In this instructional fitness video, the narrator warns viewers that training the abdomen incorrectly can lead to a "square" waist. He first critiques a common mistake in the Russian Twist, where trainees keep the hips fixed and merely shift the weight side‑to‑side without rotating the trunk, which promotes a widened waist. He demonstrates the proper execution: hips supported, trunk actively rotating, feet suspended to keep constant abdominal tension. He then moves to the basic ABS Crunch, highlighting the importance of keeping the feet on the floor with knees flexed to protect the lumbar spine, placing the hands behind the head for neck support, and limiting the upward movement to achieve full spinal flexion. He points out a frequent error where the athlete lets the back fully rest on the floor during the descent, eliminating time‑under‑tension and reducing effectiveness. Throughout, the speaker emphasizes correct form to maintain a tapered waist and avoid the “quadrado” (square) look.
