Assessing your Cardio-Pulmonary System

Time to read 4 min

What tests tell you about the heart and lungs, and how this influences your performance overall.

Aerobic fitness in simple terms is the ability of your body to take oxygen from the atmosphere and use it for physical activity. Anatomically, it is a measure of the efficiency of your heart, your lungs as well as your muscles.

Essentially, if you have a high level of cardio-respiratory fitness, you won’t have to work hard for everyday activities.

 Two parameters are typically used to measure aerobic fitness- Vo2 Max, and Lactate threshold. Before we get down to what the parameters mean, let us briefly discuss what happens in your body when you exercise or participate in physical activity.

The Mechanics Of Working Out

The moment you begin to move in any way, you are putting that muscle group to work. Like any other tissue, muscles need the energy to work, and they use glucose from the bloodstream for this purpose. In a resting state, glucose is converted into glycogen, and then broken down into energy, carbon dioxide (which we exhale) and water. However, muscles often process glycogen under anaerobic conditions too (lack of oxygen), and the by-product of this is lactic acid.

  • Lactic acid is responsible for the muscle fatigue we feel after a period of exercise.
  • Those with a higher lactate threshold are able to work out for longer without experiencing muscle fatigue.
  • Those with a higher Vo2 max are able to utilize oxygen more effectively and thus sustain for longer without their muscles working anaerobically. 

Vo2 Max- Testing

In one of our earlier articles, we deal with Vo2 max, and how it works as an independent parameter in determining how much oxygen our body receives. Now, we need to understand it in the context of how it influences our movement and exercise.

  • Vo2 is a measure of oxygen consumed in litres per minute. Vo2 max is the maximum amount of oxygen your body can consume at the present wellness level.
  • Treadmill testing is often employed to measure Vo2 max. As the treadmill slope increases, Vo2 max is measured in the last one minute of each increase in slope. When such equipment is not available, step testing is also used, but this doesn’t give you optimal results. 
  • In some tests, the percentage of oxygen and carbon dioxide are compared to the total volume of exhaled gas. Ideally, the percentage of oxygen exhaled should be every minimal.

What Do The Vo2 Max Results Mean To Me?

In simple terms, Vo2 max is a measure of the efficiency of your lungs in processing oxygen. The higher the value, the fitter you are. In general, a Vo2 max of 60% is considered desirable, and in athletes, this value may be even higher.

  • Results from Vo2 max testing, such as absolute and relative aerobic power and maximal heart rate can be used to gauge your endurance and design a workout accordingly.
  • Once a specific training program is implemented for athletes, understanding the aforementioned parameters helps determine when they are ready to move on to a level of greater intensity.
  • Coaches can also study the Vo2 max over time to see if their interventions have helped improve your overall performance.

Blood Lactate Threshold- Testing

More often than not, lactate threshold and Vo2 max are studied in tandem. The rationale for this is simple- lactate threshold is a measure of when the muscles begin to accumulate lactate; which in turn means that this is the point where anaerobic activity has started and Vo2 max has been reached. 

  • As the name suggests, blood parameters are used to measure the lactate threshold over time.
  • The first lactate threshold, or LT1, is the point where lactic acid has begun accumulating in the muscles due to a short supply of oxygen. It is exclusively measured from blood.
  • The second lactate threshold or LT2 is a measure of lactate stress on the body. It tells you at what point in time the lactate accumulation in the body is rising rapidly.  

Blood Lactate Threshold- What It Means To Me

  • LT2 is a wonderful measure of endurance performance. More significantly, it shows you how much endurance you have for an activity that lasts up to two hours.
  • Training for longer increases the LT1, meaning that you can exercise for longer in aerobic conditions without lactic acid beginning to accumulate in your muscles.
  • High intensity training raises the LT2 threshold, meaning that you can work out for longer without your body and muscles reaching the maximum level of lactic acid they can tolerate.
  • The higher the Vo2 max, the better your LT1 values.

Summing Up The Results

  • In a regular, healthy individual, lactate threshold 1 is reached at about 50-60% Vo2 max. This means that the person is able to use 50% of all inhaled oxygen efficiently before the body resorts to anaerobic means.
  • In athletes and people undergoing endurance training, LT1 is reached only at 70-80% Vo2 max. This results in them being able to use their oxygen intake more efficiently. 
  • Longer training can help you improve your LT1, while high intensity workouts can help increase the LT2, both of which are desirable outcomes.
  • If you are an endurance athlete, you must work to increase LT1 values.
  • If your physical activity involves ‘bursts’ of high activity followed by rest, you must work to increase the LT2 so your muscles aren’t fatigued easily.

 *Medical Disclaimer - The following information is for educational purposes only. No information provided on this website, including text, graphic, and images, are intended as substitutes for professional medical advice. Please consult with your doctor about specific medical advice pertaining to your condition(s)

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