Surgery – Diagnostic testing – Respiratory
Reexamination Certificate
2001-11-21
2003-04-29
Hindenburg, Max F. (Department: 3736)
Surgery
Diagnostic testing
Respiratory
C600S484000, C600S300000, C482S009000
Reexamination Certificate
active
06554776
ABSTRACT:
BACKGROUND OF THE INVENTION
I. Field of the Invention
This invention relates generally to a method for prescribing an exercise regimen for a particular subject, and more particularly to a method for correlating a heart rate or work rate to be maintained throughout an exercise session if the desired goal of the exercise is to reduce fat or to improve cardiovascular performance.
II. Discussion of the Prior Art
As is explained in the Acorn et al. U.S. Pat. No. 5,297,558, which is assigned to applicant's assignee, it is well recognized that frequent exercise is beneficial to most individuals so long as it is properly engaged in, taking into account the individual's own physiologic condition. It is important that the exercise regimen not be so intensive that it adversely affects the general well being of the subject, yet not too light that it provides little or no benefit.
It is well understood that with increasing exercise, muscles need to bum metabolic fuels to perform mechanical work. Carbohydrates and fat are the typical sources of fuel and must be oxidized, using molecular O
2
from the atmosphere to effectively provide energy. A normal response to exercise is to increase the blood flow to the working muscles, which carries oxygen and removes carbon dioxide, the bi-product of biologic metabolism. The increasing demands for oxygenated blood are met by increasing the cardiac output (increased heart rate and increased stroke volume) and redistributing the blood flow to the working muscles and away from the abdominal area.
As a consequence of the need for more oxygen and the increased production of carbon dioxide, the level of ventilation must also increase. More air is taken in, in order to oxygenate the increased amount of blood going through the lungs and to eliminate the increased amount of carbon dioxide being brought to the lungs from the working muscles. Ventilation normally increases in direct linear fashion with CO
2
output rather than oxygen uptake (VO
2
) such that the arterial carbon dioxide tension remains constant during aerobic work.
The heart rate also increases in a linear fashion with increasing VO
2
and the maximum heart rate is limited in any individual by age.
When the supply of oxygenated blood falls short of the oxygen needs of the muscles, anaerobic metabolism ensues. The bi-product of anaerobic metabolism is lactic acid, which is buffered by the bicarbonate system. Additional CO
2
is produced which must be eliminated by the lungs to keep arterial carbon dioxide tension from rising. Carbon dioxide output (VCO
2
) will be increased relative to VO
2
. This will be seen in graphic form as an increase in CO
2
output and ventilation with respect to oxygen uptake. Since the respiratory exchange ratio (RER) is the ratio of VCO
2
to VO
2
, that ratio will also be seen to increase, often to values greater than 1.
The respiratory exchange ratio represents the amount of CO
2
produced, divided by the amount of oxygen consumed. Normally, roughly 75% of the oxygen consumed is converted to CO
2
. Thus, RER at rest generally ranges from 0.70 to 0.85. Because RER depends on the type of fuel used by the cells, it can provide an index of carbohydrate or fat metabolism. If carbohydrates were the predominant fuel, RER would equal 1, given the following formula:
C
6
H
12
O
6
(glucose)+6O
2
→6CO
2
+H
2
O
RER
=VCO
2
/VO
2
=6CO
2
÷6O
2
=1.0
Because relatively more oxygen is required to burn fat, the RER for fat metabolism is lower, roughly 0.7. At high levels of exercise, CO
2
production exceed oxygen uptake. Thus, the RER exceeding 1.1 to 1.2 is often used to indicate the subject is giving a maximal effort. However, RER values vary greatly and generally are not a precise cut-off point for maximal exercise.
Individualized training programs must satisfy the basic goals of safety and effectiveness. Safety dictates that exercise be formed at the minimum effective heart rate whereas effectiveness dictates that the exercise program must result in the accomplishment of a desired goal, such as fat loss and improved cardiovascular fitness. In the past, many health professionals, and some exercise equipment manufacturers, use the so-called Karvonen method for determining what the heart rate should be during the exercise program if either fat burning or cardiovascular conditioning is the desired goal. In accordance with the Karvonen method, to determine the target heart rate to be maintained during a period of exercise to enhance fat burning, the following formula is commonly used:
Target heart rate=220−age−1.6×resting pulse rate
Likewise, for cardiovascular conditioning in accordance with the Karvonen method, the following formula is utilized:
Target heart rate=220−age−0.8×resting pulse rate
Use of the above formulas generally results in target heart rates which are too high to achieve fat reduction or higher than necessary to achieve improvements in cardiovascular fitness. Higher than necessary intensity of exercise, of course, impacts not only safety and efficacy, but also compliance. Because the high intensity of exercise results in the painful accumulation of lactate and depletion of muscle glycogen, individuals will not be able to comply with programs which specify high work intensities, such as those specified using the Karvonen predicted heart rates, and exercise will be discontinued without achieving the desired goal.
When one exercises, there are several requirements which must be met in order for the exercising muscles to perform work. At low levels of exercise, such as walking at a modest rate, the exercising muscle must have oxygen and fuel to produce energy. The two types of fuels are fats and carbohydrates. The intensity of exercise dictates which fuel will be utilized during any type of exercise. At rest, roughly equal amounts of energy are derived from carbohydrates and fats. Free fatty acids contribute greatly to energy supplied during low levels of exercise, but greater amounts of energy are derived from carbohydrates as exercise progresses. Maximal work relies virtually entirely on carbohydrates. Because endurance performance is directly related to the rate at which carbohydrates stores are depleted, two major advantages exist for both: (1) having greater glycogens stores in the muscle, and (2) deriving a relatively greater proportion of energy of from fat during prolonged exercise. Both of these benefits are conferred with training. Since carbohydrates tend to be a substantially more efficient fuel, it is the body's carbohydrates that are consumed during exercise at high levels of intensity. Fat, being a less efficient fuel, tends to be consumed by the body when exercising at relatively low levels of intensity. Therefore, if a person exercises at too high of a heart rate, fat burning objectives will not be realized.
By monitoring the Respiratory Exchange Ratio (RER), it is possible to determine which type of fuel is being utilized at any given time. It is found that the closer the RER is to 0.7, the greater the relative fat utilization. Contrariwise, the higher the intensity of exercise, the greater is the utilization of carbohydrates. By simultaneously monitoring the RER and the heart rate, it becomes possible to clearly identify the heart rate at which fat is the preferred fuel. It is commonly found that in unfit individuals, this is often at a surprisingly low level of work. In more fit individuals, fat will continue to be used as a fuel for longer periods. While exercise at an intense rate may cause a temporary weight loss due to a reduction in body water from sweating, an exercise program designed to maximize the elimination of fat should be based upon activities and exercise where the heart rate is confined to a zone corresponding to the average heart rate over an interval corresponding to a plateau of a fat metabolism curve.
Acorn et al. determined that for optimum cardiovascular improvement, exercise should be maintained in a zone such that the hear
Kaeferlein Bernhard H.
Snow Michael G.
Thieret Jeffrey G.
Hindenburg Max F.
Medical Graphics Corporation
Natnithithadha Navin
Nikolai Thomas J.
Nikolai & Mersereau , P.A.
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