Podcast
Questions and Answers
Which type of muscle architecture is designed for fine control?
Which type of muscle architecture is designed for fine control?
- Parallel muscles
- Quadriceps muscles
- Pennate muscles
- Eyelid muscles (correct)
What does the rate of force development primarily measure?
What does the rate of force development primarily measure?
- Maximal strength over prolonged contraction
- Muscle endurance over time
- Explosive strength in initial contraction (correct)
- Flexibility during muscle contraction
What type of muscles have a larger physiological cross-sectional area (PCSA) compared to parallel muscles?
What type of muscles have a larger physiological cross-sectional area (PCSA) compared to parallel muscles?
- Circular muscles
- Parallel muscles
- Pennate muscles (correct)
- Striated muscles
What factor does NOT influence the maximum tension that a muscle can produce?
What factor does NOT influence the maximum tension that a muscle can produce?
Which muscle type is likely to have a reduced range of motion?
Which muscle type is likely to have a reduced range of motion?
How do sarcomeres in parallel muscles differ from those in pennate muscles?
How do sarcomeres in parallel muscles differ from those in pennate muscles?
In the context of muscle force development, which of the following terms refers to the maximum tension a muscle can produce?
In the context of muscle force development, which of the following terms refers to the maximum tension a muscle can produce?
What happens to the maximum force generated during muscle contraction in the first 200 milliseconds?
What happens to the maximum force generated during muscle contraction in the first 200 milliseconds?
Which component does NOT form part of a lever in the skeletal and muscular system?
Which component does NOT form part of a lever in the skeletal and muscular system?
What is the primary function of levers in the skeletal and muscular systems?
What is the primary function of levers in the skeletal and muscular systems?
Why can pennate muscles generate more force compared to parallel fibered muscles?
Why can pennate muscles generate more force compared to parallel fibered muscles?
What is a consequence of maintaining a low center of gravity in a rugby player?
What is a consequence of maintaining a low center of gravity in a rugby player?
Which statement about muscle length and tension is accurate?
Which statement about muscle length and tension is accurate?
Which statement is true regarding the force development of muscles?
Which statement is true regarding the force development of muscles?
What does the angle of muscle fibers (α) influence in muscle force production?
What does the angle of muscle fibers (α) influence in muscle force production?
What is the mass of the torso and head for a body with mass M of 70 kg?
What is the mass of the torso and head for a body with mass M of 70 kg?
Which of the following best describes the role of the fulcrum in a lever system?
Which of the following best describes the role of the fulcrum in a lever system?
Which segment has the highest mass percentage of the total body mass M?
Which segment has the highest mass percentage of the total body mass M?
What increases the stability of an object according to the principles of center of gravity?
What increases the stability of an object according to the principles of center of gravity?
How is stability characterized when the center of gravity is outside the base of support?
How is stability characterized when the center of gravity is outside the base of support?
Which segmented mass is the smallest fraction of the total body mass M?
Which segmented mass is the smallest fraction of the total body mass M?
What effect does increasing the area of the base support have on stability?
What effect does increasing the area of the base support have on stability?
What is the mass of the upper arms for a body with mass M of 70 kg?
What is the mass of the upper arms for a body with mass M of 70 kg?
When a rugby player stands with their feet well apart, what aspect of stability are they primarily addressing?
When a rugby player stands with their feet well apart, what aspect of stability are they primarily addressing?
What is torque primarily dependent on?
What is torque primarily dependent on?
What does a lever use to change the direction of a force?
What does a lever use to change the direction of a force?
Which statement accurately describes how torque is calculated?
Which statement accurately describes how torque is calculated?
In a lever system, the effort is defined as:
In a lever system, the effort is defined as:
What is the direction of the moment if a force causes a clockwise rotation?
What is the direction of the moment if a force causes a clockwise rotation?
How does the angle of force application affect the torque generated?
How does the angle of force application affect the torque generated?
If a force of 445 N acts at an angle of 82°, what must be considered in torque calculation?
If a force of 445 N acts at an angle of 82°, what must be considered in torque calculation?
In applying the equation τ = F sin θ d, what does θ represent?
In applying the equation τ = F sin θ d, what does θ represent?
What is the formula used to calculate the torque produced by a force?
What is the formula used to calculate the torque produced by a force?
If the deltoid muscle exerts a force of 67 N at an angle of 15°, what is the torque generated about the shoulder joint?
If the deltoid muscle exerts a force of 67 N at an angle of 15°, what is the torque generated about the shoulder joint?
What condition must be satisfied for an object to be in equilibrium regarding torque?
What condition must be satisfied for an object to be in equilibrium regarding torque?
When the lower leg rotates clockwise about the knee, what type of torque does the hamstring muscle produce?
When the lower leg rotates clockwise about the knee, what type of torque does the hamstring muscle produce?
What is the method to find the force generated in the biceps muscle when the arm is holding a weight at equilibrium?
What is the method to find the force generated in the biceps muscle when the arm is holding a weight at equilibrium?
What is the correct equation to calculate the force in the biceps muscle given the angular distances and applied weights about the elbow?
What is the correct equation to calculate the force in the biceps muscle given the angular distances and applied weights about the elbow?
If the biceps muscle's force is calculated to be 412.5 N, what does this imply about the forces acting on the arm?
If the biceps muscle's force is calculated to be 412.5 N, what does this imply about the forces acting on the arm?
Which of the following statements is true regarding the static equilibrium of a holding arm?
Which of the following statements is true regarding the static equilibrium of a holding arm?
What is the correct expression to calculate the force FE based on the provided information?
What is the correct expression to calculate the force FE based on the provided information?
What does a mechanical advantage (M.A.) greater than 1 indicate?
What does a mechanical advantage (M.A.) greater than 1 indicate?
In a Class III lever, which of the following is true regarding the relationship of forces?
In a Class III lever, which of the following is true regarding the relationship of forces?
What is a consequence of poor lifting techniques according to the content?
What is a consequence of poor lifting techniques according to the content?
What characterizes a lever system with a mechanical advantage less than 1?
What characterizes a lever system with a mechanical advantage less than 1?
In a healthy person standing upright, which part of the body bears normal load?
In a healthy person standing upright, which part of the body bears normal load?
What force acts downward in the net force equation provided?
What force acts downward in the net force equation provided?
Which scenario is most likely to increase loading on the back muscles?
Which scenario is most likely to increase loading on the back muscles?
Flashcards
Center of Gravity
Center of Gravity
The point where the entire weight of an object is considered to act.
Stability
Stability
The ability of an object to resist tipping over or moving.
Base of Support
Base of Support
The area of contact a body has with the supporting surface.
Stable Object
Stable Object
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Unstable Object
Unstable Object
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Mass of Torso and Head
Mass of Torso and Head
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Increased Base of Support
Increased Base of Support
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Center of Gravity Location
Center of Gravity Location
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Rate of Force Development
Rate of Force Development
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Force Development
Force Development
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Parallel Muscles
Parallel Muscles
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Pennate Muscles
Pennate Muscles
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Sarcomere
Sarcomere
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Muscle Architecture
Muscle Architecture
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Force Production
Force Production
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Force Production (Pennate)
Force Production (Pennate)
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Anatomical CSA
Anatomical CSA
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Physiological CSA
Physiological CSA
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Muscle Force & Length
Muscle Force & Length
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Levers in Body
Levers in Body
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Moment of Force
Moment of Force
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Torque
Torque
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Perpendicular Distance
Perpendicular Distance
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Clockwise Moment
Clockwise Moment
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Anticlockwise Moment
Anticlockwise Moment
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Calculate Torque (Equation)
Calculate Torque (Equation)
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Lever
Lever
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Fulcrum
Fulcrum
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Net Force
Net Force
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Downward and Upward Forces
Downward and Upward Forces
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Mechanical Advantage (M.A.)
Mechanical Advantage (M.A.)
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Class I Lever
Class I Lever
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Class II Lever
Class II Lever
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Class III Lever
Class III Lever
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Back Injury Risk
Back Injury Risk
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Load on Lumbar Vertebrae
Load on Lumbar Vertebrae
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Torque Equation
Torque Equation
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Torque Calculation
Torque Calculation
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Clockwise vs. Anticlockwise Torque
Clockwise vs. Anticlockwise Torque
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Equilibrium
Equilibrium
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Solving for Force in Equilibrium
Solving for Force in Equilibrium
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Lever Arm
Lever Arm
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Biceps Muscle Force Calculation
Biceps Muscle Force Calculation
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Elbow Joint Force Calculation
Elbow Joint Force Calculation
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Study Notes
Musculoskeletal System, Nervous System & Bioelectricity, MNB.7 Skeletal Lever System
- Learning Outcomes: Define Centre of Gravity (CofG), understand its significance in biomechanical calculations, draw a diagram of force development in human muscle and factors affecting maximum tension, define moment, torque & lever, outline conditions for static equilibrium in anatomical examples, demonstrate biomechanical force calculation using moments, define & calculate mechanical advantage, differentiate between Class I, II, and III levers with anatomical examples, and discuss back injury risks associated with poor lifting technique.
Centre of Gravity
- Definition: The centre of gravity (CofG) is the point where an object's mass or weight is evenly distributed and through which gravity's force acts.
- Uniform Objects: In uniformly dense and symmetrical objects, the CofG is at the geometric center.
- Significance: Crucial for understanding and calculating forces in biomechanics and determining stability.
- Location in Body: The CofG usually lies at the midpoint of a body segment, like the arm.
- Human Body Segments: The body can be divided into segments (e.g., head, torso, arms, legs) with each segment having its own CofG and mass. Values are given for these segments within a human of 70kg mass.
Centre of Gravity and Stability
- Stability: An object is stable when its CofG lies above its base of support.
- Base of Support: The portion of a body that is in contact with the supporting surface.
- Stability & Base Area: Increasing the base area increases stability. Lowering the CofG enhances stability.
Force Development
- Rate of Force Development: Measures how quickly a muscle generates force in the initial contraction phase. It's a key factor in explosive strength.
- Force and Muscle Contraction: The maximum force generated in muscle contraction is influenced by factors during muscle contraction.
- Muscle Architecture Types: Parallel Muscles (fibers run parallel to tendon) and Pennate Muscles (fibers run at an angle to tendon). Pennate muscles generally generate more force.
- Physiological Cross-Sectional Area (PCSA): The maximum tension a muscle can produce roughly corresponds to the PCSA at the thickest part in parallel fibers.
- Muscle Length: Maximum tension is generally achieved when muscles are at their resting length.
Levers
- Lever System: Bones act as levers, muscles as forces and joints as fulcrums to generate motion.
- Fulcrum: The fixed point around which a lever pivots.
- Load: The object or force being moved or balanced.
- Effort: The force applied to overcome the load.
- Moment of Force: The turning effect of a force, calculated as the product of the force and its perpendicular distance from the fulcrum (torque).
- Torque: Rotational force, causing rotation around an axis.
- Calculating Torque: Torque is calculated by multiplying the force by the perpendicular distance from the fulcrum to the line of action of the force (τ= F sinθd) where θ is the angle between the force and the lever arm.
Equilibrium
- Static Equilibrium: When the net torque and net force on an object are zero.
- Net Torque: Sum of all torques acting on an object.
- Net Force: Sum of all forces acting on an object.
Mechanical Advantage (MA)
- Definition: The ratio of the load force to the effort (applied) force, indicating the force amplification gained by the lever.
- Efficiency: MA greater than 1 means effort needed is less than the load, (efficient). MA less than 1, effort needed is more than the load (inefficient).
Classes of Levers
-
Class I Levers: Fulcrum is in the middle between the load and effort. Examples include neck muscles acting on the head, which often provide speed of movement but are not always the most efficient.
-
Class II Levers: Load is in the middle between the fulcrum and effort. Examples include calf muscles acting when lifting a load off the floor, often efficient for strength.
-
Class III Levers: Effort is in the middle between the fulcrum and load. Examples include the biceps muscle used in flexing the elbow—often more efficient for speed and range of motion but less efficient for increased force.
Back Injury
- Normal Load: Consistent stress across the lumbar vertebrae.
- Increased Load: Depending on the type of activity, the loading on the back can vary significantly.
- Lifting Technique: Improper technique can substantially increase stress on the back muscles and increase risk for injury.
- Safe Lifting Techniques: Proper lifting techniques, including bending from the knees and using the legs/core muscles, reduce back injury risk by lowering the forces that muscles must generate.
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Description
Test your knowledge on the Skeletal Lever System, Centre of Gravity, and biomechanics. This quiz covers definitions, calculations, and anatomical examples related to leverage, moment, and torque. Understand how these concepts impact human movement and injury risk.
