Lumbar compressive and shear forces during various trunk curl-up exercises.

Area of Science:

• Biomechanics
• Exercise Physiology
• Spinal Health

Background:

• Lumbar spine injuries are common during abdominal exercises.
• Understanding the forces involved in different curl-up variations is crucial for injury prevention.
• Previous research has not comprehensively compared force generation across multiple curl-up techniques.

Purpose of the Study:

• To quantify and compare lumbar spine compressive and shear forces during longlaying, hooklaying, and bench curl-ups.
• To identify the curl-up variation that minimizes stress on the lumbar spine.
• To provide evidence-based recommendations for safer abdominal exercise performance.

Main Methods:

• Utilized the BIOMECH6 computer model to simulate biomechanical forces.
• Inputted data on lumbar spine curvature and iliopsoas tension for each exercise position.
• Analyzed compressive and shear forces at initial and 45° positions for each curl-up variation.

Main Results:

• Lumbar forces were highest during the initial position of the longlaying curl-up.
• The hooklaying curl-up showed moderate reductions in compressive and significant reductions in shear forces.
• The bench curl-up demonstrated the greatest reduction in both compressive (up to 18%) and shear forces (up to 97%).

Conclusions:

• The bench curl-up is the most beneficial exercise variation for minimizing lumbar spine compressive and shear forces.
• Performing curl-ups at a 45° angle generally reduced lumbar forces, with the exception of a slight shear force increase in the bench variation.
• These findings suggest that the bench curl-up is a safer alternative for individuals seeking to reduce lumbar spine stress during abdominal training.