VO2max

The monthly newsletter of RunCoachJason.com

Jason Karp, professional coach, consultant, freelance writer

May, 2005

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In this issue:

Integrating Science with Application—How to Lose Fat

VO2max Measurement

Public Speaking

Research

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Integrating Science with Application—How to Lose Fat

Want to maximize the amount of fat you lose by running?  It is often assumed that low-intensity exercise is best for burning fat.  During exercise at a very low intensity, fat does account for most of the energy expenditure, while at a moderate intensity, fat accounts for only about 50 percent of energy used.  However, at the moderate intensity, the number of calories used per minute is much greater compared to the low intensity, so the total number of calories expended is also greater.  The rate of energy expenditure, rather than simply the percentage of energy expenditure derived from fat, is what’s most important.  Furthermore, endurance-trained individuals rely less on carbohydrates and more on fat as fuel during submaximal exercise.  So, the more running you do, the more fat you will use during subsequent runs.

 

Now, ignore that preceding paragraph, because to decrease body fat percentage, you don’t necessarily have to use fat during your run.  (After all, sprinters have very little body fat and they do little, if any, aerobic exercise!)  Most of the fat used during exercise is in the form of intramuscular triglyceride (fat droplets stored within muscle).  Much of the fat from adipose tissue (e.g., around your waistline) is lost during the hours following exercise.  The amount of fat loss depends, in part, on the exercise intensity.  Following high-intensity exercise, there is a higher rate of fat oxidation than following low-intensity exercise.  Because a greater intensity of work can be performed by breaking up the work with periods of rest, interval training is a great way to help decrease body fat percentage.

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VO2max Measurement

Have you ever wondered how VO2max is measured?  Well, it requires some sophisticated laboratory equipment, including oxygen and carbon dioxide gas analyzers, an expiratory air flow probe, an air mixing chamber, a dehumidifier, a vacuum pump, and a data acquisition system (some knowledge of electronics also helps).  Some computerized systems contain all of these things in one unit.   

 

If you are lucky enough to have access to the equipment, there are many testing variables that can affect the determination of VO2max, including the type of exercise (typically cycling or running), whether a treadmill test incorporates increases in grade as well as increases in speed, the environment in which the test is conducted (altitude, temperature, humidity), the specific measurement system used, the sampling interval for respiratory gases, the foreign open-ended nature of the test that requires you to continue running until you no longer can, and the duration of the test and its stages.  Although the classical definition of VO2max is the maximal volume of oxygen that is consumed per minute, many laboratories collect air samples over a shorter time period (sometimes for each breath!) and extrapolate to a minute’s value.  Given all of these things, it’s difficult to compare one athlete’s VO2max obtained in one lab to another athlete’s VO2max obtained in a different lab.

 

The running test starts at a slow speed (about your normal easy running pace) and gets progressively harder with each stage, initially with increasing speed and then with increasing grade, until you are completely exhausted and can no longer keep up with the treadmill belt.  You run while breathing through a snorkel-like mouthpiece that connects you to the gas analyzers and wearing a noseclip to prevent breathing through your nose.  Sounds like fun, doesn’t it?  If planned out right, the whole test should take about 10-15 minutes.

 

VO2max can be measured either in liters of oxygen per minute (L/min) or in milliliters of oxygen per kilogram of body weight per minute (ml/kg/min).  In order to compare people of different sizes, it is usually measured relative to body weight.  The greater the amount of muscle mass used, the higher the VO2max.  For example, running results in a 10-15% higher VO2max than cycling (unless you are a trained cyclist).  The VO2max of elite male endurance athletes is over 70 ml/kg/min, while that of elite female endurance athletes is over 60 ml/kg/min.  Women have a lower VO2max than men because they have less hemoglobin in their blood to transport oxygen and less muscle mass to consume oxygen.  But there are plenty of female endurance athletes who have a higher VO2max than men.  Just ask Paula Radcliffe.

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Public Speaking

Do you or someone you know need a speaker at your coaching clinic or convention on topics related to endurance training, strength training, altitude training, or strategies for optimal recovery? 

Are you a high school, college, or club coach looking for a guest speaker for your team?

Are you a race organizer looking for a speaker for your pre-race clinic?

Are you a manager or director of a fitness club interested in educational opportunities for your personal trainers?

Are you a member of the media interested in someone who can speak on camera on a variety of fitness-related topics?

To find out more about how Coach Jason can customize a presentation for you or to book Coach Jason as a speaker for your event, e-mail jason@runcoachjason.com.  

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Research

Want to find out the latest research on running?  Want to party with some scientists (or at least with me)?  Come to the convention center in Nashville, TN, June 1-4 for the American College of Sports Medicine National Conference.

 

An abstract of my study on the training characteristics of the 2004 U.S. Olympic Marathon Trials qualifiers is published in the May, 2005 issue of Medicine and Science in Sports and Exercise and will be presented at the ACSM conference in Nashville.  Among the findings is that the men ran more than the women for the year preceding the Olympic Trials.  Men ran an average of 90 miles per week with a peak week of 120 miles, while women ran an average of 72 miles per week with a peak week of 95 miles.

 

A study published in the September, 2004 issue of Journal of Bone and Mineral Metabolism found that female high school distance runners with regular menstruation had a greater bone density than those with irregular or absent menstruation.  As one of the characteristics of the female athlete triad, menstrual irregularities increase the risk among female runners for stress fractures.

 

A study published in the May, 2005 issue of International Journal of Sports Medicine found that the oxygen consumption of middle-distance runners reaches VO2max an average of 45 seconds after the start of an 800-meter race, with VO2 actually decreasing an average of 24% during the final 38 seconds of the race.  The runners averaged 120% VO2max over the whole distance, emphasizing the importance of VO2max for this track event.

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©2005 Jason Karp.  All rights reserved.