An accelerometer-based earpiece to monitor and quantify physical activity

J Phys Act Health. 2009 Nov;6(6):781-9. doi: 10.1123/jpah.6.6.781.


Background: Physical activity is important in ill-health. Inexpensive, accurate and precise devices could help assess daily activity. We integrated novel activity-sensing technology into an earpiece used with portable music-players and phones; the physical-activity-sensing earpiece (PASE). Here we examined whether the PASE could accurately and precisely detect physical activity and measure its intensity and thence predict energy expenditure.

Methods: Experiment 1: 18 subjects wore PASE with different body postures and during graded walking. Energy expenditure was measured using indirect calorimetry. Experiment 2: 8 subjects wore the earpiece and walked a known distance. Experiment 3: 8 subjects wore the earpiece and 'jogged' at 3.5 mph.

Results: The earpiece correctly distinguished lying from sitting/standing and distinguished standing still from walking (76/76 cases). PASE output showed excellent sequential increases with increased in walking velocity and energy expenditure (r2 > .9). The PASE prediction of free-living walking velocity was, 2.5 +/- (SD) 0.18 mph c.f. actual velocity, 2.5 +/- 0.16 mph. The earpiece successfully distinguished walking at 3.5 mph from 'jogging' at the same velocity (P < .001).

Conclusions: The subjects tolerated the earpiece well and were comfortable wearing it. The PASE can therefore be used to reliably monitor free-living physical activity and its associated energy expenditure.

Publication types

  • Evaluation Study
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Body Mass Index
  • Calorimetry, Indirect / instrumentation*
  • Ear
  • Energy Metabolism / physiology*
  • Equipment Design
  • Female
  • Humans
  • Male
  • Monitoring, Physiologic / instrumentation*
  • Motor Activity / physiology*
  • Reproducibility of Results
  • Thermogenesis / physiology
  • Young Adult