Final answer:
The external oblique muscles perform both concentric and eccentric isotonic contractions, aiding in spine flexion, trunk rotation, and abdominal compression.
Step-by-step explanation:
Types of Contraction Caused by the External Obliques
The external oblique muscles are part of the anterolateral abdominal wall and contribute to various trunk movements and rotations. When discussing muscle contractions, isotonic contractions are most relevant as they involve changes in muscle length with constant tension. There are two types of isotonic contractions: concentric contractions and eccentric contractions. The external obliques primarily perform concentric contractions when they shorten to flex the spine, rotate the trunk, or compress the abdominal contents. Eccentric contractions can occur as these muscles control the return to a neutral position from a flexed or rotated position or resist overstretching by slowly elongating under tension.