Part 3 Optimizing Training

This article is the Second Part of a Series on Optimizing Run Training

The first two parts of this series can be found here:

Optimizing Running Training Part 1

Optimizing Running Training Part 2

Interestingly enough this applies to any exercise that crosses multiple energy systems.  So this is perfectly applicable to many mid range, with respect to time, workouts.

Lactate Threshold Training Programs and Workouts

There are some excellent guidelines you can follow in generating training programs and workouts in order to enhance the lactate threshold levels. Training programs that are a combination of high volume, interval and steady-state workouts have the most pronounced effect on lactate threshold improvement.

Training Volume

Initially, the best way to improve the lactate threshold levels is to simply increase training volume, whether their endurance activity is cycling, running, or swimming. Increased training volume should be gradual and in the order of approximately 10-20% per week. For example, if an individual is currently running 20 miles per week, the increase in training volume should be 2-4 miles per week. While this approach may appear conservative, it will help to prevent over training and injuries. Additionally, intensity during this phase of training, when volume is being steadily increased, should be low. The maximum training volume an individual attains is dependent on numerous factors and can be best gauged by determining the overall physical capacity and motivation.. Factors such as training status, age, body weight, and training time will all determine the training volume you are realistically capable of achieving. The premier benefit of increased training volume is an increased capacity for mitochondrial respiration, which, as explained earlier, is important to improvements in lactate threshold.

Interval and Steady-State Training

Following an adequate build-up in training volume, the next aspect that should be addressed is interval and steady-state training. Correct training intensity during this phase, which will be focused around an individual’s lactate threshold, is key to the continued success of your training program. 

Most individuals will not have access to scientific laboratories, where the lactate threshold can be accurately determined from blood sampled during an incremental VO2max test. Consequently, alternative methods have been recommended for the non-invasive, estimation of lactate threshold, including relative percentage of heart rate reserve (HRR) and rating of perceived exertion (RPE) scale. Research has shown that the lactate threshold occurs at 80-90% HRR in trained individuals and at 50-60% HRR in untrained individuals.

Steady-state workouts.

Steady-state workout sessions should be performed as close as possible to the lactate threshold (using the talk test). The length of these bouts can vary depending on training status, type of endurance-activity being performed, and distance of endurance-activity. The novice runner, training for 5-k road races, performing their first steady-state run may only do a workout 10 minutes in duration. A semi-professional cyclist, training for multiple-days of racing 80 to 100 miles distances, may complete a steady-state workout of an hour in duration.

Interval training

Interval training workouts are high-intensity training sessions performed for short durations of time at velocities or workloads above the lactate threshold. Similar to steady-state workouts, interval workout times and distances are dependent on training status, type of endurance-activity being performed, and distance of endurance-activity. The novice runner, training for 5-k road races, may complete three, 1-mile intervals at or faster than race pace, with adequate recovery time between each repeat. 

The key to successful steady-state and interval workouts is careful monitoring of training intensity. While it is necessary to perform these training sessions at an elevated intensity, avoid the pitfalls of racing these workouts, as it will eventually result in over-training. Furthermore, it has been suggested that steady-state and interval workouts should not exceed approximately 10-20% of total weekly training volume.

The Bottom Line on the Lactate, Ventilatory, Anaerobic and Heart Rate Thresholds

Hopefully, you now feel much more comfortable with much of the terminology, physiological mechanisms, and understanding of the lactate, ventilatory, anaerobic, and heart rate thresholds. The task of designing the optimal endurance-training program preparation for a 5K road race should now be less formidable. 

Lactate threshold is the most important determinant of success in mid distance endurance-related activities and events, and the main goal of endurance training programs should be the improvement of this parameter. This can be accomplished by first focusing on developing training volume, and then the incorporation of steady-state sessions (at the lactate threshold) and interval workouts (above the lactate threshold). 

Finally, remember that correct training intensity is essential to the success of any endurance-training program. Utilization of both the relative percentage of heart rate reserve (HRR) and the rating of perceived exertion (RPE) scale are proven methods for monitoring the training intensity of your clients during their workouts.

Lactate is not the Cause of Fatigue

The classical explanation for the cause of fatigue, denoted by sensations of pain and the muscle ‘burn’ experienced during intense exercise, is lactic acid build-up. Coaches, athletes, personal trainers, and scientists alike have traditionally linked lactic acidosis with an inability to continue exercise at a given intensity. Although the lactate threshold indicates that conditions within the muscle cell have shifted to a state favorable for the development of acidosis, lactate production itself does not directly contribute to the fatigue experienced at high intensities of exercise. 

It is the proton (H+) accumulation, coinciding with but not caused by lactate production, that results in decreased cellular pH (metabolic acidosis), impairing muscle contraction, and ultimately leading to fatigue. The increased proton accumulation occurs from a few different biochemical reactions during intense physical exercise, most notably in the splitting of ATP at the muscle myofilaments for sustained muscle contraction.

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Optimizing Training Part 2: Lactate and Ventilatory Threshold Training

This article is the Second Part of a Series on Optimizing Run Training

The first part of the series can be found here

Optimizing Running Training Part 1

Interestingly enough this applies to any exercise that crosses multiple energy systems.  So this is perfectly applicable to many mid range, with respect to time, workouts.

Metabolic Pathways Overview

All energy transformations that occur in the body are referred to as metabolism. A metabolic pathway is a series of chemical reactions that will result in the formation of ATP and waste products (such as carbon dioxide). 

The three energy systems of the body are the:

1. Anaerobic ATP-PC (often referred to as phosphagen) system - Short term.
2. Aerobic glycolysis (break down of sugar) - Mid Term also called the Lactate System
3. Aerobic mitochondrial respiration (cellular production of ATP in the mithochondrion) - Long term.

ATP-PC(Adenosine Tri-Phosphate - Phospho Creatine) is the simplest energy system of the body with the shortest capacity (up to 15 seconds) to maintain ATP production. During intense exercise, such as in weight lifting and sprinting, the ATP-PC is the most rapid and available source of ATP.

Energy for exercise activities requires a blend of all the energy systems. All energy system are active all of the time, but depending on the duration of the work, one energy system will predominate. The determinants of the involvement of the particular energy system are dependent on the intensity of the exercise. 

1) Lactate Removal

Although once considered a negative with respect to athletic performance, increased lactate production which occurs only during high-intensity exercise is natural.  Even at rest a small degree of lactate production takes place, which indicates there is also a lactate removal system or else there would be lactate accumulation occurring at rest. The primary means of lactate removal include its uptake by the heart, liver, and kidneys as a fuel .  Within the liver, lactate functions as a chemical building block for glucose production (known as gluconeogenesis), which is then released back into the blood stream to be used as fuel elsewhere. Additionally, non-exercising or less active muscles are capable of lactate uptake and consumption. At exercise intensities above the lactate threshold, there is a mismatch between production and uptake, with the rate of lactate removal lagging behind the rate of lactate production.

2) Fast-Twitch Motor Unit Recruitment

At low levels of intensity, long slow distance for example, primarily slow-twitch muscles fibers are recruited to support the exercise workload. Slow-twitch muscle has a high aerobic endurance capacity using the mitochondrial respiration energy system as opposed to the ATP system. With increasing exercise intensity there is a shift towards the recruitment of fast-twitch muscles, which have metabolic characteristics that are geared towards glycolysis. The recruitment of these muscles will shift energy metabolism from mitochondrial respiration towards glycolysis, which will eventually lead to increased lactate production.

Unfortunately and somewhat confusingly, the lactate threshold has been described with different terminology by researchers, including maximal steady-state, anaerobic threshold, aerobic threshold, individual anaerobic threshold, lactate threshold,  lactate breaking point, and onset of blood lactate accumulation.  Whenever reading on the topic of lactate threshold it is important to realize that these differing terms are essentially describing the same physiological event.

Traditionally there has been several ways to optimize running training: Ventilatory Threshold Training, Anaerobic Threshold Training, Heart Rate Monitoring, and VO2Max:

What is the Ventilatory Threshold?

As exercise intensity increases breathing increases in the early phases in a roughly linear fashion. As the intensity of exercise continues to increase, there is a  point at which breathing increases e in a non-linear fashion. This point where breathing increases at a much higher rate is called the ventilatory threshold. The ventilatory threshold corresponds (but is not identical) with the development of muscle and blood acidosis. Blood buffers(sodium bicarbonate), which are compounds that help to neutralize acidosis, work to reduce the muscle fibers acidosis. This leads to an increased need to expel carbon dioxide, which the body attempts to eliminate with the increase in ventilation.

Because increased ventilation occurs with increasing blood lactate values and acidosis, scientists originally believed this was an indication that the ventilatory and lactate threshold occur at similar exercise intensities. This interpretation is appealing because measuring the ventilatory threshold is non-invasive compared to the lactate threshold. And while numerous studies have shown a close correlation between the thresholds, separate studies have demonstrated that different conditions, including training status and carbohydrate nutritional supplementation, can cause thresholds in the same individual to differ substantially.

What is the Anaerobic Threshold?

The term anaerobic threshold was introduced based on the concept that at high-intensity levels of exercise, low levels of oxygen (or hypoxia) exists in the muscles. At this point, for exercise to continue, energy supply needed to shift from the aerobic energy system (mitochondrial respiration) to anaerobic energy systems (glycolysis and the phosphagen system).

The use of the term Anaerobic Threshold is misleading. Using the term 'anaerobic threshold' suggests oxygen supply to muscles is limited at specific exercise intensities. However this is not the case muscles do not become deprived of oxygen - even at maximal exercise intensities.  The limiting factor is Carbon Dioxide expulsion caused by the buffering of muscular acidosis not oxygen uptake. 

The second argument against using anaerobic threshold is that it suggests at this point in exercise intensity, metabolism shifts completely from aerobic to anaerobic energy systems.  Anaerobic energy systems (glycolysis and the phosphagen system) do not take over the task of ATP regeneration completely, even at higher intensities of exercise, but augment the energy supply provided from mitochondrial respiration.

What is the Heart Rate Threshold

In the early 1980’s, Italian researchers developed the methodology to detect the lactate threshold through a running test by determining the heart rate deflection point.  This easy and non-invasive approach to indirect lactate threshold measurement has been utilized extensively for training program design and exercise intensity recommendations

The heart rate deflection point is only visible in about half of all individuals and commonly over-estimates lactate threshold.  Because of these findings, and  errors associated with its use, heart rate variability among populations, I do not recommend the heart rate threshold method when designing endurance training programs for clients.  In part 3 I will discuss a simpler and possible more accurate way to monitor this which doesn't require constantly looking at a heart rate monitor.

Summary of Anaerobic, Ventilatory, Lactate and Heart Rate Thresholds

In summary, ventilatory and lactate thresholds, although similar, do not occur at exactly the same exercise workloads. The use of the term anaerobic threshold is not strictly correct although it is common usage and helps make the concept easier to understand (I think). 

Training and the Lactate Threshold, Lactate Threshold Training

One option for optimizing training is where training intensity would be based upon the velocity (speed) that corresponds to the lactate threshold.. Despite this, it is well known that following endurance training, the lactate threshold will occur at a higher relative percentage of an individual’s maximal oxygen uptake (VO2max) than prior to training. This adaptation allows for an individual to maintain higher steady-state running velocities or cycling workloads, while maintaining a balance between lactate production and removal. Endurance training influences both the rate of lactate production and the capability for lactate removal.

The reduced lactate production, at the same given workload, following endurance training can be attributed to increased mitochondria size, mitochondrial numbers, and mitochondrial enzymes.  The combined result of these training adaptations is an enhanced ability to generate energy through mitochondrial respiration, thus lowering the amount of lactate production at a given workload.

In addition, endurance training causes an increase in lactate usage by muscles, leading to a greater capacity for lactate removal from circulation, consequently, despite the heightened lactate production rates occurring at high levels of exercise intensity, blood lactate levels will be lower. 

Endurance training may also improve capillary density around the muscles, especially the slow-twitch muscles. This adaptation improves blood flow to and from exercising muscles, which will enhance the clearance of lactate and acidosis.

Next: Part 3: Lactate Threshold Training Programs and Workouts