Note: I have discussed physiology of muscle towards the end. It is important that you understand it first to be able to relate with the subject.
How muscles respond depends on the strength of neurostimuli and frequency of it. Let us first dwell into how we can optimise the muscles response to both and we will come back these two factors.
For the muscle to respond in an orderly manner, the neurons have to provide an excitatory stimuli causing multiple muscle twitches one after another in a coordinated manner to exert maximal force. Remember the muscle fiber recruitment rule, also explained below – the smallest fibers are easily excitable and hence they are recruited first…then second and 3rd.
Analogy: Visualise an automatic car and think of how its automatic transmission swiftly changes the gears. No matter how much race peddle you press the transmission will go in sequence from 1st, 2nd 3rd… and so on.
For a muscle to exert maximal power with highest speed, it would require all its muscle fibers to fire in sequence just like an automatic car. There is no process called ‘selective fiber recruitment’.
And for a muscle to engage all its muscle fibers; it would require all its motor units (motor neuron + number of muscle fibers it innervates) to fire.
Now, a muscle has thousands of muscle fibers and each muscle fiber have thousands of myofibrils or muscle cells (each muscle cell is multinucleated) and therefore a muscle would need many neurons to fire to engage maximum muscle fibers.
Motor units are directly related to tension/contraction. This means that the more the motor units engaged, the more force a muscle will generate.
Ques 1: And when do we engage maximum motor units in a muscle?
Ans: When all the muscle fibers are sequentially trained to engage in response to neurostimuli.
Ques 2: When do we have the maximum strength of a neurostimuli?
Ans: In order to gauge stimulus strength, the nervous system relies on the rate at which a neuron fires and number of neurons fire at any given time. A neuron firing at a faster rate or numerous neurons firing simultaneously or in rapid succession indicates a stronger intensity stimulus.
Ques 3: What defines the rate/frequency of neurostimuli or number of neurons?
Ans: In sporting context, freqency of the neurostimuli depends on the movement and coordination between your action site (muscle cell) and central nervous system (CNS). Just like how we progress to heavy load (at an appropriate time) to keep conditioning the nervous system to transmit electrical signals from the brain to muscles to increase the force production of a muscle; we should train the movement with different hurdles/load/resistance/actions to condition our nervous system both for rate and frequency.
Ques 4: How do you train that?
Ans: Well…by practicing the movements/actions matching the sport and by making it coordinated/smooth/swift.
Ques 4: How do we train all the muscle fibers?
Ans: When we build the muscle to its SHAPE. Its obvious because you can’t leave any section of the muscle and assume that it is strongest.
Example: What will happen if you make 3 legs of a 4 legged chair strong keeping one leg week?
Our first aim is to build a muscle in such a manner that any kind of stimulus can engage its maximum number of fibers depending on the strength of stimulus.
OK…so we understand now how a muscle work, the physiology and why we must focus on the muscle shape instead of size for more force production.
Let us now understand how we indulge a group of muscles in a sporting movement:
Movement: any kind of movement in any sport is an outcome of a group of muscles. It is not one muscle but a group of muscles.
Force direction: Force direction is important because the first muscle/s which is engaged in any movement will decide how much force is exerted by the rest of the muscles in a kinetic chain (sequence) until the finish. The muscle that gets engaged first has a say in the final outcome.
Example: How far you hit the ball (with the swing of your arm) would depend on how you swing your arm from the start to the finish. Right?
Ques: Can you figure out yet how biomechanics fit into all this?
Ans: Yes, biomechanics help us both with the movement and force direction. If you are a sprinter then you can never achieve your top speed if you don’t hit the foot on the ground with right biomechanics. And if you don’t do that then there is no way that your calves, hamstrings or glutes can exert your maximal force.
Biomechanics is often mistaken to be 100% technically correct movement. NO…where biomechanics is about using the body part with right technique, it is not about changing your natural/practiced action. It can be tweaked to optimise your action to produce maximum benefit.
For example: May be you are not able to change your foot contact signature on the ground but you can always bring the knee up to increase the force into the ground to exert maximal force from the ground?
Good biomechanics not only can help you smoothen your movement and work on your CNS but also help you take optimal usage of your muscle strength. Any movement is a sequence of work by different muscles and besides building muscle in the right shape, one must move it in the correct manner to exert maximal output from a muscle/s.
Submission: Muscle shape which is often compromised for size/load is an integral part of our performance and if it is supported by correct biomechanics then one can seek their best physical performance in any sport.
Muscle shape is directly proportional to Lean muscle mass. So what we require is lean muscle mass and not mass to produce force in sports.
Umesh Chhikara
Sports Scientist
PS: Below mentioned is a bit of physiology as I understand it.
Physiology, muscle fiber types, hypertrophy and muscle types
Let us dive into physiology of muscle for a bit as it will help me to drive home a point . Let us understand muscles fibers to begin with:
Type 1 (slow twitch): slow oxidative small fibers with significant amount of mitochondria are slow contractility are the first ones to be recruited
Type II a (fast twitch): largest size fast oxidative fibers with loads of mitochondria & fast contractility are recruited 2nd. Can be used to produce force rapidly – sports.
Type II X (fast twitch & power): medium size fast glycolytic fibers (anaerobic) with less mitochondria with fast contractility are 3rd to be recruited.
Muscle rule recruitment pattern: 1st then 2nd and lastly 3rd
Let us also understand the physiology behind hypertrophy:
Muscle size/hypertrophy: Load stress the muscle fibers enough to cause a longitudinal split in the muscle fibers which then are proliferated by myosatellite cells (providing additional myonuclie) finally increasing the fiber size and thereby total cell volume.
Muscle endurance: Endurance workout pushes the need to have more mitochondria and myoglobin in the muscle cells/fibers.
Fact: Muscle fibers can change their type depending on the activity. The number of fiber types depend on genetics & activity. Although it can take a few weeks to transform one muscle fiber type to another, however it can be highly individualistic and depends heavily on activity/training & focus.
In my understanding one must have a nice balance of all muscle fiber types in sports
Skeletal muscle types: Digastric, fusiform, sphrinter, bipennate, unipennate, tricipital, triangular and strap. The form of the muscle reflects the function of a muscle and hence the importance.
Not important for this discussion so lets leave it there but you must understand that muscle fibers are not laid in a similar manner in every muscle type.
Umesh Chhikara 