Exercise Physiology & Biomechanics

ExPhys fundamentals: understanding how the human body adapts to physical stress through structured TR programs. The core principle is progressive OVL — systematically increasing training stimulus to drive physiological ADP.

Energy Systems & Metabolism

Three primary ES power human movement: ATP-PC (phosphocreatine, ~10s max effort), GLYC (anaerobic glycolysis, 30s-2min), and OXP (aerobic oxidative phosphorylation, sustained effort). Training specificity dictates which ES dominates. Sprint athletes primarily train ATP-PC and GLYC pathways, while endurance athletes target OXP capacity through elevated MVO2 (maximal oxygen uptake).

MVO2 represents the ceiling of aerobic performance. Elite endurance athletes achieve 70-85 ml/kg/min. Key determinants: cardiac output (HR x stroke volume), arteriovenous O2 difference, and mitochondrial density. HIIT protocols (4x4min at 90-95% HRmax) produce significant MVO2 improvements within 8-12 weeks. LT (lactate threshold) training at 75-85% MVO2 improves the fractional utilization — the percentage of MVO2 sustainable for prolonged effort.

Muscular Physiology & Fiber Types

Skeletal muscle contains two primary FT categories: Type I (slow-twitch, oxidative, fatigue-resistant) and Type II (fast-twitch, subdivided into IIa and IIx). Type I fibers dominate endurance activities with high MITO density and capillary supply. Type IIx fibers generate peak force but fatigue rapidly. Type IIa fibers are intermediate and highly trainable — they shift characteristics based on TR stimulus.