1/4 Hour LabO #89: "Is it Possible to Target Flexion or Extension Movements?"

Understanding Flexion and Extension: Beyond Simple Movement

When discussing the concepts of flexion and extension in neuroscience, it is crucial to consider them holistically, including internal rotation, external rotation, abduction, and adduction. These movements are intrinsically linked, and their balance is fundamental for optimal motor skills.

From birth, humans exhibit a predominant flexion tone, inherited from the fetal position. Subsequent motor development involves a gradual decrease in this flexion tone in favor of an increase in extensor tone. This process is essential and is facilitated by exploring the environment, integrating sensory systems, and the sensorimotor loop.

The Crucial Influence of Primitive Reflexes

The development of motor skills and the balance between flexors and extensors are closely related to primitive reflexes. There are 72 of these reflexes, which are involuntary movements present from birth and need to be gradually integrated during the early years of life. Incomplete integration can disrupt the tonic balance and the normalization of flexion and extension.

The brainstem, the control center for several vital functions, plays a major role in this process. It is structured in different levels, each involved in the specific regulation of flexor or extensor tone. Primitive reflexes connect to these different levels, meaning that an unintegrated reflex can lead to hypertonicity of flexion, for example, creating a balance issue.

Targeting Flexion or Extension: Approach and Strategies

Yes, it is possible to target flexion or extension movements with appropriate exercises. The initial assessment, particularly through biomechanical tests, should always include both aspects: flexion and extension, internal and external rotation, abduction and adduction. This allows for determining whether the issue lies in a lack of tone in the flexors or an excess of tone in the extensors, or vice versa.

Knowledge of neuroanatomy and the descending pathways that pass through the brainstem is essential for choosing corrective exercises. Some exercises will act on flexor tone, while others will focus on extensor tone. The goal is to normalize this balance to improve mobility and function.

The Importance of Proper Muscle "Wiring"

Choosing multi-joint exercises can be beneficial, but if muscle tone is not initially regulated, these exercises may be ineffective or even counterproductive. An individual whose system is not properly "wired" in terms of tone between flexors and extensors will not fully benefit from the best exercises. The issue does not lie in the exercise itself, but in the body's ability to execute it correctly.

Training and Rehabilitation for Tone Management

Whether it involves sports training, rehabilitation, or coaching, it is imperative to consider the individual's initial tone. Tone is an involuntary and unconscious phenomenon that governs our baseline posture. An imbalance between flexor and extensor tone can influence performance and mobility.

For this reason, it is recommended to always test the flexion and extension of a given joint. Mobility is often a matter of tone rather than just muscle length. Mobility tests are quick to implement and provide instant feedback, allowing for rapid adjustments to exercise programs. Although social media may showcase exercises solely for flexion, this is because in 80% of cases, it addresses the most common issue.