Physical activity assessment in population surveys: can it really be simplified?

Area of Science:

• Epidemiology
• Public Health
• Physical Activity Assessment

Background:

• Leisure-time physical activity assessment often uses simplified methods like exercise-induced sweating frequency.
• This study compares sweating frequency with a more detailed physical activity measure.

Purpose of the Study:

• To evaluate the agreement between exercise-induced sweating frequency and detailed physical activity assessment in adults.
• To identify factors influencing the agreement between these two physical activity measures.

Main Methods:

• A sample of 4171 adults from the Health Interview Survey of Barcelona (1992) was analyzed.
• Physical activity was categorized by intensity and duration (> or =20 min) and by sweating frequency (0, 1-2, > or =3 times/week).
• Agreement was assessed using weighted Kappa (Kw) statistic with 95% confidence intervals, with stratified analyses by age, gender, and month.

Main Results:

• Prevalence of physical activity (>=3 times/week) was lower with the sweat question (12.5%) than with detailed activity questions (19.6%).
• Agreement varied by demographics and season, being lower in older adults and higher in males (Kw=0.59) than females (Kw=0.48).
• Higher agreement was observed in hotter months (Kw=0.72 for males, 0.58 for females).

Conclusions:

• The exercise-induced sweating method for assessing physical activity may be influenced by factors beyond exercise intensity.
• Further validation studies in diverse populations are recommended to assess the reliability of exercise-induced sweating as a physical activity indicator.