Cardiorespiratory fitness is best reflected by oxygen uptake and its utilization during maximal intensity exercise. The greater the peak oxygen uptake (VO2 max.), more efficiently the individual burns oxygen and thus more efficient is the functioning of his/her cardiorespiratory system and hence more is the cardiorespiratory fitness.
Aerobic capacity can also be calculated using the heart rate response from a submaximal exercise test. These submaximal tests have the added benefits of being much cheaper and do away with need of presence of clinicians and exercise physiologist to conduct the test. Thus, submaximal tests can be done in a ‘fitness centre setting’ and by qualified personal trainer.
How do they measure oxygen uptake?
There are various ways in which oxygen uptake can be measured. Metabolic equivalents, however, remains the mainstay of measuring O2 uptake.
Better known as METS, a metabolic equivalent is energy expenditure at rest which comes out to be 3.5 ml of O2 per kg body weight times minute.
Thus, 1 METs = 3.5 ml O2/ Kg x min.
To normalize for gender and age differences, regression formulae have been designed by researchers to accurately predict VO2 max from submaximal exercise testing.
Tests to measure cardiorespiratory fitness
Some of the tests that can be used to measure cardiorespiratory fitness are the 2.4 km run test, the Astrand treadmill test and the multistage bleep test. While these tests are usually reserved for athletes or fitter people, tests like the Cooper 1.5 mile walk/run test can be used for sedentary or unfit people.
Cooper 1.5 mile walk/run test
This test involves timing your client over a distance of 1.5 miles.
- a flat and smooth course
- a stop watch
- odds and ends like forms to record client details and results of the test
- Client warms up with light jogging and stretches
- When ready the client runs, jog or walks to complete the course
- Result is recorded to the nearest second
- Compare with age and gender specific norms to know the fitness level and VO2 max.
You can also calculate the VO2 max., METs and fitness level utilizing this awesome application form EXRX.
How to improve your cardiorespiratory fitness?
Coach Brian Mackenzie has outlined ways to increase oxygen uptake and thereby your fitness levels. He outlines Astrand’s workout methods for this purpose:
Method used to train for 10k:
- Sprint at maximum velocity for 5 minutes
- Measure the distance covered in those 5 minutes
- Rest for 5 minutes and run the same distance covered at a pace which is 20% slower – this should correspond to your 10k race speed
- So if you cover 1900 metres going flat out in 5 min, you should aim to cover that distance in 6 minutes
- Practicing at that time will increase your VO2 max.
To know training methods for other distances, click here.
Notwithstanding the benefits that these training methods deliver, recent research suggests that short burst interval training may have a bigger advantage in improving VO2 max. Although the underlying mechanisms are not very well-understood, anecdotal as well as research seems to support this idea overwhelming.
Thus, although the above mentioned methods can improve cardiorespiratory fitness, it would be more beneficial if the training methods more closely imitate the pattern of movement associated with an athlete’s sports.
Thank you for the article.
Note: If one first runs a distance in 5 minutes, then covers that same distance in 6 minutes, he will have gone 16.67% slower. Covering the distance at a 20% slower pace will take 6 minutes, 15 seconds.