Technology

Introduction
Submaximal testing and maximal testing are two test procedures used to determine the maximum aerobic capacity of any individual. The variables used in these experiments include heart rate, height, weight, age, and gender following both protocols. The subjects include a 29-year old male and another 32-year old male. They both completed separate exercises to determine heart rates at different exercise limits and VO2max.

The purpose of this experiment was to determine the cardiovascular fitness through the use of the Astrand-Rhyming bike and Bruce treadmill.

Materials and Methods
This experiment was conducted by using two different test machines the Astrand-Rhyming bike and Bruce treadmill.

For the Astrand-Rhyming bike test, a heart rate monitor was connected to the skin of the subjects using contact gel. The subject is allowed to sit on the seat of the bike and told to begin cycling. At the end of each minute, the subjects heart rate is recorded. One of the precautions taken was to prevent the subject from talking so as not to have an upward effect on the heart rate. After the seventh minute, the subject is allowed to cool down and cycling is stopped.

The procedure for the Bruce treadmill test involves allowing the subject to walk on a treadmill. At intervals of three minutes each, the speed and incline of the treadmill are increased. The subject is made to run the test until he comes to a point where he is fatigued and cannot continue again.

Results
Data work sheet for Astrand-Rhyming bike test.
Age 29 Gender Male Height 56. Weight 160
Time (min)Heart Rate (bpm)KGKGMMIN11222.575021262.575031322.575041292.575051262.575061392.575071282.5750
Data worksheet for the Bruce Treadmill Protocol
Age 32 Gender Male Height 58 Weight 160 HR  185.46bpm
HRmax x 0.85  157.64bpm
StageTime (min)Speed (mph)GradeMETS1 0-31.7104.72 3-62.5127.03 6-93.41410.149-124.21612.9512-155.01815.0

SMV02  (Sa x 0.2)  (S x GB x 0.9)
Where Sa  speed of the treadmill in meters per minutes (26.8 meters per min)
GB  Grade ( incline) of the treadmill in decimal form
S  Sa x 0.1
SMV02 2.1708 mlkgmin SMV02 3.4443 mlkgmin
Slope (b)  0.0289 V02max  4.2378 mlkgmin

Discussion
The results of this experiment have yielded results that verify the hypothesis that cardiovascular fitness can be examined through maximal and submaximal testing. The two protocols used, Astrand-Rhyming bike test and Bruce treadmill test, have given results that can be used to measure or predict the oxygen uptake. Basically, the VO2max (rate of oxygen usage under maximal aerobic metabolism) is the parameter being used as a measure of cardiovascular fitness.

The Bruce treadmill protocol yielded a VO2max of 4.2378 mlkgmin. The VO2max gotten here is a measure of the exercise capacity of the individual being examined. The value indicates the maximal capacity of the respiratory and cardiovascular systems to respond to the stress (in this case, exercise) and supply oxygen. It means that the maximum amount of oxygen that can be released is 4.2378mlkgmin. If the individual, who has a weight of 160kg, exercises at maximum level, the maximum amount of oxygen that can be released per minute is (4.2378 x 160) 678.048 ml. This therefore means that the two systems, cardiovascular and respiratory, cannot release more than 678.048 ml of oxygen per minute. In situations or exercises that involves almost this value or more, the individual being examined here would easily go into fatigue.

The Fick equation (VO2  Cardiac Output x a-vO2 difference) allows the rate of oxygen consumption to be determined if the cardiac output (CO) and arterial-venous oxygen difference (a-vO2 diff) are known (The Cardiovascular System and Exercise, 2009). The effect of exercise on each variable of the equation is as follows. The cardiac output is a function of the heart rate and stroke volume.

During exercise, either or both of these two variables can increase, thereby causing an increase in the cardiac output. Exercise increases the difference between arterial and venous oxygen levels. During resting conditions, the difference is about 40ml of oxygen. However, once exercise commences, the diffusing capacity for oxygen increases almost three-fold. This results mainly from increased surface area of capillaries participating in the diffusion and also from a more nearly identical ventilation-perfusion ratio in the upper part of the lungs (Guyton  Hall, 2006). The end result is an increase in the partial pressure of oxygen in the arterial compartment.

Apart from exercise, other factors can increase the variables of Ficks equation. Anything that would cause an excitation of the sympathetic nervous system will cause an increase in the cardiac output. Any form of increased emotion (anger, anxiety, excitement) will cause an increase in the sympathetic stimulus to the heart. This then causes an increase in the heart rate and an increase in the effectiveness of heart contraction (contractility). Prolonged stress on the heart (e.g. a long term workload) causes it to increase in size (hypertrophy), and thereby increasing its pumping effectiveness.

Respiratory Exchange Ratio (RER) is the ratio of the volume of carbon dioxide produced divided by the volume of oxygen consumed on a total body level (Plowman  Smith, 2009). It is usually calculated using expired air. Respiratory Quotient (RQ), on the other hand, is calculated at the cellular level. It is defined as the ratio of the amount of carbon dioxide produced divided by the amount of oxygen consumed at the cellular level (Plowman  Smith, 2009). RQ can be conducted in connection with exercise tests that measure VO2max. When the RQ is 0.7, it indicates that fat stores are the only source of energy. When it is 1.0, it implies that only carbohydrate is being burned for energy. At a RQ of 0.85, it indicates that 50 fats and 50 carbohydrates are being burned. A high RQ indicates that the excess CO2 is derived from anaerobic metabolism. Even, a RQ greater than 1.1 is a criterion for a reliable maximal test. A low RQ below 0.7 means that the amount of fat being oxidized is not enough, and also there is no compensatory release of carbohydrates. Therefore, CO2 being produced is very low.

Conclusion
Submaximal and maximal testing are integral parts of medical and sports physiology. They are relatively easy to perform. The machines used are also safe, and cheap to maintain. These test modes are practical ways in which sports and health experts can measure or determine the maximum aerobic power of any person or groups of people. The reliability of the results gotten from these machines is good in comparison to protocols that involve direct testing of VO2max.