#571: Is Zone 2 Training Actually Best for Health? – Prof. Brendon Gurd

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Jul 29, 2025

Joining the discussion is Prof. Brendon Gurd, a specialist in exercise physiology at Queen's University. He challenges the hype around Zone 2 training, evaluating its real health benefits versus popular beliefs. Key topics include the impact of exercise intensity on VO2 max, the importance of active lifestyles over strict training zones, and the nuances of aging and recovery. Prof. Gurd also highlights how individual fitness levels affect training effectiveness, emphasizing that a balanced approach can yield better health outcomes.

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INSIGHT

Defining Zone 2 Training

Zone 2 training is moderate intensity below lactate threshold with low fatigue and higher fat metabolism.
It's commonly used by endurance athletes but isn't uniquely optimal for mitochondrial adaptation.

INSIGHT

Zone 2 Not Optimal for Mitochondria

Zone 2 training can induce mitochondrial adaptations but is not the best intensity for this.
Higher intensities like zone 3 and above induce greater mitochondrial stress and adaptation.

ADVICE

Prioritize Moving Over Intensity Initially

Any physical activity is beneficial, especially starting from none to some to reduce mortality risk.
For fitness optimization, higher intensity exercise surpasses zone 2 in benefits.

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In recent years “Zone 2 training” has gained immense popularity in fitness and health circles, often being proclaimed the “best” cardiovascular training for metabolic health. Zone 2 training is sustained, low-intensity exercise below the lactate threshold that is commonly employed by many elite level endurance athletes, with a variety of proposed performance benefits. This led to interest from health-conscious folks about its ability to improve markers like VO2 max and mitochondrial function, which are associated with better health outcomes and longevity.

Prof. Brendon Gurd, an exercise physiologist at Queen’s University, is the co-author of a recent review published in Sports Medicine that examined some of the claims made around zone 2 training and health in the general population.

This episode looks at whether the evidence truly supports Zone 2 as a uniquely effective training zone or if this hype has outpaced the research. These insights help professionals and individuals make evidence-based recommendations and avoid unintended negative consequences of following certain ideas.

About The Guest

Dr. Brendon Gurd is a Professor in the School of Kinesiology and Health Studies at Queen’s University, where his research focuses on exercise physiology and skeletal muscle adaptation. His work explores how different intensities and types of exercise influence mitochondrial content and function in muscle tissue, with the goal of understanding how to optimize health and performance through training.

Timestamps

[03:23] Discussion with Professor Brendan Gurd
[05:56] Zone two training: Mechanisms and misconceptions
[10:56] Practical applications and recommendations
[22:16] Research gaps and future directions
[35:47] Key ideas segment (Sigma Nutrition Premium)

Links to Resources

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List of Sigma's Recommended Resources
Review paper: Storoschuk et al., 2025 – Much Ado About Zone 2: A Narrative Review Assessing the Efficacy of Zone 2 Training for Improving Mitochondrial Capacity and Cardiorespiratory Fitness in the General Population
Lecture Slides: Prof. Brendon Gurd – Is Zone 2 the optimal intensity for inducing mitochondrial adaptation?