Before starting any form of exercise, it’s important to understand how our bodies work and how they will benefit from the physical exercise you’re about to start. Of the body’s many unbelievable systems, the ones most directly affected by regular exercise are the skeletal, muscular, cardiovascular, respiratory, nervous, and endocrine systems.
The skeletal system
Your skeleton is made up of 206 bones that keep you upright, protect your organs, allow you to move (bones are the levers of all movements), and store important minerals.
All your bones, except one (the hyoid bone in the neck), meet with other bones to form joints. Some joints, like those in the skull, are immovable and are joined by fibrous tissue. Others, such as the vertebrae in the spine, are only partially movable; these are linked by pads of cartilage.
The majority of joints in our our bodies, however, are complex, freely movable joints, called synovial joints. Synovial joints are lubricated by synovial fluid, which helps to absorb the shock of any high-impact movements. What is more, the ends of the bones in a synovial joint are coated with smooth cartilage that provides cushioning and allows your joints to move without discomfort. The whole joint is stabilized by ligaments that connect the bones.
All these structures allow movement to happen, but it’s your skeletal muscles that provide the power. When a muscle contracts, it pulls on tendons, which connect the muscle to bones, moving the bones in the desired direction.
The muscular system
We all know that muscles enable movement, but how exactly do they do that?
The answer is that they alternately contract (shorten) and relax (lengthen). Connected to your muscle fibers are nerves that carry messages to and from your brain, and blood vessels that carry energy in the form of oxygen to your muscles and waste in the form of carbon dioxide away from them.
The human body includes three types of muscle:
• cardiac muscle—in the heart
• smooth muscle—in the walls of internal structures, e.g. the intestines
• skeletal muscle—attached to bones.
Cardiac muscle works to pump blood around your body, determining your cardiovascular fitness.
Smooth muscle works, among other things, to keep important substances moving through your body.
However, it’s skeletal muscle that’s responsible for giving your body its shape, holding it upright, stabilizing your joints, and enabling your bones and therefore your body to move. Every external movement that you make, no matter how small, is a result of skeletal muscle.
While cardiac and smooth muscle are involuntary, meaning they aren’t under your conscious control, skeletal muscle is a voluntary muscle, meaning you are able to control when and how you use it.
Given that we have more than 600 skeletal muscles in our body, it would be somewhat tricky to try to actively think about how to use them all every time we work out! Nevertheless, there are certain key muscle groups that are particularly useful to pay attention to when exercising – muscles of the arms, legs, and the back.