Ace the AAAI-ISMA Personal Trainer Exam 2026 – Flex Your Knowledge & Fuel Your Fitness Career!

Muscles protect internal organs and generate heat to keep body temperature stable. The skeletal muscles act as a protective layer around the chest and abdomen, with certain groups like the abdominal and back muscles shielding organs and stabilizing the trunk. They also produce warmth when they contract, so during activity or in cold conditions they help maintain a steady core temperature through metabolic heat production—and rapid contractions during shivering amplify that heat. The other options describe functions of different systems (gas exchange by the respiratory system, hormone production by glands, filtration of blood by the kidneys), which aren’t the roles of skeletal muscles.