Understanding Zone Two Training

Kristy Storschuk, PhD candidate in muscle physiology at Queen's University, discusses the science behind Zone 2 training and fasting, challenging popular myths about their benefits for mitochondrial health and metabolic flexibility.

• Zone 2 training may not provide the unique benefits often attributed to it on social media
• Research suggests exercise intensity is a more powerful driver of mitochondrial adaptations than staying in specific heart rate zones
• Achieving higher volume at intensities above Zone 2 appears more beneficial for metabolic health
• Elite athletes do significant Zone 2 training, but their adaptations may primarily come from their high-intensity work
• VO2 max is a stronger predictor of all-cause mortality than other metrics
• Fasting activates mitochondrial pathways in rodents but shows no similar effect in humans
• Humans don't deplete muscle glycogen during fasting the way mice do
• Metabolic flexibility refers to the body's ability to switch between fuel sources in different contexts
• Many approaches can improve health and fitness – prioritize intensity you can recover from

If you're interested in learning more about exercise physiology or following Kristy's research, you can find her online discussing the science of exercise metabolism and muscle adaptations.