Muscles of which one among the following body parts contract slowly but can remain contracted for a longer time?

The muscles of the intestine are smooth muscles, which are characterized by their ability to contract slowly and maintain that contraction for extended periods without fatigue. These spindle-shaped cells are found in the walls of the alimentary canal, including the food pipe and stomach, where they facilitate peristalsis—a wave-like movement that pushes food through the digestive system [1]. Unlike skeletal muscles in the arms, legs, or face, which are primarily composed of fast-twitch (Type II) or slow-twitch (Type I) striated fibers for voluntary movement and posture [3], smooth muscles in the intestine are involuntary and specialized for sustained, tonic contractions [3]. While slow-twitch skeletal fibers in the legs also resist fatigue, the specific physiological description of slow, prolonged contraction is a hallmark of the smooth muscle tissue found in internal organs like the intestine [3].

Sources

1. [1] Science ,Class VIII . NCERT(Revised ed 2025) > Chapter 2: The Invisible Living World: Beyond Our Naked Eye > 2.1.1 Variation in shape and structure of cells > p. 14
2. [3] https://www.ncbi.nlm.nih.gov/sites/books/NBK532258/