Biomechanics Flashcards

increase force potential and strength while limiting velocity

Answer: Greater pennation angle=

A greater pennation angle in a muscle means its fibers are oriented more obliquely to the muscle's line of pull. This arrangement allows more muscle fibers to be packed in parallel, increasing the physiological cross-sectional area and thus enhancing force potential and strength. However, this often comes at the expense of reducing the muscle's effective shortening velocity.

Contracts against the pull of contracting statically

Answer: Stabilizer

A stabilizer muscle contracts statically (isometrically) to hold a body segment in a fixed position, providing a stable base for other muscles to perform movement. It actively contracts against the pull of other muscles or external forces to prevent unwanted motion. This allows for efficient and controlled execution of dynamic actions.

The inclination of a force to rotate an object about a given fulcrum.

Answer: Torque

Torque is the rotational equivalent of force, representing the tendency of a force to rotate an object about a given fulcrum or axis. It is calculated as the product of the applied force and the perpendicular distance from the fulcrum to the line of action of that force, known as the moment arm.

optimal number of crossing bridges exist

Answer: Length-Tension relationship

The length-tension relationship describes how the force a muscle can generate is dependent on its initial length. Optimal force production occurs when the muscle is at an intermediate length, allowing for the greatest number of myosin cross-bridges to optimally interact with actin binding sites. If the muscle is too short or too long, fewer cross-bridges can form, reducing its force output.

The rate of rotation of an object

Answer: Angular Velocity

Angular velocity is a measure of the rate at which an object rotates or revolves around an axis. It quantifies how quickly an angle changes over time. This concept is crucial in biomechanics for understanding the speed of joint movements and the rotation of body segments.

Repeated explosive exertion

Answer: Explosive

Explosive exertion refers to movements characterized by a high rate of force development, where maximum force is generated in the shortest possible time. Repeated explosive exertion involves performing these rapid, powerful movements multiple times. This type of training is crucial for sports and activities requiring quick, powerful bursts of energy.

Between 0.6 and 0.8 seconds

Answer: Maximum or absolute strength

Maximum or absolute strength refers to the greatest force that can be exerted in a single, maximal effort, regardless of the time it takes. While the phrase 'Between 0.6 and 0.8 seconds' is often associated with the typical duration to achieve peak force in strength assessments, it defines the time frame over which maximal force is typically developed or sustained in a single, all-out effort, characterizing absolute strength.

Cross-sectional area of muscle

Answer: CSA

CSA stands for Cross-Sectional Area of a muscle. A larger physiological cross-sectional area (PCSA) indicates that more muscle fibers are arranged in parallel within the muscle. This directly correlates with a greater potential for force generation, meaning an increase in muscle size (specifically its CSA) leads to an increased capacity to produce force.

As velocity rises, force capability falls.

Answer: Muscle contraction velocity

The force-velocity relationship in muscle physiology dictates that as the velocity of muscle contraction increases, the force the muscle can produce decreases. This inverse relationship occurs because at higher speeds, there is less time available for myosin cross-bridges to form and cycle effectively. Conversely, maximum force can be generated during isometric contractions (zero velocity).

Sustaining a given level of intensity for an extended period of time

Answer: Dynamic

Dynamic strength or endurance refers to the ability of a muscle or muscle group to sustain a given level of intensity or perform repeated movements for an extended period. This involves continuous muscle contractions and relaxations, unlike static (isometric) contractions. It is crucial for activities requiring prolonged, rhythmic movements.

Fast with less force, conditions the nervous system

Answer: High velocity training

High velocity training involves performing movements quickly with lighter loads, prioritizing speed and power over maximal force. This type of training primarily conditions the nervous system by improving motor unit recruitment, firing frequency, and coordination. This leads to an enhanced rate of force development and overall movement efficiency.

When the ratio of the moment arm to the resistive arm is greater than 1, you have a mechanical advantage.

Answer: Mechanical advantage

Mechanical advantage occurs in a lever system when the force arm (moment arm of the muscle) is longer than the resistance arm (moment arm of the external resistance). When this ratio is greater than 1, it means the muscle can produce a greater torque with less force, making it easier to move a given resistance. This principle is fundamental in understanding how the body's musculoskeletal system generates movement and force.

Acts as a "decelerator" and opposes the prime mover.

Answer: Antagonist

An antagonist muscle is one that opposes the action of the prime mover (agonist) during a movement. It acts as a 'decelerator' by contracting eccentrically to control the speed and range of motion, preventing overextension or injury. For example, during a bicep curl, the triceps act as the antagonist, controlling the lowering phase of the weight.

Compared to external force

Answer: Muscle force & resistive force

In the context of human movement and exercise, 'muscle force' refers to the internal force generated by the contracting muscles. 'Resistive force' is the external force (like gravity, weights, or friction) that the muscles must overcome or control. These two forces are constantly interacting and are critical for understanding how the body moves and adapts to training stimuli.

Variation of velocity per unit of time

Answer: Acceleration

Acceleration is a fundamental concept in physics and biomechanics, defined as the rate at which an object's velocity changes over time. This change can involve an increase in speed, a decrease in speed (deceleration), or a change in direction. Understanding acceleration is crucial for analyzing movement patterns and the forces involved in exercise.

Right and Left

Answer: Sagittal

The sagittal plane is one of the three cardinal planes used in anatomy to describe the body's orientation and movement. It divides the body vertically into right and left halves. Movements such as flexion and extension (e.g., bicep curls, squats) primarily occur within the sagittal plane.