room, opening the lid of a jar or medi-cine bottle, spinning the knob of any machine, tightening–loosening connectors, or even turning a key. It can be said that, every day, we use our hands and fingers to exert torque and rotational forces in many activities. Therefore, a large number of studies have been conducted by the researchers to model, measure, and predict hand torque strength under specified conditions. The hand torque strength data available in the literature show variations among the members of each of the studied populations as 88 MAHMUT EK Şİ O Ğ LU well as across the populations. Hence, using the strength data of one population for another population may give rise to problems. 5.2.3.1 Types of Hand Torque Torque can be exerted in a number of ways. The orientation as well as the shape of the product (handle/ knob/fastener/lid/wheel) is important in torque application. For example, it is easier to apply torque with a T-bar as opposed to a cir-cular knob. Grip force limits the maximal torque exertion for circular knob.

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  eBook - ePub

  Biomechanics and Motor Control

  Defining Central Concepts

  • Mark L. Latash, Vladimir Zatsiorsky(Authors)
  • 2015(Publication Date)
  • Academic Press

    (Publisher)

  Part One Biomechanical Concepts

  Outline

  1 Joint Torque 2 Stiffness and Stiffness-like Measures 3 Velocity-Dependent Resistance 4 Mechanical Work and Energy

  Passage contains an image

  1

  Joint Torque

  Abstract

  Concept of joint torques —or joint moments as many prefer to call them—is one of the fundamental concepts in the biomechanics of human motion and motor control. In classical mechanics however the concept of joint torques (moments) is not defined and is not used. In this chapter the concept is defined and discussed in detail.

  Keywords

  Dynamics; Interactive forces; Joint torques; Moment of force/couple; Movements in 3-D space; Planar movements; Statics; Vector

   

  Concept of joint torques —or joint moments as many prefer to call them—is one of the fundamental concepts in the biomechanics of human motion and motor control. A computer search in Google Scholar for the expression joint torques yielded 194,000 research papers. Even if we discard the returns that are due to the possible “search noise,” the number of publications in which the above concepts were used or mentioned is huge. The authors themselves were surprised with these enormous figures.

  Such popularity should suggest that the term is well and uniformly understood and its use does not involve any ambiguity. It is not the case, however. In classical mechanics the concept of joint torques (moments) is not defined and is not used. Peruse university textbooks on mechanics. You will not find these terms there. One of the authors vividly remembers a conference on mechanics attended mainly by the university professors of mechanics where a biomechanist presented his data. He was soon interrupted with a question: “Colleague, you are using the term ‘joint moment’ which is unknown to us. Please explain what exactly you have in mind.”

  1.1. Elements of history

  An idea that muscles generate moments of force at joints was understood already by G. Borelli (1681) . Joints were represented as levers with a fulcrum at the joint center and two forces, a muscle force and external force acting on a limb, respectively. The concept of levers in the analysis of muscle action was also used by W. and E. Weber (1836)

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  Biomechanics and Exercise Physiology

  Quantitative Modeling

  • Arthur T. Johnson(Author)
  • 2007(Publication Date)
  • CRC Press

    (Publisher)

  First of these is the distribution of fast-twitch and slow-twitch muscle fibers in muscles of the joint (see Section 1.3.1; Kamon, 1981). Second of these is the work history of the muscles, where muscles composed largely of fast-twitch fibers can produce larger torques than muscles composed mostly of slow-twitch fibers at all speeds of contraction before muscle exhaustion. After muscle exhaustion, maximal torques are the same for the two muscle types (Kamon, 1981). Age and sex also influence maximum torque. Some of these torques are summarized in Table 2.2.2. In general, women seem to be 60% as strong as men (Kamon and Goldfuss, 1978). 2.2.3 Energy and Motion Maxi-mum Muscle Torque From a general viewpoint, body motion can be considered to be composed of translational motion and rotational motion. Translational Motion : Translational motion is characterized by identical velocity and acceleration for all parts of the body. To accelerate a body requires an unbalanced force according to the familiar Newton’s second law F ¼ d( mv ) d t ¼ m d v d t ¼ ma , (2 : 2 : 6) Biceps Triceps FIGURE 2.2.6 The muscles and bones of the elbow. The biceps muscle is attached as a class 3 lever and the triceps muscle is attached as a class 1 lever. (Redrawn from Davidovits, P., Physics in Biology and Medicine , Prentice-Hall, Englewood Cliffs, NJ, 1975. With permission.) Exercise Biomechanics 63 where mv is the translational momentum of a body measured in kg m/s; m is the body mass in kg; v is the body velocity in m/s; F is the force in N; t is the time in s; a is the acceleration in m/s 2 . A body that is subjected to uniform acceleration for a time t reaches a speed* 7 cm F m = 1.6 W F r = 2.4 W 71 ° 18 cm 10 cm W l W (a) FIGURE 2.2.7 The hip joint and reaction forces. (a) Normal posture, the hip including leg and pelvic bones, and a lever representation. Weight of the individual is designated W and the weight of the leg, W L .

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  Medical Devices and Human Engineering

  • Joseph D. Bronzino, Donald R. Peterson, Joseph D. Bronzino, Donald R. Peterson(Authors)
  • 2018(Publication Date)
  • CRC Press

    (Publisher)

  Torque can be measured directly if the strength-testing device has an axis of rotation that can be aligned with the anatomical axis of rotation and a torque sensor is used, as in many isokinetic test devices. When this is not the case, the moment arm can be measured and torque calculated. Thus, for neuromuscular systems producing rotational motion, torque measures make the most sense and are preferred. The use of force measurements is the result of clinical traditional and these measures can be easily converted to torque units using knowl-edge of the applicable moment arm. Force measures are appropriate in whole-body exertions, such as lifting, where the motion is fundamentally translational. Another issue is whether to measure and record peak or averaged values. However, if strength is defined as maximum torque production capac-ity, peak values are implied. In addition to single numerical values, some strength measurement systems display and print force or torque (vs. time) curves, angle-torque curves, and graphs. Computerized systems frequently compare the “involved” with the “uninvolved” extremity calculating “percent deficits.” As strength is consid-ered proportional to body weight (perhaps erroneously, see Delitto (1990)), force and torque measure-ments are frequently reported as a peak torque-to-body-weight ratio. This is seemingly to facilitate use of normative data where present, as the normalization results in a reduction in the variance of the data distribution. 30.3.4 Methods and Instruments Used to Measure Muscle Strength There are two broad categories of testing force or torque production capacity: one category consists of measuring the capacity of defined, local muscle groups (e.g., elbow flexors); the second category of tests consists of measuring several muscle groups on a whole-body basis performing a higher-level task (e.g., lifting).

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