Dr. Rhonda Patrick (@foundmyfitness)

Vigorous exercise, especially high-intensity interval training, is one of the best ways to refresh the body’s energy systems. It works in two ways: mitophagy clears out old, damaged mitochondria, and mitochondrial biogenesis builds new ones. This dual effect boosts cellular energy production, improving both physical and cognitive performance over time. High-intensity interval training is so effective because it creates metabolic stress, which increases lactate levels. That lactate sends a signal to activate PGC-1α, a protein that helps grow more mitochondria. Over time, having more mitochondria makes your muscles better at using oxygen, managing blood sugar, and reducing oxidative stress. The best part? You don’t need long workouts to get these benefits. Even short bursts of intense exercise can improve your metabolism, protect against muscle loss as you age, reduce inflammation, and boost your overall health.