Individuals underestimate moderate and vigorous intensity physical activity

Area of Science:

• Exercise Physiology
• Public Health Guidelines
• Biomedical Research

Background:

• Physical activity (PA) intensity descriptors in global guidelines lack consistent alignment with heart rate maximum (%HRmax) targets.
• Discrepancies may exist across sex, ethnicity, age, and body mass index (BMI) classifications.

Purpose of the Study:

• To assess if individuals can accurately select light, moderate, and vigorous PA intensities based on guideline descriptions.
• To identify variations in intensity perception across demographic groups (sex, ethnicity, age, BMI).

Main Methods:

• 129 adults randomly performed walking/jogging at "light," "moderate," and "vigorous" efforts.
• PA intensity was objectively measured using %HRmax ranges: light (50-63%), moderate (64-76%), vigorous (77-93%).

Main Results:

• Participants underestimated moderate (58.7±10.7%HRmax) and vigorous (69.9±11.9%HRmax) efforts, despite correctly estimating light effort (51.5±8.3%HRmax).
• When aiming for health benefits, most participants exerted light intensity (57.4±10.5%HRmax), with only 5% reaching vigorous intensity.
• No significant differences were observed based on sex, ethnicity, or BMI; however, younger adults showed greater underestimation of moderate and vigorous intensities.

Conclusions:

• Current PA intensity descriptors in guidelines are insufficient for accurate self-regulation of exercise intensity to achieve health benefits.
• Revised, clearer subjective descriptions for moderate and vigorous PA intensities are needed to improve public understanding and adherence.