Anatomy, Physiology, & Biomechanics Flashcards
What are the biomechanical factors in human strength? Describe each
Neural control Muscle cross-sectional area Arrangement of muscle fibers Muscle length Joint angle Muscle contraction velocity Joint angular velocity Strength-to-Mass ratio Body Size
Describe the sources of resistance to muscular contraction:
- Gravity: The downward force on objects from gravity, known as the weight of the object.
- Inertia: This is in addition to gravity. When weight is accelerated, it puts inertial force on the person doing the action.
- Friction: This is the force that happens when you are moving an object that is against another object.
- Fluid resistance: When moving through a liquid or gas, the fluid that moves around the object, or through an opening, puts added resistance force.
- Elasticity: The further you stretch something that is elastic, the more resistance it has.
Explain how intra-abdominal pressue works when lifting weights
When the deep torso muscles and the diaphragm contract, this creates pressure within the abdominal cavity. Because of there being little gas present, it is seen as incompressible and described as a “fluid ball”. This pressure supports the vertebral column during resistance training. All in all, this helps to reduce the forces that are needed by the erector spinae in order to perform exercises and also reduces the compressing forces that act on our disks. Weight belts are known to increase this intraabdominal pressure and help with weightlifting.
What is a First Class Lever
This is a lever where both the muscle force and the force of resistance act on opposite sides of the fulcrum. The best and one of the only examples is the triceps during a tricep extension. The tricep and the force are on opposing sides of the fulcrum.
What is a Second Class Lever
This is a lever where the weight is located between the axis and the force applied. There is a major mechanical advantage in these levers. In other words, the required force of the muscle is much smaller than the force of resistance. One example is the calf muscle during a calf raise. The muscle force is high, the moment arm is in the middle, and the fulcrum is the bottom (or the ball of your foot).
What is a Third Class Lever
This is the most common lever type in the body. Third class levers are where the force is applied between both the resistance and the fulcrum. Like when shoveling dirt, the back of the handle is the fulcrum, the force is where your hand is in the middle of the shovel, and the shovel head has the resistance. An example in the body would be a bicep curl with the biceps.
What is the formula for determining the strength to mass ratio?
Bodyweight^(2/3)
What is the definition of Power?
Force x Velocity
Define biomechanics
Study of the mechanisms through which musculoskeletal components interact to create movement
Define Mechanical Advantage
The ratio of the moment arm through which an applied force acts to that through which a resistive force acts (figure 2.1) For there to be a state of equilibrium between the applied and resistive torques, the product of the muscle force and the moment arm through which it acts must equal the product of the resistive force and the moment arm through which it acts. Therefore, a MA, represented as a ratio greater than 1.0, allows the applied (muscle) force to be less than the resistive force to produce an equal amount of torque.
Isaac Newtons 2nd Law
Force = Mass x Acceleration
Time rate of doing work
Power
The product of the force exerted on an object and the distance the object moves in the direction the force is exerted…
work
Define #work
Work = Force x Displacement
Equation for Power
Power = Work / Time
What is Angular Displacement?
The angle through which an object rotates
The angle through which an object rotates is called?
Angular Displacement
Define Angular Velocity
The objects rotational speed measured in radians per second
How do you calculate rotational work?
Rotational work = Torque x Angular Displacement
What is meant by ‘Recruitment’ and how does it affect muscle contraction?
This a Neural control and it affects the maximal force output of a muscle by determining which and how many motor units are involved in muscle contraction.