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Updated: Oct 30, 2020

In the previous blog we looked into the basics of muscle anatomy. The purpose of this blog is to look into and understand all of the key players that are engaged and super important when it comes to gaining strength and pack on muscle.

Fitness is not just about 'Aesthetics'. It has to be Holistic!!

Skeletal Muscles Interactions

When we are strength training, we are not just training the muscles. We are also training the tendons, ligaments, joints, neuromuscular components like muscle spindles and golgi tendons etc. Paying close/enough attention to all of these factors are crucial in making strength and muscle gains. Lets look into the role each of these play in any training regiment.


The tendons are strong bands of dense, regular connective tissue that connect muscles to bones. To move the skeleton(our frame), the tension created by the contraction of the fibers in most skeletal muscles is transferred to the tendons, which will pull the bones and produces a motion at a joint, thereby enabling a certain movement.

When we work our muscles, we will also work our tendons by default, however some special attention is warranted if we wanna get the most of our muscles. If we want to develop our maximum power output, then we need to devote at least some time and energy to specific tendon training. The key role of the tendon is to ensure we don't exert any undue strain on the muscles. In other words tendons are there to protect us from lifting too heavy a weight. So, tendons are always less resistant to weights/loads than what our muscles are really capable of.

Tendons take a lot longer to get stronger compared to muscle fibers, and on the flip side they can retain the strength for way longer as well.


Ligaments are made out of connective tissue that has a lot of strong collagen fibers in it. They are found in different shapes and sizes in the body. Some look like pieces of string, others look like narrow or wide bands. Ligaments often connect two bones (they also hold organs like liver, stomach etc in place and also the womb) together, particularly in the joints: Like strong, firmly attached straps or ropes, they stabilize the joint or hold the ends of two bones together. This ensures that the bones in the joint don’t twist too much or move too far apart and become dislocated.

Knee Joint, Tendons and Ligaments


Most of the joints we use during exercise are synovial joints, which has synovial fluid in the joint space between two bones. Exercise and stretching may also have a beneficial effect on synovial joints. Synovial fluid is a thin, but viscous film with the consistency of egg whites. When we first get up and start moving, our joints feel stiff for a number of reasons. After proper stretching and warm-up, the synovial fluid may become less viscous, allowing for better joint function. Understanding how these joints function, will enable us to tailor muscle movements accordingly. Will discuss more about this topic in subsequent articles.

Satellite Cells

In response to muscle injury or increased muscle tension, growth and repair of skeletal muscle are carried out by a group of quiescent (dormant) muscle stem cells known as satellite cells. These cells become activated, start proliferating and are responsible for the repair of damaged muscle fibres and the growth of muscle fibres. However, a small proportion of these activated satellite cells do not differentiate, returns to quiescence (go back to staying dormant) to maintain the pool of satellite cells on the muscle fibers.

Although the number of muscle cells is set during development, satellite cells help to repair skeletal muscle cells. A satellite cell is similar to a myoblast because it is a type of stem cell; however, satellite cells are incorporated into muscle cells and facilitate the protein synthesis required for repair and growth. These cells are located outside the sarcolemma and are stimulated to grow and fuse (hence the bigger muscles) with muscle cells by growth factors that are released by muscle fibers under certain forms of stress like ST.


Myostatin (also known as GDF8) is a key signalling protein that contributes to the regulation of muscle mass and function. From a biological point of view, the primary function of myostatin is the control of metabolism in order to support the immune system. However, myostatin has been proposed to be a key signalling molecule that signals the quiescence of satellite cells and their progeny, the myoblasts. It also inhibits satellite cells from proliferating and differentiating. Inhibition of myostatin often leads to increased number of satellite cells per single myofiber and a higher proportion of activated satellite cells. Myostatin negatively regulates muscle regeneration not only by controlling satellite cell activation but also by regulating the migration of myoblasts and macrophages to the site of injury.

Lowered levels of myostatin result in less fat and more muscle. Given this, there is considerable interest in building therapies based on myostatin inhibition, especially in the bodybuilding scene where people are always trying to push boundaries, take shortcuts and look for ways to get as big as possible. So, can we inhibit Myostatin naturally? What are the potential drawbacks and can we overcome them? Will discuss more on this in subsequent articles.

Result of Myostatin inhibition.


Follistatin is a protein that our body makes naturally. Our body uses it to control our metabolism, grow muscle, and boost fertility. Remember the role myostatin plays in inhibition of muscle growth? Well Follistatin is just the opposite. It blocks myostatin thereby enabling enhanced muscle growth, unlike the inhibition of myostain, which leads to abnormal muscle growth like the image above, as myostatin is still produced. However, using it in a targeted way, alongside a workout program, seems to be a recipe for rapid muscle gain.

In a 2014 study, healthy people took either follistatin or placebo orally for eight weeks, alongside a weight-lifting program. Follistatin suppressed myostatin by 44 percent, which tripled muscle growth. We will look into ways of boosting this protein naturally in subsequent articles!


In everyday activities we depend on signals coming from our moving bodies to be able to respond to the space around us and react rapidly in changing circumstances. Much of this knowledge about position and movement of the limbs and trunk is provided by sensations arising in proprioceptors. The information they provide allows us to manoeuvre our way around obstacles (even in the dark, or our eyes closed) and be able to manipulate objects out of view.

Our bodies are supplied by many types of proprioceptors. For example, we have receptors signalling distension of arteries, lungs, and the gut. Traditionally, however, the term proprioceptor has been restricted to receptors concerned with conscious sensations, and these include the senses of limb position and movement, the sense of tension or force, the sense of effort, and the sense of balance.

Physical exercises like strength training, if carried out sufficiently intensively, cause muscle fatigue and disturb proprioception. Two key modulators of proprioception in respect to muscle and strength training in general are:

Muscle Spindle

The muscle spindle is a proprioceptor (specialised sensory receptors), a sense organ that receives information from a muscle, that senses STRETCH and the SPEED of the stretch. When you stretch and feel the message that you are at the ENDPOINT of your stretch the spindle is sending a reflex (stretch or myotactic reflex) arc signal to your spinal column telling you not to stretch any further. This sense organ protects us from over-stretching or stretching too fast and hurting ourself. The responses of muscle spindles to changes in length also play an important role in regulating the contraction of muscles, by activating motor neurons via the stretch reflex to resist muscle stretch.

Golgi Tendon Organs

The golgi tendon organ is a proprioceptor, sense organ and unlike muscle spindles (located in parallel with muscle fibres), Golgi tendon organs are located in tendons near the myotendinous junction that senses TENSION and receives information from the tendon. When you lift weights, the golgi tendon organ is the sense organ that tells you how much tension the muscle is exerting. If there is too much muscle tension (if the load/weight is too heavy) the golgi tendon organ will inhibit the muscle from creating any force (via a reflex arc), thus protecting the muscle and the tendons themself (imagine the tendon being ripped off because of the extra tension being generated by the muscle). So, training the tendons is another way to ensure muscles can generate more tension and thereby more strength and muscle mass gains!!

GTO is sometimes inhibited in exceptional circumstances like life and death where

someone is trapped under a car, and this system gets overridden enabling one to perform extraordinary/superhuman feats!! However this comes at a cost because our

safety mechanism is disabled and hence it can damage all the parts its there

to protect, like tendons, ligaments, muscles, joints etc.

Myotatic Reflex involving the communication between the muscle’s stretch receptors and spinal cord.

Whereas muscle spindles facilitate activation of the muscle, neural input from GTOs

inhibits muscle activation.

Motor Unit – Neuromuscular Junction

Motor units often team up and work together in order to coordinate the contractions of a muscle. It comprises of motor neurons, which are specialised nerve cells responsible for stimulating skeletal muscle contraction. Motor neurons originate in the brain and spinal cord and extend to skeletal muscle fibers through nerves. Each of these skeletal muscle fibers have their own neuromuscular junction where nerve impulses passing down the motor neurone will trigger contractions in all of the muscles fibres.

Motor Unit

(a) A motor unit consists of a single motor neuron and all the muscle fibers its branches innervate. The muscle fibers shown in dark pink are part of one motor unit, and the muscle fibers shown in light pink are part of a different motor unit. In this figure the motor neuron is innervating the dark pink muscle fibers. (b) Photomicrograph of motor units.

The strength of a contraction depends largely on the number of units (spatial summation) recruited and the size of the units involved. To create a greater force of contraction the brain recruits more and larger motor units. As the muscle gets bigger, force generation increases and thereby strength. The bigger the muscle group the more the number of muscle fibers it will have. For example quadriceps would have a larger motor unit connecting to way more muscle fibers as they need to generate a lot more force, compared to a muscle group which needs more dexterity like our hands. So, they would have a smaller motor unit connecting to less number of muscle fibers.

Multiple-Motor-Unit Summation in a Muscle

Multiple-motor-unit summation occurs as stimuli of increasing strength are applied to a nerve that innervates a muscle. The amount of tension (height of peaks) is influenced by the number of motor units responding.

The muscle fibers found in a motor unit are all of the same fiber types, so when a muscle is activated, the fibers contract in an orderly manner. These muscle fibers work on ‘All or Nothing’ principle, which means there is no half measures. Either it is a full contraction or no contraction at all. Just like a switch, it is either turned ‘On’ or ‘Off’. More the number of motor units we recruit, the more sustained is the muscular contraction. Think of isometric contractions, where you are not lengthening or shortening the muscle but rather trying to hold on to a posture or weight therefore activating more motor neurons!

This covers most of the key players involved in muscle and strength building. In the next article we will look into the biomechanics of Strength Training.


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