Exclusively breastfed babies do not require additional water even when it is very hot outside, as long as baby is allowed to nurse as needed. Even in extremely hot, dry weather your baby can get all the liquids needed via breastmilk.
Smooth muscles contract very slowly, whereas skeletal muscles can contract at different rates. Skeletal muscles can be composed of fast-contracting fibers, slow-contracting fibers or a mixture of both.
Your body is composed of three types of muscle: skeletal muscle, smooth muscle, and cardiac muscle. Skeletal muscle makes up 40 percent of your total body weight, and smooth muscle and cardiac muscle each make up 5 percent of total body weight. Your muscles must contract in order to facilitate vital bodily functions.