Boost Your Aerobic Power: Mastering VO2max with HIIT and Long, Slow Distance Training

Your VO2max — or the maximum amount of oxygen your body can use during intense exercise — is a measure of your aerobic fitness and endurance.

The higher your VO2max, the more oxygen your body can take in and use, which means you can exercise harder and longer without getting as tired.

It’s like your body’s ability to fuel itself with oxygen during physical activity.

The bummer part of VO2max is its precipitous decline as we age.

Yet a high VO2max is one of the key markers of your long-term physical health.

While there are many ways to improve VO2max, we’ll look primarily at two: HIIT and long, slow distance.

Improving VO2max

Improving VO2max involves several training methods supported by research and expert recommendations.

Here are the most effective strategies to improve VO2max:

1. High-Intensity Interval Training (HIIT):

• Short bursts of high-intensity exercise followed by rest or low-intensity periods.
• HIIT significantly improves VO2max by pushing the cardiovascular system to adapt to higher levels of exertion.
• Studies have shown that HIIT can be more effective than moderate-intensity continuous training (MICT) for improving VO2max in a shorter period.

2. Long, Slow Distance (LSD) training:

• Prolonged exercise at a low to moderate intensity.
• Builds aerobic base and endurance, which is essential for sustained performance and VO2max improvement.
• Research suggests consistent LSD training enhances the heart’s efficiency and increases mitochondrial density, contributing to higher VO2max over time.

3. Threshold training (tempo):

• Sustained efforts at or just below the lactate threshold.
• Improves the body’s ability to clear lactate, allowing for higher-intensity efforts without fatigue.
• Research suggests that regular threshold training can push the lactate threshold closer to VO2max, effectively raising both thresholds. These are great intervals, used in moderation.

4. Strength training:

• Resistance exercises targeting major muscle groups.
• Enhances muscle strength and endurance, supporting overall performance and reducing fatigue during high-intensity efforts.
• Research suggests strength training can indirectly improve VO2max by increasing muscle efficiency and power output.

5. Proper recovery and nutrition:

• Ensure adequate rest and proper fueling.
• Supports muscle repair, growth, and adaptation, which are crucial for improving VO2max.
• Research suggests proper recovery and nutrition strategies, including adequate protein intake and hydration, are essential for optimizing training adaptations and performance in order for you to do the training you need to improve VO2max.

A well-rounded approach that includes HIIT, LSD, threshold training, cross-training, strength training, and proper recovery and nutrition is the most effective way to improve VO2max in endurance athletes.

Combining these methods ensures comprehensive development of aerobic capacity, endurance, and overall fitness.

Today, though, we’re just talking about the most common tools: Going slow and going fast!

Going slow improves VO2max

Long, slow distance (LSD) training, a cornerstone of endurance training, involves prolonged exercise at a low to moderate intensity.

The effectiveness of LSD training in improving VO2max is supported by several physiological mechanisms and research findings.

Here’s a detailed look at the physiology of how going slow helps improve VO2max:

1. Mitochondrial density and function:

• LSD training increases the number and efficiency of mitochondria in muscle cells.
• Studies have shown that prolonged, lower-intensity exercise enhances mitochondrial biogenesis, leading to better aerobic energy production and utilization.

2. Capillary density:

• LSD training promotes the growth of capillaries around muscle fibers.
• Enhanced capillarization improves oxygen delivery and waste removal, which supports higher aerobic performance and VO2 max.

3. Fat oxidation:

• Prolonged low-intensity exercise increases the muscles’ ability to oxidize fats.
• Research suggests improved fat oxidation spares glycogen stores, allowing for sustained exercise at higher intensities, indirectly contributing to improved VO2max.

4. Cardiac efficiency:

• LSD training enhances stroke volume (the amount of blood ejected by the heart per beat) and cardiac output (the volume of blood the heart pumps per minute).
• Research suggests increased cardiac efficiency means more oxygen can be delivered to the working muscles, supporting higher VO2max .

Going fast improves VO2

High-Intensity Interval Training (HIIT) is highly effective in improving VO2max due to several physiological adaptations it triggers.

Here’s a detailed explanation of how HIIT improves VO2max:

1. Enhanced cardiovascular function:

• Increased stroke volume: HIIT significantly increases the heart’s stroke volume, which is the amount of blood ejected with each heartbeat. This adaptation allows more oxygen to be delivered to the muscles during exercise.
• Improved cardiac output: The combination of increased stroke volume and heart rate during high-intensity intervals results in a higher overall cardiac output, enhancing the delivery of oxygen to working muscles.

2. Mitochondrial biogenesis:

• HIIT stimulates the production of new mitochondria in muscle cells, increasing the capacity for aerobic energy production. More mitochondria mean more energy production.
• Studies have shown that high-intensity exercise leads to greater increases in mitochondrial density and function compared to moderate-intensity continuous training .

3. Increased capillary density:

• HIIT promotes angiogenesis, the formation of new capillaries around muscle fibers.
• Increased capillary density improves oxygen delivery to muscles and enhances the removal of metabolic byproducts, facilitating better endurance and VO2max.

4. Improved Muscle Oxidative Capacity:

• High-intensity intervals enhance the muscles’ ability to utilize oxygen for energy production.
• Research suggests HIIT increases the activity of oxidative enzymes. This means that more activity in these enzymes means more capacity in the muscle to use oxygen to produce energy.

5. Enhanced lactate threshold:

• HIIT improves the body’s ability to clear lactate and delay the onset of fatigue.
• A higher lactate threshold allows athletes to sustain higher intensities for longer periods, indirectly improving VO2max. This means that a higher threshold allows you to work harder and therefore improve your VO2max.

These physiological adaptations collectively enhance the body’s ability to deliver and utilize oxygen during high-intensity exercise, leading to significant improvements in aerobic capacity and VO2max.

VO2max declines with age

As I mentioned, VO2max is one of the key indicators of cardiovascular health.

The issue is that it declines

On average, VO2max declines by about 1% per year after the age of 25–30. This equates to roughly 10% per decade.

However, the rate of decline can be slower in highly trained individuals and faster in those who are sedentary.

The rate of decline may increase with age.

Regular endurance training can slow the rate of decline. Trained individuals might experience a decline closer to 5–7% per decade.

Genetic factors also play a role in the baseline VO2max and its rate of decline.

Here are three things to know about improving your VO2max

1. Maintaining a high VO2max is essential for long-term cardiovascular health and athletic performance.

2. High-intensity Interval Training (HIIT) and Long, Slow Distance (LSD) training are two of the most effective strategies for boosting VO2max

3. While VO2max naturally declines with age, regular endurance training can significantly slow this process.

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Paul Warloski is a:

• USA Cycling Level 2 Coach
• RRCA Running Coach
• Training Peaks Level 2 Coach
• RYT-200 Yoga Instructor
• Certified Personal Trainer