Force - length & Torque – Joint Angle Relationships

Flashcards on Force, Length, Torque, Joint Angle Relationships

Force-Length Relationship

As muscle stretches, the maximum force increases until it hits a point where it weakens and plateaus.

Passive Force

Force generated by passive structures in the muscle.

Active Force

Force generated by the active contraction of the muscle.

Optimal Overlap

The ideal arrangement of muscle filaments for force generation.

Frog Muscles - F-L Curves

Passive structures have a large force contribution in the gastrocnemius, but low in the semitendinosus.

Energy Efficiency (F-L Curves)

Lower limb muscles move through a certain portion of the curve when walking for efficient energy use.

Gastrocnemius Insertion

The insertion point into the knee affects muscle stretch and adaptations like hypertrophy during exercises like standing calf raises.

Torque-Joint Angle Relationship

Peak torques occur at joint angles encountering the greatest loads in daily activities.

Hip Flexor Weakness

Hip flexors are weaker when stretched due to less frequent stretching in daily activities.

Elbow Flexor – Joint Angle Relationship

Force vector increases in the bicep as it flexes relative to the joint angle, however, too much flexion will lead to decreased force potential.

Knee Extensor Torque

Torque generated is based on the forces generated and the moment arm of the joint.

Measuring T-JA Relationships

Isometric strength tests at various joint angles or slow isokinetic dynamometer contractions through full ROM.

Variable Resistance Machines

Mechanical advantage changes across ROM to suit the average 'strength curve'.

Torque-Velocity Relationship of Human Muscle

Slower movements generate more torque. Eccentric actions are strongest, followed by isometric, then concentric actions.

Concentric Activation in Lifting

Lifting requires more muscle capacity than lowering the same weight eccentrically.

Aging & the Force-Velocity Curve

Both the Force and Velocity portions of the Force-Velocity Curve tends to decrease with age, especially in shortening contractions and isometric actions meaning there is a devastating loss of power.