How exactly does strength training make me a more efficient runner?

Strength training makes you a more efficient runner primarily through adaptations in your nervous system and how it controls your muscles (neuromuscular enhancements). These include:

• Enhanced Motor Unit Recruitment, Firing Rate, and Synchronization: Your brain gets better at activating more muscle fibers (motor units), making them fire faster and work together more harmoniously. This leads to more forceful and coordinated muscle contractions for each stride.

• Increased Rate of Force Development (RFD): You become able to generate force more quickly. This is vital in running where ground contact times are very short, allowing you to apply the necessary push-off forces more rapidly.

• Improved Muscular Coordination: Coordination improves both within a single muscle and between different muscle groups (agonists, antagonists, stabilizers). This results in smoother, more efficient movement patterns.

• Delayed Recruitment of Less Efficient Muscle Fibers: Strength training makes all your muscle fibers stronger, including your fatigue-resistant Type I fibers. These stronger Type I fibers can handle more of the work at a given pace. This means your body doesn't need to call upon your less economical, more quickly fatiguing Type II fibers as soon, helping you maintain efficiency for longer.

Essentially, your muscular system learns to produce the required force for running more effectively with less metabolic cost.