The aerobic threshold the “secret” to increased endurance, improved performance and better health explained for triathletes, runners and cyclists.
The aerobic threshold is the point, also known as the first lactate threshold (LT1), at which during exercise the body begins to rely on oxygen as the primary source of fuel for the muscles.
This typically occurs at a moderate intensity level, and is an important concept for triathletes, runners, and cyclists to understand because it represents the upper limit of the body’s ability to use oxygen efficiently.
Understanding and training at or around the aerobic threshold can be beneficial for these athletes, as it can improve the body’s ability to use oxygen more efficiently, leading to improved endurance and performance.
For triathletes, training at the aerobic threshold can help to improve their endurance and performance in all three disciplines (swimming, cycling, and running).
By performing workouts at or around the aerobic threshold, triathletes are able to sustain a given level of effort without producing excess lactic acid which can improve their endurance and become more efficient at using oxygen, which can help to reduce fatigue during long events.
It’s important to note that the aerobic threshold can vary widely from one person to another, and can be affected by factors such as age, fitness level, and genetics.
To determine your own aerobic threshold, you can use a variety of methods, including heart rate monitoring, blood lactate testing, and perceived exertion scales.
Why is the aerobic threshold so important and what happens as far as fat oxidation?
The aerobic threshold is important because it represents the upper limit of the body’s ability to use oxygen efficiently during exercise.
When you are exercising at or below your aerobic threshold, your body is able to sustain a given level of effort without producing excess lactic acid, which can lead to fatigue and reduced performance.
As far as fat oxidation is concerned, it’s generally thought that exercising at or below the aerobic threshold allows the body to burn a higher percentage of fat as fuel.
This is because at lower intensities, the body is able to rely more on fat stores for energy, rather than relying on carbohydrate stores.
This is why the aerobic threshold is often used as a benchmark for endurance training, as it can help athletes improve their ability to burn fat as fuel, which can help them sustain a given level of effort for longer periods of time.
However, it’s important to note that the body’s ability to burn fat as fuel can be affected by a variety of factors, including diet, genetics, and the specific demands of the activity being performed.
As a quick refresher, the body has several mechanisms through which it can produce energy.
The two main ones that are used to during long-duration, aerobic exercise are the break-down of fats and carbohydrates.
During exercise, the body uses a combination of fats and carbohydrates as fuel. The body prefers to use carbohydrates as fuel because they are easier to break down and use for energy.
However, if the body does not have enough carbohydrates available, it will begin to break down stored fats to use as fuel instead.
The process of breaking down fats and carbohydrates for energy is called metabolism.
When you exercise, your body increases its metabolic rate, which means that it is burning more calories and using more energy.
This increased metabolic rate helps to burn both fats and carbohydrates, depending on the availability of each.
Carbohydrates are broken down into glucose, which is then used by the cells to produce energy. Fats are broken down into molecules called fatty acids, which can also be used by the cells to produce energy.
The specific process by which the body breaks down fats and carbohydrates is complex and involves several different enzymes and pathways.
- “Lab” testing: This method involves testing your oxygen uptake and blood lactate levels while you exercise on a treadmill, stationary bike or smart trainer. As you increase the intensity of the exercise, your oxygen uptake and blood lactate levels will also increase. The point at which your blood lactate levels start to rise more quickly is considered your aerobic threshold.
- Field testing: This method involves testing your aerobic threshold in a real-world setting. I typically test on the road or on a track.
- Breathing rate: As you increase the intensity of your exercise, your may notice a deepening of your breathing as you approach your aerobic threshold. This can be a useful indicator of LT1.
- Rate of perceived exertion (RPE): RPE refers to how hard you feel like you are working during exercise. As you approach your aerobic threshold, you may notice that your RPE starts to increase more quickly than it did at lower intensities. LT1 typically occurs somewhere between 12 and 13 RPE on a Borg Scale (The Borg Scale ranges from 6 (no exertion at all) to 20 (maximum exertion). This can be a good indication that you are approaching your LT1. In order to determine your LT1 as accurately as possible I highly recommend to combine RPE with a blood lactate threshold testing and possibly V02max (ventilatory threshold 1= VT1, also known as the respiratory compensation threshold (RCT), is the point at which carbon dioxide production begins to increase more quickly than oxygen uptake. VT1 is typically considered to occur at a lower intensity level than VT2. It is often used as a marker of endurance performance).
- Heart rate monitoring: This method involves monitoring your heart rate while you exercise and using a specific heart rate zone to determine your aerobic threshold. The most common method is the “heart rate reserve” method, which involves calculating your maximum heart rate and your resting heart rate and then determining a specific heart rate zone based on the difference between the two.
It’s important to note that the aerobic threshold can vary depending on the method used to determine it and can also change over time.
As your fitness level improves, it is possible that your aerobic threshold (also known as lactate threshold or LT1) will move closer to your V02max. You may be able to sustain a higher intensity level (watts, pace, speed) before reaching your aerobic threshold (a good thing!).
It’s important to note that the relationship between V02max and LT1 can vary from person to person and can also change over time as your fitness level improves or drops (after off-season for example).
It can be helpful to regularly re-assess your LT1 and V02max in order to track your progress and optimize your training.
In longer endurance events (4+ hours) such as 70.3, Ironman Triathlons or ultra long trail races, the aerobic threshold (LT1) is an important performance factor because it represents the intensity at which an athlete can sustain exercise for an extended period of time without experiencing fatigue (fatigue resistance can improve with training and can help to postpone a performance decline.
With that being said, we are all going to experience fatigue (mental, muscular, mechanical, metabolic (glycogen depletion) at some point during long endurance events).
Maintaining a steady pace at or just below the aerobic threshold allows an athlete to conserve energy and avoid early fatigue, which can be crucial to success in these types of events.
Our body is able to burn the most fat closer to your aerobic threshold or lactate threshold (LT1).
Fat oxidation is typically achieved at a lower intensity of exercise than the aerobic threshold. This is because fat is a slower-burning fuel source than carbohydrates and is primarily used at lower intensities of exercise.
However, the relationship between fat oxidation (fatmax) and the aerobic threshold can vary depending on factors such as an individual’s fitness level.
It is worth noting that while fatmax may be an important consideration for some individuals, such as those looking to optimize fat burning for weight loss or improved body composition, it is not necessarily the most important factor for endurance performance.
In endurance events, maintaining a steady pace at or just below the aerobic threshold is generally more important for success than maximizing fat burning.
To improve your aerobic threshold, it is important to engage in regular aerobic exercise that challenges your cardiovascular system and increases your endurance.
Some effective training methods to use include:
- Incorporate interval training into your workouts: Interval training involves alternating periods of high-intensity exercise with periods of rest or lower-intensity exercise. This type of training can help to improve your aerobic threshold by increasing your body’s ability to use oxygen more efficiently.
- Gradually increase the intensity and duration of your workouts: As your fitness improves, gradually increasing the intensity and duration of your workouts can help to improve your aerobic threshold.
- Incorporate endurance training (zone 2) into your routine: Endurance training can help to improve your aerobic threshold by increasing your body’s ability to use oxygen more efficiently.
- Monitor your heart rate, power-output, pace or perceived exertion: Use a heart rate monitor, power-meter, GPS or rating of perceived exertion (RPE) scale to accurately gauge the intensity of your workouts and ensure that you are training at or around your aerobic threshold.
- Get enough rest and recovery: Adequate rest and recovery are important for improving your aerobic threshold and overall fitness. Make sure to get enough sleep, take rest days as needed, and incorporate recovery strategies such as stretching and foam rolling into your routine.
Aerobic threshold workouts
This involves exercising at an easy but not too easy /moderate intensity (RPE) for an extended period of time, such as 30-60 minutes or longer. This can help to improve your endurance and increase your aerobic threshold.
- Fartlek training: This is a form of interval training that involves alternating periods of fast and slow running or cycling. It is a more flexible form of interval training that can be adjusted to your fitness level.
- Hill training: This involves running or cycling up and down hills. It can help to improve your endurance and increase your aerobic threshold.
- Long slow distance (LSD) training: This involves exercising at a low intensity for an extended period of time. It is a good way to improve your endurance and increase your aerobic threshold.
It is important to find a training method & individualised training program that is tailored to your unique needs specifically and considers your experience level (history), training availability (work, life, family), physiological profile in relation to your chosen main race events, and to gradually increase the intensity and duration of your workouts as your fitness improves.
