Glossary of additional terms

Below are some terms you may come across while using the app:

• accelerometer: an instrument for measuring acceleration or for detecting and measuring vibrations*
• aerobic: occurring only in the presence of oxygen
• anaerobic: occurring, or existing, in the absence of free oxygen
• body fat percentage (BFP): fat mass expressed as a percentage of total body mass
• body mass index (BMI): a measure of body fat that is the ratio of the weight of the body in kilograms to the square of its height in meters*
• cardiac: pertaining to the heart**
• cardiorespiratory: of or relating to the heart and the respiratory system*
• cardiovascular: relating to the heart and the blood vessels or the circulation**
  
• heart rate:
  • heart rate reserve: the difference, expressed in beats per minute, between your resting heart rate and your maximum heart rate
  • maximum heart rate (age-related): the age-related number of beats per minute of the heart when working at its maximum*
    
• kilocalorie (kcal): a measuring unit of energy, often used interchangeably with “calorie”
  
• mass:
  • fat mass: the portion of the human body that is composed strictly of fat***
  • lean body mass: body mass, primarily of muscle and bone, devoid of storage fat, also known as fat-free mass***
• percentile: a measure used in statistics indicating the value below which a given percentage of observations in a group of observations fall (for example, the 20th percentile is the value (or score) below which 20% of the observations may be found)ˣ
• PPG: photoplethysmography, a simple and low-cost optical technique that can be used to detect blood volume changes - often used non-invasively to make measurements at the skin surface⁺
  
• proprioception: a sense or perception, usually at a subconscious level, of the movements and position of the body and especially its limbs, independent of vision**
  
• RR intervals: typically refers to the intervals between successive pulse peaks in an electrocardiogram (ECG)
  
  

A note on RR intervals and PPG used by LifeQ

LifeQ uses a PPG sensor instead of a traditional ECG. Therefore, in this context, RR intervals really refer to time delay between successive pulse peaks in the PPG signal.

See the image below:

Image: JMIR Publications (https://mhealth.jmir.org/2017/8/e129/)

Additional sources

*Merriam-Webster Online Dictionary (www.merriam-webster.com)

**MediLexicon (www.medilexicon.com)

***Medical Dictionary for the Health Professions and Nursing (2012)

⁺PubMed (www.ncbi.nlm.nih.gov/pubmed/17322588) 

ˣWikipedia (http://bit.ly/2Gg5Jv0)