For low cardiorespiratory fitness, which intervention is most appropriate?

Aerobic activity is the most appropriate intervention for improving low cardiorespiratory fitness because it specifically targets the cardiovascular and respiratory systems. Engaging in aerobic exercise, such as walking, running, cycling, or swimming, elevates the heart rate and promotes efficient oxygen delivery throughout the body. This type of training enhances the heart's ability to pump blood, strengthens the lungs, and improves overall stamina and endurance.

On the other hand, resistance training primarily focuses on building muscle strength and may not provide the same level of cardiovascular challenge necessary for improving cardiorespiratory fitness. Stretching routines are beneficial for flexibility and preventing injury but do not significantly impact cardiovascular health. A high-kilojoule diet is generally not associated with improving fitness levels and instead may lead to weight gain if not paired with appropriate physical activity. Therefore, incorporating regular aerobic activity is essential for those looking to enhance their cardiorespiratory fitness effectively.