A patient must exercise a MET level of 8. What grade is needed if the speed is 3 mph?

To determine the grade needed to achieve a MET level of 8 while exercising at a speed of 3 mph, we first need to understand the concept of MET (Metabolic Equivalent of Task) levels and how they are influenced by speed and grade.

1. MET Levels: MET levels are used to measure the intensity of physical activities and are expressed as multiples of a person's resting metabolic rate. For example, a MET level of 1 is equivalent to the resting metabolic rate, meaning the energy expenditure while at rest. Higher MET levels indicate higher levels of exertion during physical activity.

2. Grade: Grade refers to the inclination or slope of the surface on which the exercise is being performed. It is usually expressed as a percentage or as an angle of inclination. On a flat surface, there is no grade (0% grade).

To determine the grade needed to achieve a desired MET level:

Step 1: Find the MET level corresponding to a particular activity.

Different activities have different MET levels associated with them. You'll need to consult a reputable source or exercise physiology literature to determine the specific MET level for exercising at a certain speed. For example, brisk walking at 3 mph has a MET level of approximately 3.6.

Step 2: Determine the increase in MET level per unit of grade.

The increase in MET level per unit of grade may vary depending on the activity. In general, each 1% increase in grade adds approximately 0.1 MET to the overall MET level. This means that an incline of 1% will increase the MET level by 0.1.

Step 3: Calculate the grade needed for the desired MET level.

In the given scenario, the desired MET level is 8, and the MET level for walking at 3 mph is approximately 3.6. We need to determine the additional grade necessary to increase the MET level from 3.6 to 8.

(MET level required - MET level of the activity) / MET increase per unit of grade = Grade needed

(8 - 3.6) / 0.1 = 44

So, a grade of approximately 44% is needed to achieve a MET level of 8 while exercising at a speed of 3 mph.