## Intensity of Exercise

Intensity can be estimated using the following measures:

### Target Heart Rate Zone

Measuring increases in heart rate during a workout is a quick and easy method to gauge the intensity of your workout. To measure your heart rate follow the instructions in Figure 5-1.

Figure 5-1. Measuring Heart Rate at the Wrist

♦ Count the beats for 10 seconds.

♦ Multiply this number by 6 to get your heart rate in beats per minute (bpm).

Once you measure your exercising heart rate how do you know whether you are exercising at the appropriate intensity? Depending on your age and fitness level there is a target heart rate zone that is appropriate for your exercise intensity. Use Figure 5-2 or Worksheet 5-1 to find your target heart rate zone.

See "Training Design and Progression" on page 33 to determine what heart rates, within this range, you should aim for during exercise based on your level of physical fitness and your fitness goals.

Figure 5-2. Target Heart Rate Zones

 200-1 a 180- a £ 160- 0) 140- 120- a

Target Heart Rate Zone

Target Heart Rate Zone

Age (years)

Note: Max HR is lower during swimming and arm exercises. For these activities, subtract 13 from Max HR before calculating your target training zone.

90% max HR

60% max HR

Age (years)

Note: Max HR is lower during swimming and arm exercises. For these activities, subtract 13 from Max HR before calculating your target training zone.

Worksheet 5-1. Determine Your Target Heart Rate

Target HR Zone =_to_bpm.

### Calories

Most exercise machines display "Calories" during an exercise session and the term is very familiar to most people. Calories per hour is the amount of energy you use when maintaining the same exercise intensity for an hour.

### Perceived Exertion

Ratings of Perceived Exertion, or RPE, are the subjective measures of exercise intensity perceived by the exerciser. Measurements are based on a twenty-point scale, "6" is no exertion and "20" is maximal exertion. Most people should workout at a perceived exertion of 12 to 15 (moderate to hard).

### Other Measures of Exercise Intensity

METs and Watts are two other measures of exercise intensity that are often calculated on exercise machines. A MET (metabolic equivalent) describes the amount of energy needed to perform an activity. Rest requires 1 MET, so exercising at 5 METs requires 5 times the energy needed at rest. A Watt is the amount of work (kcal) performed in a given time period. Therefore, the greater the watts (kcal/min), the higher the exercise intensity.