Biomechanics

Biomechanics

The application of mechanical laws to living structures, specifically to the locomotor system of the human body.

Application

The various uses of biomechanics, including improvement of sport technique, design of sports equipment, injury prevention, analysis of pathology, design of prostheses, design of rehab devices, animation for film and video games, and ergonomics for the workplace.

Qualitative

A non-numerical description of a movement based on direct observation, such as advice given by a coach.

Quantitative movement analysis

The numerical analysis of a movement based on measurements from data collected during the performance of the movement, often derived from research.

Mass

The quantity of matter contained in an object, measured in kilograms (kg).

Force

The product of mass and acceleration, measured in Newtons (N) or 1 kg/1 m/s^2.

Weight

The amount of gravitational force exerted on a body, calculated as weight = mass * acceleration due to gravity, measured in Newtons (N).

Volume

The amount of space a body occupies.

Pressure

The force distributed over a given area, measured in Newtons per square meter (N/m^2).

Compression

The pressing or squeezing force directly axially through a body.

Tension

The pulling or stretching force.

Shear

The force directed parallel to a surface.

Mechanical Stress

Similar to pressure, calculated as force divided by area.

Lifting a heavy object

Steps to safely lift a heavy object, including asking someone to help, maintaining a stable base of support, keeping the object close to the body, and using the knee and hip extensor muscles to lift.

Flat back posture

A posture that minimizes compressive force on the L5/S1 disc and ligament strain, reducing the probability of disc herniation.

Lever

A rigid bar that turns about an axis, with bones representing the bars and joints representing the axes.

Force point

The exact point where effort is applied, typically the muscle insertion.

Resistance point

The exact point where resistance acts, often the segment plus external weight.

Fulcrum

The axis of motion.

Force arm

perpendicular distance from the fulcrum to the force point

Resistance arm

The perpendicular distance from the fulcrum to the resistance point.

First class lever

A lever in which the fulcrum is located between the force point and resistance point. Like a seesaw, ex tricep. Mechanical advantage = 1, <1 or >1 it depend where fulcrum is located in middle, closer to force point or close to resistance point

Second class lever

A lever in which the resistance point is located between the force point and fulcrum. ex wheel barrow. MA>1, always a force lever

Third class lever

A lever in which the force point is located between the resistance point and fulcrum. E.x bicep, permitted muscle to be inserted at joint and pull lever up. MA<1, always a speed lever

Mechanical advantage

The ratio of the force arm length to the resistance arm length.

Force lever

A lever in which the force arm is longer than the resistance arm, requiring less force to lift an object.

Speed lever

A lever in which the resistance arm is longer than the force arm, allowing for faster movement and a greater range of motion.

Moment arm

The perpendicular distance between the force's line of action and the pivot

Torque

The product of force and the moment arm, resulting in a rotary force.

Centre of Gravity

The imaginary point in the center where the weight of the body is balanced, important for stability and describing the movement of the body through space. Taller people have a high CG

Balance

The ability to control equilibrium.

Stability

The firmness of balance, which can be increased by increasing body mass, base of support, friction, and positioning the center of gravity.

Newton's Laws of Motion

Three laws that describe the behavior of objects in motion, including inertia, acceleration, and equal and opposite reactions.

Momentum

The quantity of motion of an object, calculated as mass x velocity.

Work

The product of force and distance, measured in joules (Nm).

Power

The work done per unit of time, calculated as force x distance divided by time or force x velocity, measured in watts (joules per second).

Walking vs Running

The differences between walking and running, including the presence of double support in walking and the absence of both feet on the ground during running.

Running Speed

Calculated as stride length x by stride rate

Double support

both feet are on the ground

Stance foot

the foot that is one the ground

Swing

the leg isn’t touching the ground

stride length

dependent on leg length and power of stride

stride rate

rate of muscle contraction and skill in running