{"id":506,"date":"2026-04-28T10:51:38","date_gmt":"2026-04-28T10:51:38","guid":{"rendered":"https:\/\/www.fitcart.com\/blog\/?p=506"},"modified":"2026-04-28T10:51:38","modified_gmt":"2026-04-28T10:51:38","slug":"muscle-101-by-dr-rob-wildman","status":"publish","type":"post","link":"https:\/\/www.fitcart.com\/blog\/muscle-101-by-dr-rob-wildman\/","title":{"rendered":"MUSCLE 101 by Dr. Rob Wildman"},"content":{"rendered":"\n

Dr Rob Wildman answers questions on muscle basics. These Q&As can also be found in The Nutritionist: Food, Nutrition & Optimal Heath and TheNutritionDr.com.<\/strong><\/p>\n\n\n\n

Article by Dr. Rob Wildman<\/em><\/p>\n\n\n\n

What is skeletal muscle?<\/strong><\/p>\n\n\n\n

There are over 300 pairs of skeletal muscle in the body and its principal role is to pull on bone to move the body in some manner. In addition to movement, skeletal muscle is a major metabolic tissue and a principal depot for carbohydrate and fat. Apart from reflex mechanisms, such as the knee tap by a physician, movement of our skeletal muscle is under the command of our brain. Skeletal muscle is made up of very specialized cells that can shorten when they are stimulated.<\/p>\n\n\n

\n
\"\"<\/figure>\n<\/div>\n\n\n

Because muscle cells are very long, they are often referred to as muscle fibers. Muscle fibers are bundled up like a box of dry spaghetti or straight wires in a cable. The muscle fiber bundles are themselves bundled up and are part of larger collection of similar bundles which make up a muscle. Skeletal muscle is so named because it is generally anchored at both ends to different bones of our skeleton. When muscle contracts, it pulls on a specific bone, which moves the bone, thus moving a body part.<\/p>\n\n\n\n

How does skeletal muscle work?<\/strong><\/p>\n\n\n\n

Like neurons, skeletal muscle fibers are also excitable. In fact, the excitability process of muscle cells is very similar to that of neurons, while the result is different. Excitability in muscle fibers leads to the contraction of the muscle cell while neurons merely carry the electrical nerve impulse to another neuron or to skeletal muscle or other tissue and organs.<\/p>\n\n\n

\n
\"\"<\/figure>\n<\/div>\n\n\n

The inside of skeletal muscle fibers appears unique from other cells because of the structural apparatus of contraction (shortening). Each muscle fiber contains a tremendous amount of small fibrous units called myofibrils. The prefix myo refers to muscle and fibril means little fiber. Each myofibril is a stalk-like collection of proteins. The predominant proteins are actin and myosin, which are referred to as the thin and thick filaments, respectively. They are organized into a series of tiny contraction regions called a sarcomere. Myofibrils are composed of thousands of sarcomeres situated side by side and are tethered together.<\/p>\n\n\n\n

What is calcium\u2019s role in muscle contraction?<\/strong><\/p>\n\n\n\n

Calcium isn\u2019t just important for bone, it is also the key factor that initiates muscle contraction. When skeletal muscle fibers become excited, calcium channels open and calcium floods myofibrils and bathes the sarcomeres. Calcium then interacts with specific proteins associated with actin and promotes contraction. The contraction of one muscle fiber is really the net result of the shortening of all the tiny sarcomeres in each myofibril within that cell. Further, the contraction of the muscle itself is the net result of contraction and shortening of muscle fibers that make up that muscle.<\/p>\n\n\n\n

Skeletal muscle cells have another unique characteristic. They contain an organelle called the sarcoplasmic reticulum which is a modified version of the endoplasmic reticulum found in other cells. This organelle stores large quantities of calcium. In fact, when a skeletal muscle cell is stimulated, most of the calcium that bathes the sarcomeres comes from the sarcoplasmic reticulum.<\/p>\n\n\n\n

What powers muscle contraction?<\/strong><\/p>\n\n\n\n

For muscle fibers to contract, a lot of ATP must be used. Roughly 40% of the energy released from ATP is used to power muscle contraction, while the rest is converted to heat. Interestingly, ATP is also necessary for a contracted muscle cell to \u201crelax\u201d as well. When the muscle is no longer being stimulated, ATP helps the thick and thin filaments to dissociate from each other so that each sarcomere can return to a relaxed (or unstimulated) position. Also, ATP is necessary to pump calcium out of intracellular fluid of the muscle fiber which allows the muscle cell to reset.<\/p>\n\n\n\n

As a side note, if ATP is deficient, muscle fibers become locked in a contracted state called rigor. Rigor mortis occurs when the human body dies as the integrity of muscle cell membranes decrease. This allows the calcium pumped out to leak back in and as a result, calcium bathes myofibrils and contraction is invoked as there can be enough ATP in the dying cells to power the contraction but not enough for it to then relax.<\/p>\n\n\n\n

Fitcart<\/strong><\/a> believes in True Play and Clean Sport<\/strong><\/p>\n\n\n\n

#trustedbrandsbetterhealth<\/strong><\/p>\n\n\n\n

All our nutritional information is scientific and evidence-based, to be used as a dietary guide. Before starting any new diet or fitness regime we recommend consultation with a certified healthcare professional.<\/em><\/p>\n","protected":false},"excerpt":{"rendered":"

Dr Rob Wildman answers questions on muscle basics. These Q&As can also be found in The Nutritionist: Food, Nutrition & Optimal Heath and TheNutritionDr.com. Article by Dr. Rob Wildman What is skeletal muscle? There are over 300 pairs of skeletal muscle in the body and its principal role is to pull on bone to move […]<\/p>\n","protected":false},"author":2,"featured_media":403,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[766],"tags":[992,768,991,988,990,769,989],"class_list":["post-506","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-dr-rob-wildman","tag-beginner-muscle-guide","tag-dr-rob-wildman","tag-fitness-education","tag-muscle-101","tag-muscle-basics","tag-muscle-function","tag-muscle-structure"],"_links":{"self":[{"href":"https:\/\/www.fitcart.com\/blog\/wp-json\/wp\/v2\/posts\/506","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.fitcart.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.fitcart.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.fitcart.com\/blog\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/www.fitcart.com\/blog\/wp-json\/wp\/v2\/comments?post=506"}],"version-history":[{"count":1,"href":"https:\/\/www.fitcart.com\/blog\/wp-json\/wp\/v2\/posts\/506\/revisions"}],"predecessor-version":[{"id":509,"href":"https:\/\/www.fitcart.com\/blog\/wp-json\/wp\/v2\/posts\/506\/revisions\/509"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.fitcart.com\/blog\/wp-json\/wp\/v2\/media\/403"}],"wp:attachment":[{"href":"https:\/\/www.fitcart.com\/blog\/wp-json\/wp\/v2\/media?parent=506"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.fitcart.com\/blog\/wp-json\/wp\/v2\/categories?post=506"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.fitcart.com\/blog\/wp-json\/wp\/v2\/tags?post=506"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}