Maximum isometric knee flexor and extensor muscle contractions: normal patterns of torque versus time

Area of Science:

• Biomechanics
• Human Physiology
• Gerontology

Background:

• Muscle strength is crucial for mobility and daily activities.
• Age-related muscle loss (sarcopenia) affects functional capacity.
• Understanding knee muscle torque differences is important for assessing physical function.

Purpose of the Study:

• To compare isometric knee flexor and extensor muscle torque between young and older healthy men.
• To investigate the influence of age and knee joint angle on muscle torque production.
• To characterize the time course of peak torque in knee muscles.

Main Methods:

• Isometric knee muscle torque was measured in healthy men aged 20-35 and 45-65 years.
• Torque was recorded for knee flexor and extensor muscles at three joint positions.
• Peak torque, its duration, and time to peak torque were analyzed.

Main Results:

• Mean extensor torque exceeded flexor torque across all tested knee angles and age groups.
• Younger men produced significantly higher torque than older men for both muscle groups.
• Peak torque was typically maintained for less than 0.1 second, with a maximum duration of 0.9 second.

Conclusions:

• Knee extensor muscles are stronger than flexors in healthy men.
• Age significantly impacts knee muscle torque, with younger individuals demonstrating greater strength.
• Optimal knee angles for peak torque differ between extensors and flexors.