Remote Changes of Mechanical Stiffness Following Local Stretching or Contraction: A Systematic Review with...

Area of Science:

• Biomechanical Engineering
• Human Physiology
• Sports Science

Background:

• Fascia forms a continuous network throughout the body, connecting skeletal muscles.
• Mechanical studies confirm fascia's role in transmitting forces across tissue connections.
• Exercise may influence properties of distant tissues within the same myofascial chain.

Purpose of the Study:

• To systematically review and meta-analyze the effects of local tissue lengthening and contraction on remote tissue stiffness.
• To evaluate how exercise interventions impact non-local myofascial tissues.

Main Methods:

• Systematic literature search across Web of Science, PubMed, and Google Scholar.
• Inclusion of controlled experimental trials assessing non-local tissue properties after local interventions.
• Quality assessment using a modified Downs and Black checklist; bias analysis via funnel plots and Egger's tests; meta-analysis using robust variance estimation.

Main Results:

• 15 high-quality studies were analyzed, with potential reporting bias noted for contraction and lengthening.
• Local tissue lengthening moderately increased distant tissue stiffness (Hedges' g = -0.54, very low certainty).
• Local muscle contraction significantly increased non-local stiffness with large magnitude (g = -1.25, moderate certainty).

Conclusions:

• Both muscle contraction and stretching enhance stiffness in connected body regions.
• Findings are relevant for optimizing performance and rehabilitation in exercise and therapy.
• High heterogeneity necessitates further research, especially concerning local lengthening effects.