VO2max: Maximizing Oxygen Uptake

Let’s start with VO2max, which measures the maximum amount of oxygen your body can utilize during intense exercise, usually expressed in milliliters of oxygen per minute per kilogram of body weight (ml/kg/min). It is a key indicator of cardiovascular fitness. The higher your VO2max, the more oxygen your body can deliver to the muscles during exercise, allowing for better endurance and overall performance. The science behind VO2max revolves around the ability of the cardiovascular system to transport oxygen to muscles and the muscles’ ability to utilize that oxygen. Improvements in VO2max are driven by adaptations in both the heart (increased stroke volume and cardiac output) and the muscles (increased mitochondrial density and capillary supply).

Improving VO2max: High-intensity interval training and consistent aerobic exercise are great ways to boost VO2max. These types of workouts improve cardiovascular efficiency, enabling you to maintain higher intensities for longer.

Lactate Threshold: Delaying Fatique

Another commonly know factor, the lactate threshold, marks the intensity level at which lactic acid begins to accumulate in the blood faster than it can be cleared away, leading to increased fatigue. This occurs because, at higher intensities, the body relies more on anaerobic metabolism—energy production without sufficient oxygen—which produces lactic acid as a byproduct. The rate of lactate production exceeds the rate of its clearance due to limited buffering and removal capacity. A higher lactate threshold allows you to sustain higher intensities with less fatigue. In trained athletes, the lactate threshold occurs at a higher intensity, meaning they can sustain faster paces without accumulating excess lactate.

Improving Lactate Threshold: Threshold intervals, high-intensity intervals, and sustained efforts at or near lactate threshold intensity help increase your body’s ability to clear lactate more efficiently, allowing you to maintain a faster pace for longer periods.

Running Economy: Efficient Mechanics

Running economy is the energy demand for a given velocity of running. In simple terms, it’s a measure of how efficiently your body uses energy at a given pace. The more economical your running form, the less energy you expend, which is essential for long-distance running, where energy reserves are finite. Factors like running form, muscle efficiency, and posture influence your running economy. Overstriding, poor posture, and excessive arm movement can all waste energy, reducing efficiency.

Improving Running Economy: Technique drills, strides, and strength exercises are all effective in enhancing your running economy. Focusing on proper form and reducing inefficient movements can improve endurance and help prevent fatigue during long races.

Aerobic Threshold: The Endurance Builder

Lesser known is the aerobic threshold, or the intensity level at which your body shifts from primarily burning fat for energy to relying more on carbohydrates (glycogen). At lower intensities, the body primarily uses fat, which provides a virtually unlimited energy supply. As the intensity increases, however, the body’s ability to use fat diminishes, and carbohydrate metabolism supplements fat oxidation to provide additional energy for the higher demands of faster running. The aerobic threshold represents the crossover point where this shift becomes more pronounced. For marathon runners, the aerobic threshold is crucial because it defines the pace at which your body can sustain itself for the full duration of the race. The higher the aerobic threshold, the faster you can run without tapping into your limited carbohydrate stores too early.

Improving Aerobic Threshold: Long runs and high-volume training at low and moderate intensities are key to improving your aerobic threshold. By training at these intensityies, you increase the body’s ability to burn fat and avoid relying too heavily on carbohydrates during a race, helping you maintain your pace longer.

Connecting the Dots

The key physiological factors—running economy, VO2max, lactate threshold, and aerobic threshold—are all interrelated and essential for marathon performance. Optimizing these markers requires a balanced training approach that includes both high-, moderate-, and low-intensity efforts.

Lower-intensity efforts: Focus on improving aerobic efficiency and endurance, benefiting the aerobic threshold.

Moderate-intensity efforts: Bridge the gap between endurance and speed, improving both aerobic threshold and stamina, which is essential for sustaining a strong pace during longer efforts.

Higher-intensity efforts: Target VO2max and lactate threshold improvements, enabling you to sustain faster paces for longer periods.

By targeting these intensities and physiological markers in your training, you’ll build a well-rounded foundation for peak marathon performance. However, it’s important to remember that training is not black and white—each type of effort (low, moderate, and high intensity) supports the others, creating a more holistic approach to developing your marathon potential. We’ll explore training intensity distribution in more detail in another article.