How your body compensates for an imbalance: the path of muscle chains

When you feel a back discomfort, an imbalance in running or a small instability by changing direction, you often have the reflex to point one muscle « low ». However, the body functions as a network of muscle chains connected by connective tissue (the fascia, an envelope that surrounds and connects the muscles between them), and a localized problem is often explained by a whole less effective chain rather than by an isolated muscle.

To analyze why a movement is less fluid or less powerful, two measuring tools allow to observe two complementary aspects of the body: the Neurocom test and the Myotest. Neurocom quantifies postural control, i.e. how the brain manages balance, reacts to destabilization and distributes body weight over the legs. It evaluates timing (speed of reaction), load transfer and balance strategy — via the central nervous system, sensory integration (the way the brain combines information from vision, inner ear and body sensations) and coordination — without directly measuring muscle strength. The Myotest quantifies the mechanical output of the neuromuscular system, i.e. the power actually produced by the muscles: jump height, strength, power, ground contact time and inter-member asymmetry indices (the difference in performance between the left and right sides of the body), via a force-speed profile (F-v). This profile is based on three values: F0 (the maximum theoretical force that the muscle could develop at zero speed), V0 (the maximum theoretical speed that the muscle could achieve without load) and Pmax (the maximum developed power, which combines force and speed).These Myotest measurements are particularly reliable: the flight time jump height has an ICC (intraclass correlation coefficient, which measures the reproducibility of a measurement) from 0.92 to 0.96, or 96%, and the squat and developed force/power

The table below summarizes what each test measures:

Dimension	Neurocom	Myotest
What is measured	Postural oscillation, reaction time, directional control, load transfer, lift/impact index	Jump height, force, power, contact time, inter-member asymmetry index
Nature of information	Engine control strategy and timing	Mechanical capacity and symmetry of force production
Own limit	Does not measure muscle strength or EMG (electromyography, measurement of electrical activity of muscles)	Do not provide information on sensory strategy or central timing

 

Taken separately, each test has its limits. It is by crossing the results of Neurocom and Myotest that one gets a complete picture of how the body moves.

Let us take a concrete example: a person whose Neurocom reveals a postural oscillation (an imbalance) high in support of the right leg, and whose Myotest at the same time reveals an asymmetry of power unfavourable to the right limb. Rather than conclude that there are two separate problems, this combined deficit is oriented towards the same functionally less effective muscle chain on this side of the body. This cross-reading enables manual therapy and movement to be targeted on tension-bearing connective tissue, rather than on an isolated muscle. The human body is organized into several large muscle chains (or myofascial lines, according to the concept of Anatomy Trains). — mapping of muscle chains linked by the fascia), each linking areas that seem remote but actually work together.

This line links the sole of the foot, the tendon of Achilles, the ischio-legs (the muscles at the back of the thigh), the lumbosacre fascia (the connective tissue at the bottom of the back), the erectors of the spine (the muscles that straighten the spine), to the epicranial aponeurosis (the envelope of the top of the skull). It corresponds functionally to the extension and propulsion chain.

On the Neurocom side, this line is covered by mCTSIB (a balance test on foam, eyes open and closed), unipodal support (on a single leg), standing seat (transfer time and load on the lumbar column) and crossing (lift/impact index). On the Myotest side, it is concerned with the jump height (CMY/SJ, two types of vertical jumps), the power of the hip/genou/cheville extenders and the ground contact time. In cross-reading: a high lumbar load in the sitting-standing position (less than 3 = low) associated with a reduced jump power and an elongated contact time is compatible with a lower eccentric reactive posterior chain (i.e. less capable of braking a movement) — and not just one « lumbar weakness » isolated. On the functional level, this results in a deterioration of the return of elastic energy to fast walking, running and jumping reception, with a compensatory overload of the lumbar spine during repeated sitting-standing transfers.

It connects the back of the foot, the anterior tibial (the muscle to the front of the tibia), the quadriceps (the thigh muscles), the right of the abdomen (the abdominals), to the sternocleidomastoidian (a lateral muscle of the neck) and to the scalp fascia. It is the chain of the bending and the anterior clearance of the foot.Neurocom side: the dorsifolation/franchise (the clearance of the forefoot) and the standing seat (the tibial advance). Myotest side: the concentric force of the quadriceps (the force developed in the phase of active contraction) in squat jump and pulse index. A low standing lift index (less than 40%) combined with a reduced squat jump force/power on the same side suggests a shared limitation of the anterior chain in concentric, rather than an isolated deficit of the anterior tibial or quadriceps. The main risk is a difficulty in initiating hip/kneel flexion and foot clearance in the oscillating phase of the walk, with a risk of hanging on the ground, the body compensating by postponing the load to the posterior controlateral chain.

It crosses the peron (muscles of the outer face of the leg), the ilio-tibial tractus (a fibrous band on the side of the thigh), the lateral obliques, the intercostals, up to the sternocleidomastoidian/splenus on the opposite side. It is the chain of frontal control and lateral stability.Neurocom side: lateral directional control (LOS, for Limits of Stability, the limits of stability), unipodal support and symmetry of supports. Myotest side: inter-member power asymmetry. A support asymmetry Neurocom greater than 13% combined with a consistent Myotest side-to-side index reinforces the hypothesis of a less efficient lateral chain — Peron, medium buttock, oblique — with a possible role of the homolateral cervical complex (on the same side). Functionally, this results in a change of direction instability, a frontal control of ankle and a degraded knee (with a risk of dynamic valgus, i.e. the knee moving inward), and a lower transmission of force during unipodal tasks and stroke with a change of support.

This cross journey connects the controlateral splenus/SCM (sternocleidomastoidian), rhomboids, obliques, the tensor of the fascia lata/tractus ilio-tibial and the fir trees, returning to the plantar arch and ascending by the ischio-legs. This is the chain of rotation and dissociation between the top and bottom of the body.Neurocom side: rotational crossing, oblique directional control and alignment of the centre of gravity. Myotest side: asymmetrical power when moving with rotary component and left/right differential contact time. A directional control asymmetry combined with a difference in diagonal inter-member power is compatible with an inefficiency of the cross spiral line — a clinical hypothesis to be explored before conclusion. The main alteration affects the mechanisms of trunk rotation and dissociation between the scapular belt (the shoulders) and the pelvic belt (the pelvic belt), which are particularly sought after in running, in steering changes and in asymmetric sports.

This deep line connects the pelvic floor, psoas (a deep hip muscle), diaphragm and prevertebral fascia to the base of the skull. It strongly influences the postural stability measured by Neurocom and the overall cervical function (items 6.1 to 6.7 of the test: static/dynamic visual acuity, rotation speed C1-C2, bending/extension occiput-C1, laterality C5-C7) — A loss of dynamic vision greater than 40% during a rapid cervical rotation, combined with an asymmetry of power of the lower limbs of the Myotest, oriented towards a CMOC (oculo-cervical muscle coordination, i.e. coordination between the movements of the eyes and the neck) insufficient to stabilize the gaze during the explosive effort. This can affect the accuracy of the sport gesture and the risk of falling into a dynamic task.

Once a chain is identified, two approaches combine: manual therapy (myofascial relaxation, mobilizations) and active movement.

No conclusion should attribute a deficit to a muscle isolated from the Neurocom or Myotest scores alone. The convergence between the two tests reinforces a fascial chain hypothesis, but this must always be confirmed by clinical examination. — mobility, manual testing, functional observation, load response — Before building a targeted rehabilitation program. The interpretation process follows four steps: measure (with both tests), cross-check the results, confirm by clinical examination, and then target the intervention. Some signals must alert and impose a medical orientation before any manual intervention or movement: unexplained major motor asymmetry, progressive weakness that worsens over time, or any neurological sign. By systematically crossing Neurocom and Myotest, and anchoring the assumptions in clinical examination, it becomes possible to design precise, progressive and objectivable interventions — for sports performance and injury prevention.

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