Name the muscle primarily worked in the Hundred exercise.

The Hundred exercise primarily engages the rectus abdominis, which is a key muscle of the core. This exercise is designed to increase blood flow and warm up the body while promoting core strength and stability. During the Hundred, individuals typically maintain a curled-up position that targets the abdominal muscles, particularly the rectus abdominis, to hold the position while pumping the arms in sync with a specific breathing pattern. This not only challenges endurance and control of the core but also emphasizes coordination with breath, which is a fundamental aspect of Pilates. Strengthening the rectus abdominis through this exercise contributes to overall core stability, which is essential for supporting various movements in Pilates and daily activities. The emphasis on the abdominal region is a hallmark of Pilates methodology, making this exercise a foundational practice for enhancing core strength.