This first article in a four-part series challenges traditional biomechanical models by examining the role of passive tissues in human movement. Rather than viewing muscles as the primary drivers of locomotion acting through simple lever systems, the author argues that fascia, tendons, ligaments and other passive tissues play a fundamental role in transmitting force, regulating movement and influencing performance. Drawing on concepts including biotensegrity, mechanotransduction and tissue adaptation, the article explores how passive tissues interact with the neuromuscular system to create an integrated mechanical network that governs both acute movement and long-term adaptation. It examines how tissue stiffness, loading history and force transmission influence efficiency, posture, movement quality and injury risk, while proposing that active and passive tissues should be considered as a single composite functional system rather than separate entities. The article concludes that a more holistic understanding of anatomy and mechanics provides strength and conditioning practitioners with a richer framework for interpreting movement, designing training interventions and preparing for the applied discussions on sprint performance and injury presented in subsequent articles in the series.