Which training modality is most associated with mitochondrial biogenesis?

• A. Endurance training
• B. High-intensity interval training
• C. Sprint training
• D. Resistance training

Answer: (B)

Mitochondrial biogenesis is driven by a strong energy-demand signal in muscle that activates signaling pathways, especially AMPK and PGC-1α, which turn on the genes responsible for making new mitochondria and boosting oxidative capacity.

High-intensity interval training provides that potent stimulus: short bursts of very demanding work push cellular energy demand up quickly, lowering ATP and raising AMP levels, which robustly activates AMPK. This, in turn, stimulates PGC-1α and related factors to increase mitochondrial content and oxidative enzyme capacity. Because of the intense metabolic stress delivered in a short time, HIIT can induce mitochondrial biogenesis efficiently and often more rapidly than traditional steady-state endurance training.

Endurance training also promotes mitochondrial biogenesis because it sustains energy demand over longer periods, but the question asks for the modality most associated, and HIIT tends to produce a stronger signaling boost per unit time. Sprint training can trigger some mitochondrial adaptations but typically to a lesser extent, and resistance training mainly drives muscle strength and hypertrophy with comparatively smaller changes in mitochondrial content.