Understanding Mitochondria

Mitochondria are vital components found in nearly every cell in the body, responsible for producing energy. They convert nutrients like carbohydrates and fats into usable energy, essential for daily activities. The health of these organelles is crucial for the wellbeing of our tissues and organs; any dysfunction can lead to severe health issues.

Recent research by Dr. Iñigo San Millán, a former competitive cyclist and assistant professor at the University of Colorado School of Medicine, was published in Antioxidants (April 2023) under the title, The Key Role of Mitochondrial Function in Health and Disease. He emphasizes the significance of mitochondrial function in both health and illness, as these organelles are often referred to as the "powerhouses" of the cell due to their primary role in generating adenosine triphosphate (ATP), the main energy source for cellular activities, through oxidative phosphorylation.

> "Fatty acids can be converted to energy ONLY in the mitochondria." — Iñigo San Millán

Exercise is recognized as the sole effective stimulus for maintaining and enhancing mitochondrial function. Athletes with robust mitochondrial health efficiently burn fuels and recycle lactate, a byproduct generated during intense physical activity.

Longevity and Health

As we grow older, mitochondrial function diminishes, and research has connected this decline to various conditions such as Type 2 diabetes, cardiovascular diseases, and cancer. Dr. San Millán advocates for Zone 2 training, which could significantly impact not only fitness but also longevity and overall health.

> "Exercise is the most powerful longevity DRUG." — Peter Attia

Dr. Peter Attia, a longevity physician and author of Outlive: The Science & Art of Longevity, echoes this sentiment. The way we utilize different fuel sources, including glucose and fatty acids, is crucial for our metabolic and overall health. Engaging in steady endurance training (aerobic exercise in Zone 2) enhances our capability to efficiently use glucose and fat as energy sources.

Mitochondria are essential for burning both glucose and fat, thus playing a fundamental role in our metabolic health. Healthy mitochondria also support brain health and help manage stress and inflammation.

For runners and cyclists, Zone 2 represents the highest effort level that can be sustained without accumulating lactate, allowing for efficient production and clearance through mitochondrial functions. Mitochondrial health becomes increasingly critical with age due to the reduction in both the quantity and quality of these organelles.

But there’s no need to worry. Engaging in aerobic exercise promotes the formation of new and more efficient mitochondria via a process known as mitochondrial biogenesis, while dysfunctional mitochondria are removed through a recycling mechanism called mitophagy. By training in Zone 2, individuals enhance their mitochondrial health with every run, bike ride, or swim.

> "If you don’t use them, you lose them."

The Five Zones of Training

• Zone 1 (Active Recovery): 50–60% of HRmax.
• Zone 2 (Endurance): 60–70% of HRmax.
• Zone 3 (Tempo): 70–80% of HRmax.
• Zone 4 (Lactate Threshold): 80–90% of HRmax.
• Zone 5 (VO2max): 90–95% of HRmax.

HRmax refers to your maximum heart rate.

Zone 2 Training Explained

Training in Zone 2 involves maintaining a pace where conversation is possible but may require occasional breath-catching. The intensity for this zone is set at 60–70% of HRmax.

To estimate HRmax, use the formula: [HRmax = 220 — Age]. For example, if you are 50 years old, then: - HRmax = 220 - 50 = 170

At 70% intensity for Zone 2, the target heart rate (THR) would be: - THR = 170 * 0.7 = 119

For someone aged 65, the HRmax would be 155, resulting in a THR of 109.

Studies by Dr. Attia and Dr. San Millán suggest that exercising for about an hour, three to four times a week, is optimal. Training for longer than 60 minutes per session was deemed to offer no additional benefits.

Advantages of Zone 2 Training

• Endurance Building: Zone 2 training enhances cardiovascular fitness, endurance, and aerobic capacity, allowing the body to sustain prolonged efforts.
• Mitochondrial Development: This type of training is essential for increasing mitochondrial density in slow-twitch muscle fibers, leading to improved endurance and speed.
• Enhanced Fat Utilization: Sustained training in Zone 2 teaches the body to better utilize fat, promoting fat metabolism during exercise and leading to improved body composition.
• Improved Muscle Economy: Zone 2 training fosters muscle economy by increasing mitochondrial presence, making moderate race efforts feel more manageable, especially in longer events like marathons.

Principles of Slow Jogging

Dr. Mark Cucuzzella, co-founder of the Natural Running Center and a mentor of mine, advocates for “slow jogging” as a fundamental approach to fitness and health. He discusses how Dr. Hiroaki Tanaka, a Japanese running expert and author of Slow Jogging: Lose Weight, Stay Healthy, and Have Fun with Science-Based, Natural Running, has profoundly influenced his outlook on running.

> "Jogging is steady or easy-paced running, while alternating with breath-catching periods of walking." — Bill Bowerman

Dr. Tanaka builds on the principles established by Bill Bowerman, who defined jogging as a steady or easy-paced run interspersed with walking. Slow jogging serves as an effective method to train the heart, lungs, and circulatory systems.

Interestingly, Zone 2 training or slow jogging is a viable alternative to the "No Pain, No Gain" mentality, representing a key to enhancing stamina.

In summary, mitochondria function as the energy factories of our cells, generating power, regulating energy use from food, maintaining cellular health, and influencing our aging process. By supporting our mitochondria through regular exercise and a balanced lifestyle, we can enhance our overall health and potentially extend our lifespan by ensuring our cells remain functional and resilient.