VO2 Max Lab
If you walk into the locker room of a bunch of American Football players, bragging rights are reserved for the man with the heaviest bench press. Similarly, talk to a group of endurance athletes that are "in the know", and conversation will eventually turn to "What is your VO2 max?" A high maximal oxygen consumption is indeed one of the hallmark characteristics of great endurance performers in running, cycling, rowing and cross-country skiing, so it must be pretty important. What is it and how is it measured?
VO2 max is the maximum volume of oxygen that by the body can consume during intense, whole-body exercise, while breathing air at sea level. This volume is expressed as a rate, either liters per minute (L/min) or millilitres per kg bodyweight per minute (ml/kg/min). Because oxygen consumption is linearly related to energy expenditure, when we measure oxygen consumption, we are indirectly measuring an individual's maximal capacity to do work aerobically.
Every cell consumes oxygen in order to convert food energy to usable ATP for cellular work. However, it is muscle that has the greatest range in oxygen consumption. At rest, muscle uses little energy. However, muscle cells that are contracting have high demands for ATP. So it follows that they will consume more oxygen during exercise. The sum total of billions of cells throughout the body consuming oxygen, and generating carbon dioxide, can be measured at the breath using a combination of ventilation volume-measuring and O2/CO2-sensing equipment.
The figure below is borrowed from Prof. Frank Katch, summarizes this process of moving O2 to the muscle and delivering CO2 back to the lungs. So, if we measure a greater consumption of oxygen during exercise, we know that the working muscle is working at a higher intensity. To receive this oxygen and use it to make ATP for muscle contraction, our muscle fibers are absolutely dependent on 2 things: 1) an external delivery system to bring oxygen from the atmosphere to the working muscle cells, and 2) mitochondria to carry out the process of aerobic energy transfer. Endurance athletes are characterized by both a very good cardiovascular system, and well developed Oxygen capacity in their skeletal muscles. We need a big and efficient pump to deliver oxygen rich blood to the muscles, and we need mitochondria-rich muscles to use the oxygen and support high rates of exercise. Which variable is the limiting factor in VO2 max, oxygen delivery or oxygen utilization? This is a central question that has created considerable debate among exercise physiologists over the years, but for most the jury is now out.
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I grew up being told that I could do anything and be anything I set my mind to. I think that was nice of my mother to encourage me that way. However, the biological reality is that there is a significant genetic component to VO2 max. The reality is that if an adult male with a natural, untrained VO2 max of 45 ml/min/kg trains optimally for 5 years, they might see their VO2 max climb to around 60-65 ml/min/kg. This is a huge improvement. Yet, the best runners have a VO2 max of 75 to 85 ml/kg so our hard training normal guy is still going to come up way short against the likes of these guys. If they were to stop training for a year, their VO2 max might fall to about where the average guy’s topped out after years of optimal training. The bottom line is that Olympic champions are born with unique genetic potential that is transformed into performance capacity with years of hard training.
Just to put things in perspective, the VO2 of a typical thoroughbred horse is about 600 liters/min or 150 ml/min/kg! So compared to a horse, even an Olympic endurance champion human comes out looking like a couch potato.
Copyright © 1996. Revised 2005. Stephen Seiler
Lab Assignment Name: _____________________
You are going to do the following during our lab assignment today.
Measurement 1 __________ cm
Measurement 2 ___________ cm
Measurement 3 ___________ cm
Average measurement here: ______________ cm
Measurement 1 __________ cm
Measurement 2 ___________ cm
Measurement 3 ___________ cm
Put that measurement here: _____________ cm
________________________________________________________________________
Homework Assignment:
In at least a one page paper please answer the following using your lab results and the above article:
· What did you find out from the lab?
· What were you’re your lung capacity readings
· How did your first test results vary from the second test?
· What is V02 Max and how does it relate to breathing in air?
· What factors have an impact on your Vo2 max and your lung capacity.