Final answer:
The 'gold standard' for measuring physical activity includes direct heart rate monitoring and perception-based scales like the RPE. The 2018 Physical Activity Guidelines also offer specific recommendations for exercise intensity and frequency for health benefits.
Step-by-step explanation:
The "gold standard" in measuring the physical activity of individuals is often seen as the use of objective measurements like heart rate monitors or accelerometers, but perception-based scales like the Rating of Perceived Exertion (RPE) are also highly valuable. The RPE scale provides an individualized assessment of exercise intensity, which can be more informative in some cases, especially if medical issues like medication effects need to be considered.
Additionally, the 2018 Physical Activity Guidelines provide evidence-based recommendations for physical activity, taking into account not only the duration and frequency of activities but also their intensity levels. Adults, for example, are recommended to engage in at least 150 minutes of moderate-intensity aerobic activity or 75 minutes of vigorous-intensity activity per week, along with muscle-strengthening activities on two or more days per week.