BASIC PHYSIOLOGY and TRAINING 

I.  THE SOURCE OF MUSCULAR ENERGY (ATP - Adenosine Triphosphate)

• The immediate usable form of chemical energy for muscular activity.
• Most important "energy rich" compound.
• All forms of chemical energy available from food we eat must be transferred into ATP before it can be utilized by the muscle cells.
• The amount of ATP in the muscle cell is limited and could be depleted in 1-2 seconds unless re-charged to maintain muscular activity; thus immediate synthesis of ATP is necessary.
• ATP supplies must be kept at peak concentrations and must never fall below 60% of its resting levels for muscular activity to continue.

II.  THREE SYSTEMS OF METABOLIC PATHWAYS AVAILABLE TO REPLACE ATP.

III. HOW TO TRAIN THE ENERGY SYSTEMS / NERVOUS SYSTEM

IV. ENERGY SYSTEM TRAINING BREAKDOWN  FOR SPRINT EVENTS

V. DESCRIPTION OF WORKOUT TYPES

ATP must be continuously produced at rest to maintain homeostais (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 adaptation to each of the energy systems, workouts must be designed 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. 

[Tempo work of all types listed below, are 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.]

Continuous Tempo
the concentration of lactate in the blood starts to increase when work loads exceed 60% intensity (HR 100-140) depending on 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

Extensive Tempo 
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 extensive tempo levels assists the removal and turnover of lactate and the body's ability to tolerate greater levels of lactate. This workout method involves relaxed and smooth running at 60-80% intensity, to assist recovery and enhance the oxidative mechanisms.

Intensive Tempo 
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 the circulation developed with continuous and extensive tempo preparation. Exercises of 6-12 reps can be done when a resting pulse rate of around 120 is reached.

[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 shared system.]

[Speed work is used to develop specific speed characteristics unique to the sprinter. Speed development should be addressed throughout the training calendar in order to maintain and improve upon coordination and to assure the successful acquisition of new strength levels. Speed (0-60 meters) lays the foundation for speed endurance ( 60-150 meters) work that will be introduced mid to later stage of the training year. Speed endurance and intensive endurance lay the foundation for event specific training such as special endurance work.]

Speed
The amount of ATP that can be re-synthesized can last for 4-5 seconds. This combined with the 2 second supply from ATP stores, collectively gives us 5 to 7 seconds of ATP production. The re-synthesis of ATP from CP will continue until the creatine phosphate store are depleted, usually under 10 seconds.  

[this is why "pure" speed work consists of repetitions of 60 meters or less or within 4-7 seconds. Further distances at full speed, do not allow for the re-synthesis of ATP production in sufficient quantities to maintain "full" speed. Distances run at full speed past 60 meters start go from the Anaerobic (alactic) system to the Anaerobic (lactate) system, thus are considered speed endurance.] 

To challenge this system, workouts of 4 to 7 seconds of 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.

* Time period necessary for the proper re-synthesis of ATP and CP:  The recovery rates of CP listed below, support why  "full" recovery (2-3 minutes) is necessary during speed development work

Speed Endurance
To challenge the anaerobic (glycolytic) system, runs are done at maximal or sub-maximal 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 penalizing disadvantages of heavy lactate accumulation.  No more than 2- to 2 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 1200meters 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 is done, it will take 1-2 hours to