All Muscle Functions (General only)
Do not want to rewrite titles for each muscle and their specific functions. I am using the
strengthening doc to introduce the functions of all the muscles.
Terms are not set in stone.
Muscles work in pairs; they cannot pull themselves. For example, neither bicep nor tricep
muscle can stretch itself; they must be stretched by its partner around a joint. The agonist in
the pair is the prime mover (the muscle that is largely responsible for generating a
certain movement). For example, the tibialis anterior is the prime mover in dorsiflexion of the
foot (movement towards the shin). Understand that the agonist is not always the muscle that
is shortening (contracting concentrically) in a movement. In a bicep curl for example, the
bicep is the agonist on the way up when it contracts concentrically, and on the way down
when it contracts eccentrically. This is because it is the prime mover in both cases.
 Similarly, the antagonist doesn’t always relax. Another function of antagonist muscles is to
stop or slow down the movement made by the prime mover. If the weight involved in the
bicep curl was very heavy, when the weight is lowered from the top of the movement, the
antagonist tricep muscle would produce a certain amount of tension to help control the
movement as the weight was lowered. This helps to ensure that gravity (and body mass)
doesn’t accelerate the movement causing damage to the elbow joint at the bottom of the
movement. The tricep becomes the agonist and the bicep the antagonist when the elbow
extends against gravity such as in a push up or a bench press.
 The synergist/supporter in a movement is/are the muscle(s) that perform, or help perform,
the same set of joint motion as the agonist or antagonist in the movement. Alone, the
synergist cannot perform the motion at a functional level. To understand how stabilisers,
neutralisers, synergists and even fixators, overlap, in many cases, synergists stabilise
muscle movements to keep them even and control the movement so that it falls within a
range of motion which is safe and desired.
 The pronator teres is the synergist in elbow flexion because of its size and pulling angle.
 We should understand the role of muscle stabilization better if we want to design the most
effective strength, fitness and conditioning programs possible. Stabilizers are muscles that
contract to hold a body part immobile while another body part is moving. The sustained
stabilizing contraction is frequently isometric. It is important to understand there is no
distinct, mysterious group of “stabilizer muscles.” Take the biceps muscle, for
example. During a bicep curl, the biceps are the primary working muscles. But during
deadlifts, the biceps stay stiff and taut to steady the forearm, and in doing so take on the
role of stabilizer. In fact, every muscle in the body can play a stabilizing role. Proximal
(closer to centre of the body) joints are stabilized by muscle contractions during movements
of more distal (away from the centre of the body) joints (distal mobility) – the principle of
proximal stabilization. In cases such as the quadricep, the antagonists for each motion at
the proximal joint co-contract or contract against each other to prevent motion.

Fixator, then neutralizer in that order
https://www.fgc.edu/media/12537/functional%20roles%20of%20muscles.pdf
 Perhaps the biggest misnomer about how skeletal muscles function to produce the body's
movements concerns their particular role. Most people think that a muscle performs ONE
particular and very defined role and that they always perform this role. This is not how it
works. Muscles must work together to produce different bodily movements and a particular
muscle's role changes depending on the movement.
 There is more than one way to categorize the functional role of muscles. It all depends on
the movement and also the perspective.
 Synergist/supporter muscles are those that are indirectly involved in producing a
certain joint movement. A synergist is a broad term including stabiliser, fixator and
neutralizer muscles.
 The word stabilizer or stabilization has a much broader and complex definition. This view
[Rood] sees the body as a system of motor (or mobilizer) and stabilizer muscles. Whilst
prime movers move a joint in a certain way, stabiliser muscles stabilise the joint and the
spine during that movement. Two of the 4 quadricep muscles (vastus lateralis and medialis)
are stabilisers. Also essential for good posture. When stabiliser muscles are weak, too
much movement can result, causing poor biomechanics and injuries. Some time does need
to be spent on stabilisers.
Loose foot ligaments – ligamentous laxity
loose and very mobile ligaments
How mobile is my ankle?
Remember that this is general stabilization, not the activation of deep stabilizers
How to Train for Stabilization
There are three ways you can train if you want to increase your body’s stabilization
abilities.
1. Perform exercises that sufficiently tense the entire body. Please notice
the word “sufficiently.” Practically any exercise will tense your entire body to a degree, but
some exercises are particularly effective at causing your entire body to stay tight. For your
legs and hips, try squats, deadlifts and weighted lunges instead of leg presses and leg
extensions. The former exercises require the muscles of your back and shoulders to support
and steady a barbell, while the latter exercises allow you to shift much of the stabilization
responsibility to the seat on which you recline. For similar reasons, pull-ups are better than
machine pull-downs, dips are better than bench presses, and standing military presses are
better than the seated equivalent.
2. Incorporate unilateral movements into your
workouts. Do exercises with one arm or one leg at a time. Try one-armed dumbbell bench
presses, one-legged squats, one-armed dumbbell rows, and whatever else seems
appropriate. One-armed work causes the abdominal obliques and the lower back muscles to
fire, to keep the trunk from excessively rotating. One-legged work causes all of the muscles
of the planted leg to work in a stabilizing capacity, to help maintain balance.
3. Experiment
with unstable loads. This is an advanced technique that’s not appropriate for beginners.
But some trainees would benefit from lifting unstable loads such as sandbags, kegs and
barrels half full of water, and unevenly packed boxes. When lifting unstable loads, as the
weight shifts, the muscles have to take on the role of stabilizer, then prime mover, then
stabilizer again. This teaches your body to recruit muscles in a stabilizing capacity as rapidly
as possible. If you do decide to use this technique, proceed with caution.