Isokinetic trunk extension and flexion strength-endurance relationships

Area of Science:

• Biomechanics
• Exercise Physiology
• Musculoskeletal Research

Background:

• Assessing trunk muscle strength and endurance is crucial for understanding low back health.
• Isokinetic testing provides a standardized method to evaluate muscle performance under controlled velocities.
• Limited research exists on the fatigue characteristics of trunk flexors versus extensors across different isokinetic speeds.

Purpose of the Study:

• To investigate the relationship between isokinetic trunk extension and flexion strength and endurance.
• To analyze fatigue development in trunk flexors and extensors at various isokinetic velocities (60, 120, 180°/s).
• To determine the influence of velocity and absolute strength on trunk muscle fatigue.

Main Methods:

• Healthy male subjects performed 25 maximal effort isokinetic trunk extension-flexion repetitions at three velocities (60, 120, 180°/s) with rest intervals.
• Peak torque and work were extracted from torque-position curves.
• Fatigue profiles were generated using linear regression on mean values from specific repetition sets.

Main Results:

• The rate and magnitude of fatigue were greatest at the lowest velocity (60°/s).
• Fatigue characteristics were correlated with absolute strength, indicated by maximum work output.
• Trunk flexors exhibited greater susceptibility to fatigue compared to trunk extensors.

Conclusions:

• Trunk flexor muscles are more prone to fatigue than trunk extensors during isokinetic testing.
• Lower isokinetic velocities exacerbate trunk muscle fatigue, particularly in the flexors.
• Understanding these fatigue dynamics is important for designing effective rehabilitation and training programs for the trunk musculature.