THE SCIENCE OF SPRINTING AND DISTANCE RUNNING

A closer look into the physiology of runners

Strength vs. Endurance

• Sprinting is based on muscle strength• Long distance running requires endurance • Strength is the ability to do something that

uses a lot of energy for a short period of time• Endurance is the ability to do something that

takes less energy for a longer amount of time

Lactic Acid

• Mitochondria use lactic acid to provide energy to skeletal muscles

• Endurance training reduces the level of lactic acid in an athlete’s blood even though their cells are still producing lactic acid

• Sprinting training requires quick bursts of energy

Muscle Fibers

• All muscles contain hundreds of fibers • Fibers connect to an axon• Many axons are connected to form a motor

neuron• A single motor neuron may have hundreds of

axons• As you train for whichever event you do, the

brain needs to create more contractions which causes more “motor units” to be formed

“Fast-Twitch” vs. “Slow Twitch”

• Whether a person has fast-twitch or slow-twitch muscles is based on which genes you get

• There is no science yet to prove that fast-twitch muscles can be improved by training, leaving your sprinting ability to chance

Fast-Twitch Muscles

• Fast-twitch muscles are important to sprinters• Fast-twitch muscles are made of white fibers• They have a high anaerobic capacity to allow

lots of power to develop in a short period of time

• They tire very quickly

Slow-Twitch Muscles

• They are important to endurance athletes• These muscles are red because of the blood

that is being pumped to them constantly• Better suited for aerobic activities

Lactate Threshold

• The highest steady rate of intensity an athlete can maintain for a period of time

• Lactate thresholds are measured in VO2 max• The lactate threshold is also a line between

anaerobic and aerobic respiration- the point at which you need to start using aerobic energy sources

Lactate Threshold

VO2 MAX

• The maximal amount of oxygen transported to the muscles to support

• The VO2 max depends on the activity that you are doing- it would be different for running vs. biking

• It can change for time to time due to different factors like sickness, training, racing, etc.

• As the VO2 max changes, so will the lactate threshold

ATP

• To run fast the muscles need to contract• In order for the muscles to contract they must

have a source of energy• ATP is the body’s main source of energy • When hydrolysis occurs the bonds in the ATP

break to provide the energy• ATP can be depleted within 1-2 seconds unless

it is recharged

Recharging ATP

Three main sources of resynthesis

Anaerobic Alactic

• Creatine phosphate is used as an immediate replacement of ATP

• By taking a phosphate from the creatine phosphate, the ADP can be turned into ATP

• This process can continue until all of the creatine phosphate is depleted

• This can create about 4-5 seconds of ATP reproduction, making this a good way for sprinters to account for their energy

ANAEROBIC LACTIC

• This occurs after all of the creatine phosphate is used up

• This next process uses glycolysis • The glucose is broken down into two forms: glucose

that can be used freely, and ATP• If the glucose is stored in the muscles or liver it takes

the form of glycogen• Glycogen can be broken down into 3 ATP molecules• This energy source is abundant and allows high levels

of activity, but it is limited in duration

Aerobic Energy

• Used in the case of endurance athletes and long distance runs

• Uses oxygen to create ATP• A pyruvate from glycolysis and fatty acids is

turned into acetyl-CoA and oxidized into carbon dioxide and water- the Krebs Cycle

• ATP is produced throughout the Krebs cycle, creating a source of energy

• This can last for long periods of time

Energy Sources