Effect of Performance Speed on Trunk Movement Control During the Curl-Up Exercise

Area of Science:

• Biomechanics
• Motor Control
• Exercise Physiology

Background:

• Trunk exercise speed impacts neuro-mechanical demands.
• The effect of varying exercise speeds on trunk displacement motor control is not well understood.

Purpose of the Study:

• To investigate how performance speed influences trunk motion control during curl-up exercises.
• To analyze kinematic variance in trunk displacement across different exercise cadences.

Main Methods:

• Seventeen subjects performed curl-ups at various metronome-controlled cadences.
• Measured kinematic variance using standard deviation (SD), range (RG), and detrended fluctuation analysis (DFA) of shoulder girdle medial-lateral displacement (SGML) and center of pressure medial-lateral displacement (COPML).

Main Results:

• Center of pressure medial-lateral displacement (COPML) variability (SD, RG) increased with speed.
• Shoulder girdle medial-lateral displacement (SGML) variability (SD, RG) remained unaffected by exercise cadence.
• Detrended fluctuation analysis (DFA) revealed higher scaling exponents (α) for faster movements, indicating altered long-term fluctuation strategies.

Conclusions:

• Increased performance speed in curl-ups challenges medial-lateral adjustments but does not alter linear variability of the trunk's sagittal trajectory.
• Different motor control strategies are employed at varying speeds to maintain the target trajectory, with fewer trajectory changes observed during faster exercises.