Training Effects On The Cardiopulmonary System
The ability to transport oxygen efficiently is clearly an important factor contributing to optimal performance in endurance sport, which is heavily dependent on oxidative energy production. Of course, one question that immediately comes to mind among athletes is, “Can I improve my cardiopulmonary system and oxygen transport capabilities through training?” The answer is yes.
One way to improve oxygen transport is to undertake altitude training. This type of training has the effect of increasing the number of red blood cells and hemoglobin molecules, resulting in an increased capacity to get oxygen to the exercising muscles. Many athletes, however, do not have the time or resources to undergo altitude training for a duration that will bring about an increase in red blood cells and hemoglobin. Unfortunately, some unethical athletes have chosen to induce the same physiological effect by using illegal pharmacological ergogenic aids such as recombinant human erythropoietin (rhEPO). Athletes should understand that several positive cardiopulmonary training effects can be acquired at sea level by using a training program that is well designed and scientifically sound.
This section focuses on those beneficial cardiopulmonary training effects. (Chapters 8, 9, 10, and 11 provide specific training programs that help elicit these beneficial cardiopulmonary training effects.) Many cardiopulmonary adaptations occur as a result of regular endurance training. Regular endurance training means a minimum of 30 to 45 minutes per training session and a minimum of 3 to 5 training sessions per week for at least 8 weeks. The beneficial cardiopulmonary adaptations that can occur include the following:
One way to improve oxygen transport is to undertake altitude training. This type of training has the effect of increasing the number of red blood cells and hemoglobin molecules, resulting in an increased capacity to get oxygen to the exercising muscles. Many athletes, however, do not have the time or resources to undergo altitude training for a duration that will bring about an increase in red blood cells and hemoglobin. Unfortunately, some unethical athletes have chosen to induce the same physiological effect by using illegal pharmacological ergogenic aids such as recombinant human erythropoietin (rhEPO). Athletes should understand that several positive cardiopulmonary training effects can be acquired at sea level by using a training program that is well designed and scientifically sound.
This section focuses on those beneficial cardiopulmonary training effects. (Chapters 8, 9, 10, and 11 provide specific training programs that help elicit these beneficial cardiopulmonary training effects.) Many cardiopulmonary adaptations occur as a result of regular endurance training. Regular endurance training means a minimum of 30 to 45 minutes per training session and a minimum of 3 to 5 training sessions per week for at least 8 weeks. The beneficial cardiopulmonary adaptations that can occur include the following:
- Decrease in resting and exercise heart rate
- Increase in total blood volume
- Increase in cardiac output
- Increase in exercise respiratory capacity
- Increase in maximal oxygen uptake (O2max)
- Improvement in lactate threshold
- Improvement in maximal exercise performance
- Improvement in exercise economy
- Improvement in endurance performance
- Improvement in heat tolerance
- Decrease in total body weight
- Decrease in body fat
- Decrease in blood pressure (if moderate or high blood pressure exists)
The combined effects of the training-induced improvements in cardiac output, maximal oxygen uptake, lactate threshold, exercise economy, and maximal exercise performance clearly have a positive effect on endurance performance. After all, an improvement in performance is what every endurance athlete and coach strives for. However, endurance performance will not improve significantly unless the proper training is done to bring about these beneficial cardiopulmonary training effects. The upcoming sections explore some of these benefits in greater detail.
Heart Rate
Through regular endurance training, the heart becomes stronger via a progressive overload. Because the heart is stronger, it will pump out more blood with each beat. As a result, the heart doesn’t have to work as hard, and the person’s heart rate at rest and during exercise will be lower than it was before the person began an endurance training program. During exercise, the person’s heart rate will be lower at a specific workload. For example, let’s say that the person’s heart rate taken immediately after running 800 meters on the first day of training was 175 beats per minute (bpm). After 8 weeks of endurance training, the person’s heart rate should be significantly lower after running 800 meters at the same pace that the person ran it on the first day of training. The exact amount is difficult to estimate because it varies from person to person.
A person’s recovery heart rate will also improve as a result of endurance training. Using the previous example, let’s say that it took 3 minutes for the person’s heart rate to drop from 175 bpm to 125 bpm after running 800 meters on the first day of training. After 8 weeks of endurance training, the person’s heart rate will drop from 175 bpm to 125 bpm in much less than 3 minutes. Again, the improvement in recovery heart rate will vary from person to person. Despite this individual variability, it is safe to say that after a minimum of 8 weeks of endurance training, the person can expect to see improvements in heart rate at rest (lower), heart rate during exercise at the same workload (lower), and heart rate during recovery after a hard effort (less time to recover).
Well-trained endurance athletes, such has professional cyclists, have a high cardiac output that delivers more oxygen to the muscles.
Cardiac Output
Endurance training also increases the level of a few specific hormones that regulate the amount of blood in the body. These hormones act to increase the fluid portion of the blood, which is called plasma. The overall effect of this hormonal response is an increase in total blood volume. An increase in total blood volume, along with the heart being stronger and more powerful, means that the heart can pump more blood over a specific period of time (at the same heart rate).
This increase in the amount of blood pumped over a specific time is referred to as an increase in cardiac output. Cardiac output is measured as the amount of blood that the heart pumps through the body in a single minute. An increase in cardiac output is important because more blood is delivered to the brain, liver, kidneys, and other important organs. During endurance exercise, an increased cardiac output is important because more blood is delivered to the working skeletal muscles. As a result, more oxygen is delivered to the exercising muscles for energy, whereas carbon dioxide and other metabolic by-products are removed from the exercising muscles more rapidly.
O2max
Endurance training also improves the capacity of the lungs during exercise. This means that the person’s respiratory rate (breaths per minute) and tidal volume (liters of air per breath) are improved. These improvements in lung capacity may contribute to an increase in maximal oxygen uptake (O2max). Maximal oxygen uptake is defined as the highest volume of oxygen that a person’s body is capable of taking in and using for aerobic energy production. O2max can be expressed in absolute units (liters of oxygen per minute [L × min-1]) or relative units (milliliters of oxygen per kilogram of body mass per minute [ml × kg-1 × min-1]). O2max is usually expressed in ml × kg-1 × min-1 because this value allows us to make comparisons between individuals and tells us who is the fittest “pound for pound.”
O2max can rise to levels of 65 to 75 ml × kg-1 × min-1 and 75 to 85 ml × kg-1 × min-1 in well-trained female and male endurance athletes, respectively. By comparison, typical values for untrained females and males may range from 35 to 40 ml × kg-1 × min-1 and 45 to 50 ml × kg-1 × min-1, respectively. An improvement in O2max is important because it means that more oxygen is available to the exercising muscles for energy production. Research has shown that a high O2max is one of several physiological factors that contribute to success in endurance sports such as distance running, cross-country skiing, and triathlon.
Lactate Threshold
and Maximal Exercise Performance
Scientific research has recently identified a couple of additional physiological factors that are very important contributors to endurance performance: lactate threshold (LT) and maximal exercise performance. These physiological parameters are typically measured under laboratory conditions.
During an increasingly demanding endurance training session or race, the lactate threshold represents the point at which the athlete’s body requires a greater contribution from the glycolysis energy system (short-term energy system) and a smaller contribution from the oxidative phosphorylation energy system (long-term energy system). As a result of reaching this point, lactate production exceeds lactate removal, and an exponential increase in blood lactate levels occurs. So, the higher the lactate threshold, the better in terms of endurance performance.
In evaluating lactate threshold capabilities in triathletes, swimming velocity (m × sec-1), cycling power output (watts per kilogram of body weight [W × kg-1]), and running velocity (m × min-1) are the measurements of interest. By participating in a well-designed endurance training program, a triathlete can expect to see significant improvement in these lactate threshold parameters. The athlete will certainly see an improvement in the lactate threshold over the course of a single season. In addition, the athlete will probably see improvements in the lactate threshold from season to season depending on how many years the endurance athlete has been in training.
Maximal exercise performance is simply the objective quantification of an endurance athlete’s athletic capability at the point at which the athlete voluntarily stops exercising because of exhaustion (volitional exhaustion). This is determined at the conclusion of a laboratory-based maximal exercise test (e.g., treadmill test). In evaluating maximal exercise performance in triathletes, the same physiological measurements used for evaluating lactate threshold are of interest, but they are now measured under conditions of maximal effort (instead of lactate threshold effort). Like the lactate threshold, the higher the level of maximal exercise performance, the better in terms of endurance performance. By participating in a well-designed endurance training program, an athlete can expect to see the same type of improvement in maximal exercise performance as seen in the lactate threshold (within a single season and from season to season).
Physiological Economy
Another physiological factor that contributes to endurance performance is economy. The concept of physiological economy is similar to the concept of fuel efficiency in an automobile. We know that a more economical or efficient car uses less gas at a specific speed and gets greater “miles per gallon” than a less economical car. The same is true for endurance athletes.
Endurance training also increases the level of a few specific hormones that regulate the amount of blood in the body. These hormones act to increase the fluid portion of the blood, which is called plasma. The overall effect of this hormonal response is an increase in total blood volume. An increase in total blood volume, along with the heart being stronger and more powerful, means that the heart can pump more blood over a specific period of time (at the same heart rate).
This increase in the amount of blood pumped over a specific time is referred to as an increase in cardiac output. Cardiac output is measured as the amount of blood that the heart pumps through the body in a single minute. An increase in cardiac output is important because more blood is delivered to the brain, liver, kidneys, and other important organs. During endurance exercise, an increased cardiac output is important because more blood is delivered to the working skeletal muscles. As a result, more oxygen is delivered to the exercising muscles for energy, whereas carbon dioxide and other metabolic by-products are removed from the exercising muscles more rapidly.
O2max
Endurance training also improves the capacity of the lungs during exercise. This means that the person’s respiratory rate (breaths per minute) and tidal volume (liters of air per breath) are improved. These improvements in lung capacity may contribute to an increase in maximal oxygen uptake (O2max). Maximal oxygen uptake is defined as the highest volume of oxygen that a person’s body is capable of taking in and using for aerobic energy production. O2max can be expressed in absolute units (liters of oxygen per minute [L × min-1]) or relative units (milliliters of oxygen per kilogram of body mass per minute [ml × kg-1 × min-1]). O2max is usually expressed in ml × kg-1 × min-1 because this value allows us to make comparisons between individuals and tells us who is the fittest “pound for pound.”
O2max can rise to levels of 65 to 75 ml × kg-1 × min-1 and 75 to 85 ml × kg-1 × min-1 in well-trained female and male endurance athletes, respectively. By comparison, typical values for untrained females and males may range from 35 to 40 ml × kg-1 × min-1 and 45 to 50 ml × kg-1 × min-1, respectively. An improvement in O2max is important because it means that more oxygen is available to the exercising muscles for energy production. Research has shown that a high O2max is one of several physiological factors that contribute to success in endurance sports such as distance running, cross-country skiing, and triathlon.
Lactate Threshold
and Maximal Exercise Performance
Scientific research has recently identified a couple of additional physiological factors that are very important contributors to endurance performance: lactate threshold (LT) and maximal exercise performance. These physiological parameters are typically measured under laboratory conditions.
During an increasingly demanding endurance training session or race, the lactate threshold represents the point at which the athlete’s body requires a greater contribution from the glycolysis energy system (short-term energy system) and a smaller contribution from the oxidative phosphorylation energy system (long-term energy system). As a result of reaching this point, lactate production exceeds lactate removal, and an exponential increase in blood lactate levels occurs. So, the higher the lactate threshold, the better in terms of endurance performance.
In evaluating lactate threshold capabilities in triathletes, swimming velocity (m × sec-1), cycling power output (watts per kilogram of body weight [W × kg-1]), and running velocity (m × min-1) are the measurements of interest. By participating in a well-designed endurance training program, a triathlete can expect to see significant improvement in these lactate threshold parameters. The athlete will certainly see an improvement in the lactate threshold over the course of a single season. In addition, the athlete will probably see improvements in the lactate threshold from season to season depending on how many years the endurance athlete has been in training.
Maximal exercise performance is simply the objective quantification of an endurance athlete’s athletic capability at the point at which the athlete voluntarily stops exercising because of exhaustion (volitional exhaustion). This is determined at the conclusion of a laboratory-based maximal exercise test (e.g., treadmill test). In evaluating maximal exercise performance in triathletes, the same physiological measurements used for evaluating lactate threshold are of interest, but they are now measured under conditions of maximal effort (instead of lactate threshold effort). Like the lactate threshold, the higher the level of maximal exercise performance, the better in terms of endurance performance. By participating in a well-designed endurance training program, an athlete can expect to see the same type of improvement in maximal exercise performance as seen in the lactate threshold (within a single season and from season to season).
Physiological Economy
Another physiological factor that contributes to endurance performance is economy. The concept of physiological economy is similar to the concept of fuel efficiency in an automobile. We know that a more economical or efficient car uses less gas at a specific speed and gets greater “miles per gallon” than a less economical car. The same is true for endurance athletes.
In endurance competitions, having greater physiological economy is essential for success.
For example, let’s say that athlete A and athlete B both have a similar O2max value of 65 ml × kg-1 × min-1. However, athlete A uses 50 ml × kg-1 × min-1 while running at a pace of 5 minutes per mile in the first half of a 10K race, whereas athlete B uses 53 ml × kg-1 × min-1 while running at the same pace in the first half of a 10K race. Thus, athlete A is more efficient and economical in terms of energy expenditure than athlete B because he uses less oxygen (“less gas”) at the 5-minute-per-mile pace. Athlete A should have a competitive advantage over athlete B in the second half of the race because of his better physiological economy. Several factors can improve physiological economy, including a well-designed endurance training program, individual running biomechanics, uphill running, bungee running, and plyometrics training.
Tolerance to Heat and Humidity
A person’s ability to work and exercise in heat and humidity is also significantly improved as a result of endurance training. As mentioned earlier, the body produces more plasma and increases the total blood volume when a person performs endurance training on a consistent basis. Think of total blood volume as radiator coolant in a car or truck. Endurance training leads to an increase in total blood volume, which allows a person to have more “radiator coolant” in the body. As a result, the person is able to produce more sweat and dissipate heat more effectively from the body, particularly when exercising in a hot and humid environment. This is a particularly beneficial effect for endurance athletes who often compete in arid or tropical environments.
Body Weight and Body Fat
Endurance training can lower a person’s total body weight and reduce body fat. This may not be a major concern for well-trained endurance athletes, because these athletes are typically “lean and mean.” However, it may become more important as athletes get older, especially when they reach a point when their lifestyle (job, family, travel, and so on) prevents them from training as they did earlier in their career. For individuals with moderate to high blood pressure, regular endurance training can have a significant lowering effect, thereby decreasing the risk of cardiovascular disease and premature death. Again, this is probably not a major concern for most well-trained endurance athletes, because their blood pressure is typically normal. However, elevated blood pressure may become an issue as an athlete gets older and becomes less active.
For example, let’s say that athlete A and athlete B both have a similar O2max value of 65 ml × kg-1 × min-1. However, athlete A uses 50 ml × kg-1 × min-1 while running at a pace of 5 minutes per mile in the first half of a 10K race, whereas athlete B uses 53 ml × kg-1 × min-1 while running at the same pace in the first half of a 10K race. Thus, athlete A is more efficient and economical in terms of energy expenditure than athlete B because he uses less oxygen (“less gas”) at the 5-minute-per-mile pace. Athlete A should have a competitive advantage over athlete B in the second half of the race because of his better physiological economy. Several factors can improve physiological economy, including a well-designed endurance training program, individual running biomechanics, uphill running, bungee running, and plyometrics training.
Tolerance to Heat and Humidity
A person’s ability to work and exercise in heat and humidity is also significantly improved as a result of endurance training. As mentioned earlier, the body produces more plasma and increases the total blood volume when a person performs endurance training on a consistent basis. Think of total blood volume as radiator coolant in a car or truck. Endurance training leads to an increase in total blood volume, which allows a person to have more “radiator coolant” in the body. As a result, the person is able to produce more sweat and dissipate heat more effectively from the body, particularly when exercising in a hot and humid environment. This is a particularly beneficial effect for endurance athletes who often compete in arid or tropical environments.
Body Weight and Body Fat
Endurance training can lower a person’s total body weight and reduce body fat. This may not be a major concern for well-trained endurance athletes, because these athletes are typically “lean and mean.” However, it may become more important as athletes get older, especially when they reach a point when their lifestyle (job, family, travel, and so on) prevents them from training as they did earlier in their career. For individuals with moderate to high blood pressure, regular endurance training can have a significant lowering effect, thereby decreasing the risk of cardiovascular disease and premature death. Again, this is probably not a major concern for most well-trained endurance athletes, because their blood pressure is typically normal. However, elevated blood pressure may become an issue as an athlete gets older and becomes less active.
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