There is no secret or mystery about
the energy systems and their effectiveness when clearly understood. Track and
field coaches must understand energy system capabilities and limitations to
design appropriate and sequenced training programs. In teaching athletes to
listen to their body and pay attention to their performance during training
sessions, adjustments can be furnished in the sequenced workout with careful
understanding of the energy systems.
It is the intention of this paper to provide the coach with a workout training system based on accurate scientific knowledge as it relates to the energy systems.
ATP - The source of muscular energy
Adenosine Triphosphate, or more simply ATP, is the immediate usable form of
chemical energy for muscular activity. This is one of the most important of the
"energy rich" compounds which is stored in all cells, particularly muscle
cells. All forms of chemical energy available from the food we eat must
eventually be transferred into ATP form before they can be utilized by the
The ATP molecule consists of a large complex molecule called adenosine with three simple components called phosphate groups.
The amount of ATP in the muscle cell is limited and could be depleted in 1 - 2 seconds unless recharged to maintain muscular activity, thus, immediate synthesis of ATP is necessary. ATP supplies must be kept at peak concentration and must never fall below 60% 'of its resting levels for muscular activity to continue.
The three systems of metabolic pathways available to replace ATP concentrations are:
1. Anaerobic Phosphagen (ATP-CP) Energy System
2. Anaerobic Lactate (Glycolytic) Energy System
3. Aerobic Energy System
THE ANAEROBIC (ATP-CP) ENERGY SYSTEM
An energy rich compound called Creatine Phosphate (CP) is present in the muscle cell. This compound is used for the immediate resynthesis of ATP following very high intensity exercise. The resynthesis of ATP from CP will continue until all the creatine phosphate stores are depleted, usually under 10 seconds. The enzyme that makes this reaction possible is Creatine Kinase (CK) as follows:
This diagram shows that the reaction is reversible
The amount of ATP that can be resynthesized can last for 4 to 5 seconds. Remember the 1 to 2 second supply from ATP stores, so collectively, you have about 5 to 7 seconds of ATP production.
To challenge this system, high intensity, workouts of 4 to 7 seconds. High intensity work (Sprints) involves moving the limbs at near peak velocity. More specifically, it involves the selective recruitment of motor unit pathways to improve the efficiency and firing of correct motor units that are available depending on the TYPE, INTENSITY, and. DURATION of work executed. This motor learning must be rehearsed (Practiced) at high speeds to develop and implant the complex recruitment for synchronized firing of these motor units.
Points that must be followed in the training sessions:
1. The speed component of anaerobic metabolism should be trained when no fatigue is present.
2. Most athletes require 24-36 hours of rest with low intensity work before doing maximum speed work again.
3. In weight training, work sets of around 3-4 repetitions, where the athlete is unable to perform more than 4 repetitions (4 rep max) with sufficient recovery, usually a few minutes between sets.
4. The time period necessary for the proper resynthesis of ATP and CP.
Recovery rates for CP resynthesis.
A. 30 seconds - 50%
B. 1 minute - 75%
C. 90 seconds - 80%
D. 3 minutes - 98%
It is obvious why 2 to 3 minutes minimum between sets is necessary for recovery.
5. Four (4) sets, involving 480 meters (i.e., 4 X 4 X 120m/set) in total distance in a practice session is sufficient to stimulate this system.
ANAEROBIC (ATP-CP) SPEED WORK
DISTANCE OF RUN 20-60 meters
NUMBER OF REPS 3-4
SET NUMBER OF SETS 3-4 (5)
TOTAL DISTANCE IN SET 80-120 Meters
TOTAL DISTANCE IN SESSION 400-600 Meters
SPRINTS A B C 5X30 4X30 4X40 4X40 4X40 4X50 ---- 4X50 4X60 310 METERS 480 METERS 600 METERS
A B 5X50 5X50 5X35 5X70 425 METERS 600 METERS
SPEED RESISTANCE WEIGHT TRAINING
4-6 SECONDS DURATION/SET
THE ANAEROBIC LACTATE (GLYCOLYTIC) SYSTEM
The demand for energy (ATP) dictates which energy system will be challenged.
After 10 seconds of high-intensity training, CP stores are depleted and the body
must look for another source of ATP to maintain that level of exercise. Muscle
must then resort to stored glucose for ATP. This process is called the Anaerobic
Lactate System. To challenge the lactate (glycolytic) system, the breakdown of
glucose or glycogen anaerobically produces energy plus lactate and hydrogen ions
(H+ ). When the demand for energy exceeds the body's ability to produce energy
with oxygen, the muscle will become acidic. The presence of hydrogen ions, not
lactate, makes the muscle acidic which will eventually halt muscle function.
For each lactate molecule, one corresponding hydrogen ion is formed. This system operates in the muscle cell and its chemical reaction is:
When hydrogen ion concentrations increase, the blood and muscle become acidic. This acidic environment resulting from anaerobic glycolysis will slow down enzyme activity and ultimately the breakdown of glucose itself. Also, acidic muscle will aggravate associated nerve endings causing pain and increase irritation of the central nervous system.
Glucose or Glycogen is broken down to pyruvate to provide high energy
phosphates. Simultaneously, the reduction of the co-enzyme NAD, which acts as a
hydrogen acceptor (Electron Carrier) forms NADH2. Pyruvate is reduced by the
enzyme lactate dehydrogenase (LDH) by releasing the hydrogen to NADH2 to form
The formation of lactate is not necessary for the delivery of energy, but it serves a storehouse for the hydrogen ion, and thereby keeps the reaction going. Under anaerobic conditions, the accumulation of hydrogen ions is the limiting factor causing fatigue in runs of 300-800 meters.
The task now is to link this scientific information and to develop accurate and working methods to design training sessions that challenge the lactate energy system. Distances of 300-600 meters may be used by coaches to train the anaerobic glycolysis system. Due to the possibility of injury, it is necessary to mentally and physically prepare to do this intense anaerobic training. High quality lactate work can shock the body and the central nervous system. Thus, loads (Total Distance and Volume) and intensities (Percent of Maximum) must be progressively sequenced. For example, sequencing workouts to prevent injuries may be achieved by planning each day of the week for an entire year. Each workout is a single unit of preparation designed to produce a desired result and each session is more demanding than the previous in some way.
Recovery sessions from high quality lactate work must be sequenced in a set pattern. A second year athlete will not work at the same level that a sixth year athlete would. Prior knowledge of the athlete's work capacities and prior experience is essential in dictating the load and intensity in each unit.
The accumulation of lactate in working skeletal muscle is associated with fatigue of this system after 50 to 60 seconds of maximum effort. Although all energy systems basically turn on at the same time, be aware that progressive recruitment of alternative pathways or systems occurs when one system is challenged more heavily, since another energy source has been depleted. In most cases only 1-5 reps with full or near full recovery can be done twice a week. Only by challenging the energy systems required for each event will the desired physiological change and maximal performance occur. Understand, at times, less work gives greater rewards.
To tie together this enormous lactate puzzle requires an understanding of 3 different working units within this energy system.
Speed Endurance: To challenge the
anaerobic (glycolytic) system, runs are done at maximal or submaximal speed
(95-100%) for approximately 8 to 20 seconds (60-150 meters), like speed, this
involves a motor educational process to implant the correct patterns, not the
actual energy source. Speed endurance runs can be done without the penalizing
disadvantage of heavy lactate accumulation. No more than 2 to 3 sets or 300-1200 meters in total distance should be run. Sets of 2 to 5 reps with 2 to 5
minutes recovery between sets, and 8 to 10 minutes between reps is recommended.
Special Endurance I: This refers to the technical demand and/or the anaerobic glycolytic energy system demands. Runs are done at 90 to 100% for approximately 20 to 40 seconds (150 - 300 meters) with complete or near complete recovery (10-20 minutes) between reps. 1 to 5 reps are done for this competition specific type endurance for 300 to 1200 meters in total distance.
Special Endurance II: 1 to 3 runs are done at 90 to 100% intensity for approximately 40 seconds to 2 minutes, 300-600 meters, with complete or near complete recovery (20-30 minutes). Low intensity jogging or tempo runs (60% VO2 intensity) will help recovery and removal of lactate in 20 to 30 minutes. If just walking or sitting recovery is done, it will take 1-2 hours to remove lactate accumulation.
SPECIAL ENDURANCE I
SPECIAL ENDURANCE II
DISTANCE OF RUN
NUMBER OF REPS PER SET
NUMBER OF SETS
DISTANCE PER SESSION
SPECIAL ENDURANCE I
SPECIAL ENDURANCE II
|DISTANCE OF RUNS||60, 80, 100 METERS||150, 200 METERS||400 METERS|
|NUMBER OF REPS||1||1||1|
|NUMBER OF SETS||3||2||3|
|DISTANCE PER SESSION||720 METERS||700 METERS||1200 METERS|
|DISTANCE OF RUNS||120 & 150 METERS||250 METERS||300 & 350 METERS|
|NUMBER OF REPS||5 (3 @ 120 & 2 @ 120 + 150)||1||2 (1 @ 300 & 1 @ 300 + 350)|
|NUMBER OF SETS||2||3||1|
|DISTANCE PER SESSION||900 METERS||750 METERS||950 METERS|
|DISTANCE OF RUNS||600 METERS|
|NUMBER OF REPS||3|
|NUMBER OF SETS||1|
|DISTANCE PER SESSION||1800 METERS|
SPECIAL ENDURANCE I
SPECIAL ENDURANCE II
|DISTANCE OF RUNS||100 METERS (HURDLES)||200 & 250 METERS (HURDLES)||300 METERS (HURDLES)|
|NUMBER OF REPS||2||3 (2 @ 200 & 1 @ 200 + 250)||3|
|NUMBER OF SETS||3||1||1|
|DISTANCE PER SESSION||600 METERS||850 METERS||900 METERS|
THE AEROBIC ENERGY SYSTEM
The aerobic system is able to utilize proteins, fats and carbohydrates
(glycogen) for re-synthesizing large amounts of ATP without simultaneously
generating limiting by- products. The aerobic system is particularly suited for
manufacturing ATP during prolonged, endurance type activities. Again, the
intensity of the run dictates which energy system will be challenged and the
method of ATP production in the muscle.
In the aerobic system, pyruvate from
the glucose, glycogen and/or fatty acids is first converted to acetyl CoA, which
is then oxidized to Carbon Dioxide (CO2), and water (H2O). Oxidation of acetyl
CoA occurs in the Krebs Cycle (Citric Acid Cycle) and the electron transport
system located in the mitochondrion.
For each molecule of blood glucose oxidized aerobically, 36 molecules of ATP are produced while liver glycogen produces 37-39 molecules of ATP. liver glycogen is capable of producing 1 more molecule of ATP than blood glucose because it takes 1 ATP molecule to transfer blood glucose into the cell. The energy production in aerobic metabolism is 18 times greater than in the anaerobic system production of ATP.
The carbon atoms of acetyl CoA are converted to carbon dioxide and the hydrogen atoms (containing electrons) are transferred to oxygen to form water. Note: that for this system to function, oxygen must be available, hence the term aerobic. It is the availability of oxygen, coupled with the intensity and duration, factors previously mentioned, in the cell that helps determine what extent the process is aerobic and anaerobic.
If the aerobic energy system cannot
supply enough oxygen (anaerobic), pyruvate accumulates. This is a critical step
because, as pyruvate concentration increases, it becomes a hydrogen acceptor and
forms lactate. The rapid increase in hydrogen ions, not lactate, creates an
acidic environment which will eventually lead to the slowing down of all energy
Lactate is a small molecule that easily diffuses from the cell into the bloodstream. Once in the bloodstream, the buffering system allows anaerobic glycolysis to continue for up to several minutes depending on the intensity of the exercise. In recovery, lactate is a preferred fuel source that is quickly metabolized by the body.
The following diagram illustrates various ways in which the aerobic metabolic pathway can be challenged and conditioned for athletes.
(Tempo refers to
intensity of the run and may involve runs between 40 - 90% intensity)
CONTINUOUS TEMPO (General Endurance):
Heart rate is a good indicator of work stress. If you know the athletes maximum heart rate, you may u&e this number to determine their exercise work intensity. If you do not know the maximum heart rate, you may predict it by using: 220 minus Age. Using a twenty year old athlete (220 minus AGE = predicted maximum heart rate), his/her assumed maximal heart rate would be 200 BPM. The concentration of lactate in the blood starts to increase when work loads exceed 60% intensity. (HR 100-140) depending of the condition of the athlete. Easy runs using the continuous method, commonly referred to as tempo runs, help to improve recovery and the athlete's fatiguing mechanisms. The body's capability of oxygen absorption depends upon the size and strength of the heart, the extensive network of capillary blood vessels, number of mitochondria, the quality (hemoglobin and hematocrit) and blood volume.
Note: The above formula does not work for the older "well conditioned" athlete. For the 50+ year old athlete, 210 minus 1/2 of the athletes age is a better predictor. RKD
The most important part of blood, with respect to oxygen uptake, is the red
corpuscle (Er) erythrocyte which transports the iron-containing hemoglobin (Hb)
which readily combines with oxygen. Hemoglobin has the potential to combine with
1.34 mL/grams of oxygen. For example, a hemoglobin level of 15 g/dL of blood
would transport approximately 20 mL of oxygen per dL It is clear that the more
hemoglobin the red blood cell contains, the more oxygen it will be able to carry
from the heart and lungs to the working muscles. From this point of view, it is
of primary importance to develop the aerobic energy system to assist recovery
and lower the athlete's fatigue levels. This method involves runs at 50-70% (HR
100-140) intensity continuously, as long slow distance runs.
Slow, continuous long term exercise places a great load on muscle and liver glycogen. Long duration activity will decrease levels of muscle and liver glycogen. For example, the limiting factor in long duration activity (marathon) is glucose availability. The normal adaptation response to this type of activity will ultimately enhance muscle and liver glycogen storage capacities and glycolytic activity associated with these processes.
When running at 60-80% (HR 120-160) intensity, the trained athlete will experience lactate formation but only a fraction of those levels reached while running at 90-100% intensity. Continuous running at ex1:ensive tempo levels assists the removal and turnover of lactate and the body's ability to tolerate greater levels of lactate. Submaximal work levels of 60-80%, lactate forms in large amounts, because the oxidative system is insufficient to meet the demands of the muscle. Thus, creating a state of oxygen shortage or oxygen debt which accelerates the demand for anaerobic energy production. This level may not occur until well into the workout or during intensive tempo work. This method involves relaxed and smooth running at 60-80% intensity, to assist recovery and enhance the oxidative mechanisms.
While running at 80-90% intensity, a relaxed, smooth and controlled tempo will
allow an athlete to run without undue stress. Theoretically, tempo training
enhances an athlete's ability to recruit fewer muscle fibers at the same race
speed which would reduce the energy cost and improve individual performance.
Insufficient oxygen and the build-up of lactate is associated with muscle
fatigue, owing to a build-up of waste products causing fatigue. The onset of
this condition is determined to a large extent by the efficiency of circulation
developed with continuous and extensive tempo preparation. Exercise of 6 to 12
reps can be done when a resting pulse rate of around 120 is reached. Tempo work
of all three levels is used by progressively increasing intensity and gradually
working into special and speed endurance sessions. Intensive tempo training lays
the base for the development of anaerobic energy systems which follow.
Note that lactate levels can become quite high using intensive tempo work since it borders on speed endurance and special endurance. Remembering that all energy systems turn on at basically the same time, intensive tempo running makes high demands on both the aerobic and anaerobic, and thus, is a sharing system.
The chart and diagram below illustrates the energy continuum or energy spectrum which shows the relative contributions of aerobic and anaerobic energy sources during various durations of maximal exercise.
ATP - CP and Lactic Acid System Oxygen System
ATP must be continually produced at rest to maintain homeostasis (maintenance of
internal environment) and during exercise to meet increasing energy demands. The
three metabolic pathways by which the body can produce ATP include: the
anaerobic (ATP-CP) energy system, the anaerobic lactate (glycolytic) energy
system, and the aerobic energy system. In order to get specific adaptations to
each of the energy systems, the coach must scientifically design workouts to
challenge them. Anaerobic phosphagen speed work stresses the alactate system.
Speed endurance, special endurance I, and special endurance II workouts stress
the lactate system in different ways. The aerobic energy system is stressed by
having athletes engage in continuous, extensive, and intensive tempo runs.
Finally, if a coach has a general understanding of the energy systems and the
energy continuum, he/she can more effectively design workouts that meet the
specific energy demands for the events that their athletes compete in.
A Practical Example:
An example of how one might apply the knowledge you have learned about the
energy systems utilizing the principle of specificity, discussed in training
methodology, is as follows: suppose you are coaching a high school female miler
who has run a 5:00 mile. Which energy systems are challenged by running the
mile? What types of training should you do based on a task analysis of the
energy systems challenged? One approach might be to use the energy continuum or
energy spectrum chart above which indicates that the 1500 or mile requires about
50% of the energy needs from anaerobic sources and 50% from aerobic sources. As
a coach you might then determine that you should do training which stresses both
energy sources and vary the training based on periodization principles (see
Training Theory Lecture). Based upon her mile race pace of 75 seconds per lap,
you could determine the intensity and durations of runs as discussed in the
above text which would optimize her individualized training program.
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FROM: USATF COACHING EDUCATION PROGRAM--BY: Jack Ransome, Ph.D., Tinker Murray, Ph.D., Bob LeFavi, Ph.D., Robert Vaughn, Ph.D., Joe Vigil, Ph.D.