Hi, I'm Dr.Emerson Frank. Our group represent how to determine the energy systems in sports that are difficult to be reproduced in control environments such as exercise physiology labs. Each sport has specific characteristics that confer different metabolic demands to them.
One of the most important aspects of the metabolic demand is the relative contribution of the energy systems, namely the aerobic, lactic, anaerobic, lactic and aerobic. Some sports can be somewhat easily mimicked in therefore studied in a laboratory setting as they are cyclic and predictable. On the other hand, some sports are unpredictable and dependent on a complex interaction between teammates and or opponents.
This is the case that the majority of team sports in a number of individual sports. Here we'll show how the relative contribution of the energy systems can be assessed during exercise. Although the method is suitable to any type of exercise, we'll emphasize its adaptation to unpredictable parts due to its particular characteristics.
Judo will be used as an example on how the procedure can be adapted. Depending on the athlete's movements, researches focuses on other sports may easily adapt to the procedure. Based on what is shown here, The following physiological variables will be assessed.
Rest, oxygen consumption, exercise, oxygen consumption, post exercise, oxygen consumption, rest plasma lactate, concentration, post exercise, plasma peak lactate. First, a restin blood sample Must be collected and rest oxygen consumption measured for at least five minutes. The oxygen uptake during the last 30 seconds of this period is used to calculate the baseline value and the oxidative metabolism Contribution for blood sample collection is small volume of capillary blood is taken from the ear lobe or from the fingertip after collection placed with the help of a micro ppa, a known volume of the blood in the same volume of a 1%sodium fluoride solution.Exercise.
Oxygen consumption has to be measured through the use of a portable gas analyzer. Capable of measuring oxygen consumption on a breath by breath basis. Place the mask and make sure that it is properly sealed so there is no leakage of the expired air.
Always calibrate equipment following manufacturer's instructions before data collection. Normally the equipment is placed at the athlete's back. However, in complex sports, the position of the equipment must be adapted using judo.
As an example, if the technique requires dorsal contact, the equipment is placed at the chest. If the technique requires frontal contact, the equipment is placed at the back. The same has to be done if the back touches the ground.
If the technique requires lateral contact, the equipment is placed at the opposite lateral. With a few adaptations to competition's rules, it is possible to create an exercise in which the athlete is submitted to a very similar demand of the sport. For example, here we simulate a judo combat to avoid any damage to the equipment.
The opponent does not apply any effective throw. Also, the athlete being evaluated may not apply any throw that requires dorsal contact. Once the data collection is finished, we'll be ready to start the procedures to calculate the energy contribution.
Let's see how to do it. First, plasma lactate has to be measured, spin the blood to separate plasma from erythrocytes. Then plasma lactate can be measured, spectro, photometrically, fluor metrically, or electrochemically.
In our lab, we normally use the electrochemical method through an automatized lactate analyzer. The result is immediately shown in a small screen and it then needs to be corrected by The dilution factor. This is a typical curve of oxygen Consumption at rest or baseline during exercise After exercise.
Taking a close look at the post exercise curve, it is possible to see two different components. The fast component, the slow component to calculate the contribution of the aerobic metabolism to the total energy spend during exercise, determine the baseline or rest value for oxygen consumption. This can be done by calculating the average of the last 30 seconds of the curve.
Then multiply the value obtained by the total time of exercise. For example, if the exercise duration was five minutes, multiply the rest oxygen consumption by five. Determine total oxygen consumption during exercise by calculating the area under the curve of the exercise oxygen consumption.
Use the trapezoidal method to calculate area under the curve. Finally, subtract the baseline oxygen consumption from the exercise oxygen Consumption. To calculate the Contribution of the L anaerobic metabolism, the kinetics of the post-exercise curve has to be adjusted to a mono or by exponential model.
Using the data obtained in each breath adjusted for a mono exponential curve and for a bio exponential curve. This may be done with the help of a mathematical software. If the exercise you're studying has a unknown curve pattern, then both mono and bio exponential models should be tested to verify, which then best fits to your data.
To do so, use the software to generate the mono exponential and the bi exponential adjustments. In the best model, the real curve is closer to the fitted curve. Using the data of the real curve and the fitted curve, calculate the residue of the model for each breath.
That is subtract the fitted value from the real value and square the result. After calculating the residue of each point of the curve for both mono and by exponential adjustments test whether the residues are different between the models through the use of the F test. The best model is the one that generated the smallest residue.
If there is no significant difference between the models, use the simplest one that is the mono exponential. Finally, use the terms of the equation provided by the best feeded curve to calculate the contribution of the electric metabolism. As an example, this is the equation for the mono exponential adjustment.
Used these terms to calculate the anaerobic elastic contribution with the following equation. Amplitude A one has to be divided by 60, so the unit milliliters per minute is converted to milliliters per second. To calculate the contribution of the lactic and anaerobic metabolism, we assume that one millimole of lactate above the resting values corresponds to three milliliters of oxygen consumed per kilogram of body mass.
Thus, the delta peak plasma lactate that is peak plasma lactate minus resting plasma lactate is multiplied by three and by the athlete's body mass. The result in milliliters is then converted to liters and in energy, assuming that each liter of oxygen is equal to 20.92 kilojoules. Lastly, the result obtained by each system is summed, so you have the total energy spend during the exercise and relative contribution of each system to the total can be then calculated.
The method that we have shown here can be used for both continuous and intermittent exercises. The greater advantage of the method is that it can be adapted to exercises and sports that are difficult to be mimicked in, controlled the laboratory settings. Also, this is the only available method capable of estimating the contribution of the three different energy systems.
Thus, this method allows the studio of physiological responses with great similarity to real part situations, providing desirable ecological validity to this study. For example, I studied from Benefit L, confirmed that the main source of the energy during one of the most used anaerobic testis, the wing gauge anaerobic test, is the anaerobic metabolism. More precisely 50%glycolytic, 30%atic, and 20%aerobic.
Recent studies by our group have also characterized the energy contributions of indoor rock climbing, rowing, and judo as presented in this example. Indeed, the knowledge of the energetic contribution is critical for the development of genic strategies, training, monitoring, or even for validating a test.
