Using heart rate to determine exercise intensity, which relationship BEST supports this approach?

• A. Negative linear relationship with age
• B. Positive linear relationship with age
• C. Positive linear relationship with oxygen consumption
• D. Negative linear relationship with oxygen consumption

Answer: (C)

Using heart rate to set exercise intensity relies on how the body's oxygen demand drives the cardiovascular response. When muscles work harder, they require more oxygen, so oxygen consumption (VO2) rises. In submaximal exercise, heart rate increases in a positive, roughly linear way with the rise in VO2. This means as VO2 goes up, heart rate goes up proportionally, making heart rate a practical proxy for intensity. Therefore, the relationship that best supports this approach is a positive linear relationship with oxygen consumption. Relationships with age don’t reflect the real-time metabolic demand of a workout, and a negative link with oxygen consumption would misrepresent the body's response to increasing effort.