MyofascialSystemandPhysicalExercise:ANarrativeReviewonStretching(PartI)

The human body is far more interconnected than traditional anatomy textbooks once suggested. Over the past two to three decades, researchers have increasingly recognized that what was previously thought of as simply "muscle" is actually a complex blend of contractile tissue and connective tissue called fascia. This fascial system forms a continuous, three-dimensional web throughout the body that plays crucial roles in movement, posture, stability, and even pain perception. When this system malfunctions, it can lead to myofascial pain syndrome, a condition characterized by painful trigger points in taut bands of muscle and surrounding fascia.

Despite growing interest in fascia, most research has focused on manual therapies like massage or manipulation. Surprisingly little evidence exists about how therapeutic exercise, particularly stretching, might treat fascial dysfunctions. This gap is significant because exercise is accessible, low-cost, and could be self-administered by patients. This narrative review aims to bridge that gap by examining how different stretching techniques might specifically target fascial tissues, and by proposing a new hypothesis for how myofascial trigger points develop from imbalanced mechanical loading.

The authors conducted a comprehensive narrative review of the scientific literature on fascia, myofascial pain, and stretching techniques. Rather than following the strict systematic methodology of a systematic review or meta-analysis, they synthesized information from multiple disciplines including anatomy, physiology, biomechanics, and rehabilitation science to build an integrated conceptual framework. The review introduces Hill's three-element model—a classic biomechanical framework that divides muscle-tendon units into contractile elements, series elastic elements (like tendons), and parallel elastic elements (like the epimysium and other connective tissues surrounding muscles). The authors use this model as a lens to analyze how different stretching methods might load different fascial components.

They examine three main stretching approaches: classic passive stretching, contract-relax (CR) stretching, and contract-relax with agonist contraction (CRAC) stretching. For each technique, they analyze which fascial structures are primarily stressed based on whether the muscle is relaxed or contracted during the stretch. The review also critically examines the traditional neurophysiological explanations for why proprioceptive neuromuscular facilitation (PNF) stretching works, particularly the role of Golgi tendon organs in producing muscle relaxation.

The review presents several key findings that challenge conventional thinking about stretching. First, the authors found that only about 70% of muscle tension is transmitted through tendons—the remaining 30% is conveyed to surrounding connective tissues, highlighting fascia's substantial mechanical role. Second, they identified that different stretching techniques load different fascial components in predictable ways based on Hill's model. Classic passive stretching, where the muscle is relaxed, primarily loads parallel fascial components because the elastic muscle fibers absorb most of the stretch, shielding the series elements.

In contrast, CR stretching activates the contractile component while in a stretched position, which loads the series fascial elements (like tendons and intramuscular connective tissue in line with muscle fibers) while reducing tension on parallel components. The CRAC technique, particularly its second phase involving antagonist contraction, further separates muscle insertion points and thereby engages both series and parallel fascial elements. Third, the authors found that traditional explanations for PNF stretching effects—particularly autogenic inhibition via Golgi tendon organs—are not well supported by recent research. Studies using surface electromyography showed that PNF techniques actually increase, not decrease, muscle activation during stretching, contrary to what the GTO inhibition hypothesis would predict.

Golgi tendon organs appear to respond throughout the range of motion and provide spatial information to the cortex rather than simply acting as "safety switches" that shut down muscle activity. Fourth, the review documents that ultrasound shear-wave elastography studies confirm stretching acutely reduces muscle stiffness at rest, an effect that cannot be explained merely by increased stretch tolerance. Finally, the authors propose a novel hypothesis: myofascial trigger points may develop from imbalanced loading between series and parallel fascial components, where compensatory muscle activation within non-extensible connective tissue sheaths increases internal pressure, reduces blood flow, and creates a cycle of hypoxia and sustained contraction.

This review has significant practical implications for clinicians, therapists, and patients dealing with myofascial pain and movement limitations. The most important takeaway is that stretching is not a monolithic intervention—different techniques target different tissues, and a complete fascial stretching program should incorporate multiple methods used in sequence. For optimal fascial health, practitioners should consider using classic passive stretching for parallel fascial components, CR techniques for series elements, and CRAC methods for comprehensive loading of both components. This represents a shift from viewing stretching as simply "lengthening muscle" to a more nuanced approach of selectively loading specific connective tissue structures.

For patients with myofascial pain syndrome, the proposed hypothesis suggests that treatment should address fascial stiffness and loading imbalances, not just the contractile muscle itself. The finding that sustained low-level muscle contractions (even at just 10-25% of maximum effort) can significantly compromise blood flow helps explain why prolonged static postures—like slumped sitting—may contribute to trigger point formation. This supports the importance of movement variety and postural breaks in prevention. The questioning of traditional neurophysiological explanations for PNF also matters practically: clinicians need not rely on outdated concepts of "reflex inhibition" to justify these techniques, but can instead understand them through mechanical loading principles.

Finally, the review emphasizes that fascial training should be integrated with strengthening, cardiovascular, and coordination exercises for comprehensive musculoskeletal health, rather than treated as an isolated intervention.