Exercise testing and conditioning are done on treadmills, cycles, and arm ergometers. For all these testing modalities, there are metabolic equations that determine oxygen consumption and caloric expenditure. The equation for walking on a motor driven treadmill is .1 (m/min.) +( 1.8 x m/min. x % grade) + 3.5 with the result being in the units of ml/kg/min. The equation for running on a motor driven treadmill is .2(m/min.) +( .9 x m/min. x % grade) + 3.5. There is a horizontal, vertical, and resting component. The first part of the equation is the horizontal or speed. The grade is the vertical component with the first number representing the foot drag, the second is meters per minute, and last is percent grade. The foot drag decreases when someone runs because of the short flight component. Meters per minute is the product of 26.8 and mile per hour. A two-hundred-pound man walks at 3.6 mph at a ten percent grade for twenty-five minutes. Use the walking equation and multiply 26.8 by 3.6 mph for the conversion to meters per minute. In this example, it equals 96.48 m/min. The product of the meters per minute and .1 is 9.648 which is the horizontal component. The vertical component calculation is (1.8 x 96.48 x .10) which equals 17.37 ml/kg/min. The resting component is 3.5 ml/kg/min. When added, the total is 30.52 milliliters of oxygen per kilogram of bodyweight per unit of time or one minute. This is the measure of the amount of oxygen a person takes in and utilizes for the activity. In this case the man weighs two hundred pounds or 90.9 kilograms and exercised for twenty-five minutes to arrive at 69,357 milliliters of oxygen being utilized during this exercise bout. Divide this by one thousand to get 69.36 liters. The liters of oxygen us multiplied by five. The product is 346.78 calories burned.
Cycle and arm ergometers can also be used. To determine the workload on either is the product of revolutions per minute, flywheel travel, and kilograms of resistance. This calculation yields kilogram meters which is a unit of force. The metabolic equation for a cycle is 2(kgm) + 3.5 (bodyweight in kilograms). The equation for arm ergometry is 3 (kgm)+ 3.5 (kg). A two hundred pound or 90.9-kilogram man pedals at 60 rpm on a cycle with a 6-meter flywheel travel at a resistance of two and a half kilograms. Flywheel travel means if you turn the pedals one complete revolution, it takes you a certain distance. The workload is calculated at 900 kgm. This is doubled to yield 1800 which is added to the product of 3.5 and 90.9 kg. The total is 2118 ml/min. This person pedals for twenty minutes and takes in and utilizes 42360 milliliters of oxygen for the exercise. Again, this is converted to 42.36 liters and multiplied by five for a total of 212 calories burned.
Another mode of testing and conditioning is stepping. The stepping equation is (f x .2) + (f x ht. X 1.8 x 1.33) + 3.5. The letter “f” is stepping frequency. The ht. In the equation represents the step height in meters which is calculated by taking the height in inches and multiplying by.0254 to convert to meters. The following example will be for a one hundred eighty-pound subject stepping at a frequency of thirty steps per minute using a step height of eighteen inches for ten minutes. The bench height is converted to meters by multiplying eighteen by .0254 for a height of .46 meters. The equation with value is the following: (30 x.2) + (30 x .46 x1.8 x 1.33) + 3.5. The values of the components obtained are (6 + 33.04 + 3.5) which yields 42.5 ml/kg/min. The subject’s weight is converted to eighty-two kilograms by dividing one hundred eighty by 2.2 to arrive at this value. So, 42.5 ml/kg/min. Is multiplied by eighty-two kilograms and ten minutes to produce 34, 850 milliliters of oxygen consumed. This value is converted to 34.85 liters and multiplied by five to yield one hundred seventy-five calories burned.
The resting component as I mentioned earlier is the value 3.5. At rest, people consume and utilize 3.5 ml/kg/min. or one MET. MET stand for metabolic equivalent to oxygen consumption. METs can be used to gauge exercise intensity for clients or patients as related to activities. A cardiac rehab patient asks “Do you think it is safe for me to go deer hunting this weekend?” His Met levels are higher than the values to go hunting if he doesn’t drag the carcass. You tell him this and he is very happy that he can go hunting with his son and can be almost certain he will have no difficulties. There is a MET table for activities from a to z in ACSM Guidelines for Exercise Testing and Prescription that may be used to determine appropriate exercise intensity levels for patients and clients. Please visit tpnbodyperfect.com and check out our blog.