Create a 5-second ultra-realistic cinematic Instagram fitness video based on the provided source image of the woman. She is performing a seated leg extension in a modern commercial gym with natural overhead lighting and blurred gym equipment in the background. Focus on smooth, powerful movement with realistic muscle tension, subtle sweat as in the reference image, and natural hair motion. Start with a high side-angle shot emphasizing the weight stack and leg extension, then slightly push in toward her focused expression. Include realistic machine movement and foot placement. No Audio. Visual style should feel premium, athletic, and social-media ready with shallow depth of field, cinematic motion blur, high detail, and no AI artifacts. Vertical 9:16 aspect ratio for Instagram Reels.