Foot temperature in healthy individuals: effects of ambient temperature and age.

Background: Patient complaints of excessively warm or cold feet are common in medical practice. Such symptoms can be caused by underlying vascular or neurologic disease, and measurement of foot temperature during daily activity and sleep could provide a deeper understanding of their actual thermal basis.

Methods: We used a Thermochron iButton to assess surface foot temperature variation and its relationship to ambient temperature during the day with activity and at night during sleep in 39 healthy individuals aged 18 to 65 years in a temperate region of the United States. We simultaneously used actigraphy to record leg movement.

Results: We identified a mean +/- SD awake temperature of 30.6 degrees +/- 2.6 degrees C and asleep temperature of 34.0 degrees +/- 1.8 degrees C, with values reaching as low as 15.9 degrees C in the winter and as high as 37.5 degrees C in the summer. Foot temperature was found to be independent of foot movement or sex; however, there was, as expected, a strong association between foot temperature and ambient temperature (r = .59, P < .001). Several measures of foot temperature variation demonstrated a significant or near-significant reduction with increasing age, including the Euclidean distance (r = -.38, P = .02) for awake periods and the variance (r = -.30, P = .06) during sleep.

Conclusions: These results provide data on the normal variation of foot temperature in individuals living in a temperate climate and demonstrate the potential use of Thermochron iButton technology in clinical contexts, including the evaluation of patients with excessively warm or cold feet.