The document provides an overview of the physiology of running, describing three key points: 1) It explains how muscles produce movement through shortening in response to neural impulses, and how this requires energy in the form of ATP produced through cellular respiration and the breakdown of carbohydrates and oxygen. 2) It outlines three metabolic pathways that produce ATP - two aerobic pathways using fat or carbs with oxygen, and one anaerobic pathway using carbs without oxygen. The best pathway depends on the distance and intensity of running. 3) It presents a chart describing nine areas of training focus at different intensities and durations to progressively improve cardiovascular fitness, aerobic capacity, and anaerobic ability over the course of

1. The Physiology of Running
The act of running is elegantly simple. Running gives one a sense of being liberated, partly breaking the
bonds of earth, freeing the mind, body, and spirit to soar. One has the opportunity to truly test one’s
physical and mental stamina and to push to one’s limits. Running was an act of survival for prehistoric
man as he hunted or avoided being hunted. Running became an honored event in the ancient Olympics
as marathoners were considered heroes. The simple goal of competitive running is to complete a course
at the highest average speed without over-fatiguing and slowing down. The specific physical traits that
allow a runner to do this can be developed and improved through rigorous exercise. This improvement
can be maximized through a thoughtfully designed training program based on a working knowledge of
running mechanics and physiology. The following information is a basic overview of the physiology of
running to give you an understanding of what your body is doing and how our workouts will help you run
longer and faster.
Muscles in the human body cause movement by shortening in response to electrical neural impulses from
the brain. Millions of muscle fibers simultaneously shorten, and depending on where the muscle
attaches, pulls bone in a motion called the power stroke. The work done by a muscle obviously requires
energy and this energy comes from the food we eat. The chemical reactions in the body that release this
energy from food is called metabolism. The chemical used by muscles is called adenosine triphosphate
(ATP). In the presence of water and enzymes, ATP breaks down in the muscle as one phosphate
molecule (P) comes off, and chemical bonding energy is released for muscles to use. The other product
of this reaction is adenosine diphosphate (ADP). ADP can be recombined with the P to form ATP, but it
takes more energy from more food. This is the process of cellular respiration.
ATP ADP + P + ENERGY
Some ATP is stored in muscles at all times for a quick burst of energy, but this amount is used up in
seconds. Therefore, the key to moderately fast sustained running is for the body to efficiently resupply
the muscles with ATP. This new metabolic energy to reform ATP comes from carbohydrates (CH),
specifically glucose (C6H12O6), delivered to the muscles through the circulatory system and then
chemically broken down. Oxygen (O2) must also be delivered to complete this process.
C6H12O6 + 6O2 6CO2 + 6H2O + ENERGY
In order for muscles to continue to work efficiently for long periods of time without excessive fatigue, the
circulatory and respiratory systems must deliver adequate amounts of CH and O2 to the muscles and
carry away the products of carbon dioxide and water. At faster running speeds, all of the glucose cannot
be broken down completely to CO2 and H2O, and the intermediate substance called lactate is produced.
This useable substance must either be broken down in the muscle cells (mitochondria) or be carried
away. If all of these reactants cannot be carried away fast enough then the blood system becomes
overloaded and acidic. The high acidity impairs the power stroke of muscles, painful muscle fatigue sets
in, and running pace must slow down. This overall process can be improved through training.
There are 3 metabolic pathways that the body produces ATP, 2 with oxygen present in the muscles and 1
when oxygen is not.
A. Aerobic lipolysis produces ATP from fat and oxygen
Fat + O2 ATP (130 ATP molecules per fat molecule)
B. Aerobic glycolysis produces ATP from carbohydrates and oxygen
CH + O2 ATP (36 ATP molecules per glucose molecule)
C. Anaerobic glycolysis produces ATP without oxygen
CH ATP (2 ATP molecules per glucose molecule)
The ATP-producing pathway that seems the best is A. Unfortunately, fat is stored in the body and breaks
down slowly, so it delivers ATP at a slow rate. This slow rate is good for marathon runners, but not
runners competing at 5000 meters that need ATP faster. Of the remaining 2 pathways, aerobic glycolysis

2. generates about 90% of the ATP at a 5000 meter pace. At shorter race distances or during the sprinting
portions of a longer race, anaerobic glycolysis becomes more important when oxygen cannot be delivered
to the muscles fast enough. In an 800 meter race, the anaerobic pathway may generate up to 50% of the
required ATP.
Physiologists have created an indicator of aerobic fitness called VO2max. This measurement is the
maximum volume of oxygen that the body’s muscles can use per minute to continue to make ATP
aerobically. If running intensity increases past this point, oxygen consumption cannot, so the extra
energy to run faster or up a steeper grade must come from the anaerobic pathway. VO2max is hard to
measure, but since the heart rate increases with increasing training intensity, then heart rate can be used
to indicate at what percentage of VO2max one is training. The maximum heart rate (HRmax) of an
individual can be determined by subtracting one’s age from 220 beats per minute. High school runners
have a HRmax of about 200.
The expression “practice makes perfect” comes from the fact that the human body’s response to
repetitive training is to improve one’s ability to perform a desired action. When the human body is
physically stressed during running, the body’s response is to adapt in such a way as to improve the
critical body systems. If a runner trains at a slow speed for an adequate period of time, say 55-65%
HRmax, then the metabolic pathway being stressed is aerobic lipolysis. If a runner trains at 65-75%
HRmax for an adequate length of time, then the cardiovascular system and the aerobic glycolysis
pathway is being improved. If a runner trains at 75-95% HRmax, then a maximum benefit to the aerobic
system and VO2max can be achieved for racing purposes. If a runner trains at 100% HRmax, then the
anaerobic system can be developed. Having a working knowledge of this physiology, a sequential
season-long training program can be developed that will help a runner to progress from their individual
starting point to an optimum performance at the end of the current season. In addition, the same runner
can then use progressively more challenging workouts in future years to continue their development
through their high school career.
The following chart shows nine areas of training focus for distance runners, the purpose of the training,
and the general workout conditions required. We will use this system as the basis for our workout
program. Credit for this running physiology-based training system goes to Dr. Larry Greene from the
University of Colorado and Dr. Russ Pate from the University of South Carolina. The season will
generally progress from concentrations of strength endurance and cardiovascular fitness in the summer,
increasing aerobic conditioning into the mid-season, and then anaerobic fitness and race training in the
latter portion of the season, leading up to our final state competitions.
Training Focus Purpose Workouts
Running Form
Minimize energy needs during running
Maintain good posture to avoid injury
Technique drills and strides in
warm-up or cool-down
Flexibility and mobility
Avoid injury
Maximize power stroke
Dynamic and static stretching
in WU and CD
Strength endurance
Improve power stroke
Develop moderately high muscle force over
long periods of time
Use light resistive loads and high
# of repetitions:
Circuit training with and without
weights in WU or CD
Hill running
Cardiovascular fitness
Improve capacity of heart and vasculature
to supply working muscles with high rate
of O2-rich blood flow
Continuous aerobic running
65-75% HRmax
20-70 min.
Aerobic training Increase VO2max, max. cardiac output,
blood flow and O2 delivery, capillary
density in muscles, lactate clearance from
muscles, size and number of
mitochondria in muscle cells, aerobic
enzyme concentration, capacity to
metabolize fat
“Train fast to race fast”
Tempo running 75-85% HRmax
Interval: 3-10 min/rep
2-10 reps / 30-90s jog rest
Continuous: 12-40 min.
Max. aerobic intervals
85-95% HRmax

3. Decrease resting and submax HR 600m-1600m
2-10 reps
Run:jog rest 1:0.5, 1:1, 1:1.5
Fartlek (“Speed play”)
Unstructured series of long
runs and race pace or faster
surges
15-75 min.
Anaerobic training
Increase anaerobic enzyme production,
lactate threshold, blood buffers to
neutralize acidity, tolerance of muscle
fatigue
“Train fast to race fast”
Anaerobic intervals:
100% HRmax
200-800m
105-115% race pace
2-8 reps / 1:2-1:4 rest walk/jog
Race-specific
Race simulation
Stress all physiological and mental
capacities
Race intervals:
Race pace
1/3-1/2 event distance
2-4 reps
20-60s rest stand
Time trials or practice races
50-200% event distance
Progress through season
Nutrition and rest
Proper diet high in carbohydrates and
protein to replace body’s small store
2300-3300 Calories with age
70% carbohydrates, 15% protein, 15% fat
CH: bread,cereal,pasta,beans,fruits,vegs.
8-9 hours of sleep
Drink plenty of water / sports
drink before thirsty and
throughout WO
Mental toughness
Improve ability to maintain race pace with
muscle fatigue and pain
Positive attitude
Goals
Commitment to all forms of
Training
Race practice
Bibliography
Larry Greene and Russ Pate (2004), Training for Young Distance Runners, Human Kinetics.
Joe Newton and Dr. John Durkin (1988), Running to the Top of the Mountain, J&J Winning Edge Press.
Joe Newton and Joe Henderson (1998), Coaching Cross Country Successfully, Human Kinetics.