London Marathon winners, 2019, Eliud Kipchoge and Brigid Kosgei. Photo credit: Facundo Arrizabalaga / Shutterstock
The 40th anniversary of the London Marathon takes place on Sunday 4th October 2020. Athletes will run on a closed circuit around St. James’s Park before landing in the mall. This year’s line-up includes the current masters Eliud Kipchoge and Brigid Kosgei. These athletes can run for more than two hours at speeds that the average person can hold for seconds. What is she doing so fast?
Years of training have resulted in physical adaptations that enable elite endurance athletes to perform at their peak. First, let’s take a look at the important cardiovascular system, which is adapted to regularly supply the working muscles with oxygenated blood.
Regular exercise leads to an increase in the thickness of the muscle that makes up the wall of the heart, especially the left side of the heart. This is the side of the heart that is responsible for circulating oxygenated blood around the body and to the muscles during exercise.
The increased thickness of the left ventricular wall (the lower chamber of the heart) allows endurance athletes to pump more blood out of their heart with each stroke. We call this the “stroke volume”.
A normal adult exercising maximally can have a stroke volume of 120 ml. Due to the increased thickness of the heart wall, endurance athletes have a stroke volume of around 200 ml under maximum stress.
An endurance athlete’s heart can beat 200 times per minute at maximum stress, which means that these athletes can circulate nearly 40 liters of blood in the body every minute. The amount of blood that the heart pumps in one minute is called cardiac output. For elite endurance athletes, it can be almost twice as high at maximum exertion as it is for the average adult.
It is not just a strong heart that is critical to the success of these athletes. It is also important to get enough oxygen for the working muscles.
Activities that last longer than a few minutes rely mostly on aerobic metabolism (the process by which we use oxygen to convert fuels such as fats and sugars into energy), which makes a constant supply of oxygen essential to success. Elite marathon runners can breathe around 200 liters of air per minute at maximum stress. This combined ability of the lungs and heart to take in and transport oxygen means that elite athletes have a very high VO2 maximum – the maximum amount of oxygen the body can use in a minute. VO2 max is seen as one of the key factors for endurance success.
The VO2 maximum values for an average adult are 30-45 milliliters of oxygen per kilogram of body weight per minute. In elite endurance athletes, however, the VO2 max value increases to 65-80 ml / kg / min.
Not only the size of an athlete’s engine (VO2 max) is important for success, just like with a car, the economy of the engine also plays an important role. Most marathons are run at around 75-85% of VO2 max, which means that being able to work efficiently at lower training intensities is also the key to success. When running, this is measured in terms of the “running economy”.
Athletes with a good running economy need less oxygen to run at a certain speed than their competitors, which saves life energy for later in the race. Elite endurance athletes have incredibly low running economy scores, showing that they can move at high speeds while using much less oxygen than the average person.
At a given speed, an average person typically needs 220 ml of oxygen per kilogram of body weight to run a kilometer. Elite marathon runners are more economical and may only need 180 ml of oxygen per kilogram of body weight to cover the same distance.
An important factor in running a fast marathon is the ability to run at the fastest possible speed without getting tired. This optimal speed, or “threshold”, is related to various changes that occur in our bodies during exercise, including the build up of chemicals in the blood. Blood lactate is one such substance that builds up in the blood during exercise.
The lactate threshold is a term used in exercise physiology to describe certain changes (or breakpoints) in this substance during exercise.
Blood lactate is often mistaken for a waste product and mistaken for being responsible for muscle fatigue, but it is now recognized as an important source of energy. However, exercise above the lactate threshold is associated with faster fatigue, and as such, speed at the lactate threshold is a strong predictor of endurance performance.
A higher lactate threshold makes it possible to maintain a higher running speed without blood lactate building up, which allows the running speed to be maintained for an extended period of time. Elite male and female marathon runners have reported threshold lactate speeds of 18-21 km / h
When the runners lap St. James’s Park on Sunday, all of the above will add to their success – they will be the key factors in the runners’ performance.
Fitness tracker data could predict your marathon performance – new research from The Conversation
This article is republished by The Conversation under a Creative Commons license. Read the original article.
Quote: Science of Champion Runners: In the Body of Elite Endurance Athletes (2020, September 30), accessed September 30, 2020 from https://medicalxpress.com/news/2020-09-science-champion-runners-body- elite.html
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