A nurse is providing instruction about measuring the intensity of physical activity to a client who recently started an exercise program. The nurse should include that which of the following intensity levels is an indicator of an effective aerobic workout?

A. On the 0–10 Borg Rating of Perceived Exertion scale, a level of 5 corresponds to “strong” exertion. While it may indicate moderate-to-vigorous activity for some individuals, perceived exertion is subjective and should be interpreted in context. Effective aerobic exercise is better gauged by heart rate or ability to talk during activity. B. Target heart rate for aerobic exercise is generally 50–85% of the client’s maximum heart rate. A 10% increase above maximum would exceed safe limits and is not recommended; it could be unsafe and indicate overexertion. C. This describes the “talk test”, a practical method to measure aerobic exercise intensity. Moderate-intensity exercise allows the client to talk but not sing comfortably, while vigorous exercise may make conversation difficult. Labored but manageable breathing indicates that the client is exercising at an effective aerobic level without overexertion.